[llvm] Remove redundant assumes (PR #123518)
Florian Hahn via llvm-commits
llvm-commits at lists.llvm.org
Sun Jan 19 08:40:28 PST 2025
https://github.com/fhahn created https://github.com/llvm/llvm-project/pull/123518
ValueTracking.
>From 28fe0189640a16e26f8676b0c44bc3e598ed009c Mon Sep 17 00:00:00 2001
From: Florian Hahn <flo at fhahn.com>
Date: Sat, 18 Jan 2025 20:29:00 +0000
Subject: [PATCH] Remove redundant assumes
ValueTracking.
---
llvm/include/llvm/Analysis/SimplifyQuery.h | 7 +++
llvm/include/llvm/Analysis/ValueTracking.h | 4 +-
llvm/lib/Analysis/ScalarEvolution.cpp | 2 +-
llvm/lib/Analysis/ValueTracking.cpp | 53 ++++++++++++++-----
.../Target/ARM/MVEGatherScatterLowering.cpp | 4 +-
.../RISCV/RISCVGatherScatterLowering.cpp | 4 +-
.../Transforms/Scalar/LoopStrengthReduce.cpp | 2 +-
7 files changed, 57 insertions(+), 19 deletions(-)
diff --git a/llvm/include/llvm/Analysis/SimplifyQuery.h b/llvm/include/llvm/Analysis/SimplifyQuery.h
index e8f43c8c2e91f8..902e2ab7bb4312 100644
--- a/llvm/include/llvm/Analysis/SimplifyQuery.h
+++ b/llvm/include/llvm/Analysis/SimplifyQuery.h
@@ -18,6 +18,7 @@ class AssumptionCache;
class DomConditionCache;
class DominatorTree;
class TargetLibraryInfo;
+class GetElementPtrInst;
/// InstrInfoQuery provides an interface to query additional information for
/// instructions like metadata or keywords like nsw, which provides conservative
@@ -45,6 +46,12 @@ struct InstrInfoQuery {
return false;
}
+ template <class InstT> bool isInBounds(const InstT *Op) const {
+ if (UseInstrInfo)
+ return Op->isInBounds();
+ return false;
+ }
+
bool isExact(const BinaryOperator *Op) const {
if (UseInstrInfo && isa<PossiblyExactOperator>(Op))
return cast<PossiblyExactOperator>(Op)->isExact();
diff --git a/llvm/include/llvm/Analysis/ValueTracking.h b/llvm/include/llvm/Analysis/ValueTracking.h
index b4918c2d1e8a18..e4978a4ef476a8 100644
--- a/llvm/include/llvm/Analysis/ValueTracking.h
+++ b/llvm/include/llvm/Analysis/ValueTracking.h
@@ -1241,11 +1241,11 @@ canConvertToMinOrMaxIntrinsic(ArrayRef<Value *> VL);
///
/// NOTE: This is intentional simple. If you want the ability to analyze
/// non-trivial loop conditons, see ScalarEvolution instead.
-bool matchSimpleRecurrence(const PHINode *P, BinaryOperator *&BO, Value *&Start,
+bool matchSimpleRecurrence(const PHINode *P, Instruction *&BO, Value *&Start,
Value *&Step);
/// Analogous to the above, but starting from the binary operator
-bool matchSimpleRecurrence(const BinaryOperator *I, PHINode *&P, Value *&Start,
+bool matchSimpleRecurrence(const Instruction *I, PHINode *&P, Value *&Start,
Value *&Step);
/// Return true if RHS is known to be implied true by LHS. Return false if
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 7673c354817579..f3282424d9d5e7 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -6465,7 +6465,7 @@ getRangeForUnknownRecurrence(const SCEVUnknown *U) {
if (!DT.isReachableFromEntry(Pred))
return FullSet;
- BinaryOperator *BO;
+ Instruction*BO;
Value *Start, *Step;
if (!matchSimpleRecurrence(P, BO, Start, Step))
return FullSet;
diff --git a/llvm/lib/Analysis/ValueTracking.cpp b/llvm/lib/Analysis/ValueTracking.cpp
index 6e2f0ebde9bb6c..e46dec42738211 100644
--- a/llvm/lib/Analysis/ValueTracking.cpp
+++ b/llvm/lib/Analysis/ValueTracking.cpp
@@ -1489,7 +1489,7 @@ static void computeKnownBitsFromOperator(const Operator *I,
}
case Instruction::PHI: {
const PHINode *P = cast<PHINode>(I);
- BinaryOperator *BO = nullptr;
+ Instruction *BO = nullptr;
Value *R = nullptr, *L = nullptr;
if (matchSimpleRecurrence(P, BO, R, L)) {
// Handle the case of a simple two-predecessor recurrence PHI.
