Author: Shilei Tian
Date: 2024-07-16T13:17:24-04:00
New Revision: f38baad3e7395af94290aac21e587bc1c5f00946
URL: https://github.com/llvm/llvm-project/commit/f38baad3e7395af94290aac21e587bc1c5f00946
DIFF: https://github.com/llvm/llvm-project/commit/f38baad3e7395af94290aac21e587bc1c5f00946.diff
LOG: [InstCombine] Fix a crash in `PointerReplacer` (#98987)
A crash could happen in `PointerReplacer::replace` when constructing a
new
select instruction and there is no replacement for one of its operand.
This can
happen when the operand is a load instruction that has been replaced
earlier
such that the operand itself is already the new value. In this case, it
is not
in the replacement map and `getReplacement` simply returns nullptr.
Fix SWDEV-472192.
Added:
llvm/test/Transforms/InstCombine/AMDGPU/select-from-load.ll
Modified:
llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
index 21d5e1dece024..1661fa564c65c 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineLoadStoreAlloca.cpp
@@ -394,9 +394,14 @@ void PointerReplacer::replace(Instruction *I) {
NewI->setNoWrapFlags(GEP->getNoWrapFlags());
WorkMap[GEP] = NewI;
} else if (auto *SI = dyn_cast<SelectInst>(I)) {
- auto *NewSI = SelectInst::Create(
- SI->getCondition(), getReplacement(SI->getTrueValue()),
- getReplacement(SI->getFalseValue()), SI->getName(), nullptr, SI);
+ Value *TrueValue = SI->getTrueValue();
+ Value *FalseValue = SI->getFalseValue();
+ if (Value *Replacement = getReplacement(TrueValue))
+ TrueValue = Replacement;
+ if (Value *Replacement = getReplacement(FalseValue))
+ FalseValue = Replacement;
+ auto *NewSI = SelectInst::Create(SI->getCondition(), TrueValue, FalseValue,
+ SI->getName(), nullptr, SI);
IC.InsertNewInstWith(NewSI, SI->getIterator());
NewSI->takeName(SI);
WorkMap[SI] = NewSI;
diff --git a/llvm/test/Transforms/InstCombine/AMDGPU/select-from-load.ll b/llvm/test/Transforms/InstCombine/AMDGPU/select-from-load.ll
new file mode 100644
index 0000000000000..d9af665e663f3
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/AMDGPU/select-from-load.ll
@@ -0,0 +1,33 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt -passes=instcombine -S -o - %s | FileCheck %s
+; REQUIRES: amdgpu-registered-target
+
+target triple = "amdgcn-amd-amdhsa"
+
+%anon = type { i32, [8 x ptr], ptr }
+
+define void @foo(ptr addrspace(4) byref(%anon) align 8 %0) {
+; CHECK-LABEL: @foo(
+; CHECK-NEXT: entry:
+; CHECK-NEXT: [[TMP1:%.*]] = load ptr, ptr addrspace(4) [[TMP0:%.*]], align 8
+; CHECK-NEXT: br label [[FOR_COND10:%.*]]
+; CHECK: for.cond10:
+; CHECK-NEXT: [[TMP2:%.*]] = load i64, ptr [[TMP1]], align 8
+; CHECK-NEXT: store i64 [[TMP2]], ptr addrspace(1) null, align 8
+; CHECK-NEXT: br label [[FOR_COND10]]
+;
+entry:
+ %coerce = alloca %anon, addrspace(5)
+ call void @llvm.memcpy.p5.p4.i64(ptr addrspace(5) %coerce, ptr addrspace(4) %0, i64 0, i1 false)
+ %asc = addrspacecast ptr addrspace(5) %coerce to ptr
+ %load = load ptr, ptr addrspace(5) %coerce
+ %retval.0.i = select i1 false, ptr %asc, ptr %load
+ br label %for.cond10
+
+for.cond10: ; preds = %for.cond10, %entry
+ %3 = load i64, ptr %retval.0.i
+ store i64 %3, ptr addrspace(1) null
+ br label %for.cond10
+}
+
+declare void @llvm.memcpy.p5.p4.i64(ptr addrspace(5), ptr addrspace(4), i64, i1 immarg)