Refactor FunctionCx::codgen_terminator

 - Move closures defined in codegen_terminator into a separate helper
   structure and implementation.
 - Create helper functions for each of the complex match arms on the
   terminators kind in codegen_terminator.

1 files changed, 771 insertions, 671 deletions

diff --git a/src/librustc_codegen_ssa/mir/block.rs b/src/librustc_codegen_ssa/mir/block.rs
index f40aa0cb6d1..684dfac991b 100644
--- a/src/librustc_codegen_ssa/mir/block.rs
+++ b/src/librustc_codegen_ssa/mir/block.rs
@@ -13,6 +13,8 @@ use crate::meth;
 
 use crate::traits::*;
 
+use std::borrow::Cow;
+
 use syntax::symbol::Symbol;
 use syntax_pos::Pos;
 
@@ -21,764 +23,862 @@ use super::place::PlaceRef;
 use super::operand::{OperandValue, OperandRef};
 use super::operand::OperandValue::{Pair, Ref, Immediate};
 
-impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
-    pub fn codegen_block(
-        &mut self,
-        bb: mir::BasicBlock,
-    ) {
-        let mut bx = self.build_block(bb);
-        let data = &self.mir[bb];
+/// Used by `FunctionCx::codegen_terminator` for emitting common patterns
+/// e.g., creating a basic block, calling a function, etc.
+struct TerminatorCodegenHelper<'a, 'tcx> {
+    bb: &'a mir::BasicBlock,
+    terminator: &'a mir::Terminator<'tcx>,
+    funclet_bb: Option<mir::BasicBlock>,
+}
 
-        debug!("codegen_block({:?}={:?})", bb, data);
+impl<'a, 'tcx> TerminatorCodegenHelper<'a, 'tcx> {
+    /// Returns the associated funclet from `FunctionCx::funclets` for the
+    /// `funclet_bb` member if it is not `None`.
+    fn funclet<'c, 'b, Bx: BuilderMethods<'b, 'tcx>>(
+        &self,
+        fx: &'c mut FunctionCx<'b, 'tcx, Bx>,
+    ) -> Option<&'c Bx::Funclet> {
+        match self.funclet_bb {
+            Some(funcl) => fx.funclets[funcl].as_ref(),
+            None => None,
+        }
+    }
 
-        for statement in &data.statements {
-            bx = self.codegen_statement(bx, statement);
+    fn lltarget<'b, 'c, Bx: BuilderMethods<'b, 'tcx>>(
+        &self,
+        fx: &'c mut FunctionCx<'b, 'tcx, Bx>,
+        target: mir::BasicBlock,
+    ) -> (Bx::BasicBlock, bool) {
+        let span = self.terminator.source_info.span;
+        let lltarget = fx.blocks[target];
+        let target_funclet = fx.cleanup_kinds[target].funclet_bb(target);
+        match (self.funclet_bb, target_funclet) {
+            (None, None) => (lltarget, false),
+            (Some(f), Some(t_f)) if f == t_f || !base::wants_msvc_seh(fx.cx.tcx().sess) =>
+                (lltarget, false),
+            // jump *into* cleanup - need a landing pad if GNU
+            (None, Some(_)) => (fx.landing_pad_to(target), false),
+            (Some(_), None) => span_bug!(span, "{:?} - jump out of cleanup?", self.terminator),
+            (Some(_), Some(_)) => (fx.landing_pad_to(target), true),
         }
+    }
 
-        self.codegen_terminator(bx, bb, data.terminator());
+    /// Create a basic block.
+    fn llblock<'c, 'b, Bx: BuilderMethods<'b, 'tcx>>(
+        &self,
+        fx: &'c mut FunctionCx<'b, 'tcx, Bx>,
+        target: mir::BasicBlock,
+    ) -> Bx::BasicBlock {
+        let (lltarget, is_cleanupret) = self.lltarget(fx, target);
+        if is_cleanupret {
+            // MSVC cross-funclet jump - need a trampoline
+
+            debug!("llblock: creating cleanup trampoline for {:?}", target);
+            let name = &format!("{:?}_cleanup_trampoline_{:?}", self.bb, target);
+            let mut trampoline = fx.new_block(name);
+            trampoline.cleanup_ret(self.funclet(fx).unwrap(),
+                                   Some(lltarget));
+            trampoline.llbb()
+        } else {
+            lltarget
+        }
     }
 
-    fn codegen_terminator(
-        &mut self,
-        mut bx: Bx,
-        bb: mir::BasicBlock,
-        terminator: &mir::Terminator<'tcx>
+    fn funclet_br<'c, 'b, Bx: BuilderMethods<'b, 'tcx>>(
+        &self,
+        fx: &'c mut FunctionCx<'b, 'tcx, Bx>,
+        bx: &mut Bx,
+        target: mir::BasicBlock,
     ) {
-        debug!("codegen_terminator: {:?}", terminator);
-
-        // Create the cleanup bundle, if needed.
-        let tcx = self.cx.tcx();
-        let span = terminator.source_info.span;
-        let funclet_bb = self.cleanup_kinds[bb].funclet_bb(bb);
+        let (lltarget, is_cleanupret) = self.lltarget(fx, target);
+        if is_cleanupret {
+            // micro-optimization: generate a `ret` rather than a jump
+            // to a trampoline.
+            bx.cleanup_ret(self.funclet(fx).unwrap(), Some(lltarget));
+        } else {
+            bx.br(lltarget);
+        }
+    }
 
-        // HACK(eddyb) force the right lifetimes, NLL can't figure them out.
-        fn funclet_closure_factory<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>>(
-            funclet_bb: Option<mir::BasicBlock>
-        ) -> impl for<'b> Fn(
-            &'b FunctionCx<'a, 'tcx, Bx>,
-        ) -> Option<&'b Bx::Funclet> {
-            move |this| {
-                match funclet_bb {
-                    Some(funclet_bb) => this.funclets[funclet_bb].as_ref(),
-                    None => None,
-                }
+    /// Call `fn_ptr` of `fn_ty` with the arguments `llargs`, the optional
+    /// return destination `destination` and the cleanup function `cleanup`.
+    fn do_call<'c, 'b, Bx: BuilderMethods<'b, 'tcx>>(
+        &self,
+        fx: &'c mut FunctionCx<'b, 'tcx, Bx>,
+        bx: &mut Bx,
+        fn_ty: FnType<'tcx, Ty<'tcx>>,
+        fn_ptr: Bx::Value,
+        llargs: &[Bx::Value],
+        destination: Option<(ReturnDest<'tcx, Bx::Value>, mir::BasicBlock)>,
+        cleanup: Option<mir::BasicBlock>,
+    ) {
+        if let Some(cleanup) = cleanup {
+            let ret_bx = if let Some((_, target)) = destination {
+                fx.blocks[target]
+            } else {
+                fx.unreachable_block()
+            };
+            let invokeret = bx.invoke(fn_ptr,
+                                      &llargs,
+                                      ret_bx,
+                                      self.llblock(fx, cleanup),
+                                      self.funclet(fx));
+            bx.apply_attrs_callsite(&fn_ty, invokeret);
+
+            if let Some((ret_dest, target)) = destination {
+                let mut ret_bx = fx.build_block(target);
+                fx.set_debug_loc(&mut ret_bx, self.terminator.source_info);
+                fx.store_return(&mut ret_bx, ret_dest, &fn_ty.ret, invokeret);
             }
-        }
-        let funclet = funclet_closure_factory(funclet_bb);
-
-        let lltarget = |this: &mut Self, target: mir::BasicBlock| {
-            let lltarget = this.blocks[target];
-            let target_funclet = this.cleanup_kinds[target].funclet_bb(target);
-            match (funclet_bb, target_funclet) {
-                (None, None) => (lltarget, false),
-                (Some(f), Some(t_f))
-                    if f == t_f || !base::wants_msvc_seh(tcx.sess)
-                    => (lltarget, false),
-                (None, Some(_)) => {
-                    // jump *into* cleanup - need a landing pad if GNU
-                    (this.landing_pad_to(target), false)
-                }
-                (Some(_), None) => span_bug!(span, "{:?} - jump out of cleanup?", terminator),
-                (Some(_), Some(_)) => {
-                    (this.landing_pad_to(target), true)
-                }
+        } else {
+            let llret = bx.call(fn_ptr, &llargs, self.funclet(fx));
+            bx.apply_attrs_callsite(&fn_ty, llret);
+            if fx.mir[*self.bb].is_cleanup {
+                // Cleanup is always the cold path. Don't inline
+                // drop glue. Also, when there is a deeply-nested
+                // struct, there are "symmetry" issues that cause
+                // exponential inlining - see issue #41696.
+                bx.do_not_inline(llret);
             }
-        };
-
-        let llblock = |this: &mut Self, target: mir::BasicBlock| {
-            let (lltarget, is_cleanupret) = lltarget(this, target);
-            if is_cleanupret {
-                // MSVC cross-funclet jump - need a trampoline
 
