[PATCH] D87709: InferAddressSpaces: Fix assert with unreachable code

[Matt Arsenault via Phabricator via llvm-commits]

arsenm created this revision.
arsenm added reviewers: hliao, tra, jdoerfert, yaxunl, rampitec.
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Invalid IR in unreachable code is technically valid IR. In this case,
the address space of the value was never inferred, and we tried to
rewrite it with an invalid address space value which would assert.


https://reviews.llvm.org/D87709

Files:
  llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp
  llvm/test/Transforms/InferAddressSpaces/AMDGPU/unreachable-code-assert.ll


Index: llvm/test/Transforms/InferAddressSpaces/AMDGPU/unreachable-code-assert.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/InferAddressSpaces/AMDGPU/unreachable-code-assert.ll
@@ -0,0 +1,27 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -mtriple=amdgcn-amd-amdhsa -mcpu=gfx900 -S -infer-address-spaces %s | FileCheck %s
+
+define amdgpu_kernel void @subclass_data_assert() {
+; CHECK-LABEL: @subclass_data_assert(
+; CHECK-NEXT:  entry:
+; CHECK-NEXT:    unreachable
+; CHECK:       strlen.while11:
+; CHECK-NEXT:    [[I:%.*]] = getelementptr i8, i8* [[I]], i64 1
+; CHECK-NEXT:    [[I1:%.*]] = load i8, i8* [[I]], align 1
+; CHECK-NEXT:    [[I2:%.*]] = icmp eq i8 [[I1]], 0
+; CHECK-NEXT:    br i1 [[I2]], label [[STRLEN_WHILE_DONE12:%.*]], label [[STRLEN_WHILE11:%.*]]
+; CHECK:       strlen.while.done12:
+; CHECK-NEXT:    ret void
+;
+entry:
+  unreachable
+
+strlen.while11:                                   ; preds = %strlen.while11
+  %i = getelementptr i8, i8* %i, i64 1
+  %i1 = load i8, i8* %i, align 1
+  %i2 = icmp eq i8 %i1, 0
+  br i1 %i2, label %strlen.while.done12, label %strlen.while11
+
+strlen.while.done12:                              ; preds = %strlen.while11
+  ret void
+}
Index: llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp
+++ llvm/lib/Transforms/Scalar/InferAddressSpaces.cpp
@@ -997,6 +997,12 @@
   SmallVector<const Use *, 32> UndefUsesToFix;
   for (Value* V : Postorder) {
     unsigned NewAddrSpace = InferredAddrSpace.lookup(V);
+
+    // In some degenerate cases (e.g. invalid IR in unreachable code), we may
+    // not even infer the value to have its original address space.
+    if (NewAddrSpace == UninitializedAddressSpace)
+      continue;
+
     if (V->getType()->getPointerAddressSpace() != NewAddrSpace) {
       Value *New = cloneValueWithNewAddressSpace(
           V, NewAddrSpace, ValueWithNewAddrSpace, &UndefUsesToFix);


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