[llvm] [ConstraintElim] Extend `checkOrAndOpImpliedByOther` to handle and/or expr trees. (PR #117123)
Yingwei Zheng via llvm-commits
llvm-commits at lists.llvm.org
Thu Nov 21 00:36:00 PST 2024
https://github.com/dtcxzyw updated https://github.com/llvm/llvm-project/pull/117123
>From e48a70ea4d633a84748ea57b287b092d1d7fa7a0 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Thu, 21 Nov 2024 14:08:42 +0800
Subject: [PATCH 1/3] [ConstraintElim] Add pre-commit tests. NFC.
---
.../ConstraintElimination/unreachable-bb.ll | 36 +++++++++++++++++++
1 file changed, 36 insertions(+)
create mode 100644 llvm/test/Transforms/ConstraintElimination/unreachable-bb.ll
diff --git a/llvm/test/Transforms/ConstraintElimination/unreachable-bb.ll b/llvm/test/Transforms/ConstraintElimination/unreachable-bb.ll
new file mode 100644
index 00000000000000..4e65f5ad385b85
--- /dev/null
+++ b/llvm/test/Transforms/ConstraintElimination/unreachable-bb.ll
@@ -0,0 +1,36 @@
+; NOTE: Assertions have been autogenerated by utils/update_test_checks.py UTC_ARGS: --version 5
+; RUN: opt -p constraint-elimination -S %s | FileCheck %s
+
+define void @f(i32 noundef %v0, i32 noundef %v1, i32 noundef %v2) {
+; CHECK-LABEL: define void @f(
+; CHECK-SAME: i32 noundef [[V0:%.*]], i32 noundef [[V1:%.*]], i32 noundef [[V2:%.*]]) {
+; CHECK-NEXT: [[ENTRY:.*:]]
+; CHECK-NEXT: [[CMP0:%.*]] = icmp sge i32 [[V0]], [[V1]]
+; CHECK-NEXT: [[CMP1:%.*]] = icmp sge i32 [[V1]], [[V2]]
+; CHECK-NEXT: [[AND1:%.*]] = and i1 [[CMP0]], [[CMP1]]
+; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[V0]], [[V2]]
+; CHECK-NEXT: [[AND2:%.*]] = and i1 [[CMP2]], [[AND1]]
+; CHECK-NEXT: br i1 [[AND2]], label %[[IF_THEN:.*]], label %[[RETURN:.*]]
+; CHECK: [[IF_THEN]]:
+; CHECK-NEXT: call void @side_effect()
+; CHECK-NEXT: br label %[[RETURN]]
+; CHECK: [[RETURN]]:
+; CHECK-NEXT: ret void
+;
+entry:
+ %cmp0 = icmp sge i32 %v0, %v1
+ %cmp1 = icmp sge i32 %v1, %v2
+ %and1 = and i1 %cmp0, %cmp1
+ %cmp2 = icmp slt i32 %v0, %v2
+ %and2 = and i1 %cmp2, %and1
+ br i1 %and2, label %if.then, label %return
+
+if.then:
+ call void @side_effect()
+ br label %return
+
+return:
+ ret void
+}
+
+declare void @side_effect()
>From d5a87434037fb898cebe34f24acee3708036768b Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Thu, 21 Nov 2024 15:25:56 +0800
Subject: [PATCH 2/3] [ConstraintElim] Extend `checkOrAndOpImpliedByOther` to
handle and/or expr trees
---
.../Scalar/ConstraintElimination.cpp | 31 +++++++++++++------
.../Transforms/ConstraintElimination/or.ll | 2 +-
.../ConstraintElimination/unreachable-bb.ll | 2 +-
3 files changed, 23 insertions(+), 12 deletions(-)
diff --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
index d03e3a0570cd3f..45cb38ce042f05 100644
--- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -1511,18 +1511,29 @@ static bool checkOrAndOpImpliedByOther(
if (OtherOpIdx != 0 && isa<SelectInst>(JoinOp))
return false;
- if (!match(JoinOp->getOperand(OtherOpIdx),
- m_ICmp(Pred, m_Value(A), m_Value(B))))
- return false;
-
- // For OR, check if the negated condition implies CmpToCheck.
- bool IsOr = match(JoinOp, m_LogicalOr());
- if (IsOr)
- Pred = CmpInst::getInversePredicate(Pred);
-
// Optimistically add fact from first condition.
unsigned OldSize = DFSInStack.size();
- Info.addFact(Pred, A, B, CB.NumIn, CB.NumOut, DFSInStack);
+ // For OR, check if the negated condition implies CmpToCheck.
