InstCombine optimizes gep(bitcast(x)) even when the bitcasts casts away address

space info. We crash with an assert in this case. This change checks that the
address space of the bitcasted pointer is the same as the gep ptr.

llvm-svn: 128884

2 files changed, 27 insertions, 8 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 21851768cbb..4be671f031e 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -849,22 +849,23 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
         GetElementPtrInst::Create(Src->getOperand(0), Indices.begin(),
                                   Indices.end(), GEP.getName());
   }
-  
+
   // Handle gep(bitcast x) and gep(gep x, 0, 0, 0).
   Value *StrippedPtr = PtrOp->stripPointerCasts();
-  if (StrippedPtr != PtrOp) {
-    const PointerType *StrippedPtrTy =cast<PointerType>(StrippedPtr->getType());
+  const PointerType *StrippedPtrTy =cast<PointerType>(StrippedPtr->getType());
+  if (StrippedPtr != PtrOp &&
+    StrippedPtrTy->getAddressSpace() == GEP.getPointerAddressSpace()) {
 
     bool HasZeroPointerIndex = false;
     if (ConstantInt *C = dyn_cast<ConstantInt>(GEP.getOperand(1)))
       HasZeroPointerIndex = C->isZero();
-    
+
     // Transform: GEP (bitcast [10 x i8]* X to [0 x i8]*), i32 0, ...
     // into     : GEP [10 x i8]* X, i32 0, ...
     //
     // Likewise, transform: GEP (bitcast i8* X to [0 x i8]*), i32 0, ...
     //           into     : GEP i8* X, ...
-    // 
+    //
     // This occurs when the program declares an array extern like "int X[];"
     if (HasZeroPointerIndex) {
       const PointerType *CPTy = cast<PointerType>(PtrOp->getType());
@@ -975,7 +976,7 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
       }
     }
   }
-  
+
   /// See if we can simplify:
   ///   X = bitcast A* to B*
   ///   Y = gep X, <...constant indices...>
@@ -983,12 +984,14 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) {
   /// analysis of unions.  If "A" is also a bitcast, wait for A/X to be merged.
   if (BitCastInst *BCI = dyn_cast<BitCastInst>(PtrOp)) {
     if (TD &&
-        !isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices()) {
+        !isa<BitCastInst>(BCI->getOperand(0)) && GEP.hasAllConstantIndices() &&
+        StrippedPtrTy->getAddressSpace() == GEP.getPointerAddressSpace()) {
+
       // Determine how much the GEP moves the pointer.  We are guaranteed to get
       // a constant back from EmitGEPOffset.
       ConstantInt *OffsetV = cast<ConstantInt>(EmitGEPOffset(&GEP));
       int64_t Offset = OffsetV->getSExtValue();
-      
+
       // If this GEP instruction doesn't move the pointer, just replace the GEP
       // with a bitcast of the real input to the dest type.
       if (Offset == 0) {
diff --git a/llvm/test/Transforms/InstCombine/gep-addrspace.ll b/llvm/test/Transforms/InstCombine/gep-addrspace.ll
new file mode 100644
index 00000000000..4c971072cfb
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/gep-addrspace.ll
@@ -0,0 +1,16 @@
+; RUN: opt < %s -instcombine -S
+
+%myStruct = type { float, [3 x float], [4 x float], i32 }
+
+; make sure that we are not crashing when creating an illegal type
+define void @func(%myStruct addrspace(1)* nocapture %p) nounwind {
+ST:
+  %A = getelementptr inbounds %myStruct addrspace(1)* %p, i64 0
+  %B = bitcast %myStruct addrspace(1)* %A to %myStruct*
+  %C = getelementptr inbounds %myStruct* %B, i32 0, i32 1
+  %D = getelementptr inbounds [3 x float]* %C, i32 0, i32 2
+  %E = load float* %D, align 4
+  %F = fsub float %E, undef
+  ret void
+}
+