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[Clang][HLSL][GVN] Prevent phi codgen of isTokenLike types #162363

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Merged
merged 3 commits into from
Oct 10, 2025
Merged

[Clang][HLSL][GVN] Prevent phi codgen of isTokenLike types #162363

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e2ef66f
[HLSL] prevent phi codgen of isTokenLike types
farzonl Oct 7, 2025
863a8eb
move isTokenLikeTy check from to processLoad to capture all the proc…
farzonl Oct 8, 2025
967f6a8
address pr comment
farzonl Oct 10, 2025
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3 changes: 3 additions & 0 deletions llvm/lib/Transforms/Scalar/GVN.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2244,6 +2244,9 @@ bool GVNPass::processLoad(LoadInst *L) {
if (!L->isUnordered())
return false;

if (L->getType()->isTokenLikeTy())
return false;

if (L->use_empty()) {
salvageAndRemoveInstruction(L);
return true;
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34 changes: 34 additions & 0 deletions llvm/test/Transforms/GVN/PRE/no-pre-load-for-token-like.ll
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@@ -0,0 +1,34 @@
; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 6
; RUN: opt -S -passes=gvn %s | FileCheck %s

; NOTE: A test to confirm GVN doesn't collapse loads of token-like types into
; NOTE: phi nodes.

define ptr @main() {
; CHECK-LABEL: define ptr @main() {
; CHECK-NEXT: [[ENTRY:.*:]]
; CHECK-NEXT: br i1 false, label %[[ENTRY_IF_END_I_CRIT_EDGE:.*]], label %[[IF_THEN_I:.*]]
; CHECK: [[ENTRY_IF_END_I_CRIT_EDGE]]:
; CHECK-NEXT: br label %[[IF_END_I:.*]]
; CHECK: [[IF_THEN_I]]:
; CHECK-NEXT: [[TMP0:%.*]] = load target("dx.RawBuffer", half, 1, 0), ptr null, align 4
; CHECK-NEXT: [[TMP1:%.*]] = tail call ptr @llvm.dx.resource.getpointer.p0.tdx.RawBuffer_f16_1_0t(target("dx.RawBuffer", half, 1, 0) [[TMP0]], i32 0)
; CHECK-NEXT: br label %[[IF_END_I]]
; CHECK: [[IF_END_I]]:
; CHECK-NEXT: [[TMP2:%.*]] = load target("dx.RawBuffer", half, 1, 0), ptr null, align 4
; CHECK-NEXT: [[TMP3:%.*]] = tail call ptr @llvm.dx.resource.getpointer.p0.tdx.RawBuffer_f16_1_0t(target("dx.RawBuffer", half, 1, 0) [[TMP2]], i32 0)
; CHECK-NEXT: ret ptr [[TMP3]]
;
entry:
br i1 false, label %if.end.i, label %if.then.i

if.then.i: ; preds = %entry
%0 = load target("dx.RawBuffer", half, 1, 0), ptr null, align 4
%1 = tail call ptr @llvm.dx.resource.getpointer.p0.tdx.RawBuffer_f16_1_0t(target("dx.RawBuffer", half, 1, 0) %0, i32 0)
br label %if.end.i

if.end.i: ; preds = %if.then.i, %entry
%2 = load target("dx.RawBuffer", half, 1, 0), ptr null, align 4
%3 = tail call ptr @llvm.dx.resource.getpointer.p0.tdx.RawBuffer_f16_1_0t(target("dx.RawBuffer", half, 1, 0) %2, i32 0)
ret ptr %3
}