+++ /dev/null
-//===-- CmpInstAnalysis.h - Utils to help fold compare insts ----*- C++ -*-===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file holds routines to help analyse compare instructions
-// and fold them into constants or other compare instructions
-//
-//===----------------------------------------------------------------------===//
-
-#ifndef LLVM_TRANSFORMS_UTILS_CMPINSTANALYSIS_H
-#define LLVM_TRANSFORMS_UTILS_CMPINSTANALYSIS_H
-
-#include "llvm/IR/InstrTypes.h"
-
-namespace llvm {
- class ICmpInst;
- class Value;
-
- /// Encode a icmp predicate into a three bit mask. These bits are carefully
- /// arranged to allow folding of expressions such as:
- ///
- /// (A < B) | (A > B) --> (A != B)
- ///
- /// Note that this is only valid if the first and second predicates have the
- /// same sign. It is illegal to do: (A u< B) | (A s> B)
- ///
- /// Three bits are used to represent the condition, as follows:
- /// 0 A > B
- /// 1 A == B
- /// 2 A < B
- ///
- /// <=> Value Definition
- /// 000 0 Always false
- /// 001 1 A > B
- /// 010 2 A == B
- /// 011 3 A >= B
- /// 100 4 A < B
- /// 101 5 A != B
- /// 110 6 A <= B
- /// 111 7 Always true
- ///
- unsigned getICmpCode(const ICmpInst *ICI, bool InvertPred = false);
-
- /// This is the complement of getICmpCode, which turns an opcode and two
- /// operands into either a constant true or false, or the predicate for a new
- /// ICmp instruction. The sign is passed in to determine which kind of
- /// predicate to use in the new icmp instruction.
- /// Non-NULL return value will be a true or false constant.
- /// NULL return means a new ICmp is needed. The predicate for which is output
- /// in NewICmpPred.
- Value *getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS,
- CmpInst::Predicate &NewICmpPred);
-
- /// Return true if both predicates match sign or if at least one of them is an
- /// equality comparison (which is signless).
- bool PredicatesFoldable(CmpInst::Predicate p1, CmpInst::Predicate p2);
-
- /// Decompose an icmp into the form ((X & Y) pred Z) if possible. The returned
- /// predicate is either == or !=. Returns false if decomposition fails.
- bool decomposeBitTestICmp(const ICmpInst *I, CmpInst::Predicate &Pred,
- Value *&X, Value *&Y, Value *&Z);
-
-} // end namespace llvm
-
-#endif
CallGraphSCCPass.cpp
CallPrinter.cpp
CaptureTracking.cpp
+ CmpInstAnalysis.cpp
CostModel.cpp
CodeMetrics.cpp
ConstantFolding.cpp
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/CaptureTracking.h"
+#include "llvm/Analysis/CmpInstAnalysis.h"
#include "llvm/Analysis/ConstantFolding.h"
#include "llvm/Analysis/LoopAnalysisManager.h"
#include "llvm/Analysis/MemoryBuiltins.h"
/// An alternative way to test if a bit is set or not uses sgt/slt instead of
/// eq/ne.
-static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *TrueVal,
- Value *FalseVal,
- bool TrueWhenUnset) {
+static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *CmpRHS,
+ ICmpInst::Predicate Pred,
+ Value *TrueVal, Value *FalseVal) {
+ Value *X;
+ APInt Mask;
+ if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask))
+ return nullptr;
+
unsigned BitWidth = TrueVal->getType()->getScalarSizeInBits();
if (!BitWidth)
return nullptr;
- APInt MinSignedValue;
- Value *X;
- if (match(CmpLHS, m_Trunc(m_Value(X))) && (X == TrueVal || X == FalseVal)) {
+ Value *ExtX;
+ if (match(X, m_Trunc(m_Value(ExtX))) &&
+ (ExtX == TrueVal || ExtX == FalseVal)) {
// icmp slt (trunc X), 0 <--> icmp ne (and X, C), 0
// icmp sgt (trunc X), -1 <--> icmp eq (and X, C), 0
- unsigned DestSize = CmpLHS->getType()->getScalarSizeInBits();
- MinSignedValue = APInt::getSignedMinValue(DestSize).zext(BitWidth);
- } else {
- // icmp slt X, 0 <--> icmp ne (and X, C), 0
- // icmp sgt X, -1 <--> icmp eq (and X, C), 0
- X = CmpLHS;
- MinSignedValue = APInt::getSignedMinValue(BitWidth);
+ X = ExtX;
+ Mask = Mask.zext(BitWidth);
}
- if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, &MinSignedValue,
- TrueWhenUnset))
- return V;
-
- return nullptr;
+ return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask,
+ Pred == ICmpInst::ICMP_EQ);
}
/// Try to simplify a select instruction when its condition operand is an
if (!match(CondVal, m_ICmp(Pred, m_Value(CmpLHS), m_Value(CmpRHS))))
return nullptr;
- // FIXME: This code is nearly duplicated in InstCombine. Using/refactoring
- // decomposeBitTestICmp() might help.
