diff options
Diffstat (limited to 'compiler/cmm/MkGraph.hs')
| -rw-r--r-- | compiler/cmm/MkGraph.hs | 73 |
1 files changed, 11 insertions, 62 deletions
diff --git a/compiler/cmm/MkGraph.hs b/compiler/cmm/MkGraph.hs index bcd03bfa67..70229d067d 100644 --- a/compiler/cmm/MkGraph.hs +++ b/compiler/cmm/MkGraph.hs @@ -38,7 +38,6 @@ import OrdList import SMRep (ByteOff) import UniqSupply import Util -import Panic ----------------------------------------------------------------------------- @@ -310,33 +309,18 @@ copyIn :: DynFlags -> Convention -> Area copyIn dflags conv area formals extra_stk = (stk_size, [r | (_, RegisterParam r) <- args], map ci (stk_args ++ args)) where - -- See Note [Width of parameters] - ci (reg, RegisterParam r@(VanillaReg {})) = - let local = CmmLocal reg - global = CmmReg (CmmGlobal r) - width = cmmRegWidth dflags local - expr - | width == wordWidth dflags = global - | width < wordWidth dflags = - CmmMachOp (MO_XX_Conv (wordWidth dflags) width) [global] - | otherwise = panic "Parameter width greater than word width" + ci (reg, RegisterParam r) = + CmmAssign (CmmLocal reg) (CmmReg (CmmGlobal r)) + ci (reg, StackParam off) = + CmmAssign (CmmLocal reg) (CmmLoad (CmmStackSlot area off) ty) + where ty = localRegType reg - in CmmAssign local expr + init_offset = widthInBytes (wordWidth dflags) -- infotable - -- Non VanillaRegs - ci (reg, RegisterParam r) = - CmmAssign (CmmLocal reg) (CmmReg (CmmGlobal r)) + (stk_off, stk_args) = assignStack dflags init_offset localRegType extra_stk - ci (reg, StackParam off) = - CmmAssign (CmmLocal reg) (CmmLoad (CmmStackSlot area off) ty) - where ty = localRegType reg - - init_offset = widthInBytes (wordWidth dflags) -- infotable - - (stk_off, stk_args) = assignStack dflags init_offset localRegType extra_stk - - (stk_size, args) = assignArgumentsPos dflags stk_off conv - localRegType formals + (stk_size, args) = assignArgumentsPos dflags stk_off conv + localRegType formals -- Factoring out the common parts of the copyout functions yielded something -- more complicated: @@ -362,21 +346,8 @@ copyOutOflow dflags conv transfer area actuals updfr_off extra_stack_stuff where (regs, graph) = foldr co ([], mkNop) (setRA ++ args ++ stack_params) - -- See Note [Width of parameters] - co (v, RegisterParam r@(VanillaReg {})) (rs, ms) = - let width = cmmExprWidth dflags v - value - | width == wordWidth dflags = v - | width < wordWidth dflags = - CmmMachOp (MO_XX_Conv width (wordWidth dflags)) [v] - | otherwise = panic "Parameter width greater than word width" - - in (r:rs, mkAssign (CmmGlobal r) value <*> ms) - - -- Non VanillaRegs - co (v, RegisterParam r) (rs, ms) = - (r:rs, mkAssign (CmmGlobal r) v <*> ms) - + co (v, RegisterParam r) (rs, ms) + = (r:rs, mkAssign (CmmGlobal r) v <*> ms) co (v, StackParam off) (rs, ms) = (rs, mkStore (CmmStackSlot area off) v <*> ms) @@ -403,28 +374,6 @@ copyOutOflow dflags conv transfer area actuals updfr_off extra_stack_stuff (cmmExprType dflags) actuals --- Note [Width of parameters] --- --- Consider passing a small (< word width) primitive like Int8# to a function --- through a register. It's actually non-trivial to do this without --- extending/narrowing: --- * Global registers are considered to have native word width (i.e., 64-bits on --- x86-64), so CmmLint would complain if we assigne an 8-bit parameter to a --- global register. --- * Same problem exists with LLVM IR. --- * Lowering gets harder since on x86-32 not every register exposes its lower --- 8 bits (e.g., for %eax we can use %al, but there isn't a corresponding --- 8-bit register for %edi). So we would either need to extend/narrow anyway, --- or complicate the calling convention. --- So instead, we always extend every parameter smaller than native word width --- in copyOutOflow and then truncate it back to the expected width in copyIn. --- Note that we do this in cmm using MO_XX_Conv to avoid requiring --- zero-/sign-extending - it's up to a backend to handle this in a most --- efficient way (e.g., a simple register move) --- --- There was some discussion about this on this PR: --- https://github.com/ghc-proposals/ghc-proposals/pull/74 - mkCallEntry :: DynFlags -> Convention -> [CmmFormal] -> [CmmFormal] -> (Int, [GlobalReg], CmmAGraph) |