@@ -1553,6 +1553,7 @@ static void computeKnownBitsFromOperator(const Operator *I,
case Instruction::Sub:
case Instruction::And:
case Instruction::Or:
+ case Instruction::GetElementPtr:
case Instruction::Mul: {
// Change the context instruction to the "edge" that flows into the
// phi. This is important because that is where the value is actually
@@ -1571,6 +1572,10 @@ static void computeKnownBitsFromOperator(const Operator *I,
// We need to take the minimum number of known bits
KnownBits Known3(BitWidth);
+ if (BitWidth != getBitWidth(L->getType(), Q.DL)) {
+ assert(isa<GetElementPtrInst>(BO));
+ break;
+ }
RecQ.CxtI = LInst;
computeKnownBits(L, DemandedElts, Known3, Depth + 1, RecQ);
@@ -1578,7 +1583,9 @@ static void computeKnownBitsFromOperator(const Operator *I,
Known3.countMinTrailingZeros()));
auto *OverflowOp = dyn_cast<OverflowingBinaryOperator>(BO);
- if (!OverflowOp || !Q.IIQ.hasNoSignedWrap(OverflowOp))
+ if (!isa<GetElementPtrInst, OverflowingBinaryOperator>(BO))
+ break;
+ if ((isa<GetElementPtrInst>(BO) && !Q.IIQ.isInBounds(cast<GetElementPtrInst>(BO))) || (OverflowOp && !Q.IIQ.hasNoSignedWrap(OverflowOp)))
break;
switch (Opcode) {
@@ -1737,6 +1744,14 @@ static void computeKnownBitsFromOperator(const Operator *I,
Known.resetAll();
}
}
+
+ // Aligned pointers have trailing zeros - refine Known.Zero set
+ if (isa<PointerType>(CB->getType())) {
+ Align Alignment = CB->getPointerAlignment(Q.DL);
+ Known.Zero.setLowBits(Log2(Alignment));
+ }
+
+
if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(I)) {
switch (II->getIntrinsicID()) {
default:
@@ -2270,7 +2285,7 @@ void computeKnownBits(const Value *V, const APInt &DemandedElts,
/// always a power of two (or zero).
static bool isPowerOfTwoRecurrence(const PHINode *PN, bool OrZero,
unsigned Depth, SimplifyQuery &Q) {
- BinaryOperator *BO = nullptr;
+ Instruction *BO = nullptr;
Value *Start = nullptr, *Step = nullptr;
if (!matchSimpleRecurrence(PN, BO, Start, Step))
return false;
@@ -2308,7 +2323,7 @@ static bool isPowerOfTwoRecurrence(const PHINode *PN, bool OrZero,
// Divisor must be a power of two.
// If OrZero is false, cannot guarantee induction variable is non-zero after
// division, same for Shr, unless it is exact division.
- return (OrZero || Q.IIQ.isExact(BO)) &&
+ return (OrZero || Q.IIQ.isExact(cast<BinaryOperator>(BO))) &&
isKnownToBeAPowerOfTwo(Step, false, Depth, Q);
case Instruction::Shl:
return OrZero || Q.IIQ.hasNoUnsignedWrap(BO) || Q.IIQ.hasNoSignedWrap(BO);
@@ -2317,7 +2332,7 @@ static bool isPowerOfTwoRecurrence(const PHINode *PN, bool OrZero,
return false;
[[fallthrough]];
case Instruction::LShr:
- return OrZero || Q.IIQ.isExact(BO);
+ return OrZero || Q.IIQ.isExact(cast<BinaryOperator>(BO));
default:
return false;
}
@@ -2727,7 +2742,7 @@ static bool rangeMetadataExcludesValue(const MDNode* Ranges, const APInt& Value)
/// Try to detect a recurrence that monotonically increases/decreases from a
/// non-zero starting value. These are common as induction variables.
static bool isNonZeroRecurrence(const PHINode *PN) {
- BinaryOperator *BO = nullptr;
+ Instruction *BO = nullptr;
Value *Start = nullptr, *Step = nullptr;
const APInt *StartC, *StepC;
if (!matchSimpleRecurrence(PN, BO, Start, Step) ||
@@ -3560,9 +3575,9 @@ getInvertibleOperands(const Operator *Op1,
// If PN1 and PN2 are both recurrences, can we prove the entire recurrences
// are a single invertible function of the start values? Note that repeated
// application of an invertible function is also invertible
- BinaryOperator *BO1 = nullptr;
+ Instruction *BO1 = nullptr;
Value *Start1 = nullptr, *Step1 = nullptr;
- BinaryOperator *BO2 = nullptr;
+ Instruction *BO2 = nullptr;
Value *Start2 = nullptr, *Step2 = nullptr;
if (PN1->getParent() != PN2->getParent() ||
!matchSimpleRecurrence(PN1, BO1, Start1, Step1) ||
@@ -9197,7 +9212,7 @@ llvm::canConvertToMinOrMaxIntrinsic(ArrayRef<Value *> VL) {
return {Intrinsic::not_intrinsic, false};
}
-bool llvm::matchSimpleRecurrence(const PHINode *P, BinaryOperator *&BO,
+bool llvm::matchSimpleRecurrence(const PHINode *P, Instruction *&BO,
Value *&Start, Value *&Step) {
// Handle the case of a simple two-predecessor recurrence PHI.
