[llvm] r332302 - [InstCombine] fix crash due to ignored addrspacecast

[Keno Fischer via llvm-commits]

Author: kfischer
Date: Mon May 14 15:05:01 2018
New Revision: 332302

URL: http://llvm.org/viewvc/llvm-project?rev=332302&view=rev
Log:
[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 at juliacomputing.com>

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

Modified:
    llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
    llvm/trunk/test/Transforms/InstCombine/gep-addrspace.ll

Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=332302&r1=332301&r2=332302&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Mon May 14 15:05:01 2018
@@ -1937,16 +1937,17 @@ Instruction *InstCombiner::visitGetEleme
   // 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 (auto *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 (auto *BC = dyn_cast<BitCastInst>(ASC->getOperand(0)))
-      PtrOp = BC;
+      ASCStrippedPtrOp = BC;
   }
 
-  if (auto *BCI = dyn_cast<BitCastInst>(PtrOp)) {
+  if (auto *BCI = dyn_cast<BitCastInst>(ASCStrippedPtrOp)) {
     Value *SrcOp = BCI->getOperand(0);
     PointerType *SrcType = cast<PointerType>(BCI->getSrcTy());
     Type *SrcEltType = SrcType->getElementType();

Modified: llvm/trunk/test/Transforms/InstCombine/gep-addrspace.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/gep-addrspace.ll?rev=332302&r1=332301&r2=332302&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/gep-addrspace.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/gep-addrspace.ll Mon May 14 15:05:01 2018
@@ -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
+}