[llvm] goldsteinn/cmp eq fold select op (PR #88298)
via llvm-commits
llvm-commits at lists.llvm.org
Wed Apr 10 10:12:37 PDT 2024
https://github.com/goldsteinn created https://github.com/llvm/llvm-project/pull/88298
- **[InstCombine] Add tests for expanding `foldSelectValueEquivalence`; NFC**
- **[InstCombine] Improve coverage of `foldSelectValueEquivalence`**
>From 116265128cf4b2e63dd86ffc67381db52a805f22 Mon Sep 17 00:00:00 2001
From: Noah Goldstein <goldstein.w.n at gmail.com>
Date: Wed, 10 Apr 2024 12:07:37 -0500
Subject: [PATCH 1/2] [InstCombine] Add tests for expanding
`foldSelectValueEquivalence`; NFC
---
.../InstCombine/select-cmp-eq-op-fold.ll | 139 ++++++++++++++++++
1 file changed, 139 insertions(+)
create mode 100644 llvm/test/Transforms/InstCombine/select-cmp-eq-op-fold.ll
diff --git a/llvm/test/Transforms/InstCombine/select-cmp-eq-op-fold.ll b/llvm/test/Transforms/InstCombine/select-cmp-eq-op-fold.ll
new file mode 100644
index 00000000000000..dbe5043a582ea0
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/select-cmp-eq-op-fold.ll
@@ -0,0 +1,139 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
+; RUN: opt < %s -passes=instcombine -S | FileCheck %s
+
+declare void @use.i1(i1)
+declare void @use.i8(i8)
+define i8 @replace_with_y_noundef(i8 %x, i8 noundef %y, i8 %z) {
+; CHECK-LABEL: @replace_with_y_noundef(
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: [[AND:%.*]] = and i8 [[X]], [[Y]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[AND]], i8 [[Z:%.*]]
+; CHECK-NEXT: ret i8 [[SEL]]
+;
+ %cmp = icmp eq i8 %x, %y
+ %and = and i8 %x, %y
+ %sel = select i1 %cmp, i8 %and, i8 %z
+ ret i8 %sel
+}
+
+define i8 @replace_with_x_noundef(i8 noundef %x, i8 %y, i8 %z) {
+; CHECK-LABEL: @replace_with_x_noundef(
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: call void @use.i1(i1 [[CMP]])
+; CHECK-NEXT: [[AND:%.*]] = or i8 [[X]], [[Y]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[Z:%.*]], i8 [[AND]]
+; CHECK-NEXT: ret i8 [[SEL]]
+;
+ %cmp = icmp ne i8 %x, %y
+ call void @use.i1(i1 %cmp)
+ %and = or i8 %x, %y
+ %sel = select i1 %cmp, i8 %z, i8 %and
+ ret i8 %sel
+}
+
+define i8 @replace_with_x_maybe_undef_fail(i8 %x, i8 %y, i8 %z) {
+; CHECK-LABEL: @replace_with_x_maybe_undef_fail(
+; CHECK-NEXT: [[CMP:%.*]] = icmp ne i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: call void @use.i1(i1 [[CMP]])
+; CHECK-NEXT: [[AND:%.*]] = or i8 [[X]], [[Y]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[Z:%.*]], i8 [[AND]]
+; CHECK-NEXT: ret i8 [[SEL]]
+;
+ %cmp = icmp ne i8 %x, %y
+ call void @use.i1(i1 %cmp)
+ %and = or i8 %x, %y
+ %sel = select i1 %cmp, i8 %z, i8 %and
+ ret i8 %sel
+}
+
+define i8 @replace_with_y_for_new_oneuse(i8 noundef %xx, i8 noundef %y, i8 %z) {
+; CHECK-LABEL: @replace_with_y_for_new_oneuse(
+; CHECK-NEXT: [[X:%.*]] = mul i8 [[XX:%.*]], 13
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X]], [[Y:%.*]]
+; CHECK-NEXT: [[ADD:%.*]] = add nuw i8 [[X]], [[Y]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[ADD]], i8 [[Z:%.*]]
+; CHECK-NEXT: ret i8 [[SEL]]
+;
+ %x = mul i8 %xx, 13
+ %cmp = icmp eq i8 %x, %y
+ %add = add nuw i8 %x, %y
