[AMDGPU][LowerBufferFatPointers] Fix crash with select false
#166471
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If the input to LowerBufferFatPointers is such that the resource- and offset-specific `select` instructions generated for a `select` on `ptr addrspae(7)` fold away, the pass would crash when trying to replace an instruction with itself. This commit resolves the issue. Fixes iree-org/iree#22551 While I'm here, make myself a code owner for buffer fat pointer ling.
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@llvm/pr-subscribers-backend-amdgpu Author: Krzysztof Drewniak (krzysz00) ChangesIf the input to LowerBufferFatPointers is such that the resource- and offset-specific Fixes iree-org/iree#22551 While I'm here, make myself a code owner for buffer fat pointer ling. Full diff: https://github.com/llvm/llvm-project/pull/166471.diff 3 Files Affected:
diff --git a/.github/CODEOWNERS b/.github/CODEOWNERS
index 3a0a291ccb24c..3f2657a707860 100644
--- a/.github/CODEOWNERS
+++ b/.github/CODEOWNERS
@@ -166,5 +166,8 @@
/llvm/**/dsymutil/ @JDevlieghere
/llvm/**/llvm-dwarfutil/ @JDevlieghere
+# AMDGPULowerBufferFatPointers
+/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp @krzysz00
+
# libclang/Python bindings
/clang/bindings/python @DeinAlptraum
diff --git a/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp b/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp
index 0a5913293238a..fdff21b6ef8df 100644
--- a/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp
+++ b/llvm/lib/Target/AMDGPU/AMDGPULowerBufferFatPointers.cpp
@@ -1565,8 +1565,11 @@ void SplitPtrStructs::processConditionals() {
} else if (isa<SelectInst>(I)) {
if (MaybeRsrc) {
if (auto *RsrcInst = dyn_cast<Instruction>(Rsrc)) {
- ConditionalTemps.push_back(RsrcInst);
- RsrcInst->replaceAllUsesWith(*MaybeRsrc);
+ // Guard against conditionals that were already folded away.
+ if (RsrcInst != *MaybeRsrc) {
+ ConditionalTemps.push_back(RsrcInst);
+ RsrcInst->replaceAllUsesWith(*MaybeRsrc);
+ }
}
for (Value *V : Seen)
FoundRsrcs[V] = *MaybeRsrc;
diff --git a/llvm/test/CodeGen/AMDGPU/lower-buffer-fat-pointers-control-flow.ll b/llvm/test/CodeGen/AMDGPU/lower-buffer-fat-pointers-control-flow.ll
index 4fa7c29bfde02..71005224dd1e5 100644
--- a/llvm/test/CodeGen/AMDGPU/lower-buffer-fat-pointers-control-flow.ll
+++ b/llvm/test/CodeGen/AMDGPU/lower-buffer-fat-pointers-control-flow.ll
@@ -481,3 +481,15 @@ define void @dominance_not_in_program_order(ptr addrspace(7) inreg %arg) {
%lsr.iv11 = phi ptr addrspace(7) [ %arg, %.loopexit ], [ %arg, %.preheader15 ]
br label %.loopexit
}
+
+;; iree-org/iree#22551 - crash on something that reduces to the below non-canonical select.
+define ptr addrspace(7) @noncanonical_const_cond(ptr addrspace(7) %x) {
+; CHECK-LABEL: define { ptr addrspace(8), i32 } @noncanonical_const_cond
+; CHECK-SAME: ({ ptr addrspace(8), i32 } [[RET:%.*]]) #[[ATTR0]] {
+; CHECK-NEXT: [[X_RSRC:%.*]] = extractvalue { ptr addrspace(8), i32 } [[RET]], 0
+; CHECK-NEXT: [[X_OFF:%.*]] = extractvalue { ptr addrspace(8), i32 } [[RET]], 1
+; CHECK-NEXT: ret { ptr addrspace(8), i32 } [[RET]]
+;
+ %ret = select i1 false, ptr addrspace(7) %x, ptr addrspace(7) %x
+ ret ptr addrspace(7) %ret
+}
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arsenm
reviewed
Nov 5, 2025
shiltian
approved these changes
Nov 5, 2025
arsenm
approved these changes
Nov 5, 2025
Collaborator
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/138/builds/21383 Here is the relevant piece of the build log for the reference |
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If the input to LowerBufferFatPointers is such that the resource- and offset-specific
selectinstructions generated for aselectonptr addrspae(7)fold away, the pass would crash when trying to replace an instruction with itself. This commit resolves the issue.Fixes iree-org/iree#22551