-                debug!("llblock: creating cleanup trampoline for {:?}", target);
-                let name = &format!("{:?}_cleanup_trampoline_{:?}", bb, target);
-                let mut trampoline = this.new_block(name);
-                trampoline.cleanup_ret(funclet(this).unwrap(), Some(lltarget));
-                trampoline.llbb()
+            if let Some((ret_dest, target)) = destination {
+                fx.store_return(bx, ret_dest, &fn_ty.ret, llret);
+                self.funclet_br(fx, bx, target);
             } else {
-                lltarget
+                bx.unreachable();
             }
-        };
-
-        let funclet_br =
-            |this: &mut Self, bx: &mut Bx, target: mir::BasicBlock| {
-                let (lltarget, is_cleanupret) = lltarget(this, target);
-                if is_cleanupret {
-                    // micro-optimization: generate a `ret` rather than a jump
-                    // to a trampoline.
-                    bx.cleanup_ret(funclet(this).unwrap(), Some(lltarget));
-                } else {
-                    bx.br(lltarget);
-                }
-            };
+        }
+    }
+}
 
-        let do_call = |
-            this: &mut Self,
-            bx: &mut Bx,
-            fn_ty: FnType<'tcx, Ty<'tcx>>,
-            fn_ptr: Bx::Value,
-            llargs: &[Bx::Value],
-            destination: Option<(ReturnDest<'tcx, Bx::Value>, mir::BasicBlock)>,
-            cleanup: Option<mir::BasicBlock>
-        | {
-            if let Some(cleanup) = cleanup {
-                let ret_bx = if let Some((_, target)) = destination {
-                    this.blocks[target]
-                } else {
-                    this.unreachable_block()
-                };
-                let invokeret = bx.invoke(fn_ptr,
-                                          &llargs,
-                                          ret_bx,
-                                          llblock(this, cleanup),
-                                          funclet(this));
-                bx.apply_attrs_callsite(&fn_ty, invokeret);
-
-                if let Some((ret_dest, target)) = destination {
-                    let mut ret_bx = this.build_block(target);
-                    this.set_debug_loc(&mut ret_bx, terminator.source_info);
-                    this.store_return(&mut ret_bx, ret_dest, &fn_ty.ret, invokeret);
-                }
+/// Codegen implementations for some terminator variants.
+impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
+    /// Generates code for a `Resume` terminator.
+    fn codegen_resume_terminator<'b>(
+        &mut self,
+        helper: TerminatorCodegenHelper<'b, 'tcx>,
+        mut bx: Bx,
+    ) {
+        if let Some(funclet) = helper.funclet(self) {
+            bx.cleanup_ret(funclet, None);
+        } else {
+            let slot = self.get_personality_slot(&mut bx);
+            let lp0 = slot.project_field(&mut bx, 0);
+            let lp0 = bx.load_operand(lp0).immediate();
+            let lp1 = slot.project_field(&mut bx, 1);
+            let lp1 = bx.load_operand(lp1).immediate();
+            slot.storage_dead(&mut bx);
+
+            if !bx.sess().target.target.options.custom_unwind_resume {
+                let mut lp = bx.const_undef(self.landing_pad_type());
+                lp = bx.insert_value(lp, lp0, 0);
+                lp = bx.insert_value(lp, lp1, 1);
+                bx.resume(lp);
             } else {
-                let llret = bx.call(fn_ptr, &llargs, funclet(this));
-                bx.apply_attrs_callsite(&fn_ty, llret);
-                if this.mir[bb].is_cleanup {
-                    // Cleanup is always the cold path. Don't inline
-                    // drop glue. Also, when there is a deeply-nested
-                    // struct, there are "symmetry" issues that cause
-                    // exponential inlining - see issue #41696.
-                    bx.do_not_inline(llret);
-                }
-
-                if let Some((ret_dest, target)) = destination {
-                    this.store_return(bx, ret_dest, &fn_ty.ret, llret);
-                    funclet_br(this, bx, target);
-                } else {
-                    bx.unreachable();
-                }
+                bx.call(bx.eh_unwind_resume(), &[lp0],
+                        helper.funclet(self));
+                bx.unreachable();
             }
-        };
+        }
+    }
 
-        self.set_debug_loc(&mut bx, terminator.source_info);
-        match terminator.kind {
-            mir::TerminatorKind::Resume => {
-                if let Some(funclet) = funclet(self) {
-                    bx.cleanup_ret(funclet, None);
+    fn codegen_switchint_terminator<'b>(
+        &mut self,
+        helper: TerminatorCodegenHelper<'b, 'tcx>,
+        mut bx: Bx,
+        discr: &mir::Operand<'tcx>,
+        switch_ty: Ty<'tcx>,
+        values: &Cow<'tcx, [u128]>,
+        targets: &Vec<mir::BasicBlock>,
+    ) {
+        let discr = self.codegen_operand(&mut bx, &discr);
+        if targets.len() == 2 {
+            // If there are two targets, emit br instead of switch
+            let lltrue = helper.llblock(self, targets[0]);
+            let llfalse = helper.llblock(self, targets[1]);
+            if switch_ty == bx.tcx().types.bool {
+                // Don't generate trivial icmps when switching on bool
+                if let [0] = values[..] {
+                    bx.cond_br(discr.immediate(), llfalse, lltrue);
                 } else {
-                    let slot = self.get_personality_slot(&mut bx);
-                    let lp0 = slot.project_field(&mut bx, 0);
-                    let lp0 = bx.load_operand(lp0).immediate();
-                    let lp1 = slot.project_field(&mut bx, 1);
-                    let lp1 = bx.load_operand(lp1).immediate();
-                    slot.storage_dead(&mut bx);
-
-                    if !bx.sess().target.target.options.custom_unwind_resume {
-                        let mut lp = bx.const_undef(self.landing_pad_type());
-                        lp = bx.insert_value(lp, lp0, 0);
-                        lp = bx.insert_value(lp, lp1, 1);
-                        bx.resume(lp);
-                    } else {
-                        bx.call(bx.eh_unwind_resume(), &[lp0], funclet(self));
-                        bx.unreachable();
-                    }
+                    assert_eq!(&values[..], &[1]);
+                    bx.cond_br(discr.immediate(), lltrue, llfalse);
                 }
+            } else {
+                let switch_llty = bx.immediate_backend_type(
+                    bx.layout_of(switch_ty)
+                );
+                let llval = bx.const_uint_big(switch_llty, values[0]);
+                let cmp = bx.icmp(IntPredicate::IntEQ, discr.immediate(), llval);
+                bx.cond_br(cmp, lltrue, llfalse);
+            }
+        } else {
+            let (otherwise, targets) = targets.split_last().unwrap();
+            let switch = bx.switch(discr.immediate(),
+                                   helper.llblock(self, *otherwise),
+                                   values.len());
+            let switch_llty = bx.immediate_backend_type(
+                bx.layout_of(switch_ty)
+            );
+            for (&value, target) in values.iter().zip(targets) {
+                let llval = bx.const_uint_big(switch_llty, value);
+                let llbb = helper.llblock(self, *target);
+                bx.add_case(switch, llval, llbb)
             }
+        }
+    }
 
