[llvm] r310869 - [InstSimplify][InstCombine] Modify the interface of decomposeBitTestICmp and use it in the InstSimplify
Craig Topper via llvm-commits
llvm-commits at lists.llvm.org
Mon Aug 14 12:04:21 PDT 2017
Forgot to 'git add' the moved files when I reapplied the patch for commit.
Fixed in r310870.
~Craig
On Mon, Aug 14, 2017 at 11:49 AM, Craig Topper via llvm-commits <
llvm-commits at lists.llvm.org> wrote:
> Author: ctopper
> Date: Mon Aug 14 11:49:42 2017
> New Revision: 310869
>
> URL: http://llvm.org/viewvc/llvm-project?rev=310869&view=rev
> Log:
> [InstSimplify][InstCombine] Modify the interface of decomposeBitTestICmp
> and use it in the InstSimplify
>
> This addresses a fixme in InstSimplify about using decomposeBitTest. This
> also fixes InstSimplify to handle ugt and ult compares too.
>
> I've modified the interface a little to return only the APInt version of
> the mask that InstSimplify needs. InstCombine now has a small wrapper
> routine to create a Constant out of it. I've also dropped the returning of
> 0 since InstSimplify doesn't need that. So InstCombine creates a zero
> constant itself.
>
> I also had to make decomposeBitTest support vectors since InstSimplify
> needs that.
>
> As InstSimplify can't use something from the Transforms library, I've
> moved the CmpInstAnalysis code to the Analysis library.
>
> Differential Revision: https://reviews.llvm.org/D36593
>
> Removed:
> llvm/trunk/include/llvm/Transforms/Utils/CmpInstAnalysis.h
> llvm/trunk/lib/Transforms/Utils/CmpInstAnalysis.cpp
> Modified:
> llvm/trunk/lib/Analysis/CMakeLists.txt
> llvm/trunk/lib/Analysis/InstructionSimplify.cpp
> llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
> llvm/trunk/lib/Transforms/Utils/CMakeLists.txt
> llvm/trunk/test/Transforms/InstSimplify/select.ll
>
> Removed: llvm/trunk/include/llvm/Transforms/Utils/CmpInstAnalysis.h
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/
> llvm/Transforms/Utils/CmpInstAnalysis.h?rev=310868&view=auto
> ============================================================
> ==================
> --- llvm/trunk/include/llvm/Transforms/Utils/CmpInstAnalysis.h (original)
> +++ llvm/trunk/include/llvm/Transforms/Utils/CmpInstAnalysis.h (removed)
> @@ -1,70 +0,0 @@
> -//===-- 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
>
> Modified: llvm/trunk/lib/Analysis/CMakeLists.txt
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> Analysis/CMakeLists.txt?rev=310869&r1=310868&r2=310869&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/Analysis/CMakeLists.txt (original)
> +++ llvm/trunk/lib/Analysis/CMakeLists.txt Mon Aug 14 11:49:42 2017
> @@ -18,6 +18,7 @@ add_llvm_library(LLVMAnalysis
> CallGraphSCCPass.cpp
> CallPrinter.cpp
> CaptureTracking.cpp
> + CmpInstAnalysis.cpp
> CostModel.cpp
> CodeMetrics.cpp
> ConstantFolding.cpp
>
> Modified: llvm/trunk/lib/Analysis/InstructionSimplify.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> Analysis/InstructionSimplify.cpp?rev=310869&r1=310868&r2=310869&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/Analysis/InstructionSimplify.cpp (original)
> +++ llvm/trunk/lib/Analysis/InstructionSimplify.cpp Mon Aug 14 11:49:42
> 2017
> @@ -23,6 +23,7 @@
> #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"
> @@ -3620,32 +3621,29 @@ static Value *simplifySelectBitTest(Valu
>
> /// 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
> @@ -3658,9 +3656,6 @@ static Value *simplifySelectWithICmpCond
> 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;
> @@ -3668,18 +3663,13 @@ static Value *simplifySelectWithICmpCond
> 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))) {
>
> Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> Transforms/InstCombine/InstCombineAndOrXor.cpp?rev=
> 310869&r1=310868&r2=310869&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp
> (original)
> +++ llvm/trunk/lib/Transforms/InstCombine/InstCombineAndOrXor.cpp Mon Aug
> 14 11:49:42 2017
> @@ -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;
> @@ -292,6 +292,18 @@ static unsigned conjugateICmpMask(unsign
> 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.
> @@ -316,7 +328,7 @@ static unsigned getMaskedTypeForICmpPair
> 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.
> @@ -347,7 +359,7 @@ static unsigned getMaskedTypeForICmpPair
> 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;
>
> Modified: llvm/trunk/lib/Transforms/Utils/CMakeLists.txt
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/
> Transforms/Utils/CMakeLists.txt?rev=310869&r1=310868&r2=310869&view=diff
> ============================================================
> ==================
> --- llvm/trunk/lib/Transforms/Utils/CMakeLists.txt (original)
> +++ llvm/trunk/lib/Transforms/Utils/CMakeLists.txt Mon Aug 14 11:49:42
> 2017
> @@ -7,7 +7,6 @@ add_llvm_library(LLVMTransformUtils
> BypassSlowDivision.cpp
> CloneFunction.cpp
> CloneModule.cpp
> - CmpInstAnalysis.cpp
> CodeExtractor.cpp
> CtorUtils.cpp
> DemoteRegToStack.cpp
>
> Removed: llvm/trunk/lib/Transforms/Utils/CmpInstAnalysis.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Utils/
> CmpInstAnalysis.cpp?rev=310868&view=auto
> ============================================================
> ==================
> --- llvm/trunk/lib/Transforms/Utils/CmpInstAnalysis.cpp (original)
> +++ llvm/trunk/lib/Transforms/Utils/CmpInstAnalysis.cpp (removed)
> @@ -1,108 +0,0 @@
> -//===- 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;
> -}
>
> Modified: llvm/trunk/test/Transforms/InstSimplify/select.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/
> Transforms/InstSimplify/select.ll?rev=310869&r1=310868&r2=310869&view=diff
> ============================================================
> ==================
> --- llvm/trunk/test/Transforms/InstSimplify/select.ll (original)
> +++ llvm/trunk/test/Transforms/InstSimplify/select.ll Mon Aug 14 11:49:42
> 2017
> @@ -160,13 +160,10 @@ 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: [[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
> @@ -189,13 +186,10 @@ 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: [[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
>
>
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