+ %sel = select i1 %cmp, i8 %add, i8 %z
+ ret i8 %sel
+}
+
+define i8 @replace_with_x_for_new_oneuse(i8 noundef %xx, i8 noundef %yy, i8 %z, i8 %w) {
+; CHECK-LABEL: @replace_with_x_for_new_oneuse(
+; CHECK-NEXT: [[X:%.*]] = mul i8 [[XX:%.*]], 13
+; CHECK-NEXT: [[Y:%.*]] = add i8 [[YY:%.*]], [[W:%.*]]
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X]], [[Y]]
+; CHECK-NEXT: [[MUL:%.*]] = mul i8 [[X]], [[Y]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[MUL]], i8 [[Z:%.*]]
+; CHECK-NEXT: ret i8 [[SEL]]
+;
+ %x = mul i8 %xx, 13
+ %y = add i8 %yy, %w
+ %cmp = icmp eq i8 %x, %y
+ %mul = mul i8 %x, %y
+ %sel = select i1 %cmp, i8 %mul, i8 %z
+ ret i8 %sel
+}
+
+define i8 @replace_with_x_for_simple_binop(i8 noundef %xx, i8 %yy, i8 %z, i8 %w) {
+; CHECK-LABEL: @replace_with_x_for_simple_binop(
+; CHECK-NEXT: [[X:%.*]] = mul i8 [[XX:%.*]], 13
+; CHECK-NEXT: [[Y:%.*]] = add i8 [[YY:%.*]], [[W:%.*]]
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X]], [[Y]]
+; CHECK-NEXT: [[MUL:%.*]] = mul i8 [[X]], [[Y]]
+; CHECK-NEXT: call void @use.i8(i8 [[Y]])
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[MUL]], i8 [[Z:%.*]]
+; CHECK-NEXT: ret i8 [[SEL]]
+;
+ %x = mul i8 %xx, 13
+ %y = add i8 %yy, %w
+ %cmp = icmp eq i8 %x, %y
+ %mul = mul i8 %x, %y
+ call void @use.i8(i8 %y)
+ %sel = select i1 %cmp, i8 %mul, i8 %z
+ ret i8 %sel
+}
+
+define i8 @replace_with_none_for_new_oneuse_fail_maybe_undef(i8 %xx, i8 %y, i8 %z) {
+; CHECK-LABEL: @replace_with_none_for_new_oneuse_fail_maybe_undef(
+; CHECK-NEXT: [[X:%.*]] = mul i8 [[XX:%.*]], 13
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X]], [[Y:%.*]]
+; CHECK-NEXT: [[MUL:%.*]] = mul i8 [[X]], [[Y]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[MUL]], i8 [[Z:%.*]]
+; CHECK-NEXT: ret i8 [[SEL]]
+;
+ %x = mul i8 %xx, 13
+ %cmp = icmp eq i8 %x, %y
+ %mul = mul i8 %x, %y
+ %sel = select i1 %cmp, i8 %mul, i8 %z
+ ret i8 %sel
+}
+
+define i8 @replace_with_y_for_simple_binop(i8 %x, i8 noundef %y, i8 %z) {
+; CHECK-LABEL: @replace_with_y_for_simple_binop(
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: [[MUL:%.*]] = mul nsw i8 [[X]], [[Y]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[MUL]], i8 [[Z:%.*]]
+; CHECK-NEXT: ret i8 [[SEL]]
+;
+ %cmp = icmp eq i8 %x, %y
+ %mul = mul nsw i8 %x, %y
+ %sel = select i1 %cmp, i8 %mul, i8 %z
+ ret i8 %sel
+}
+
+define i8 @replace_with_y_for_simple_binop_fail(i8 %x, i8 noundef %y, i8 %z, i8 %q) {
+; CHECK-LABEL: @replace_with_y_for_simple_binop_fail(
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X:%.*]], [[Y:%.*]]
+; CHECK-NEXT: [[MUL:%.*]] = mul nsw i8 [[X]], [[Q:%.*]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[MUL]], i8 [[Z:%.*]]
+; CHECK-NEXT: ret i8 [[SEL]]
+;
+ %cmp = icmp eq i8 %x, %y
+ %mul = mul nsw i8 %x, %q
+ %sel = select i1 %cmp, i8 %mul, i8 %z
+ ret i8 %sel
+}
>From 3fb91443ee51ad99f9d9a5cb80956071a3ae4f43 Mon Sep 17 00:00:00 2001
From: Noah Goldstein <goldstein.w.n at gmail.com>
Date: Wed, 3 Apr 2024 23:56:56 -0500
Subject: [PATCH 2/2] [InstCombine] Improve coverage of
`foldSelectValueEquivalence`
1) We don't need the `noundef` check if the new simplification is a
constant.