-            mir::TerminatorKind::Abort => {
-                bx.abort();
-                bx.unreachable();
+    fn codegen_return_terminator<'b>(
+        &mut self,
+        mut bx: Bx,
+    ) {
+        if self.fn_ty.variadic {
+            if let Some(va_list) = self.va_list_ref {
+                bx.va_end(va_list.llval);
+            }
+        }
+        let llval = match self.fn_ty.ret.mode {
+            PassMode::Ignore(IgnoreMode::Zst) | PassMode::Indirect(..) => {
+                bx.ret_void();
+                return;
             }
 
-            mir::TerminatorKind::Goto { target } => {
-                funclet_br(self, &mut bx, target);
+            PassMode::Ignore(IgnoreMode::CVarArgs) => {
+                bug!("C-variadic arguments should never be the return type");
             }
 
-            mir::TerminatorKind::SwitchInt { ref discr, switch_ty, ref values, ref targets } => {
-                let discr = self.codegen_operand(&mut bx, discr);
-                if targets.len() == 2 {
-                    // If there are two targets, emit br instead of switch
-                    let lltrue = llblock(self, targets[0]);
-                    let llfalse = llblock(self, targets[1]);
-                    if switch_ty == bx.tcx().types.bool {
-                        // Don't generate trivial icmps when switching on bool
-                        if let [0] = values[..] {
-                            bx.cond_br(discr.immediate(), llfalse, lltrue);
-                        } else {
-                            assert_eq!(&values[..], &[1]);
-                            bx.cond_br(discr.immediate(), lltrue, llfalse);
-                        }
-                    } else {
-                        let switch_llty = bx.immediate_backend_type(
-                            bx.layout_of(switch_ty)
-                        );
-                        let llval = bx.const_uint_big(switch_llty, values[0]);
-                        let cmp = bx.icmp(IntPredicate::IntEQ, discr.immediate(), llval);
-                        bx.cond_br(cmp, lltrue, llfalse);
-                    }
+            PassMode::Direct(_) | PassMode::Pair(..) => {
+                let op =
+                    self.codegen_consume(&mut bx, &mir::Place::Local(mir::RETURN_PLACE));
+                if let Ref(llval, _, align) = op.val {
+                    bx.load(llval, align)
                 } else {
-                    let (otherwise, targets) = targets.split_last().unwrap();
-                    let switch = bx.switch(discr.immediate(),
-                                           llblock(self, *otherwise),
-                                           values.len());
-                    let switch_llty = bx.immediate_backend_type(
-                        bx.layout_of(switch_ty)
-                    );
-                    for (&value, target) in values.iter().zip(targets) {
-                        let llval = bx.const_uint_big(switch_llty, value);
-                        let llbb = llblock(self, *target);
-                        bx.add_case(switch, llval, llbb)
-                    }
+                    op.immediate_or_packed_pair(&mut bx)
                 }
             }
 
-            mir::TerminatorKind::Return => {
-                if self.fn_ty.variadic {
-                    if let Some(va_list) = self.va_list_ref {
-                        bx.va_end(va_list.llval);
+            PassMode::Cast(cast_ty) => {
+                let op = match self.locals[mir::RETURN_PLACE] {
+                    LocalRef::Operand(Some(op)) => op,
+                    LocalRef::Operand(None) => bug!("use of return before def"),
+                    LocalRef::Place(cg_place) => {
+                        OperandRef {
+                            val: Ref(cg_place.llval, None, cg_place.align),
+                            layout: cg_place.layout
+                        }
                     }
-                }
-                let llval = match self.fn_ty.ret.mode {
-                    PassMode::Ignore(IgnoreMode::Zst) | PassMode::Indirect(..) => {
-                        bx.ret_void();
-                        return;
+                    LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
+                };
+                let llslot = match op.val {
+                    Immediate(_) | Pair(..) => {
+                        let scratch =
+                            PlaceRef::alloca(&mut bx, self.fn_ty.ret.layout, "ret");
+                        op.val.store(&mut bx, scratch);
+                        scratch.llval
                     }
-
-                    PassMode::Ignore(IgnoreMode::CVarArgs) => {
-                        bug!("C variadic arguments should never be the return type");
+                    Ref(llval, _, align) => {
+                        assert_eq!(align, op.layout.align.abi,
+                                   "return place is unaligned!");
+                        llval
                     }
+                };
+                let addr = bx.pointercast(llslot, bx.type_ptr_to(
+                    bx.cast_backend_type(&cast_ty)
+                ));
+                bx.load(addr, self.fn_ty.ret.layout.align.abi)
+            }
+        };
+        bx.ret(llval);
+    }
 
-                    PassMode::Direct(_) | PassMode::Pair(..) => {
-                        let op =
-                            self.codegen_consume(&mut bx, &mir::Place::Local(mir::RETURN_PLACE));
-                        if let Ref(llval, _, align) = op.val {
-                            bx.load(llval, align)
-                        } else {
-                            op.immediate_or_packed_pair(&mut bx)
-                        }
-                    }
 
-                    PassMode::Cast(cast_ty) => {
-                        let op = match self.locals[mir::RETURN_PLACE] {
-                            LocalRef::Operand(Some(op)) => op,
-                            LocalRef::Operand(None) => bug!("use of return before def"),
-                            LocalRef::Place(cg_place) => {
-                                OperandRef {
-                                    val: Ref(cg_place.llval, None, cg_place.align),
-                                    layout: cg_place.layout
-                                }
-                            }
-                            LocalRef::UnsizedPlace(_) => bug!("return type must be sized"),
-                        };
-                        let llslot = match op.val {
-                            Immediate(_) | Pair(..) => {
-                                let scratch =
-                                    PlaceRef::alloca(&mut bx, self.fn_ty.ret.layout, "ret");
-                                op.val.store(&mut bx, scratch);
-                                scratch.llval
-                            }
-                            Ref(llval, _, align) => {
-                                assert_eq!(align, op.layout.align.abi,
-                                           "return place is unaligned!");
-                                llval
-                            }
-                        };
-                        let addr = bx.pointercast(llslot, bx.type_ptr_to(
-                            bx.cast_backend_type(&cast_ty)
-                        ));
-                        bx.load(addr, self.fn_ty.ret.layout.align.abi)
-                    }
-                };
-                bx.ret(llval);
+    fn codegen_drop_terminator<'b>(
+        &mut self,
+        helper: TerminatorCodegenHelper<'b, 'tcx>,
+        mut bx: Bx,
+        location: &mir::Place<'tcx>,
+        target: mir::BasicBlock,
+        unwind: Option<mir::BasicBlock>,
+    ) {
+        let ty = location.ty(self.mir, bx.tcx()).to_ty(bx.tcx());
+        let ty = self.monomorphize(&ty);
+        let drop_fn = monomorphize::resolve_drop_in_place(bx.tcx(), ty);
+
+        if let ty::InstanceDef::DropGlue(_, None) = drop_fn.def {
+            // we don't actually need to drop anything.
+            helper.funclet_br(self, &mut bx, target);
+            return
+        }
+
+        let place = self.codegen_place(&mut bx, location);
+        let (args1, args2);
+        let mut args = if let Some(llextra) = place.llextra {
+            args2 = [place.llval, llextra];
+            &args2[..]
+        } else {
+            args1 = [place.llval];
+            &args1[..]
+        };
+        let (drop_fn, fn_ty) = match ty.sty {
+            ty::Dynamic(..) => {
+                let sig = drop_fn.fn_sig(self.cx.tcx());
+                let sig = self.cx.tcx().normalize_erasing_late_bound_regions(
+                    ty::ParamEnv::reveal_all(),
+                    &sig,
+                );
+                let fn_ty = bx.new_vtable(sig, &[]);
+                let vtable = args[1];
+                args = &args[..1];
+                (meth::DESTRUCTOR.get_fn(&mut bx, vtable, &fn_ty), fn_ty)
             }
+            _ => {
+                (bx.get_fn(drop_fn),
+                 bx.fn_type_of_instance(&drop_fn))
+            }
+        };
+        helper.do_call(self, &mut bx, fn_ty, drop_fn, args,
+                       Some((ReturnDest::Nothing, target)),
+                       unwind);
+    }
 
