[llvm] 98a6b6e - [SCEV] Improve code using SCEVPatternMatch (NFC) (#163946)
via llvm-commits
llvm-commits at lists.llvm.org
Fri Oct 17 06:49:56 PDT 2025
Author: Ramkumar Ramachandra
Date: 2025-10-17T14:49:52+01:00
New Revision: 98a6b6e78ae4cf53329ef5b5464a055fed259014
URL: https://github.com/llvm/llvm-project/commit/98a6b6e78ae4cf53329ef5b5464a055fed259014
DIFF: https://github.com/llvm/llvm-project/commit/98a6b6e78ae4cf53329ef5b5464a055fed259014.diff
LOG: [SCEV] Improve code using SCEVPatternMatch (NFC) (#163946)
Added:
Modified:
llvm/include/llvm/Analysis/ScalarEvolutionPatternMatch.h
llvm/lib/Analysis/ScalarEvolution.cpp
Removed:
################################################################################
diff --git a/llvm/include/llvm/Analysis/ScalarEvolutionPatternMatch.h b/llvm/include/llvm/Analysis/ScalarEvolutionPatternMatch.h
index 68198ec9b8a9f..9354eef98fe91 100644
--- a/llvm/include/llvm/Analysis/ScalarEvolutionPatternMatch.h
+++ b/llvm/include/llvm/Analysis/ScalarEvolutionPatternMatch.h
@@ -256,6 +256,18 @@ m_scev_UDiv(const Op0_t &Op0, const Op1_t &Op1) {
return m_scev_Binary<SCEVUDivExpr>(Op0, Op1);
}
+template <typename Op0_t, typename Op1_t>
+inline SCEVBinaryExpr_match<SCEVSMaxExpr, Op0_t, Op1_t>
+m_scev_SMax(const Op0_t &Op0, const Op1_t &Op1) {
+ return m_scev_Binary<SCEVSMaxExpr>(Op0, Op1);
+}
+
+template <typename Op0_t, typename Op1_t>
+inline SCEVBinaryExpr_match<SCEVMinMaxExpr, Op0_t, Op1_t>
+m_scev_MinMax(const Op0_t &Op0, const Op1_t &Op1) {
+ return m_scev_Binary<SCEVMinMaxExpr>(Op0, Op1);
+}
+
/// Match unsigned remainder pattern.
/// Matches patterns generated by getURemExpr.
template <typename Op0_t, typename Op1_t> struct SCEVURem_match {
diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 442b9d1e8a30e..e06b0956d4c82 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -1840,19 +1840,19 @@ const SCEV *ScalarEvolution::getZeroExtendExprImpl(const SCEV *Op, Type *Ty,
// = zext((2^K * (trunc X to i{N-K}))<nuw>) to iM
// = (2^K * (zext(trunc X to i{N-K}) to iM))<nuw>.
//
- if (SM->getNumOperands() == 2)
- if (auto *MulLHS = dyn_cast<SCEVConstant>(SM->getOperand(0)))
- if (MulLHS->getAPInt().isPowerOf2())
- if (auto *TruncRHS = dyn_cast<SCEVTruncateExpr>(SM->getOperand(1))) {
- int NewTruncBits = getTypeSizeInBits(TruncRHS->getType()) -
- MulLHS->getAPInt().logBase2();
- Type *NewTruncTy = IntegerType::get(getContext(), NewTruncBits);
- return getMulExpr(
- getZeroExtendExpr(MulLHS, Ty),
- getZeroExtendExpr(
- getTruncateExpr(TruncRHS->getOperand(), NewTruncTy), Ty),
- SCEV::FlagNUW, Depth + 1);
- }
+ const APInt *C;
+ const SCEV *TruncRHS;
+ if (match(SM,
+ m_scev_Mul(m_scev_APInt(C), m_scev_Trunc(m_SCEV(TruncRHS)))) &&
+ C->isPowerOf2()) {
+ int NewTruncBits =
+ getTypeSizeInBits(SM->getOperand(1)->getType()) - C->logBase2();
+ Type *NewTruncTy = IntegerType::get(getContext(), NewTruncBits);
+ return getMulExpr(
+ getZeroExtendExpr(SM->getOperand(0), Ty),
+ getZeroExtendExpr(getTruncateExpr(TruncRHS, NewTruncTy), Ty),
+ SCEV::FlagNUW, Depth + 1);
+ }
}
// zext(umin(x, y)) -> umin(zext(x), zext(y))
@@ -3144,20 +3144,19 @@ const SCEV *ScalarEvolution::getMulExpr(SmallVectorImpl<const SCEV *> &Ops,
if (const SCEVConstant *LHSC = dyn_cast<SCEVConstant>(Ops[0])) {
if (Ops.size() == 2) {
// C1*(C2+V) -> C1*C2 + C1*V
- if (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[1]))
- // If any of Add's ops are Adds or Muls with a constant, apply this
- // transformation as well.
- //
- // TODO: There are some cases where this transformation is not
- // profitable; for example, Add = (C0 + X) * Y + Z. Maybe the scope of
- // this transformation should be narrowed down.
- if (Add->getNumOperands() == 2 && containsConstantInAddMulChain(Add)) {
- const SCEV *LHS = getMulExpr(LHSC, Add->getOperand(0),
- SCEV::FlagAnyWrap, Depth + 1);
- const SCEV *RHS = getMulExpr(LHSC, Add->getOperand(1),
- SCEV::FlagAnyWrap, Depth + 1);
- return getAddExpr(LHS, RHS, SCEV::FlagAnyWrap, Depth + 1);
- }
+ // If any of Add's ops are Adds or Muls with a constant, apply this
+ // transformation as well.