2) There are a few more cases we can easily cover.
- If f(Y) simplifies to Y
- If replace X with Y makes X one-use (and make Y non one-use).
This cleans up regressions from folding multiuse:
`(icmp eq/ne (sub/xor x, y), 0)` -> `(icmp eq/ne x, y)`.
---
.../InstCombine/InstCombineSelect.cpp | 104 ++++++++++++++----
llvm/test/Transforms/InstCombine/abs-1.ll | 7 +-
.../InstCombine/select-cmp-eq-op-fold.ll | 14 +--
llvm/test/Transforms/InstCombine/select.ll | 6 +-
4 files changed, 90 insertions(+), 41 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index 2d78fcee1152d7..8a1eabef8d3589 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1285,22 +1285,76 @@ Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel,
Swapped = true;
}
- // In X == Y ? f(X) : Z, try to evaluate f(Y) and replace the operand.
- // Make sure Y cannot be undef though, as we might pick different values for
- // undef in the icmp and in f(Y). Additionally, take care to avoid replacing
- // X == Y ? X : Z with X == Y ? Y : Z, as that would lead to an infinite
- // replacement cycle.
Value *CmpLHS = Cmp.getOperand(0), *CmpRHS = Cmp.getOperand(1);
- if (TrueVal != CmpLHS &&
- isGuaranteedNotToBeUndefOrPoison(CmpRHS, SQ.AC, &Sel, &DT)) {
- if (Value *V = simplifyWithOpReplaced(TrueVal, CmpLHS, CmpRHS, SQ,
- /* AllowRefinement */ true))
- // Require either the replacement or the simplification result to be a
- // constant to avoid infinite loops.
- // FIXME: Make this check more precise.
- if (isa<Constant>(CmpRHS) || isa<Constant>(V))
- return replaceOperand(Sel, Swapped ? 2 : 1, V);
+ auto ReplaceLHSOpWithRHSOp = [&](Value *OldOp,
+ Value *NewOp) -> Instruction * {
+ // In X == Y ? f(X) : Z, try to evaluate f(Y) and replace the operand.
+ // Take care to avoid replacing X == Y ? X : Z with X == Y ? Y : Z, as that
+ // would lead to an infinite replacement cycle.
+ // If we will be able to evaluate f(Y) to a constant, we can allow undef,
+ // otherwise Y cannot be undef as we might pick different values for undef
+ // in the icmp and in f(Y).
+ if (TrueVal == OldOp)
+ return nullptr;
+
+ std::optional<bool> IsNeverUndefCached;
+ auto IsNeverUndef = [&](Value *Op) {
+ if (!IsNeverUndefCached.has_value())
+ IsNeverUndefCached =
+ isGuaranteedNotToBeUndefOrPoison(Op, SQ.AC, &Sel, &DT);
+ return *IsNeverUndefCached;
+ };
+ if (Value *V = simplifyWithOpReplaced(TrueVal, OldOp, NewOp, SQ,
+ /* AllowRefinement */ true)) {
+ // Need some gurantees about the new simplified op to ensure we don't inf
+ // loop.
+ // If we simplify to a constant, replace.
