[llvm] r263047 - InstCombine: Restrict computeKnownBits() on all Values to OptLevel > 2
Matthias Braun via llvm-commits
llvm-commits at lists.llvm.org
Wed Mar 9 10:47:11 PST 2016
Author: matze
Date: Wed Mar 9 12:47:11 2016
New Revision: 263047
URL: http://llvm.org/viewvc/llvm-project?rev=263047&view=rev
Log:
InstCombine: Restrict computeKnownBits() on all Values to OptLevel > 2
As part of r251146 InstCombine was extended to call computeKnownBits on
every value in the function to determine whether it happens to be
constant. This increases typical compiletime by 1-3% (5% in irgen+opt
time) in my measurements. On the other hand this case did not trigger
once in the whole llvm-testsuite.
This patch introduces the notion of ExpensiveCombines which are only
enabled for OptLevel > 2. I removed the check in InstructionSimplify as
that is called from various places where the OptLevel is not known but
given the rarity of the situation I think a check in InstCombine is
enough.
Differential Revision: http://reviews.llvm.org/D16835
Modified:
llvm/trunk/include/llvm/Transforms/IPO/PassManagerBuilder.h
llvm/trunk/include/llvm/Transforms/InstCombine/InstCombine.h
llvm/trunk/include/llvm/Transforms/Scalar.h
llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
llvm/trunk/test/Analysis/ValueTracking/known-bits-from-range-md.ll
llvm/trunk/test/Transforms/InstCombine/all-bits-shift.ll
Modified: llvm/trunk/include/llvm/Transforms/IPO/PassManagerBuilder.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/IPO/PassManagerBuilder.h?rev=263047&r1=263046&r2=263047&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/IPO/PassManagerBuilder.h (original)
+++ llvm/trunk/include/llvm/Transforms/IPO/PassManagerBuilder.h Wed Mar 9 12:47:11 2016
@@ -163,6 +163,7 @@ private:
void addLateLTOOptimizationPasses(legacy::PassManagerBase &PM);
void addPGOInstrPasses(legacy::PassManagerBase &MPM);
void addFunctionSimplificationPasses(legacy::PassManagerBase &MPM);
+ void addInstructionCombiningPass(legacy::PassManagerBase &MPM) const;
public:
/// populateFunctionPassManager - This fills in the function pass manager,
Modified: llvm/trunk/include/llvm/Transforms/InstCombine/InstCombine.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/InstCombine/InstCombine.h?rev=263047&r1=263046&r2=263047&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/InstCombine/InstCombine.h (original)
+++ llvm/trunk/include/llvm/Transforms/InstCombine/InstCombine.h Wed Mar 9 12:47:11 2016
@@ -26,15 +26,20 @@ namespace llvm {
class InstCombinePass : public PassBase<InstCombinePass> {
InstCombineWorklist Worklist;
+ bool ExpensiveCombines;
public:
static StringRef name() { return "InstCombinePass"; }
// Explicitly define constructors for MSVC.
- InstCombinePass() {}
- InstCombinePass(InstCombinePass &&Arg) : Worklist(std::move(Arg.Worklist)) {}
+ InstCombinePass(bool ExpensiveCombines = true)
+ : ExpensiveCombines(ExpensiveCombines) {}
+ InstCombinePass(InstCombinePass &&Arg)
+ : Worklist(std::move(Arg.Worklist)),
+ ExpensiveCombines(Arg.ExpensiveCombines) {}
InstCombinePass &operator=(InstCombinePass &&RHS) {
Worklist = std::move(RHS.Worklist);
+ ExpensiveCombines = RHS.ExpensiveCombines;
return *this;
}
@@ -47,11 +52,13 @@ public:
/// will try to combine all instructions in the function.