-            mir::TerminatorKind::Unreachable => {
-                bx.unreachable();
+    fn codegen_assert_terminator<'b>(
+        &mut self,
+        helper: TerminatorCodegenHelper<'b, 'tcx>,
+        mut bx: Bx,
+        terminator: &mir::Terminator<'tcx>,
+        cond: &mir::Operand<'tcx>,
+        expected: bool,
+        msg: &mir::AssertMessage<'tcx>,
+        target: mir::BasicBlock,
+        cleanup: Option<mir::BasicBlock>,
+    ) {
+        let span = terminator.source_info.span;
+        let cond = self.codegen_operand(&mut bx, cond).immediate();
+        let mut const_cond = bx.const_to_opt_u128(cond, false).map(|c| c == 1);
+
+        // This case can currently arise only from functions marked
+        // with #[rustc_inherit_overflow_checks] and inlined from
+        // another crate (mostly core::num generic/#[inline] fns),
+        // while the current crate doesn't use overflow checks.
+        // NOTE: Unlike binops, negation doesn't have its own
+        // checked operation, just a comparison with the minimum
+        // value, so we have to check for the assert message.
+        if !bx.check_overflow() {
+            if let mir::interpret::EvalErrorKind::OverflowNeg = *msg {
+                const_cond = Some(expected);
             }
+        }
 
-            mir::TerminatorKind::Drop { ref location, target, unwind } => {
-                let ty = location.ty(self.mir, bx.tcx()).to_ty(bx.tcx());
-                let ty = self.monomorphize(&ty);
-                let drop_fn = monomorphize::resolve_drop_in_place(bx.tcx(), ty);
-
-                if let ty::InstanceDef::DropGlue(_, None) = drop_fn.def {
-                    // we don't actually need to drop anything.
-                    funclet_br(self, &mut bx, target);
-                    return
-                }
+        // Don't codegen the panic block if success if known.
+        if const_cond == Some(expected) {
+            helper.funclet_br(self, &mut bx, target);
+            return;
+        }
 
-                let place = self.codegen_place(&mut bx, location);
-                let (args1, args2);
-                let mut args = if let Some(llextra) = place.llextra {
-                    args2 = [place.llval, llextra];
-                    &args2[..]
-                } else {
-                    args1 = [place.llval];
-                    &args1[..]
-                };
-                let (drop_fn, fn_ty) = match ty.sty {
-                    ty::Dynamic(..) => {
-                        let sig = drop_fn.fn_sig(tcx);
-                        let sig = tcx.normalize_erasing_late_bound_regions(
-                            ty::ParamEnv::reveal_all(),
-                            &sig,
-                        );
-                        let fn_ty = bx.new_vtable(sig, &[]);
-                        let vtable = args[1];
-                        args = &args[..1];
-                        (meth::DESTRUCTOR.get_fn(&mut bx, vtable, &fn_ty), fn_ty)
-                    }
-                    _ => {
-                        (bx.get_fn(drop_fn),
-                         bx.fn_type_of_instance(&drop_fn))
-                    }
-                };
-                do_call(self, &mut bx, fn_ty, drop_fn, args,
-                        Some((ReturnDest::Nothing, target)),
-                        unwind);
+        // Pass the condition through llvm.expect for branch hinting.
+        let cond = bx.expect(cond, expected);
+
+        // Create the failure block and the conditional branch to it.
+        let lltarget = helper.llblock(self, target);
+        let panic_block = self.new_block("panic");
+        if expected {
+            bx.cond_br(cond, lltarget, panic_block.llbb());
+        } else {
+            bx.cond_br(cond, panic_block.llbb(), lltarget);
+        }
+
+        // After this point, bx is the block for the call to panic.
+        bx = panic_block;
+        self.set_debug_loc(&mut bx, terminator.source_info);
+
+        // Get the location information.
+        let loc = bx.sess().source_map().lookup_char_pos(span.lo());
+        let filename = Symbol::intern(&loc.file.name.to_string()).as_str();
+        let filename = bx.const_str_slice(filename);
+        let line = bx.const_u32(loc.line as u32);
+        let col = bx.const_u32(loc.col.to_usize() as u32 + 1);
+        let align = self.cx.tcx().data_layout.aggregate_align.abi
+            .max(self.cx.tcx().data_layout.i32_align.abi)
+            .max(self.cx.tcx().data_layout.pointer_align.abi);
+
+        // Put together the arguments to the panic entry point.
+        let (lang_item, args) = match *msg {
+            EvalErrorKind::BoundsCheck { ref len, ref index } => {
+                let len = self.codegen_operand(&mut bx, len).immediate();
+                let index = self.codegen_operand(&mut bx, index).immediate();
+
+                let file_line_col = bx.const_struct(&[filename, line, col], false);
+                let file_line_col = bx.static_addr_of(
+                    file_line_col,
+                    align,
+                    Some("panic_bounds_check_loc")
+                );
+                (lang_items::PanicBoundsCheckFnLangItem,
+                 vec![file_line_col, index, len])
             }
+            _ => {
+                let str = msg.description();
+                let msg_str = Symbol::intern(str).as_str();
+                let msg_str = bx.const_str_slice(msg_str);
+                let msg_file_line_col = bx.const_struct(
+                    &[msg_str, filename, line, col],
+                    false
+                );
+                let msg_file_line_col = bx.static_addr_of(
+                    msg_file_line_col,
+                    align,
+                    Some("panic_loc")
+                );
+                (lang_items::PanicFnLangItem,
+                 vec![msg_file_line_col])
+            }
+        };
 
-            mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, cleanup } => {
-                let cond = self.codegen_operand(&mut bx, cond).immediate();
-                let mut const_cond = bx.const_to_opt_u128(cond, false).map(|c| c == 1);
-
-                // This case can currently arise only from functions marked
-                // with #[rustc_inherit_overflow_checks] and inlined from
-                // another crate (mostly core::num generic/#[inline] fns),
-                // while the current crate doesn't use overflow checks.
-                // NOTE: Unlike binops, negation doesn't have its own
-                // checked operation, just a comparison with the minimum
-                // value, so we have to check for the assert message.
-                if !bx.check_overflow() {
-                    if let mir::interpret::EvalErrorKind::OverflowNeg = *msg {
-                        const_cond = Some(expected);
-                    }
-                }
+        // Obtain the panic entry point.
+        let def_id = common::langcall(bx.tcx(), Some(span), "", lang_item);
+        let instance = ty::Instance::mono(bx.tcx(), def_id);
+        let fn_ty = bx.fn_type_of_instance(&instance);
+        let llfn = bx.get_fn(instance);
 
-                // Don't codegen the panic block if success if known.
-                if const_cond == Some(expected) {
-                    funclet_br(self, &mut bx, target);
-                    return;
-                }
+        // Codegen the actual panic invoke/call.
+        helper.do_call(self, &mut bx, fn_ty, llfn, &args, None, cleanup);
+    }
 
-                // Pass the condition through llvm.expect for branch hinting.
-                let cond = bx.expect(cond, expected);
+    fn codegen_call_terminator<'b>(
+        &mut self,
+        helper: TerminatorCodegenHelper<'b, 'tcx>,
+        mut bx: Bx,
+        terminator: &mir::Terminator<'tcx>,
+        func: &mir::Operand<'tcx>,
+        args: &Vec<mir::Operand<'tcx>>,
+        destination: &Option<(mir::Place<'tcx>, mir::BasicBlock)>,
+        cleanup: Option<mir::BasicBlock>,
+    ) {
+        let span = terminator.source_info.span;
+        // Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
+        let callee = self.codegen_operand(&mut bx, func);
+
+        let (instance, mut llfn) = match callee.layout.ty.sty {
+            ty::FnDef(def_id, substs) => {
+                (Some(ty::Instance::resolve(bx.tcx(),
+                                            ty::ParamEnv::reveal_all(),
+                                            def_id,
+                                            substs).unwrap()),
+                 None)
+            }
+            ty::FnPtr(_) => {
+                (None, Some(callee.immediate()))
+            }
+            _ => bug!("{} is not callable", callee.layout.ty),
+        };
+        let def = instance.map(|i| i.def);
+        let sig = callee.layout.ty.fn_sig(bx.tcx());
+        let sig = bx.tcx().normalize_erasing_late_bound_regions(
+            ty::ParamEnv::reveal_all(),
+            &sig,
+        );
+        let abi = sig.abi;
+
+        // Handle intrinsics old codegen wants Expr's for, ourselves.
+        let intrinsic = match def {
+            Some(ty::InstanceDef::Intrinsic(def_id)) =>
+                Some(bx.tcx().item_name(def_id).as_str()),
+            _ => None
+        };
+        let intrinsic = intrinsic.as_ref().map(|s| &s[..]);
 