+ bool ShouldReplace = match(V, m_ImmConstant());
+ bool NeedsNoUndef = !ShouldReplace;
+ // Or replace if either NewOp is a constant
+ if (!ShouldReplace && match(NewOp, m_ImmConstant()))
+ ShouldReplace = true;
+ // Or if we end up simplifying f(Y) -> Y i.e: Old & New -> New & New ->
+ // New.
+ if (!ShouldReplace && V == NewOp)
+ ShouldReplace = true;
+
+ // Finally, if we are going to create a new one-use instruction, replace.
+ if (!ShouldReplace && isa<Instruction>(OldOp) && OldOp->hasNUses(2) &&
+ (!isa<Instruction>(NewOp) || !NewOp->hasOneUse()))
+ ShouldReplace = true;
+
+ // Unless we simplify the new instruction to a constant, need to ensure Y
+ // is not undef.
+ if (NeedsNoUndef && ShouldReplace)
+ ShouldReplace = IsNeverUndef(NewOp);
+
+ if (ShouldReplace)
+ return replaceOperand(Sel, Swapped ? 2 : 1, V);
+ }
+ // If we can't simplify, but we will either:
+ // 1) Create a new binop where both ops are NewOp i.e (add x, y) is "worse"
+ // than (add y, y) in this case, wait until the second call so we don't
+ // miss a one-use simplification.
+ // 2) Create a new one-use instruction.
+ // proceed.
+ else if (match(TrueVal, m_c_BinOp(m_Specific(OldOp), m_Specific(NewOp))) ||
+ (isa<Instruction>(TrueVal) && TrueVal->hasOneUse() &&
+ isa<Instruction>(OldOp) && OldOp->hasNUses(2) &&
+ (!isa<Instruction>(NewOp) || !NewOp->hasOneUse()))) {
+ auto *TrueIns = cast<Instruction>(TrueVal);
+ for (unsigned OpIdx = 0; OpIdx < TrueIns->getNumOperands(); ++OpIdx) {
+ if (TrueIns->getOperand(OpIdx) == OldOp) {
+ // Need to ensure NewOp is noundef (same reason as above). Wait until
+ // the last moment to do this check as it can be relatively expensive.
+ if (!IsNeverUndef(NewOp))
+ break;
+ TrueIns->setOperand(OpIdx, NewOp);
+ return replaceOperand(Sel, Swapped ? 2 : 1, TrueIns);
+ }
+ }
+ }
// Even if TrueVal does not simplify, we can directly replace a use of
// CmpLHS with CmpRHS, as long as the instruction is not used anywhere
// else and is safe to speculatively execute (we may end up executing it
@@ -1308,17 +1362,19 @@ Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel,
// undefined behavior). Only do this if CmpRHS is a constant, as
// profitability is not clear for other cases.
// FIXME: Support vectors.
- if (match(CmpRHS, m_ImmConstant()) && !match(CmpLHS, m_ImmConstant()) &&
- !Cmp.getType()->isVectorTy())
- if (replaceInInstruction(TrueVal, CmpLHS, CmpRHS))
+ if (OldOp == CmpLHS && match(NewOp, m_ImmConstant()) &&
+ !match(OldOp, m_ImmConstant()) && !Cmp.getType()->isVectorTy() &&
+ IsNeverUndef(NewOp))
+ if (replaceInInstruction(TrueVal, OldOp, NewOp))
return &Sel;
- }
- if (TrueVal != CmpRHS &&
- isGuaranteedNotToBeUndefOrPoison(CmpLHS, SQ.AC, &Sel, &DT))
- if (Value *V = simplifyWithOpReplaced(TrueVal, CmpRHS, CmpLHS, SQ,
- /* AllowRefinement */ true))
- if (isa<Constant>(CmpLHS) || isa<Constant>(V))
