Merging r332302:

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r332302 | kfischer | 2018-05-14 15:05:01 -0700 (Mon, 14 May 2018) | 15 lines

[InstCombine] fix crash due to ignored addrspacecast

Summary:
Part of the InstCombine code for simplifying GEPs looks through
addrspacecasts. However, this was done by updating a variable
also used by the next transformation, for marking GEPs as
inbounds. This led to replacing a GEP with a similar instruction
in a different addrspace, which caused an assertion failure in RAUW.

This caused julia issue https://github.com/JuliaLang/julia/issues/27055

Patch by Jeff Bezanson <jeff@juliacomputing.com>

Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D46722
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llvm-svn: 333477

2 files changed, 22 insertions, 2 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 35ed592ac07d..8fa7d0684b94 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -1947,13 +1947,14 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
   // addrspacecast between types is canonicalized as a bitcast, then an
   // addrspacecast. To take advantage of the below bitcast + struct GEP, look
   // through the addrspacecast.
+  Value *ASCStrippedPtrOp = PtrOp;
   if (AddrSpaceCastInst *ASC = dyn_cast<AddrSpaceCastInst>(PtrOp)) {
     //   X = bitcast A addrspace(1)* to B addrspace(1)*
     //   Y = addrspacecast A addrspace(1)* to B addrspace(2)*
     //   Z = gep Y, <...constant indices...>
     // Into an addrspacecasted GEP of the struct.
     if (BitCastInst *BC = dyn_cast<BitCastInst>(ASC->getOperand(0)))
-      PtrOp = BC;
+      ASCStrippedPtrOp = BC;
   }
 
   /// See if we can simplify:
@@ -1961,7 +1962,7 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
   ///   Y = gep X, <...constant indices...>
   /// into a gep of the original struct.  This is important for SROA and alias
   /// analysis of unions.  If "A" is also a bitcast, wait for A/X to be merged.
-  if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
+  if (BitCastInst *BCI = dyn_cast<BitCastInst>(ASCStrippedPtrOp)) {
     Value *Operand = BCI->getOperand(0);
     PointerType *OpType = cast<PointerType>(Operand->getType());
     unsigned OffsetBits = DL.getPointerTypeSizeInBits(GEP.getType());
diff --git a/llvm/test/Transforms/InstCombine/gep-addrspace.ll b/llvm/test/Transforms/InstCombine/gep-addrspace.ll
index aa46ea671302..4a4951dee7fd 100644
--- a/llvm/test/Transforms/InstCombine/gep-addrspace.ll
+++ b/llvm/test/Transforms/InstCombine/gep-addrspace.ll
@@ -32,3 +32,22 @@ entry:
   ret void
 }
 
+declare void @escape_alloca(i16*)
+
+; check that addrspacecast is not ignored (leading to an assertion failure)
+; when trying to mark a GEP as inbounds
+define { i8, i8 } @inbounds_after_addrspacecast() {
+top:
+; CHECK-LABEL: @inbounds_after_addrspacecast
+  %0 = alloca i16, align 2
+  call void @escape_alloca(i16* %0)
+  %tmpcast = bitcast i16* %0 to [2 x i8]*
+; CHECK: addrspacecast [2 x i8]* %tmpcast to [2 x i8] addrspace(11)*
+  %1 = addrspacecast [2 x i8]* %tmpcast to [2 x i8] addrspace(11)*
+; CHECK: getelementptr [2 x i8], [2 x i8] addrspace(11)* %1, i64 0, i64 1
+  %2 = getelementptr [2 x i8], [2 x i8] addrspace(11)* %1, i64 0, i64 1
+; CHECK: addrspace(11)
+  %3 = load i8, i8 addrspace(11)* %2, align 1
+  %.fca.1.insert = insertvalue { i8, i8 } zeroinitializer, i8 %3, 1
+  ret { i8, i8 } %.fca.1.insert
+}