-                // Create the failure block and the conditional branch to it.
-                let lltarget = llblock(self, target);
-                let panic_block = self.new_block("panic");
-                if expected {
-                    bx.cond_br(cond, lltarget, panic_block.llbb());
-                } else {
-                    bx.cond_br(cond, panic_block.llbb(), lltarget);
-                }
+        if intrinsic == Some("transmute") {
+            if let Some(destination_ref) = destination.as_ref() {
+                let &(ref dest, target) = destination_ref;
+                self.codegen_transmute(&mut bx, &args[0], dest);
+                helper.funclet_br(self, &mut bx, target);
+            } else {
+                // If we are trying to transmute to an uninhabited type,
+                // it is likely there is no allotted destination. In fact,
+                // transmuting to an uninhabited type is UB, which means
+                // we can do what we like. Here, we declare that transmuting
+                // into an uninhabited type is impossible, so anything following
+                // it must be unreachable.
+                assert_eq!(bx.layout_of(sig.output()).abi, layout::Abi::Uninhabited);
+                bx.unreachable();
+            }
+            return;
+        }
 
-                // After this point, bx is the block for the call to panic.
-                bx = panic_block;
-                self.set_debug_loc(&mut bx, terminator.source_info);
+        // The "spoofed" `VaList` added to a C-variadic functions signature
+        // should not be included in the `extra_args` calculation.
+        let extra_args_start_idx = sig.inputs().len() - if sig.variadic { 1 } else { 0 };
+        let extra_args = &args[extra_args_start_idx..];
+        let extra_args = extra_args.iter().map(|op_arg| {
+            let op_ty = op_arg.ty(self.mir, bx.tcx());
+            self.monomorphize(&op_ty)
+        }).collect::<Vec<_>>();
+
+        let fn_ty = match def {
+            Some(ty::InstanceDef::Virtual(..)) => {
+                bx.new_vtable(sig, &extra_args)
+            }
+            Some(ty::InstanceDef::DropGlue(_, None)) => {
+                // Empty drop glue; a no-op.
+                let &(_, target) = destination.as_ref().unwrap();
+                helper.funclet_br(self, &mut bx, target);
+                return;
+            }
+            _ => bx.new_fn_type(sig, &extra_args)
+        };
 
-                // Get the location information.
+        // Emit a panic or a no-op for `panic_if_uninhabited`.
+        if intrinsic == Some("panic_if_uninhabited") {
+            let ty = instance.unwrap().substs.type_at(0);
+            let layout = bx.layout_of(ty);
+            if layout.abi.is_uninhabited() {
                 let loc = bx.sess().source_map().lookup_char_pos(span.lo());
                 let filename = Symbol::intern(&loc.file.name.to_string()).as_str();
                 let filename = bx.const_str_slice(filename);
                 let line = bx.const_u32(loc.line as u32);
                 let col = bx.const_u32(loc.col.to_usize() as u32 + 1);
-                let align = tcx.data_layout.aggregate_align.abi
-                    .max(tcx.data_layout.i32_align.abi)
-                    .max(tcx.data_layout.pointer_align.abi);
-
-                // Put together the arguments to the panic entry point.
-                let (lang_item, args) = match *msg {
-                    EvalErrorKind::BoundsCheck { ref len, ref index } => {
-                        let len = self.codegen_operand(&mut bx, len).immediate();
-                        let index = self.codegen_operand(&mut bx, index).immediate();
-
-                        let file_line_col = bx.const_struct(&[filename, line, col], false);
-                        let file_line_col = bx.static_addr_of(
-                            file_line_col,
-                            align,
-                            Some("panic_bounds_check_loc")
-                        );
-                        (lang_items::PanicBoundsCheckFnLangItem,
-                         vec![file_line_col, index, len])
-                    }
-                    _ => {
-                        let str = msg.description();
-                        let msg_str = Symbol::intern(str).as_str();
-                        let msg_str = bx.const_str_slice(msg_str);
-                        let msg_file_line_col = bx.const_struct(
-                            &[msg_str, filename, line, col],
-                            false
-                        );
-                        let msg_file_line_col = bx.static_addr_of(
-                            msg_file_line_col,
-                            align,
-                            Some("panic_loc")
-                        );
-                        (lang_items::PanicFnLangItem,
-                         vec![msg_file_line_col])
-                    }
-                };
+                let align = self.cx.tcx().data_layout.aggregate_align.abi
+                    .max(self.cx.tcx().data_layout.i32_align.abi)
+                    .max(self.cx.tcx().data_layout.pointer_align.abi);
+
+                let str = format!(
+                    "Attempted to instantiate uninhabited type {}",
+                    ty
+                );
+                let msg_str = Symbol::intern(&str).as_str();
+                let msg_str = bx.const_str_slice(msg_str);
+                let msg_file_line_col = bx.const_struct(
+                    &[msg_str, filename, line, col],
+                    false,
+                );
+                let msg_file_line_col = bx.static_addr_of(
+                    msg_file_line_col,
+                    align,
+                    Some("panic_loc"),
+                );
 
                 // Obtain the panic entry point.
-                let def_id = common::langcall(bx.tcx(), Some(span), "", lang_item);
+                let def_id =
+                    common::langcall(bx.tcx(), Some(span), "", lang_items::PanicFnLangItem);
                 let instance = ty::Instance::mono(bx.tcx(), def_id);
                 let fn_ty = bx.fn_type_of_instance(&instance);
                 let llfn = bx.get_fn(instance);
 
                 // Codegen the actual panic invoke/call.
-                do_call(self, &mut bx, fn_ty, llfn, &args, None, cleanup);
-            }
-
-            mir::TerminatorKind::DropAndReplace { .. } => {
-                bug!("undesugared DropAndReplace in codegen: {:?}", terminator);
+                helper.do_call(
+                    self,
+                    &mut bx,
+                    fn_ty,
+                    llfn,
+                    &[msg_file_line_col],
+                    destination.as_ref().map(|(_, bb)| (ReturnDest::Nothing, *bb)),
+                    cleanup,
+                );
+            } else {
+                // a NOP
+                helper.funclet_br(self, &mut bx, destination.as_ref().unwrap().1)
             }
+            return;
+        }
 
-            mir::TerminatorKind::Call {
-                ref func,
-                ref args,
-                ref destination,
-                cleanup,
-                from_hir_call: _
-            } => {
-                // Create the callee. This is a fn ptr or zero-sized and hence a kind of scalar.
-                let callee = self.codegen_operand(&mut bx, func);
-
-                let (instance, mut llfn) = match callee.layout.ty.sty {
-                    ty::FnDef(def_id, substs) => {
-                        (Some(ty::Instance::resolve(bx.tcx(),
-                                                    ty::ParamEnv::reveal_all(),
-                                                    def_id,
-                                                    substs).unwrap()),
-                         None)
-                    }
-                    ty::FnPtr(_) => {
-                        (None, Some(callee.immediate()))
-                    }
-                    _ => bug!("{} is not callable", callee.layout.ty)
-                };
-                let def = instance.map(|i| i.def);
-                let sig = callee.layout.ty.fn_sig(bx.tcx());
-                let sig = bx.tcx().normalize_erasing_late_bound_regions(
-                    ty::ParamEnv::reveal_all(),
-                    &sig,
-                );
-                let abi = sig.abi;
+        // The arguments we'll be passing. Plus one to account for outptr, if used.
+        let arg_count = fn_ty.args.len() + fn_ty.ret.is_indirect() as usize;
+        let mut llargs = Vec::with_capacity(arg_count);
 
