[InstCombine] Preserve nneg in foldLogicCastConstant #157865
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llvm:instcombine
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@llvm/pr-subscribers-llvm-transforms Author: Hongyu Chen (XChy) ChangesThis patch makes use of the new public helper function to preserve nneg in Full diff: https://github.com/llvm/llvm-project/pull/157865.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
index 8b9df62d7c652..2d7524e8018b2 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
@@ -1801,10 +1801,14 @@ static Instruction *foldLogicCastConstant(BinaryOperator &Logic, CastInst *Cast,
Value *X;
auto &DL = IC.getDataLayout();
if (match(Cast, m_OneUse(m_ZExt(m_Value(X))))) {
- if (Constant *TruncC = getLosslessUnsignedTrunc(C, SrcTy, DL)) {
+ PreservedCastFlags Flags;
+ if (Constant *TruncC = getLosslessUnsignedTrunc(C, SrcTy, DL, &Flags)) {
// LogicOpc (zext X), C --> zext (LogicOpc X, C)
Value *NewOp = IC.Builder.CreateBinOp(LogicOpc, X, TruncC);
- return new ZExtInst(NewOp, DestTy);
+ auto *ZExt = new ZExtInst(NewOp, DestTy);
+ ZExt->setNonNeg(Flags.NNeg);
+ ZExt->andIRFlags(Cast);
+ return ZExt;
}
}
diff --git a/llvm/test/Transforms/InstCombine/or.ll b/llvm/test/Transforms/InstCombine/or.ll
index a5cc933278982..60a2c786c8bb4 100644
--- a/llvm/test/Transforms/InstCombine/or.ll
+++ b/llvm/test/Transforms/InstCombine/or.ll
@@ -2047,3 +2047,69 @@ define i1 @or_truncs(i8 %x) {
%or1 = or i1 %trunc1, %trunc2
ret i1 %or1
}
+
+define i32 @or_zext_constant(i8 %a) {
+; CHECK-LABEL: @or_zext_constant(
+; CHECK-NEXT: [[TMP1:%.*]] = or i8 [[A:%.*]], 1
+; CHECK-NEXT: [[AND:%.*]] = zext i8 [[TMP1]] to i32
+; CHECK-NEXT: ret i32 [[AND]]
+;
+ %zext = zext i8 %a to i32
+ %or = or i32 %zext, 1
+ ret i32 %or
+}
+
+define i32 @or_zext_minus_constant(i8 %a) {
+; CHECK-LABEL: @or_zext_minus_constant(
+; CHECK-NEXT: [[TMP1:%.*]] = or i8 [[A:%.*]], 1
+; CHECK-NEXT: [[OR:%.*]] = zext i8 [[TMP1]] to i32
+; CHECK-NEXT: ret i32 [[OR]]
+;
+ %zext = zext i8 %a to i32
+ %or = or i32 %zext, 1
+ ret i32 %or
+}
+
+define i32 @or_zext_nneg_constant(i8 %a) {
+; CHECK-LABEL: @or_zext_nneg_constant(
+; CHECK-NEXT: [[TMP1:%.*]] = or i8 [[A:%.*]], 9
+; CHECK-NEXT: [[AND:%.*]] = zext nneg i8 [[TMP1]] to i32
+; CHECK-NEXT: ret i32 [[AND]]
+;
+ %zext = zext nneg i8 %a to i32
+ %or = or i32 %zext, 9
+ ret i32 %or
+}
+
+define <4 x i32> @or_zext_nneg_constant_splat(<4 x i8> %a) {
+; CHECK-LABEL: @or_zext_nneg_constant_splat(
+; CHECK-NEXT: [[TMP1:%.*]] = or <4 x i8> [[A:%.*]], splat (i8 9)
+; CHECK-NEXT: [[OR:%.*]] = zext nneg <4 x i8> [[TMP1]] to <4 x i32>
+; CHECK-NEXT: ret <4 x i32> [[OR]]
+;
+ %zext = zext nneg <4 x i8> %a to <4 x i32>
+ %or = or <4 x i32> %zext, splat (i32 9)
+ ret <4 x i32> %or
+}
+
+define i32 @or_zext_nneg_minus_constant(i8 %a) {
+; CHECK-LABEL: @or_zext_nneg_minus_constant(
+; CHECK-NEXT: [[TMP1:%.*]] = or i8 [[A:%.*]], -9
+; CHECK-NEXT: [[ZEXT:%.*]] = sext i8 [[TMP1]] to i32
+; CHECK-NEXT: ret i32 [[ZEXT]]
+;
+ %zext = zext nneg i8 %a to i32
+ %or = or i32 %zext, -9
+ ret i32 %or
+}
+
+define <4 x i32> @or_zext_nneg_minus_constant_splat(<4 x i8> %a) {
+; CHECK-LABEL: @or_zext_nneg_minus_constant_splat(
+; CHECK-NEXT: [[TMP1:%.*]] = or <4 x i8> [[A:%.*]], splat (i8 -9)
+; CHECK-NEXT: [[OR:%.*]] = sext <4 x i8> [[TMP1]] to <4 x i32>
+; CHECK-NEXT: ret <4 x i32> [[OR]]
+;
+ %zext = zext nneg <4 x i8> %a to <4 x i32>
+ %or = or <4 x i32> %zext, splat (i32 -9)
+ ret <4 x i32> %or
+}
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dtcxzyw
reviewed
Sep 10, 2025
|
@zyw-bot mfuzz |
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/10/builds/13210 Here is the relevant piece of the build log for the reference |
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This patch makes use of the new public helper function to preserve nneg in
foldLogicCastConstant.