release/18.x: [InstCombine] Fix unexpected overwriting in foldSelectWithSRem (#89539)#89546
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tstellar merged 1 commit intollvm:release/18.xfrom Apr 23, 2024
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release/18.x: [InstCombine] Fix unexpected overwriting in foldSelectWithSRem (#89539)#89546tstellar merged 1 commit intollvm:release/18.xfrom
foldSelectWithSRem (#89539)#89546tstellar merged 1 commit intollvm:release/18.xfrom
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@nikic What do you think about merging this PR to the release branch? |
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@llvm/pr-subscribers-llvm-transforms Author: None (llvmbot) ChangesBackport 6309440 Requested by: @dtcxzyw Full diff: https://github.com/llvm/llvm-project/pull/89546.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 9f220ec003ec33..8cc7901cbac7fa 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -2606,7 +2606,7 @@ static Instruction *foldSelectWithSRem(SelectInst &SI, InstCombinerImpl &IC,
// %cnd = icmp slt i32 %rem, 0
// %add = add i32 %rem, %n
// %sel = select i1 %cnd, i32 %add, i32 %rem
- if (match(TrueVal, m_Add(m_Value(RemRes), m_Value(Remainder))) &&
+ if (match(TrueVal, m_Add(m_Specific(RemRes), m_Value(Remainder))) &&
match(RemRes, m_SRem(m_Value(Op), m_Specific(Remainder))) &&
IC.isKnownToBeAPowerOfTwo(Remainder, /*OrZero*/ true) &&
FalseVal == RemRes)
diff --git a/llvm/test/Transforms/InstCombine/select-divrem.ll b/llvm/test/Transforms/InstCombine/select-divrem.ll
index f007c53359ca5a..e0c460c37451db 100644
--- a/llvm/test/Transforms/InstCombine/select-divrem.ll
+++ b/llvm/test/Transforms/InstCombine/select-divrem.ll
@@ -343,3 +343,20 @@ define i32 @rem_euclid_pow2_false_arm_folded(i32 %n) {
%res = select i1 %nonneg, i32 %rem, i32 1
ret i32 %res
}
+
+define i8 @pr89516(i8 %n, i8 %x) {
+; CHECK-LABEL: @pr89516(
+; CHECK-NEXT: [[COND:%.*]] = icmp slt i8 [[X:%.*]], 0
+; CHECK-NEXT: [[POW2:%.*]] = shl nuw i8 1, [[N:%.*]]
+; CHECK-NEXT: [[SREM:%.*]] = srem i8 1, [[POW2]]
+; CHECK-NEXT: [[ADD:%.*]] = select i1 [[COND]], i8 [[POW2]], i8 0
+; CHECK-NEXT: [[RES:%.*]] = add nuw i8 [[SREM]], [[ADD]]
+; CHECK-NEXT: ret i8 [[RES]]
+;
+ %cond = icmp slt i8 %x, 0
+ %pow2 = shl nuw i8 1, %n
+ %srem = srem i8 1, %pow2
+ %add = add nuw i8 %srem, %pow2
+ %res = select i1 %cond, i8 %add, i8 %srem
+ ret i8 %res
+}
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…vm#89539) Fixes llvm#89516 (cherry picked from commit 6309440)
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Hi @dtcxzyw (or anyone else). If you would like to add a note about this fix in the release notes (completely optional). Please reply to this comment with a one or two sentence description of the fix. When you are done, please add the release:note label to this PR. |
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Backport 6309440
Requested by: @dtcxzyw