-                // Handle intrinsics old codegen wants Expr's for, ourselves.
-                let intrinsic = match def {
-                    Some(ty::InstanceDef::Intrinsic(def_id))
-                        => Some(bx.tcx().item_name(def_id).as_str()),
-                    _ => None
-                };
-                let intrinsic = intrinsic.as_ref().map(|s| &s[..]);
+        // Prepare the return value destination
+        let ret_dest = if let Some((ref dest, _)) = *destination {
+            let is_intrinsic = intrinsic.is_some();
+            self.make_return_dest(&mut bx, dest, &fn_ty.ret, &mut llargs,
+                                  is_intrinsic)
+        } else {
+            ReturnDest::Nothing
+        };
 
-                if intrinsic == Some("transmute") {
-                    if let Some(destination_ref) = destination.as_ref() {
-                        let &(ref dest, target) = destination_ref;
-                        self.codegen_transmute(&mut bx, &args[0], dest);
-                        funclet_br(self, &mut bx, target);
-                    } else {
-                        // If we are trying to transmute to an uninhabited type,
-                        // it is likely there is no allotted destination. In fact,
-                        // transmuting to an uninhabited type is UB, which means
-                        // we can do what we like. Here, we declare that transmuting
-                        // into an uninhabited type is impossible, so anything following
-                        // it must be unreachable.
-                        assert_eq!(bx.layout_of(sig.output()).abi, layout::Abi::Uninhabited);
-                        bx.unreachable();
-                    }
-                    return;
-                }
+        if intrinsic.is_some() && intrinsic != Some("drop_in_place") {
+            let dest = match ret_dest {
+                _ if fn_ty.ret.is_indirect() => llargs[0],
+                ReturnDest::Nothing =>
+                    bx.const_undef(bx.type_ptr_to(bx.memory_ty(&fn_ty.ret))),
+                ReturnDest::IndirectOperand(dst, _) | ReturnDest::Store(dst) =>
+                    dst.llval,
+                ReturnDest::DirectOperand(_) =>
+                    bug!("Cannot use direct operand with an intrinsic call"),
+            };
 
-                // The "spoofed" `VaList` added to a C-variadic functions signature
-                // should not be included in the `extra_args` calculation.
-                let extra_args_start_idx = sig.inputs().len() - if sig.variadic { 1 } else { 0 };
-                let extra_args = &args[extra_args_start_idx..];
-                let extra_args = extra_args.iter().map(|op_arg| {
-                    let op_ty = op_arg.ty(self.mir, bx.tcx());
-                    self.monomorphize(&op_ty)
-                }).collect::<Vec<_>>();
-
-                let fn_ty = match def {
-                    Some(ty::InstanceDef::Virtual(..)) => {
-                        bx.new_vtable(sig, &extra_args)
-                    }
-                    Some(ty::InstanceDef::DropGlue(_, None)) => {
-                        // empty drop glue - a nop.
-                        let &(_, target) = destination.as_ref().unwrap();
-                        funclet_br(self, &mut bx, target);
-                        return;
-                    }
-                    _ => bx.new_fn_type(sig, &extra_args)
-                };
+            let args: Vec<_> = args.iter().enumerate().map(|(i, arg)| {
+                // The indices passed to simd_shuffle* in the
+                // third argument must be constant. This is
+                // checked by const-qualification, which also
+                // promotes any complex rvalues to constants.
+                if i == 2 && intrinsic.unwrap().starts_with("simd_shuffle") {
+                    match *arg {
+                        // The shuffle array argument is usually not an explicit constant,
+                        // but specified directly in the code. This means it gets promoted
+                        // and we can then extract the value by evaluating the promoted.
+                        mir::Operand::Copy(mir::Place::Promoted(box(index, ty))) |
+                        mir::Operand::Move(mir::Place::Promoted(box(index, ty))) => {
+                            let param_env = ty::ParamEnv::reveal_all();
+                            let cid = mir::interpret::GlobalId {
+                                instance: self.instance,
+                                promoted: Some(index),
+                            };
+                            let c = bx.tcx().const_eval(param_env.and(cid));
+                            let (llval, ty) = self.simd_shuffle_indices(
+                                &bx,
+                                terminator.source_info.span,
+                                ty,
+                                c,
+                            );
+                            return OperandRef {
+                                val: Immediate(llval),
+                                layout: bx.layout_of(ty),
+                            };
 
-                // emit a panic or a NOP for `panic_if_uninhabited`
-                if intrinsic == Some("panic_if_uninhabited") {
-                    let ty = instance.unwrap().substs.type_at(0);
-                    let layout = bx.layout_of(ty);
-                    if layout.abi.is_uninhabited() {
-                        let loc = bx.sess().source_map().lookup_char_pos(span.lo());
-                        let filename = Symbol::intern(&loc.file.name.to_string()).as_str();
-                        let filename = bx.const_str_slice(filename);
-                        let line = bx.const_u32(loc.line as u32);
-                        let col = bx.const_u32(loc.col.to_usize() as u32 + 1);
-                        let align = tcx.data_layout.aggregate_align.abi
-                            .max(tcx.data_layout.i32_align.abi)
-                            .max(tcx.data_layout.pointer_align.abi);
-
-                        let str = format!(
-                            "Attempted to instantiate uninhabited type {}",
-                            ty
-                        );
-                        let msg_str = Symbol::intern(&str).as_str();
-                        let msg_str = bx.const_str_slice(msg_str);
-                        let msg_file_line_col = bx.const_struct(
-                            &[msg_str, filename, line, col],
-                            false,
-                        );
-                        let msg_file_line_col = bx.static_addr_of(
-                            msg_file_line_col,
-                            align,
-                            Some("panic_loc"),
-                        );
-
-                        // Obtain the panic entry point.
-                        let def_id =
-                            common::langcall(bx.tcx(), Some(span), "", lang_items::PanicFnLangItem);
-                        let instance = ty::Instance::mono(bx.tcx(), def_id);
-                        let fn_ty = bx.fn_type_of_instance(&instance);
-                        let llfn = bx.get_fn(instance);
-
-                        // Codegen the actual panic invoke/call.
-                        do_call(
-                            self,
-                            &mut bx,
-                            fn_ty,
-                            llfn,
-                            &[msg_file_line_col],
-                            destination.as_ref().map(|(_, bb)| (ReturnDest::Nothing, *bb)),
-                            cleanup,
-                        );
-                    } else {
-                        // a NOP
-                        funclet_br(self, &mut bx, destination.as_ref().unwrap().1);
+                        }
+                        mir::Operand::Copy(_) |
+                        mir::Operand::Move(_) => {
+                            span_bug!(span, "shuffle indices must be constant");
+                        }
+                        mir::Operand::Constant(ref constant) => {
+                            let c = self.eval_mir_constant(&bx, constant);
+                            let (llval, ty) = self.simd_shuffle_indices(
+                                &bx,
+                                constant.span,
+                                constant.ty,
+                                c,
+                            );
+                            return OperandRef {
+                                val: Immediate(llval),
+                                layout: bx.layout_of(ty)
+                            };
+                        }
                     }
-                    return;
                 }
 