- return replaceOperand(Sel, Swapped ? 2 : 1, V);
+
+ return nullptr;
+ };
+
+ if (Instruction *R = ReplaceLHSOpWithRHSOp(CmpLHS, CmpRHS))
+ return R;
+ if (Instruction *R = ReplaceLHSOpWithRHSOp(CmpRHS, CmpLHS))
+ return R;
auto *FalseInst = dyn_cast<Instruction>(FalseVal);
if (!FalseInst)
diff --git a/llvm/test/Transforms/InstCombine/abs-1.ll b/llvm/test/Transforms/InstCombine/abs-1.ll
index 7355c560c820b2..71021d069f1350 100644
--- a/llvm/test/Transforms/InstCombine/abs-1.ll
+++ b/llvm/test/Transforms/InstCombine/abs-1.ll
@@ -852,11 +852,8 @@ define i8 @abs_diff_signed_sgt_nuw_extra_use3(i8 %a, i8 %b) {
define i32 @abs_diff_signed_slt_swap_wrong_pred1(i32 %a, i32 %b) {
; CHECK-LABEL: @abs_diff_signed_slt_swap_wrong_pred1(
-; CHECK-NEXT: [[CMP:%.*]] = icmp eq i32 [[A:%.*]], [[B:%.*]]
-; CHECK-NEXT: [[SUB_BA:%.*]] = sub nsw i32 [[B]], [[A]]
-; CHECK-NEXT: [[SUB_AB:%.*]] = sub nsw i32 [[A]], [[B]]
-; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i32 [[SUB_BA]], i32 [[SUB_AB]]
-; CHECK-NEXT: ret i32 [[COND]]
+; CHECK-NEXT: [[SUB_AB:%.*]] = sub nsw i32 [[A:%.*]], [[B:%.*]]
+; CHECK-NEXT: ret i32 [[SUB_AB]]
;
%cmp = icmp eq i32 %a, %b
%sub_ba = sub nsw i32 %b, %a
diff --git a/llvm/test/Transforms/InstCombine/select-cmp-eq-op-fold.ll b/llvm/test/Transforms/InstCombine/select-cmp-eq-op-fold.ll
index dbe5043a582ea0..e8ecd0c166ee1e 100644
--- a/llvm/test/Transforms/InstCombine/select-cmp-eq-op-fold.ll
+++ b/llvm/test/Transforms/InstCombine/select-cmp-eq-op-fold.ll
@@ -6,8 +6,7 @@ declare void @use.i8(i8)
define i8 @replace_with_y_noundef(i8 %x, i8 noundef %y, i8 %z) {
; CHECK-LABEL: @replace_with_y_noundef(
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT: [[AND:%.*]] = and i8 [[X]], [[Y]]
-; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[AND]], i8 [[Z:%.*]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[Y]], i8 [[Z:%.*]]
; CHECK-NEXT: ret i8 [[SEL]]
;
%cmp = icmp eq i8 %x, %y
@@ -20,8 +19,7 @@ define i8 @replace_with_x_noundef(i8 noundef %x, i8 %y, i8 %z) {
; CHECK-LABEL: @replace_with_x_noundef(
; CHECK-NEXT: [[CMP:%.*]] = icmp ne i8 [[X:%.*]], [[Y:%.*]]
; CHECK-NEXT: call void @use.i1(i1 [[CMP]])
-; CHECK-NEXT: [[AND:%.*]] = or i8 [[X]], [[Y]]
-; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[Z:%.*]], i8 [[AND]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[Z:%.*]], i8 [[X]]
; CHECK-NEXT: ret i8 [[SEL]]
;
%cmp = icmp ne i8 %x, %y
@@ -50,7 +48,7 @@ define i8 @replace_with_y_for_new_oneuse(i8 noundef %xx, i8 noundef %y, i8 %z) {
; CHECK-LABEL: @replace_with_y_for_new_oneuse(
; CHECK-NEXT: [[X:%.*]] = mul i8 [[XX:%.*]], 13
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X]], [[Y:%.*]]
-; CHECK-NEXT: [[ADD:%.*]] = add nuw i8 [[X]], [[Y]]
+; CHECK-NEXT: [[ADD:%.*]] = shl nuw i8 [[Y]], 1
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[ADD]], i8 [[Z:%.*]]
; CHECK-NEXT: ret i8 [[SEL]]
;