+ //
+ // TODO: There are some cases where this transformation is not
+ // profitable; for example, Add = (C0 + X) * Y + Z. Maybe the scope of
+ // this transformation should be narrowed down.
+ const SCEV *Op0, *Op1;
+ if (match(Ops[1], m_scev_Add(m_SCEV(Op0), m_SCEV(Op1))) &&
+ containsConstantInAddMulChain(Ops[1])) {
+ const SCEV *LHS = getMulExpr(LHSC, Op0, SCEV::FlagAnyWrap, Depth + 1);
+ const SCEV *RHS = getMulExpr(LHSC, Op1, SCEV::FlagAnyWrap, Depth + 1);
+ return getAddExpr(LHS, RHS, SCEV::FlagAnyWrap, Depth + 1);
+ }
if (Ops[0]->isAllOnesValue()) {
// If we have a mul by -1 of an add, try distributing the -1 among the
@@ -3578,20 +3577,12 @@ const SCEV *ScalarEvolution::getUDivExpr(const SCEV *LHS,
}
// ((-C + (C smax %x)) /u %x) evaluates to zero, for any positive constant C.
- if (const auto *AE = dyn_cast<SCEVAddExpr>(LHS);
- AE && AE->getNumOperands() == 2) {
- if (const auto *VC = dyn_cast<SCEVConstant>(AE->getOperand(0))) {
- const APInt &NegC = VC->getAPInt();
- if (NegC.isNegative() && !NegC.isMinSignedValue()) {
- const auto *MME = dyn_cast<SCEVSMaxExpr>(AE->getOperand(1));
- if (MME && MME->getNumOperands() == 2 &&
- isa<SCEVConstant>(MME->getOperand(0)) &&
- cast<SCEVConstant>(MME->getOperand(0))->getAPInt() == -NegC &&
- MME->getOperand(1) == RHS)
- return getZero(LHS->getType());
- }
- }
- }
+ const APInt *NegC, *C;
+ if (match(LHS,
+ m_scev_Add(m_scev_APInt(NegC),
+ m_scev_SMax(m_scev_APInt(C), m_scev_Specific(RHS)))) &&
+ NegC->isNegative() && !NegC->isMinSignedValue() && *C == -*NegC)
+ return getZero(LHS->getType());
// TODO: Generalize to handle any common factors.
// udiv (mul nuw a, vscale), (mul nuw b, vscale) --> udiv a, b
@@ -10791,19 +10782,15 @@ static bool HasSameValue(const SCEV *A, const SCEV *B) {
}
static bool MatchBinarySub(const SCEV *S, const SCEV *&LHS, const SCEV *&RHS) {
- const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(S);
- if (!Add || Add->getNumOperands() != 2)
+ const SCEV *Op0, *Op1;
+ if (!match(S, m_scev_Add(m_SCEV(Op0), m_SCEV(Op1))))
return false;
- if (auto *ME = dyn_cast<SCEVMulExpr>(Add->getOperand(0));
- ME && ME->getNumOperands() == 2 && ME->getOperand(0)->isAllOnesValue()) {
- LHS = Add->getOperand(1);
- RHS = ME->getOperand(1);
+ if (match(Op0, m_scev_Mul(m_scev_AllOnes(), m_SCEV(RHS)))) {
+ LHS = Op1;
return true;
}
- if (auto *ME = dyn_cast<SCEVMulExpr>(Add->getOperand(1));
- ME && ME->getNumOperands() == 2 && ME->getOperand(0)->isAllOnesValue()) {
- LHS = Add->getOperand(0);
- RHS = ME->getOperand(1);
+ if (match(Op1, m_scev_Mul(m_scev_AllOnes(), m_SCEV(RHS)))) {
+ LHS = Op0;
return true;
}
return false;
@@ -12166,13 +12153,10 @@ bool ScalarEvolution::isImpliedCondBalancedTypes(
bool ScalarEvolution::splitBinaryAdd(const SCEV *Expr,
const SCEV *&L, const SCEV *&R,
SCEV::NoWrapFlags &Flags) {
- const auto *AE = dyn_cast<SCEVAddExpr>(Expr);
- if (!AE || AE->getNumOperands() != 2)
+ if (!match(Expr, m_scev_Add(m_SCEV(L), m_SCEV(R))))
return false;
- L = AE->getOperand(0);
- R = AE->getOperand(1);
- Flags = AE->getNoWrapFlags();
+ Flags = cast<SCEVAddExpr>(Expr)->getNoWrapFlags();
return true;
}
@@ -15550,19 +15534,10 @@ void ScalarEvolution::LoopGuards::collectFromBlock(
auto IsMinMaxSCEVWithNonNegativeConstant =
[&](const SCEV *Expr, SCEVTypes &SCTy, const SCEV *&LHS,
const SCEV *&RHS) {
- if (auto *MinMax = dyn_cast<SCEVMinMaxExpr>(Expr)) {
- if (MinMax->getNumOperands() != 2)
- return false;
- if (auto *C = dyn_cast<SCEVConstant>(MinMax->getOperand(0))) {
- if (C->getAPInt().isNegative())
- return false;
- SCTy = MinMax->getSCEVType();
- LHS = MinMax->getOperand(0);
- RHS = MinMax->getOperand(1);
- return true;
- }
- }
- return false;
+ const APInt *C;
+ SCTy = Expr->getSCEVType();
+ return match(Expr, m_scev_MinMax(m_SCEV(LHS), m_SCEV(RHS))) &&
+ match(LHS, m_scev_APInt(C)) && C->isNonNegative();
};
// Return a new SCEV that modifies \p Expr to the closest number divides by
More information about the llvm-commits
mailing list