-                // The arguments we'll be passing. Plus one to account for outptr, if used.
-                let arg_count = fn_ty.args.len() + fn_ty.ret.is_indirect() as usize;
-                let mut llargs = Vec::with_capacity(arg_count);
-
-                // Prepare the return value destination
-                let ret_dest = if let Some((ref dest, _)) = *destination {
-                    let is_intrinsic = intrinsic.is_some();
-                    self.make_return_dest(&mut bx, dest, &fn_ty.ret, &mut llargs,
-                                          is_intrinsic)
-                } else {
-                    ReturnDest::Nothing
-                };
-
-                if intrinsic.is_some() && intrinsic != Some("drop_in_place") {
-                    let dest = match ret_dest {
-                        _ if fn_ty.ret.is_indirect() => llargs[0],
-                        ReturnDest::Nothing => {
-                            bx.const_undef(bx.type_ptr_to(bx.memory_ty(&fn_ty.ret)))
-                        }
-                        ReturnDest::IndirectOperand(dst, _) |
-                        ReturnDest::Store(dst) => dst.llval,
-                        ReturnDest::DirectOperand(_) =>
-                            bug!("Cannot use direct operand with an intrinsic call")
-                    };
-
-                    let args: Vec<_> = args.iter().enumerate().map(|(i, arg)| {
-                        // The indices passed to simd_shuffle* in the
-                        // third argument must be constant. This is
-                        // checked by const-qualification, which also
-                        // promotes any complex rvalues to constants.
-                        if i == 2 && intrinsic.unwrap().starts_with("simd_shuffle") {
-                            match *arg {
-                                // The shuffle array argument is usually not an explicit constant,
-                                // but specified directly in the code. This means it gets promoted
-                                // and we can then extract the value by evaluating the promoted.
-                                mir::Operand::Copy(mir::Place::Promoted(box(index, ty))) |
-                                mir::Operand::Move(mir::Place::Promoted(box(index, ty))) => {
-                                    let param_env = ty::ParamEnv::reveal_all();
-                                    let cid = mir::interpret::GlobalId {
-                                        instance: self.instance,
-                                        promoted: Some(index),
-                                    };
-                                    let c = bx.tcx().const_eval(param_env.and(cid));
-                                    let (llval, ty) = self.simd_shuffle_indices(
-                                        &bx,
-                                        terminator.source_info.span,
-                                        ty,
-                                        c,
-                                    );
-                                    return OperandRef {
-                                        val: Immediate(llval),
-                                        layout: bx.layout_of(ty),
-                                    };
-
-                                },
-                                mir::Operand::Copy(_) |
-                                mir::Operand::Move(_) => {
-                                    span_bug!(span, "shuffle indices must be constant");
-                                }
-                                mir::Operand::Constant(ref constant) => {
-                                    let c = self.eval_mir_constant(&bx, constant);
-                                    let (llval, ty) = self.simd_shuffle_indices(
-                                        &bx,
-                                        constant.span,
-                                        constant.ty,
-                                        c,
-                                    );
-                                    return OperandRef {
-                                        val: Immediate(llval),
-                                        layout: bx.layout_of(ty)
-                                    };
-                                }
-                            }
-                        }
+                self.codegen_operand(&mut bx, arg)
+            }).collect();
 
-                        self.codegen_operand(&mut bx, arg)
-                    }).collect();
 
+            let callee_ty = instance.as_ref().unwrap().ty(bx.tcx());
+            bx.codegen_intrinsic_call(callee_ty, &fn_ty, &args, dest,
+                                      terminator.source_info.span);
 
-                    let callee_ty = instance.as_ref().unwrap().ty(bx.tcx());
-                    bx.codegen_intrinsic_call(callee_ty, &fn_ty, &args, dest,
-                                               terminator.source_info.span);
+            if let ReturnDest::IndirectOperand(dst, _) = ret_dest {
+                self.store_return(&mut bx, ret_dest, &fn_ty.ret, dst.llval);
+            }
 
-                    if let ReturnDest::IndirectOperand(dst, _) = ret_dest {
-                        self.store_return(&mut bx, ret_dest, &fn_ty.ret, dst.llval);
-                    }
+            if let Some((_, target)) = *destination {
+                helper.funclet_br(self, &mut bx, target);
+            } else {
+                bx.unreachable();
+            }
 
-                    if let Some((_, target)) = *destination {
-                        funclet_br(self, &mut bx, target);
-                    } else {
-                        bx.unreachable();
-                    }
+            return;
+        }
 
-                    return;
-                }
+        // Split the rust-call tupled arguments off.
+        let (first_args, untuple) = if abi == Abi::RustCall && !args.is_empty() {
+            let (tup, args) = args.split_last().unwrap();
+            (args, Some(tup))
+        } else {
+            (&args[..], None)
+        };
 
-                // Split the rust-call tupled arguments off.
-                let (first_args, untuple) = if abi == Abi::RustCall && !args.is_empty() {
-                    let (tup, args) = args.split_last().unwrap();
-                    (args, Some(tup))
-                } else {
-                    (&args[..], None)
+        // Useful determining if the current argument is the "spoofed" `VaList`
+        let last_arg_idx = if sig.inputs().is_empty() {
+            None
+        } else {
+            Some(sig.inputs().len() - 1)
+        };
+        'make_args: for (i, arg) in first_args.iter().enumerate() {
+            // If this is a C-variadic function the function signature contains
+            // an "spoofed" `VaList`. This argument is ignored, but we need to
+            // populate it with a dummy operand so that the users real arguments
+            // are not overwritten.
+            let i = if sig.variadic && last_arg_idx.map(|x| x == i).unwrap_or(false) {
+                let layout = match self.cx.tcx().lang_items().va_list() {
+                    Some(did) => bx.cx().layout_of(bx.tcx().type_of(did)),
+                    None => bug!("`va_list` language item required for C-variadics"),
                 };
-
-                // Useful determining if the current argument is the "spoofed" `VaList`
-                let last_arg_idx = if sig.inputs().is_empty() {
-                    None
-                } else {
-                    Some(sig.inputs().len() - 1)
+                let op = OperandRef {
+                    val: OperandValue::Immediate(
+                        bx.cx().const_undef(bx.cx().immediate_backend_type(layout)
+                    )),
+                    layout: layout,
                 };
-                'make_args: for (i, arg) in first_args.iter().enumerate() {
-                    // If this is a C-variadic function the function signature contains
-                    // an "spoofed" `VaList`. This argument is ignored, but we need to
-                    // populate it with a dummy operand so that the users real arguments
-                    // are not overwritten.
-                    let i = if sig.variadic && last_arg_idx.map(|x| x == i).unwrap_or(false) {
-                        let layout = match tcx.lang_items().va_list() {
-                            Some(did) => bx.cx().layout_of(bx.tcx().type_of(did)),
-                            None => bug!("va_list language item required for C variadics"),
-                        };
-                        let op = OperandRef {
-                            val: OperandValue::Immediate(
-                                bx.cx().const_undef(bx.cx().immediate_backend_type(layout))
-                            ),
-                            layout: layout,
-                        };
-                        self.codegen_argument(&mut bx, op, &mut llargs, &fn_ty.args[i]);
-                        if i + 1 < fn_ty.args.len() {
-                            i + 1
-                        } else {
-                            break 'make_args
-                        }
-                    } else {
-                        i
-                    };
-                    let mut op = self.codegen_operand(&mut bx, arg);
-
-                    if let (0, Some(ty::InstanceDef::Virtual(_, idx))) = (i, def) {
-                        if let Pair(..) = op.val {
-                            // In the case of Rc<Self>, we need to explicitly pass a
-                            // *mut RcBox<Self> with a Scalar (not ScalarPair) ABI. This is a hack
-                            // that is understood elsewhere in the compiler as a method on
-                            // `dyn Trait`.
-                            // To get a `*mut RcBox<Self>`, we just keep unwrapping newtypes until
-                            // we get a value of a built-in pointer type
-                            'descend_newtypes: while !op.layout.ty.is_unsafe_ptr()
-                                            && !op.layout.ty.is_region_ptr()
-                            {
-                                'iter_fields: for i in 0..op.layout.fields.count() {
-                                    let field = op.extract_field(&mut bx, i);
-                                    if !field.layout.is_zst() {
-                                        // we found the one non-zero-sized field that is allowed
-                                        // now find *its* non-zero-sized field, or stop if it's a
-                                        // pointer
-                                        op = field;
-                                        continue 'descend_newtypes
-                                    }
-                                }
-
-                                span_bug!(span, "receiver has no non-zero-sized fields {:?}", op);
+                self.codegen_argument(&mut bx, op, &mut llargs, &fn_ty.args[i]);
+                if i + 1 < fn_ty.args.len() {
+                    i + 1
+                } else {
+                    break 'make_args
+                }
+            } else {
+                i
+            };
+            let mut op = self.codegen_operand(&mut bx, arg);
+
+            if let (0, Some(ty::InstanceDef::Virtual(_, idx))) = (i, def) {
+                if let Pair(..) = op.val {
+                    // In the case of Rc<Self>, we need to explicitly pass a
+                    // *mut RcBox<Self> with a Scalar (not ScalarPair) ABI. This is a hack
+                    // that is understood elsewhere in the compiler as a method on
+                    // `dyn Trait`.
+                    // To get a `*mut RcBox<Self>`, we just keep unwrapping newtypes until
+                    // we get a value of a built-in pointer type
+                    'descend_newtypes: while !op.layout.ty.is_unsafe_ptr()
+                                    && !op.layout.ty.is_region_ptr()
+                    {
+                        'iter_fields: for i in 0..op.layout.fields.count() {
+                            let field = op.extract_field(&mut bx, i);
+                            if !field.layout.is_zst() {
+                                // we found the one non-zero-sized field that is allowed
+                                // now find *its* non-zero-sized field, or stop if it's a
+                                // pointer
+                                op = field;
+                                continue 'descend_newtypes
                             }
+                        }
 