// There's a lot more that could theoretically be done here, but
@@ -9208,7 +9223,7 @@ bool llvm::matchSimpleRecurrence(const PHINode *P, BinaryOperator *&BO,
for (unsigned i = 0; i != 2; ++i) {
Value *L = P->getIncomingValue(i);
Value *R = P->getIncomingValue(!i);
- auto *LU = dyn_cast<BinaryOperator>(L);
+ auto *LU = dyn_cast<Instruction>(L);
if (!LU)
continue;
unsigned Opcode = LU->getOpcode();
@@ -9240,6 +9255,20 @@ bool llvm::matchSimpleRecurrence(const PHINode *P, BinaryOperator *&BO,
break; // Match!
}
+ case Instruction::GetElementPtr: {
+ if (LU->getNumOperands() != 2 || !cast<GetElementPtrInst>(L)->getSourceElementType()->isIntegerTy(8))
+ continue;
+
+ Value *LL = LU->getOperand(0);
+ Value *LR = LU->getOperand(1);
+ // Find a recurrence.
+ if (LL == P) {
+ // Found a match
+ L = LR;
+ break;
+ }
+ continue;
+ }
};
// We have matched a recurrence of the form:
@@ -9256,9 +9285,9 @@ bool llvm::matchSimpleRecurrence(const PHINode *P, BinaryOperator *&BO,
return false;
}
-bool llvm::matchSimpleRecurrence(const BinaryOperator *I, PHINode *&P,
+bool llvm::matchSimpleRecurrence(const Instruction *I, PHINode *&P,
Value *&Start, Value *&Step) {
- BinaryOperator *BO = nullptr;
+ Instruction *BO = nullptr;
P = dyn_cast<PHINode>(I->getOperand(0));
if (!P)
P = dyn_cast<PHINode>(I->getOperand(1));
diff --git a/llvm/lib/Target/ARM/MVEGatherScatterLowering.cpp b/llvm/lib/Target/ARM/MVEGatherScatterLowering.cpp
index 7efd2989aa7fa4..b4b3536ddcf21f 100644
--- a/llvm/lib/Target/ARM/MVEGatherScatterLowering.cpp
+++ b/llvm/lib/Target/ARM/MVEGatherScatterLowering.cpp
@@ -1025,10 +1025,10 @@ bool MVEGatherScatterLowering::optimiseOffsets(Value *Offsets, BasicBlock *BB,
return false;
// We're looking for a simple add recurrence.
- BinaryOperator *IncInstruction;
+ Instruction *IncInstruction;
Value *Start, *IncrementPerRound;
if (!matchSimpleRecurrence(Phi, IncInstruction, Start, IncrementPerRound) ||
- IncInstruction->getOpcode() != Instruction::Add)
+ IncInstruction->getOpcode() != Instruction::Add || !isa<BinaryOperator>(IncInstruction))
return false;
int IncrementingBlock = Phi->getIncomingValue(0) == IncInstruction ? 0 : 1;
diff --git a/llvm/lib/Target/RISCV/RISCVGatherScatterLowering.cpp b/llvm/lib/Target/RISCV/RISCVGatherScatterLowering.cpp
index 39c0af79859719..59f1d8292908b6 100644
--- a/llvm/lib/Target/RISCV/RISCVGatherScatterLowering.cpp
+++ b/llvm/lib/Target/RISCV/RISCVGatherScatterLowering.cpp
@@ -203,9 +203,11 @@ bool RISCVGatherScatterLowering::matchStridedRecurrence(Value *Index, Loop *L,
return false;
Value *Step, *Start;
- if (!matchSimpleRecurrence(Phi, Inc, Start, Step) ||
+ Instruction *Inc2;
+ if (!matchSimpleRecurrence(Phi, Inc2, Start, Step) ||
Inc->getOpcode() != Instruction::Add)
return false;
+ Inc = cast<BinaryOperator>(Inc2);
assert(Phi->getNumIncomingValues() == 2 && "Expected 2 operand phi.");
unsigned IncrementingBlock = Phi->getIncomingValue(0) == Inc ? 0 : 1;
assert(Phi->getIncomingValue(IncrementingBlock) == Inc &&
diff --git a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index d51d043f9f0d9b..cb32a8ff07cd14 100644
--- a/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -6108,7 +6108,7 @@ void LSRInstance::ImplementSolution(
// chosen a non-optimal result for the actual schedule. (And yes, this
// scheduling decision does impact later codegen.)
for (PHINode &PN : L->getHeader()->phis()) {
- BinaryOperator *BO = nullptr;
+ Instruction *BO = nullptr;
Value *Start = nullptr, *Step = nullptr;
if (!matchSimpleRecurrence(&PN, BO, Start, Step))
continue;
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