class InstructionCombiningPass : public FunctionPass {
InstCombineWorklist Worklist;
+ const bool ExpensiveCombines;
public:
static char ID; // Pass identification, replacement for typeid
- InstructionCombiningPass() : FunctionPass(ID) {
+ InstructionCombiningPass(bool ExpensiveCombines = true)
+ : FunctionPass(ID), ExpensiveCombines(ExpensiveCombines) {
initializeInstructionCombiningPassPass(*PassRegistry::getPassRegistry());
}
Modified: llvm/trunk/include/llvm/Transforms/Scalar.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Transforms/Scalar.h?rev=263047&r1=263046&r2=263047&view=diff
==============================================================================
--- llvm/trunk/include/llvm/Transforms/Scalar.h (original)
+++ llvm/trunk/include/llvm/Transforms/Scalar.h Wed Mar 9 12:47:11 2016
@@ -132,7 +132,7 @@ Pass *createIndVarSimplifyPass();
// into:
// %Z = add int 2, %X
//
-FunctionPass *createInstructionCombiningPass();
+FunctionPass *createInstructionCombiningPass(bool ExpensiveCombines = true);
//===----------------------------------------------------------------------===//
//
Modified: llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp?rev=263047&r1=263046&r2=263047&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp (original)
+++ llvm/trunk/lib/Transforms/IPO/PassManagerBuilder.cpp Wed Mar 9 12:47:11 2016
@@ -185,6 +185,12 @@ void PassManagerBuilder::addInitialAlias
PM.add(createScopedNoAliasAAWrapperPass());
}
+void PassManagerBuilder::addInstructionCombiningPass(
+ legacy::PassManagerBase &PM) const {
+ bool ExpensiveCombines = OptLevel > 2;
+ PM.add(createInstructionCombiningPass(ExpensiveCombines));
+}
+
void PassManagerBuilder::populateFunctionPassManager(
legacy::FunctionPassManager &FPM) {
addExtensionsToPM(EP_EarlyAsPossible, FPM);
@@ -230,7 +236,8 @@ void PassManagerBuilder::addFunctionSimp
MPM.add(createJumpThreadingPass()); // Thread jumps.
MPM.add(createCorrelatedValuePropagationPass()); // Propagate conditionals
MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
- MPM.add(createInstructionCombiningPass()); // Combine silly seq's
+ // Combine silly seq's
+ addInstructionCombiningPass(MPM);
addExtensionsToPM(EP_Peephole, MPM);
MPM.add(createTailCallEliminationPass()); // Eliminate tail calls
@@ -238,7 +245,7 @@ void PassManagerBuilder::addFunctionSimp
MPM.add(createReassociatePass()); // Reassociate expressions
if (PrepareForThinLTO) {
MPM.add(createAggressiveDCEPass()); // Delete dead instructions
- MPM.add(createInstructionCombiningPass()); // Combine silly seq's
+ addInstructionCombiningPass(MPM); // Combine silly seq's
return;
}
// Rotate Loop - disable header duplication at -Oz
@@ -246,7 +253,7 @@ void PassManagerBuilder::addFunctionSimp
MPM.add(createLICMPass()); // Hoist loop invariants
MPM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3));
MPM.add(createCFGSimplificationPass());
- MPM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(MPM);
MPM.add(createIndVarSimplifyPass()); // Canonicalize indvars
MPM.add(createLoopIdiomPass()); // Recognize idioms like memset.
MPM.add(createLoopDeletionPass()); // Delete dead loops
@@ -273,7 +280,7 @@ void PassManagerBuilder::addFunctionSimp
// Run instcombine after redundancy elimination to exploit opportunities
// opened up by them.