+ bool IsOr = match(JoinOp, m_LogicalOr());
+ SmallVector<Value *, 4> Worklist({JoinOp->getOperand(OtherOpIdx)});
+ while (!Worklist.empty()) {
+ Value *Val = Worklist.pop_back_val();
+ Value *LHS, *RHS;
+ ICmpInst::Predicate Pred;
+ if (match(Val, m_ICmp(Pred, m_Value(LHS), m_Value(RHS)))) {
+ if (IsOr)
+ Pred = CmpInst::getInversePredicate(Pred);
+ Info.addFact(Pred, LHS, RHS, CB.NumIn, CB.NumOut, DFSInStack);
+ continue;
+ }
+ if (IsOr ? match(Val, m_LogicalOr(m_Value(LHS), m_Value(RHS)))
+ : match(Val, m_LogicalAnd(m_Value(LHS), m_Value(RHS)))) {
+ Worklist.push_back(LHS);
+ Worklist.push_back(RHS);
+ continue;
+ }
+ return false;
+ }
if (OldSize == DFSInStack.size())
return false;
diff --git a/llvm/test/Transforms/ConstraintElimination/or.ll b/llvm/test/Transforms/ConstraintElimination/or.ll
index 01b8ca973efa56..b401d6f1813695 100644
--- a/llvm/test/Transforms/ConstraintElimination/or.ll
+++ b/llvm/test/Transforms/ConstraintElimination/or.ll
@@ -124,7 +124,7 @@ define i1 @test_or_chain_ule_1(i4 %x, i4 %y, i4 %z, i4 %a, i4 %b) {
; CHECK-NEXT: [[C_3:%.*]] = icmp ule i4 2, [[X]]
; CHECK-NEXT: [[C_4:%.*]] = icmp ule i4 2, [[A:%.*]]
; CHECK-NEXT: [[OR_1:%.*]] = or i1 [[C_1]], [[C_2]]
-; CHECK-NEXT: [[OR_2:%.*]] = or i1 [[OR_1]], [[C_3]]
+; CHECK-NEXT: [[OR_2:%.*]] = or i1 [[OR_1]], true
; CHECK-NEXT: [[OR_3:%.*]] = or i1 [[C_4]], [[OR_2]]
; CHECK-NEXT: br i1 [[OR_3]], label [[BB1:%.*]], label [[EXIT:%.*]]
; CHECK: bb1:
diff --git a/llvm/test/Transforms/ConstraintElimination/unreachable-bb.ll b/llvm/test/Transforms/ConstraintElimination/unreachable-bb.ll
index 4e65f5ad385b85..a3cea2e3b7889d 100644
--- a/llvm/test/Transforms/ConstraintElimination/unreachable-bb.ll
+++ b/llvm/test/Transforms/ConstraintElimination/unreachable-bb.ll
@@ -9,7 +9,7 @@ define void @f(i32 noundef %v0, i32 noundef %v1, i32 noundef %v2) {
; CHECK-NEXT: [[CMP1:%.*]] = icmp sge i32 [[V1]], [[V2]]
; CHECK-NEXT: [[AND1:%.*]] = and i1 [[CMP0]], [[CMP1]]
; CHECK-NEXT: [[CMP2:%.*]] = icmp slt i32 [[V0]], [[V2]]
-; CHECK-NEXT: [[AND2:%.*]] = and i1 [[CMP2]], [[AND1]]
+; CHECK-NEXT: [[AND2:%.*]] = and i1 false, [[AND1]]
; CHECK-NEXT: br i1 [[AND2]], label %[[IF_THEN:.*]], label %[[RETURN:.*]]
; CHECK: [[IF_THEN]]:
; CHECK-NEXT: call void @side_effect()
>From a90be3ac98e38415894bea1f2e68c475954b6ec3 Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Thu, 21 Nov 2024 16:34:47 +0800
Subject: [PATCH 3/3] [ConstraintElim] Fix miscompilation
---
.../Scalar/ConstraintElimination.cpp | 22 +++++++++----------
1 file changed, 10 insertions(+), 12 deletions(-)
diff --git a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
index 45cb38ce042f05..31e9691ecde4c7 100644
--- a/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
+++ b/llvm/lib/Transforms/Scalar/ConstraintElimination.cpp
@@ -1498,9 +1498,6 @@ static bool checkOrAndOpImpliedByOther(
FactOrCheck &CB, ConstraintInfo &Info, Module *ReproducerModule,
SmallVectorImpl<ReproducerEntry> &ReproducerCondStack,
SmallVectorImpl<StackEntry> &DFSInStack) {
-
- CmpInst::Predicate Pred;
- Value *A, *B;
Instruction *JoinOp = CB.getContextInst();
CmpInst *CmpToCheck = cast<CmpInst>(CB.getInstructionToSimplify());
unsigned OtherOpIdx = JoinOp->getOperand(0) == CmpToCheck ? 1 : 0;
@@ -1513,6 +1510,14 @@ static bool checkOrAndOpImpliedByOther(
// Optimistically add fact from first condition.
unsigned OldSize = DFSInStack.size();
+ auto InfoRestorer = make_scope_exit([&]() {
+ // Remove entries again.
+ while (OldSize < DFSInStack.size()) {
+ StackEntry E = DFSInStack.back();
+ removeEntryFromStack(E, Info, ReproducerModule, ReproducerCondStack,
+ DFSInStack);
+ }
+ });
// For OR, check if the negated condition implies CmpToCheck.
bool IsOr = match(JoinOp, m_LogicalOr());
SmallVector<Value *, 4> Worklist({JoinOp->getOperand(OtherOpIdx)});
@@ -1537,7 +1542,6 @@ static bool checkOrAndOpImpliedByOther(
if (OldSize == DFSInStack.size())
return false;
- bool Changed = false;
// Check if the second condition can be simplified now.
if (auto ImpliedCondition =
checkCondition(CmpToCheck->getPredicate(), CmpToCheck->getOperand(0),
@@ -1551,16 +1555,10 @@ static bool checkOrAndOpImpliedByOther(
1 - OtherOpIdx,
ConstantInt::getBool(JoinOp->getType(), *ImpliedCondition));
- Changed = true;
+ return true;
}
- // Remove entries again.
- while (OldSize < DFSInStack.size()) {
- StackEntry E = DFSInStack.back();
- removeEntryFromStack(E, Info, ReproducerModule, ReproducerCondStack,
- DFSInStack);
- }
- return Changed;
+ return false;
}
void ConstraintInfo::addFact(CmpInst::Predicate Pred, Value *A, Value *B,
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