- // FIXME this should support ICMP_SLE/SGE forms as well
if (ICmpInst::isEquality(Pred) && match(CmpRHS, m_Zero())) {
Value *X;
const APInt *Y;
if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, Y,
Pred == ICmpInst::ICMP_EQ))
return V;
- } else if (Pred == ICmpInst::ICMP_SLT && match(CmpRHS, m_Zero())) {
- // Comparing signed-less-than 0 checks if the sign bit is set.
- if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, TrueVal, FalseVal,
- false))
- return V;
- } else if (Pred == ICmpInst::ICMP_SGT && match(CmpRHS, m_AllOnes())) {
- // Comparing signed-greater-than -1 checks if the sign bit is not set.
- if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, TrueVal, FalseVal,
- true))
- return V;
}
+ // Check for other compares that behave like bit test.
+ if (Value *V = simplifySelectWithFakeICmpEq(CmpLHS, CmpRHS, Pred,
+ TrueVal, FalseVal))
+ return V;
+
if (CondVal->hasOneUse()) {
const APInt *C;
if (match(CmpRHS, m_APInt(C))) {
//===----------------------------------------------------------------------===//
#include "InstCombineInternal.h"
+#include "llvm/Analysis/CmpInstAnalysis.h"
#include "llvm/Analysis/InstructionSimplify.h"
#include "llvm/IR/ConstantRange.h"
#include "llvm/IR/Intrinsics.h"
#include "llvm/IR/PatternMatch.h"
-#include "llvm/Transforms/Utils/CmpInstAnalysis.h"
#include "llvm/Transforms/Utils/Local.h"
using namespace llvm;
using namespace PatternMatch;
return NewMask;
}
+// Adapts the external decomposeBitTestICmp for local use.
+static bool decomposeBitTestICmp(Value *LHS, Value *RHS, CmpInst::Predicate &Pred,
+ Value *&X, Value *&Y, Value *&Z) {
+ APInt Mask;
+ if (!llvm::decomposeBitTestICmp(LHS, RHS, Pred, X, Mask))
+ return false;
+
+ Y = ConstantInt::get(X->getType(), Mask);
+ Z = ConstantInt::get(X->getType(), 0);
+ return true;
+}
+
/// Handle (icmp(A & B) ==/!= C) &/| (icmp(A & D) ==/!= E).
/// Return the set of pattern classes (from MaskedICmpType) that both LHS and
/// RHS satisfy.
Value *L2 = LHS->getOperand(1);
Value *L11, *L12, *L21, *L22;
// Check whether the icmp can be decomposed into a bit test.
- if (decomposeBitTestICmp(LHS, PredL, L11, L12, L2)) {
+ if (decomposeBitTestICmp(L1, L2, PredL, L11, L12, L2)) {
L21 = L22 = L1 = nullptr;
} else {
// Look for ANDs in the LHS icmp.
Value *R2 = RHS->getOperand(1);
Value *R11, *R12;
bool Ok = false;
- if (decomposeBitTestICmp(RHS, PredR, R11, R12, R2)) {
+ if (decomposeBitTestICmp(R1, R2, PredR, R11, R12, R2)) {
if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) {
A = R11;
D = R12;
BypassSlowDivision.cpp
CloneFunction.cpp
CloneModule.cpp
- CmpInstAnalysis.cpp
CodeExtractor.cpp
CtorUtils.cpp
DemoteRegToStack.cpp
+++ /dev/null
-//===- CmpInstAnalysis.cpp - Utils to help fold compares ---------------===//
-//
-// The LLVM Compiler Infrastructure
-//
-// This file is distributed under the University of Illinois Open Source
-// License. See LICENSE.TXT for details.
-//
-//===----------------------------------------------------------------------===//
-//
-// This file holds routines to help analyse compare instructions
-// and fold them into constants or other compare instructions
-//
-//===----------------------------------------------------------------------===//
-
-#include "llvm/Transforms/Utils/CmpInstAnalysis.h"
-#include "llvm/IR/Constants.h"
-#include "llvm/IR/Instructions.h"
-
-using namespace llvm;
-
-unsigned llvm::getICmpCode(const ICmpInst *ICI, bool InvertPred) {
- ICmpInst::Predicate Pred = InvertPred ? ICI->getInversePredicate()
- : ICI->getPredicate();
- switch (Pred) {
- // False -> 0
- case ICmpInst::ICMP_UGT: return 1; // 001
- case ICmpInst::ICMP_SGT: return 1; // 001
- case ICmpInst::ICMP_EQ: return 2; // 010
- case ICmpInst::ICMP_UGE: return 3; // 011
- case ICmpInst::ICMP_SGE: return 3; // 011
- case ICmpInst::ICMP_ULT: return 4; // 100
- case ICmpInst::ICMP_SLT: return 4; // 100
- case ICmpInst::ICMP_NE: return 5; // 101
- case ICmpInst::ICMP_ULE: return 6; // 110
- case ICmpInst::ICMP_SLE: return 6; // 110
- // True -> 7
- default:
- llvm_unreachable("Invalid ICmp predicate!");
- }
-}
-
-Value *llvm::getICmpValue(bool Sign, unsigned Code, Value *LHS, Value *RHS,
- CmpInst::Predicate &NewICmpPred) {
- switch (Code) {
- default: llvm_unreachable("Illegal ICmp code!");
- case 0: // False.