- MPM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(MPM);
addExtensionsToPM(EP_Peephole, MPM);
MPM.add(createJumpThreadingPass()); // Thread jumps
MPM.add(createCorrelatedValuePropagationPass());
@@ -290,7 +297,7 @@ void PassManagerBuilder::addFunctionSimp
if (BBVectorize) {
MPM.add(createBBVectorizePass());
- MPM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(MPM);
addExtensionsToPM(EP_Peephole, MPM);
if (OptLevel > 1 && UseGVNAfterVectorization)
MPM.add(createGVNPass(DisableGVNLoadPRE)); // Remove redundancies
@@ -308,7 +315,8 @@ void PassManagerBuilder::addFunctionSimp
MPM.add(createAggressiveDCEPass()); // Delete dead instructions
MPM.add(createCFGSimplificationPass()); // Merge & remove BBs
- MPM.add(createInstructionCombiningPass()); // Clean up after everything.
+ // Clean up after everything.
+ addInstructionCombiningPass(MPM);
addExtensionsToPM(EP_Peephole, MPM);
}
@@ -359,7 +367,7 @@ void PassManagerBuilder::populateModuleP
MPM.add(createDeadArgEliminationPass()); // Dead argument elimination
- MPM.add(createInstructionCombiningPass()); // Clean up after IPCP & DAE
+ addInstructionCombiningPass(MPM); // Clean up after IPCP & DAE
addExtensionsToPM(EP_Peephole, MPM);
MPM.add(createCFGSimplificationPass()); // Clean up after IPCP & DAE
}
@@ -480,7 +488,7 @@ void PassManagerBuilder::populateModuleP
// on -O1 and no #pragma is found). Would be good to have these two passes
// as function calls, so that we can only pass them when the vectorizer
// changed the code.
- MPM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(MPM);
if (OptLevel > 1 && ExtraVectorizerPasses) {
// At higher optimization levels, try to clean up any runtime overlap and
// alignment checks inserted by the vectorizer. We want to track correllated
@@ -490,11 +498,11 @@ void PassManagerBuilder::populateModuleP
// dead (or speculatable) control flows or more combining opportunities.
MPM.add(createEarlyCSEPass());
MPM.add(createCorrelatedValuePropagationPass());
- MPM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(MPM);
MPM.add(createLICMPass());
MPM.add(createLoopUnswitchPass(SizeLevel || OptLevel < 3));
MPM.add(createCFGSimplificationPass());
- MPM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(MPM);
}
if (RunSLPAfterLoopVectorization) {
@@ -507,7 +515,7 @@ void PassManagerBuilder::populateModuleP
if (BBVectorize) {
MPM.add(createBBVectorizePass());
- MPM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(MPM);
addExtensionsToPM(EP_Peephole, MPM);
if (OptLevel > 1 && UseGVNAfterVectorization)
MPM.add(createGVNPass(DisableGVNLoadPRE)); // Remove redundancies
@@ -522,13 +530,13 @@ void PassManagerBuilder::populateModuleP
addExtensionsToPM(EP_Peephole, MPM);
MPM.add(createCFGSimplificationPass());
- MPM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(MPM);
if (!DisableUnrollLoops) {
MPM.add(createLoopUnrollPass()); // Unroll small loops
// LoopUnroll may generate some redundency to cleanup.
- MPM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(MPM);
// Runtime unrolling will introduce runtime check in loop prologue. If the
// unrolled loop is a inner loop, then the prologue will be inside the
@@ -595,7 +603,7 @@ void PassManagerBuilder::addLTOOptimizat
// simplification opportunities, and both can propagate functions through
// function pointers. When this happens, we often have to resolve varargs
// calls, etc, so let instcombine do this.
- PM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(PM);
addExtensionsToPM(EP_Peephole, PM);
// Inline small functions
@@ -617,7 +625,7 @@ void PassManagerBuilder::addLTOOptimizat
PM.add(createArgumentPromotionPass());
// The IPO passes may leave cruft around. Clean up after them.
- PM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(PM);
addExtensionsToPM(EP_Peephole, PM);
PM.add(createJumpThreadingPass());
@@ -656,10 +664,10 @@ void PassManagerBuilder::addLTOOptimizat
// Now that we've optimized loops (in particular loop induction variables),
// we may have exposed more scalar opportunities. Run parts of the scalar
// optimizer again at this point.
