From: Craig Topper Date: Mon, 14 Aug 2017 19:09:32 +0000 (+0000) Subject: Revert r310869 "[InstSimplify][InstCombine] Modify the interface of decomposeBitTestI... X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=74b28d63c3227f9a9eb375560b3a0464cadec9bc;p=llvm Revert r310869 "[InstSimplify][InstCombine] Modify the interface of decomposeBitTestICmp and use it in the InstSimplify" Failed to add the two files that moved. And then added an extra change I didn't mean to while trying to fix that. Reverting everything. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@310873 91177308-0d34-0410-b5e6-96231b3b80d8 --- diff --git a/include/llvm/Transforms/Utils/CmpInstAnalysis.h b/include/llvm/Transforms/Utils/CmpInstAnalysis.h new file mode 100644 index 00000000000..5ec3888d453 --- /dev/null +++ b/include/llvm/Transforms/Utils/CmpInstAnalysis.h @@ -0,0 +1,70 @@ +//===-- 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 diff --git a/lib/Analysis/CMakeLists.txt b/lib/Analysis/CMakeLists.txt index 45268dd5c76..161709a4846 100644 --- a/lib/Analysis/CMakeLists.txt +++ b/lib/Analysis/CMakeLists.txt @@ -18,7 +18,6 @@ add_llvm_library(LLVMAnalysis CallGraphSCCPass.cpp CallPrinter.cpp CaptureTracking.cpp - CmpInstAnalysis.cpp CostModel.cpp CodeMetrics.cpp ConstantFolding.cpp diff --git a/lib/Analysis/InstructionSimplify.cpp b/lib/Analysis/InstructionSimplify.cpp index d155f6b4803..9729629b167 100644 --- a/lib/Analysis/InstructionSimplify.cpp +++ b/lib/Analysis/InstructionSimplify.cpp @@ -23,7 +23,6 @@ #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" @@ -3621,29 +3620,32 @@ static Value *simplifySelectBitTest(Value *TrueVal, Value *FalseVal, Value *X, /// 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 *CmpRHS, - ICmpInst::Predicate Pred, - Value *TrueVal, Value *FalseVal) { - Value *X; - APInt Mask; - if (!decomposeBitTestICmp(CmpLHS, CmpRHS, Pred, X, Mask)) - return nullptr; - +static Value *simplifySelectWithFakeICmpEq(Value *CmpLHS, Value *TrueVal, + Value *FalseVal, + bool TrueWhenUnset) { unsigned BitWidth = TrueVal->getType()->getScalarSizeInBits(); if (!BitWidth) return nullptr; - Value *ExtX; - if (match(X, m_Trunc(m_Value(ExtX))) && - (ExtX == TrueVal || ExtX == FalseVal)) { + APInt MinSignedValue; + Value *X; + if (match(CmpLHS, m_Trunc(m_Value(X))) && (X == TrueVal || X == FalseVal)) { // icmp slt (trunc X), 0 <--> icmp ne (and X, C), 0 // icmp sgt (trunc X), -1 <--> icmp eq (and X, C), 0 - X = ExtX; - Mask = Mask.zext(BitWidth); + 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); } - return simplifySelectBitTest(TrueVal, FalseVal, X, &Mask, - Pred == ICmpInst::ICMP_EQ); + if (Value *V = simplifySelectBitTest(TrueVal, FalseVal, X, &MinSignedValue, + TrueWhenUnset)) + return V; + + return nullptr; } /// Try to simplify a select instruction when its condition operand is an @@ -3656,6 +3658,9 @@ static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal, 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; @@ -3663,13 +3668,18 @@ static Value *simplifySelectWithICmpCond(Value *CondVal, Value *TrueVal, 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))) { diff --git a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp index dc5b5bfefe6..dfc2ea3e4de 100644 --- a/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp +++ b/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp @@ -12,11 +12,11 @@ //===----------------------------------------------------------------------===// #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; @@ -292,18 +292,6 @@ static unsigned conjugateICmpMask(unsigned Mask) { 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. @@ -328,7 +316,7 @@ static unsigned getMaskedTypeForICmpPair(Value *&A, Value *&B, Value *&C, Value *L2 = LHS->getOperand(1); Value *L11, *L12, *L21, *L22; // Check whether the icmp can be decomposed into a bit test. - if (decomposeBitTestICmp(L1, L2, PredL, L11, L12, L2)) { + if (decomposeBitTestICmp(LHS, PredL, L11, L12, L2)) { L21 = L22 = L1 = nullptr; } else { // Look for ANDs in the LHS icmp. @@ -359,7 +347,7 @@ static unsigned getMaskedTypeForICmpPair(Value *&A, Value *&B, Value *&C, Value *R2 = RHS->getOperand(1); Value *R11, *R12; bool Ok = false; - if (decomposeBitTestICmp(R1, R2, PredR, R11, R12, R2)) { + if (decomposeBitTestICmp(RHS, PredR, R11, R12, R2)) { if (R11 == L11 || R11 == L12 || R11 == L21 || R11 == L22) { A = R11; D = R12; diff --git a/lib/Transforms/Utils/CMakeLists.txt b/lib/Transforms/Utils/CMakeLists.txt index 8561ec78b1c..83bc05d0311 100644 --- a/lib/Transforms/Utils/CMakeLists.txt +++ b/lib/Transforms/Utils/CMakeLists.txt @@ -7,6 +7,7 @@ add_llvm_library(LLVMTransformUtils BypassSlowDivision.cpp CloneFunction.cpp CloneModule.cpp + CmpInstAnalysis.cpp CodeExtractor.cpp CtorUtils.cpp DemoteRegToStack.cpp diff --git a/lib/Transforms/Utils/CmpInstAnalysis.cpp b/lib/Transforms/Utils/CmpInstAnalysis.cpp new file mode 100644 index 00000000000..d9294c49930 --- /dev/null +++ b/lib/Transforms/Utils/CmpInstAnalysis.cpp @@ -0,0 +1,108 @@ +//===- 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(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 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; +} diff --git a/test/Transforms/InstSimplify/select.ll b/test/Transforms/InstSimplify/select.ll index 4134191a3cf..e9c94170a94 100644 --- a/test/Transforms/InstSimplify/select.ll +++ b/test/Transforms/InstSimplify/select.ll @@ -160,10 +160,13 @@ define <2 x i8> @test11vec(<2 x i8> %X) { ret <2 x i8> %sel } +; TODO: we should be able to simplify this define i32 @test12(i32 %X) { ; CHECK-LABEL: @test12( -; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], 3 -; CHECK-NEXT: ret i32 [[AND]] +; 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]] ; %cmp = icmp ult i32 %X, 4 %and = and i32 %X, 3 @@ -186,10 +189,13 @@ define i32 @test12noncanon(i32 %X) { ret i32 %cond } +; TODO: we should be able to simplify this define i32 @test13(i32 %X) { ; CHECK-LABEL: @test13( -; CHECK-NEXT: [[AND:%.*]] = and i32 [[X:%.*]], 3 -; CHECK-NEXT: ret i32 [[AND]] +; 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]] ; %cmp = icmp ugt i32 %X, 3 %and = and i32 %X, 3