[llvm] [InstCombine] Improve coverage of `foldSelectValueEquivalence` for non-constants (PR #94719)
via llvm-commits
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Fri Jun 21 17:07:30 PDT 2024
https://github.com/goldsteinn updated https://github.com/llvm/llvm-project/pull/94719
>From 9895c9920f914bba5eb613842300d166fa238abc 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 | 186 ++++++++++++++++++
1 file changed, 186 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 0000000000000..ec82b1944f723
--- /dev/null
+++ b/llvm/test/Transforms/InstCombine/select-cmp-eq-op-fold.ll
@@ -0,0 +1,186 @@
+; 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_y_for_new_oneuse2(i8 %xx, i8 noundef %y, i8 %z, i8 %q) {
+; CHECK-LABEL: @replace_with_y_for_new_oneuse2(
+; CHECK-NEXT: [[X:%.*]] = mul i8 [[XX:%.*]], 13
+; CHECK-NEXT: [[CMP:%.*]] = icmp eq i8 [[X]], [[Y:%.*]]
+; CHECK-NEXT: [[ADD:%.*]] = add nuw i8 [[X]], [[Q:%.*]]
+; 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, %q
+ %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_new_oneuse2(i8 noundef %xx, i8 %yy, i8 %z, i8 %w, i8 %q) {
+; CHECK-LABEL: @replace_with_x_for_new_oneuse2(
+; 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 [[Y]], [[Q:%.*]]
+; 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 %q, %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_multiuse(i8 %x, i8 noundef %y, i8 %z) {
+; CHECK-LABEL: @replace_with_y_for_simple_binop_fail_multiuse(
+; 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: call void @use.i8(i8 [[MUL]])
+; 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
+ call void @use.i8(i8 %mul)
+ 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 78d332b67c125cdef3de7f2a4c25478a84011d8b Mon Sep 17 00:00:00 2001
From: Noah Goldstein <goldstein.w.n at gmail.com>
Date: Wed, 5 Jun 2024 11:35:13 -0500
Subject: [PATCH 2/2] [InstCombine] Improve coverage of
`foldSelectValueEquivalence` for non-constants
If f(Y) simplifies to Y. This requires that Y is not undef or poison.
This handles things like `or`/`min`/`max`/`select`/etc...
---
.../InstCombine/InstCombineSelect.cpp | 23 +++++++++++++------
.../InstCombine/select-cmp-eq-op-fold.ll | 6 ++---
2 files changed, 18 insertions(+), 11 deletions(-)
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
index fbac209c3da6f..840f2f2314754 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineSelect.cpp
@@ -1299,6 +1299,8 @@ Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel,
if (TrueVal == OldOp)
return nullptr;
+ bool NewOpNeverUndef = false;
+
if (Value *V = simplifyWithOpReplaced(TrueVal, OldOp, NewOp, SQ,
/* AllowRefinement=*/true)) {
// Need some guarantees about the new simplified op to ensure we don't inf
@@ -1308,13 +1310,20 @@ Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel,
isGuaranteedNotToBeUndef(V, SQ.AC, &Sel, &DT))
return replaceOperand(Sel, Swapped ? 2 : 1, V);
- // If NewOp is a constant and OldOp is not replace iff NewOp doesn't
- // contain and undef elements.
- if (match(NewOp, m_ImmConstant())) {
- if (isGuaranteedNotToBeUndef(NewOp, SQ.AC, &Sel, &DT))
- return replaceOperand(Sel, Swapped ? 2 : 1, V);
+ // We can't do any further replacement if NewOp may be undef.
+ if (!isGuaranteedNotToBeUndef(NewOp, SQ.AC, &Sel, &DT))
return nullptr;
- }
+
+ // If NewOp is a constant, replace.
+ if (match(NewOp, m_ImmConstant()))
+ return replaceOperand(Sel, Swapped ? 2 : 1, V);
+
+ // If we simplified the TrueArm -> NewOp then replace.
+ // This handles things like `select`/`min`/`max`/`or`/`and`/etc...
+ if (NewOp == V)
+ return replaceOperand(Sel, Swapped ? 2 : 1, V);
+
+ NewOpNeverUndef = true;
}
// Even if TrueVal does not simplify, we can directly replace a use of
@@ -1326,7 +1335,7 @@ Instruction *InstCombinerImpl::foldSelectValueEquivalence(SelectInst &Sel,
// FIXME: Support vectors.
if (OldOp == CmpLHS && match(NewOp, m_ImmConstant()) &&
!match(OldOp, m_ImmConstant()) && !Cmp.getType()->isVectorTy() &&
- isGuaranteedNotToBeUndef(NewOp, SQ.AC, &Sel, &DT))
+ (NewOpNeverUndef || isGuaranteedNotToBeUndef(NewOp, SQ.AC, &Sel, &DT)))
if (replaceInInstruction(TrueVal, OldOp, NewOp))
return &Sel;
return nullptr;
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 ec82b1944f723..2f2c2d3ec0250 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
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