Bug 31948: Fix assertion when bitcasting constantexpr pointers

[arpith-jacob]

Thank you for this. LGTM.

[arsenm]

r295387

lib/Transforms/Scalar/InferAddressSpaces.cpp

if (CE->getOpcode() == Instruction::AddrSpaceCast) {
     // Because CE is flat, the source address space must be specific.
     // Therefore, the inferred address space must be the source space according
     // to our algorithm.
     assert(CE->getOperand(0)->getType()->getPointerAddressSpace() ==
            NewAddrSpace);
     return ConstantExpr::getBitCast(CE->getOperand(0), TargetType);
   }
 
+  if (CE->getOpcode() == Instruction::BitCast) {
+    if (Value *NewOperand = ValueWithNewAddrSpace.lookup(CE->getOperand(0)))
+      return ConstantExpr::getBitCast(cast<Constant>(NewOperand), TargetType);
+    return ConstantExpr::getAddrSpaceCast(CE, TargetType);
+  }
+
   if (CE->getOpcode() == Instruction::Select) {
     Constant *Src0 = CE->getOperand(1);
     Constant *Src1 = CE->getOperand(2);
     if (Src0->getType()->getPointerAddressSpace() ==
         Src1->getType()->getPointerAddressSpace()) {
 
       return ConstantExpr::getSelect(
           CE->getOperand(0), ConstantExpr::getAddrSpaceCast(Src0, TargetType),

test/Transforms/InferAddressSpaces/NVPTX/bug31948.ll

+; RUN: opt -S -mtriple=nvptx64-nvidia-cuda -infer-address-spaces %s | FileCheck %s
+
+target datalayout = "e-i64:64-v16:16-v32:32-n16:32:64"
+
+%struct.bar = type { float, float* }
+
+@var1 = local_unnamed_addr addrspace(3) externally_initialized global %struct.bar undef, align 8
+
+; CHECK-LABEL: @bug31948(
+; CHECK: %tmp = load float*, float* addrspace(3)* getelementptr inbounds (%struct.bar, %struct.bar addrspace(3)* @var1, i64 0, i32 1), align 8
+; CHECK: %tmp1 = load float, float* %tmp, align 4
+; CHECK: store float %conv1, float* %tmp, align 4
+; CHECK: store i32 32, i32 addrspace(3)* addrspacecast (i32* bitcast (float** getelementptr (%struct.bar, %struct.bar* addrspacecast (%struct.bar addrspace(3)* @var1 to %struct.bar*), i64 0, i32 1) to i32*) to i32 addrspace(3)*), align 4
+define void @bug31948(float %a, float* nocapture readnone %x, float* nocapture readnone %y) local_unnamed_addr #0 {
+entry:
+  %tmp = load float*, float** getelementptr (%struct.bar, %struct.bar* addrspacecast (%struct.bar addrspace(3)* @var1 to %struct.bar*), i64 0, i32 1), align 8
+  %tmp1 = load float, float* %tmp, align 4
+  %conv1 = fadd float %tmp1, 1.000000e+00
+  store float %conv1, float* %tmp, align 4
+  store i32 32, i32* bitcast (float** getelementptr (%struct.bar, %struct.bar* addrspacecast (%struct.bar addrspace(3)* @var1 to %struct.bar*), i64 0, i32 1) to i32*), align 4
+  ret void
+}
+
+attributes #0 = { norecurse nounwind }

test/Transforms/InferAddressSpaces/NVPTX/lit.local.cfg

+if not 'NVPTX' in config.root.targets:
+    config.unsupported = True