-                            // now that we have `*dyn Trait` or `&dyn Trait`, split it up into its
-                            // data pointer and vtable. Look up the method in the vtable, and pass
-                            // the data pointer as the first argument
-                            match op.val {
-                                Pair(data_ptr, meta) => {
-                                    llfn = Some(meth::VirtualIndex::from_index(idx)
-                                        .get_fn(&mut bx, meta, &fn_ty));
-                                    llargs.push(data_ptr);
-                                    continue 'make_args
-                                }
-                                other => bug!("expected a Pair, got {:?}", other)
-                            }
-                        } else if let Ref(data_ptr, Some(meta), _) = op.val {
-                            // by-value dynamic dispatch
+                        span_bug!(span, "receiver has no non-zero-sized fields {:?}", op);
+                    }
+
+                    // now that we have `*dyn Trait` or `&dyn Trait`, split it up into its
+                    // data pointer and vtable. Look up the method in the vtable, and pass
+                    // the data pointer as the first argument
+                    match op.val {
+                        Pair(data_ptr, meta) => {
                             llfn = Some(meth::VirtualIndex::from_index(idx)
                                 .get_fn(&mut bx, meta, &fn_ty));
                             llargs.push(data_ptr);
-                            continue;
-                        } else {
-                            span_bug!(span, "can't codegen a virtual call on {:?}", op);
-                        }
-                    }
-
-                    // The callee needs to own the argument memory if we pass it
-                    // by-ref, so make a local copy of non-immediate constants.
-                    match (arg, op.val) {
-                        (&mir::Operand::Copy(_), Ref(_, None, _)) |
-                        (&mir::Operand::Constant(_), Ref(_, None, _)) => {
-                            let tmp = PlaceRef::alloca(&mut bx, op.layout, "const");
-                            op.val.store(&mut bx, tmp);
-                            op.val = Ref(tmp.llval, None, tmp.align);
+                            continue 'make_args
                         }
-                        _ => {}
+                        other => bug!("expected a Pair, got {:?}", other),
                     }
-
-                    self.codegen_argument(&mut bx, op, &mut llargs, &fn_ty.args[i]);
+                } else if let Ref(data_ptr, Some(meta), _) = op.val {
+                    // by-value dynamic dispatch
+                    llfn = Some(meth::VirtualIndex::from_index(idx)
+                        .get_fn(&mut bx, meta, &fn_ty));
+                    llargs.push(data_ptr);
+                    continue;
+                } else {
+                    span_bug!(span, "can't codegen a virtual call on {:?}", op);
                 }
-                if let Some(tup) = untuple {
-                    self.codegen_arguments_untupled(&mut bx, tup, &mut llargs,
-                        &fn_ty.args[first_args.len()..])
+            }
+
+            // The callee needs to own the argument memory if we pass it
+            // by-ref, so make a local copy of non-immediate constants.
+            match (arg, op.val) {
+                (&mir::Operand::Copy(_), Ref(_, None, _)) |
+                (&mir::Operand::Constant(_), Ref(_, None, _)) => {
+                    let tmp = PlaceRef::alloca(&mut bx, op.layout, "const");
+                    op.val.store(&mut bx, tmp);
+                    op.val = Ref(tmp.llval, None, tmp.align);
                 }
+                _ => {}
+            }
 
-                let fn_ptr = match (llfn, instance) {
-                    (Some(llfn), _) => llfn,
-                    (None, Some(instance)) => bx.get_fn(instance),
-                    _ => span_bug!(span, "no llfn for call"),
-                };
+            self.codegen_argument(&mut bx, op, &mut llargs, &fn_ty.args[i]);
+        }
+        if let Some(tup) = untuple {
+            self.codegen_arguments_untupled(&mut bx, tup, &mut llargs,
+                &fn_ty.args[first_args.len()..])
+        }
+
+        let fn_ptr = match (llfn, instance) {
+            (Some(llfn), _) => llfn,
+            (None, Some(instance)) => bx.get_fn(instance),
+            _ => span_bug!(span, "no llfn for call"),
+        };
+
+        helper.do_call(self, &mut bx, fn_ty, fn_ptr, &llargs,
+                       destination.as_ref().map(|&(_, target)| (ret_dest, target)),
+                       cleanup);
+    }
+}
+
+impl<'a, 'tcx: 'a, Bx: BuilderMethods<'a, 'tcx>> FunctionCx<'a, 'tcx, Bx> {
+    pub fn codegen_block(
+        &mut self,
+        bb: mir::BasicBlock,
+    ) {
+        let mut bx = self.build_block(bb);
+        let data = &self.mir[bb];
+
+        debug!("codegen_block({:?}={:?})", bb, data);
+
+        for statement in &data.statements {
+            bx = self.codegen_statement(bx, statement);
+        }
+
+        self.codegen_terminator(bx, bb, data.terminator());
+    }
 
-                do_call(self, &mut bx, fn_ty, fn_ptr, &llargs,
-                        destination.as_ref().map(|&(_, target)| (ret_dest, target)),
-                        cleanup);
+    fn codegen_terminator(
+        &mut self,
+        mut bx: Bx,
+        bb: mir::BasicBlock,
+        terminator: &mir::Terminator<'tcx>
+    ) {
+        debug!("codegen_terminator: {:?}", terminator);
+
+        // Create the cleanup bundle, if needed.
+        let funclet_bb = self.cleanup_kinds[bb].funclet_bb(bb);
+        let helper = TerminatorCodegenHelper {
+            bb: &bb, terminator, funclet_bb
+        };
+
+        self.set_debug_loc(&mut bx, terminator.source_info);
+        match terminator.kind {
+            mir::TerminatorKind::Resume => {
+                self.codegen_resume_terminator(helper, bx)
+            }
+
+            mir::TerminatorKind::Abort => {
+                bx.abort();
+                bx.unreachable();
+            }
+
+            mir::TerminatorKind::Goto { target } => {
+                helper.funclet_br(self, &mut bx, target);
+            }
+
+            mir::TerminatorKind::SwitchInt {
+                ref discr, switch_ty, ref values, ref targets
+            } => {
+                self.codegen_switchint_terminator(helper, bx, discr, switch_ty,
+                                                  values, targets);
+            }
+
+            mir::TerminatorKind::Return => {
+                self.codegen_return_terminator(bx);
+            }
+
+            mir::TerminatorKind::Unreachable => {
+                bx.unreachable();
+            }
+
+            mir::TerminatorKind::Drop { ref location, target, unwind } => {
+                self.codegen_drop_terminator(helper, bx, location, target, unwind);
+            }
+
+            mir::TerminatorKind::Assert { ref cond, expected, ref msg, target, cleanup } => {
+                self.codegen_assert_terminator(helper, bx, terminator, cond,
+                                               expected, msg, target, cleanup);
+            }
+
+            mir::TerminatorKind::DropAndReplace { .. } => {
+                bug!("undesugared DropAndReplace in codegen: {:?}", terminator);
+            }
+
+            mir::TerminatorKind::Call {
+                ref func,
+                ref args,
+                ref destination,
+                cleanup,
+                from_hir_call: _
+            } => {
+                self.codegen_call_terminator(helper, bx, terminator, func,
+                                             args, destination, cleanup);
             }
             mir::TerminatorKind::GeneratorDrop |
             mir::TerminatorKind::Yield { .. } => bug!("generator ops in codegen"),