- return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 0);
- case 1: NewICmpPred = Sign ? ICmpInst::ICMP_SGT : ICmpInst::ICMP_UGT; break;
- case 2: NewICmpPred = ICmpInst::ICMP_EQ; break;
- case 3: NewICmpPred = Sign ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_UGE; break;
- case 4: NewICmpPred = Sign ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_ULT; break;
- case 5: NewICmpPred = ICmpInst::ICMP_NE; break;
- case 6: NewICmpPred = Sign ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_ULE; break;
- case 7: // True.
- return ConstantInt::get(CmpInst::makeCmpResultType(LHS->getType()), 1);
- }
- return nullptr;
-}
-
-bool llvm::PredicatesFoldable(ICmpInst::Predicate p1, ICmpInst::Predicate p2) {
- return (CmpInst::isSigned(p1) == CmpInst::isSigned(p2)) ||
- (CmpInst::isSigned(p1) && ICmpInst::isEquality(p2)) ||
- (CmpInst::isSigned(p2) && ICmpInst::isEquality(p1));
-}
-
-bool llvm::decomposeBitTestICmp(const ICmpInst *I, CmpInst::Predicate &Pred,
- Value *&X, Value *&Y, Value *&Z) {
- ConstantInt *C = dyn_cast<ConstantInt>(I->getOperand(1));
- if (!C)
- return false;
-
- switch (I->getPredicate()) {
- default:
- return false;
- case ICmpInst::ICMP_SLT:
- // X < 0 is equivalent to (X & SignMask) != 0.
- if (!C->isZero())
- return false;
- Y = ConstantInt::get(I->getContext(), APInt::getSignMask(C->getBitWidth()));
- Pred = ICmpInst::ICMP_NE;
- break;
- case ICmpInst::ICMP_SGT:
- // X > -1 is equivalent to (X & SignMask) == 0.
- if (!C->isMinusOne())
- return false;
- Y = ConstantInt::get(I->getContext(), APInt::getSignMask(C->getBitWidth()));
- Pred = ICmpInst::ICMP_EQ;
- break;
- case ICmpInst::ICMP_ULT:
- // X <u 2^n is equivalent to (X & ~(2^n-1)) == 0.
- if (!C->getValue().isPowerOf2())
- return false;
- Y = ConstantInt::get(I->getContext(), -C->getValue());
- Pred = ICmpInst::ICMP_EQ;
- break;
- case ICmpInst::ICMP_UGT:
- // X >u 2^n-1 is equivalent to (X & ~(2^n-1)) != 0.
- if (!(C->getValue() + 1).isPowerOf2())
- return false;
- Y = ConstantInt::get(I->getContext(), ~C->getValue());
- Pred = ICmpInst::ICMP_NE;
- break;
- }
-
- X = I->getOperand(0);
- Z = ConstantInt::getNullValue(C->getType());
- return true;
-}
ret <2 x i8> %sel
}
-; TODO: we should be able to simplify this
define i32 @test12(i32 %X) {
; CHECK-LABEL: @test12(
-; CHECK-NEXT: [[CMP:%.*]] = icmp ult i32 [[X:%.*]], 4
-; CHECK-NEXT: [[AND:%.*]] = and i32 [[X]], 3
-; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i32 [[X]], i32 [[AND]]
-; CHECK-NEXT: ret i32 [[COND]]
+; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], 3
+; CHECK-NEXT: ret i32 [[AND]]
;
%cmp = icmp ult i32 %X, 4
%and = and i32 %X, 3
ret i32 %cond
}
-; TODO: we should be able to simplify this
define i32 @test13(i32 %X) {
; CHECK-LABEL: @test13(
-; CHECK-NEXT: [[CMP:%.*]] = icmp ugt i32 [[X:%.*]], 3
-; CHECK-NEXT: [[AND:%.*]] = and i32 [[X]], 3
-; CHECK-NEXT: [[COND:%.*]] = select i1 [[CMP]], i32 [[AND]], i32 [[X]]
-; CHECK-NEXT: ret i32 [[COND]]
+; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], 3
+; CHECK-NEXT: ret i32 [[AND]]
;
%cmp = icmp ugt i32 %X, 3
%and = and i32 %X, 3
projects / llvm / commitdiff