@@ -66,7 +64,7 @@ define i8 @replace_with_x_for_new_oneuse(i8 noundef %xx, i8 noundef %yy, i8 %z,
; CHECK-NEXT: [[X:%.*]] = mul i8 [[XX:%.*]], 13
; CHECK-NEXT: [[Y:%.*]] = add i8 [[YY:%.*]], [[W:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X]], [[Y]]
-; CHECK-NEXT: [[MUL:%.*]] = mul i8 [[X]], [[Y]]
+; CHECK-NEXT: [[MUL:%.*]] = mul i8 [[X]], [[X]]
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[MUL]], i8 [[Z:%.*]]
; CHECK-NEXT: ret i8 [[SEL]]
;
@@ -83,7 +81,7 @@ define i8 @replace_with_x_for_simple_binop(i8 noundef %xx, i8 %yy, i8 %z, i8 %w)
; CHECK-NEXT: [[X:%.*]] = mul i8 [[XX:%.*]], 13
; CHECK-NEXT: [[Y:%.*]] = add i8 [[YY:%.*]], [[W:%.*]]
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X]], [[Y]]
-; CHECK-NEXT: [[MUL:%.*]] = mul i8 [[X]], [[Y]]
+; CHECK-NEXT: [[MUL:%.*]] = mul i8 [[X]], [[X]]
; CHECK-NEXT: call void @use.i8(i8 [[Y]])
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[MUL]], i8 [[Z:%.*]]
; CHECK-NEXT: ret i8 [[SEL]]
@@ -115,7 +113,7 @@ define i8 @replace_with_none_for_new_oneuse_fail_maybe_undef(i8 %xx, i8 %y, i8 %
define i8 @replace_with_y_for_simple_binop(i8 %x, i8 noundef %y, i8 %z) {
; CHECK-LABEL: @replace_with_y_for_simple_binop(
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT: [[MUL:%.*]] = mul nsw i8 [[X]], [[Y]]
+; CHECK-NEXT: [[MUL:%.*]] = mul nsw i8 [[Y]], [[Y]]
; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[MUL]], i8 [[Z:%.*]]
; CHECK-NEXT: ret i8 [[SEL]]
;
diff --git a/llvm/test/Transforms/InstCombine/select.ll b/llvm/test/Transforms/InstCombine/select.ll
index 05fcf662352954..b577def762d53c 100644
--- a/llvm/test/Transforms/InstCombine/select.ll
+++ b/llvm/test/Transforms/InstCombine/select.ll
@@ -2787,8 +2787,7 @@ define <2 x i8> @select_replacement_add_eq_vec_nonuniform(<2 x i8> %x, <2 x i8>
define <2 x i8> @select_replacement_add_eq_vec_poison(<2 x i8> %x, <2 x i8> %y) {
; CHECK-LABEL: @select_replacement_add_eq_vec_poison(
; CHECK-NEXT: [[CMP:%.*]] = icmp eq <2 x i8> [[X:%.*]], <i8 1, i8 poison>
-; CHECK-NEXT: [[ADD:%.*]] = add <2 x i8> [[X]], <i8 1, i8 1>
-; CHECK-NEXT: [[SEL:%.*]] = select <2 x i1> [[CMP]], <2 x i8> [[ADD]], <2 x i8> [[Y:%.*]]
+; CHECK-NEXT: [[SEL:%.*]] = select <2 x i1> [[CMP]], <2 x i8> <i8 2, i8 poison>, <2 x i8> [[Y:%.*]]
; CHECK-NEXT: ret <2 x i8> [[SEL]]
;
%cmp = icmp eq <2 x i8> %x, <i8 1, i8 poison>
@@ -2839,8 +2838,7 @@ define i8 @select_replacement_sub_noundef(i8 %x, i8 noundef %y, i8 %z) {
define i8 @select_replacement_sub(i8 %x, i8 %y, i8 %z) {
; CHECK-LABEL: @select_replacement_sub(
; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X:%.*]], [[Y:%.*]]
-; CHECK-NEXT: [[SUB:%.*]] = sub i8 [[X]], [[Y]]
-; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 [[SUB]], i8 [[Z:%.*]]
+; CHECK-NEXT: [[SEL:%.*]] = select i1 [[CMP]], i8 0, i8 [[Z:%.*]]
; CHECK-NEXT: ret i8 [[SEL]]
;
%cmp = icmp eq i8 %x, %y
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