[InstCombine] Use m_NotForbidPoison when folding (X u< Y) ? -1 : (~X + Y) --> uadd.sat(~X, Y)
#114345
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…~X + Y) --> uadd.sat(~X, Y)`
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@llvm/pr-subscribers-llvm-transforms Author: Yingwei Zheng (dtcxzyw) ChangesAlive2: https://alive2.llvm.org/ce/z/mTGCo- Fixes #113869. Full diff: https://github.com/llvm/llvm-project/pull/114345.diff 2 Files Affected:
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index c5f39a4c381ed1..b442e79377740d 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1051,7 +1051,7 @@ static Value *canonicalizeSaturatedAdd(ICmpInst *Cmp, Value *TVal, Value *FVal,
// Strictness of the comparison is irrelevant.
X = Cmp0;
Y = Cmp1;
- if (match(FVal, m_c_Add(m_Not(m_Specific(X)), m_Specific(Y)))) {
+ if (match(FVal, m_c_Add(m_NotForbidPoison(m_Specific(X)), m_Specific(Y)))) {
// (X u< Y) ? -1 : (~X + Y) --> uadd.sat(~X, Y)
// (X u< Y) ? -1 : (Y + ~X) --> uadd.sat(Y, ~X)
BinaryOperator *BO = cast<BinaryOperator>(FVal);
diff --git a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
index a88fd3cc21f1bc..af8a9314a08049 100644
--- a/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
+++ b/llvm/test/Transforms/InstCombine/saturating-add-sub.ll
@@ -1890,6 +1890,21 @@ define <2 x i32> @uadd_sat_not_ugt_commute_add(<2 x i32> %x, <2 x i32> %yp) {
ret <2 x i32> %r
}
+define <2 x i32> @uadd_sat_not_ugt_commute_add_partial_poison(<2 x i32> %x, <2 x i32> %yp) {
+; CHECK-LABEL: @uadd_sat_not_ugt_commute_add_partial_poison(
+; CHECK-NEXT: [[NOTX:%.*]] = xor <2 x i32> [[X:%.*]], <i32 -1, i32 poison>
+; CHECK-NEXT: [[A:%.*]] = add nuw <2 x i32> [[YP:%.*]], [[NOTX]]
+; CHECK-NEXT: [[C:%.*]] = icmp ugt <2 x i32> [[YP]], [[X]]
+; CHECK-NEXT: [[R:%.*]] = select <2 x i1> [[C]], <2 x i32> <i32 -1, i32 -1>, <2 x i32> [[A]]
+; CHECK-NEXT: ret <2 x i32> [[R]]
+;
+ %notx = xor <2 x i32> %x, <i32 -1, i32 poison>
+ %a = add nuw <2 x i32> %yp, %notx
+ %c = icmp ugt <2 x i32> %yp, %x
+ %r = select <2 x i1> %c, <2 x i32> <i32 -1, i32 -1>, <2 x i32> %a
+ ret <2 x i32> %r
+}
+
define i32 @uadd_sat_not_commute_select(i32 %x, i32 %y) {
; CHECK-LABEL: @uadd_sat_not_commute_select(
; CHECK-NEXT: [[NOTX:%.*]] = xor i32 [[X:%.*]], -1
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This was referenced Oct 31, 2024
goldsteinn
approved these changes
Oct 31, 2024
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LLVM Buildbot has detected a new failure on builder Full details are available at: https://lab.llvm.org/buildbot/#/builders/195/builds/478 Here is the relevant piece of the build log for the reference |
smallp-o-p
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Nov 3, 2024
…~X + Y) --> uadd.sat(~X, Y)` (llvm#114345) Alive2: https://alive2.llvm.org/ce/z/mTGCo- We cannot reuse `~X` if `m_AllOnes` matches a vector constant with some poison elts. An alternative solution is to create a new not instead of reusing `~X`. But it doesn't worth the effort because we need to add a one-use check. Fixes llvm#113869.
NoumanAmir657
pushed a commit
to NoumanAmir657/llvm-project
that referenced
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Nov 4, 2024
…~X + Y) --> uadd.sat(~X, Y)` (llvm#114345) Alive2: https://alive2.llvm.org/ce/z/mTGCo- We cannot reuse `~X` if `m_AllOnes` matches a vector constant with some poison elts. An alternative solution is to create a new not instead of reusing `~X`. But it doesn't worth the effort because we need to add a one-use check. Fixes llvm#113869.
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Alive2: https://alive2.llvm.org/ce/z/mTGCo-
We cannot reuse
~Xifm_AllOnesmatches a vector constant with some poison elts. An alternative solution is to create a new not instead of reusing~X. But it doesn't worth the effort because we need to add a one-use check.Fixes #113869.