- PM.add(createInstructionCombiningPass()); // Initial cleanup
+ addInstructionCombiningPass(PM); // Initial cleanup
PM.add(createCFGSimplificationPass()); // if-convert
PM.add(createSCCPPass()); // Propagate exposed constants
- PM.add(createInstructionCombiningPass()); // Clean up again
+ addInstructionCombiningPass(PM); // Clean up again
PM.add(createBitTrackingDCEPass());
// More scalar chains could be vectorized due to more alias information
@@ -675,7 +683,7 @@ void PassManagerBuilder::addLTOOptimizat
PM.add(createLoadCombinePass());
// Cleanup and simplify the code after the scalar optimizations.
- PM.add(createInstructionCombiningPass());
+ addInstructionCombiningPass(PM);
addExtensionsToPM(EP_Peephole, PM);
PM.add(createJumpThreadingPass());
Modified: llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h?rev=263047&r1=263046&r2=263047&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstCombineInternal.h Wed Mar 9 12:47:11 2016
@@ -177,6 +177,8 @@ public:
private:
// Mode in which we are running the combiner.
const bool MinimizeSize;
+ /// Enable combines that trigger rarely but are costly in compiletime.
+ const bool ExpensiveCombines;
AliasAnalysis *AA;
@@ -195,11 +197,12 @@ private:
public:
InstCombiner(InstCombineWorklist &Worklist, BuilderTy *Builder,
- bool MinimizeSize, AliasAnalysis *AA,
+ bool MinimizeSize, bool ExpensiveCombines, AliasAnalysis *AA,
AssumptionCache *AC, TargetLibraryInfo *TLI,
DominatorTree *DT, const DataLayout &DL, LoopInfo *LI)
: Worklist(Worklist), Builder(Builder), MinimizeSize(MinimizeSize),
- AA(AA), AC(AC), TLI(TLI), DT(DT), DL(DL), LI(LI), MadeIRChange(false) {}
+ ExpensiveCombines(ExpensiveCombines), AA(AA), AC(AC), TLI(TLI), DT(DT),
+ DL(DL), LI(LI), MadeIRChange(false) {}
/// \brief Run the combiner over the entire worklist until it is empty.
///
Modified: llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp?rev=263047&r1=263046&r2=263047&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp (original)
+++ llvm/trunk/lib/Transforms/InstCombine/InstructionCombining.cpp Wed Mar 9 12:47:11 2016
@@ -78,6 +78,10 @@ STATISTIC(NumExpand, "Number of expan
STATISTIC(NumFactor , "Number of factorizations");
STATISTIC(NumReassoc , "Number of reassociations");
+static cl::opt<bool>
+EnableExpensiveCombines("expensive-combines",
+ cl::desc("Enable expensive instruction combines"));
+
Value *InstCombiner::EmitGEPOffset(User *GEP) {
return llvm::EmitGEPOffset(Builder, DL, GEP);
}
@@ -2770,9 +2774,9 @@ bool InstCombiner::run() {
}
}
- // In general, it is possible for computeKnownBits to determine all bits in a
- // value even when the operands are not all constants.
- if (!I->use_empty() && I->getType()->isIntegerTy()) {
+ // In general, it is possible for computeKnownBits to determine all bits in
+ // a value even when the operands are not all constants.
+ if (ExpensiveCombines && !I->use_empty() && I->getType()->isIntegerTy()) {
unsigned BitWidth = I->getType()->getScalarSizeInBits();
APInt KnownZero(BitWidth, 0);
APInt KnownOne(BitWidth, 0);
@@ -3043,8 +3047,10 @@ static bool
combineInstructionsOverFunction(Function &F, InstCombineWorklist &Worklist,
AliasAnalysis *AA, AssumptionCache &AC,
TargetLibraryInfo &TLI, DominatorTree &DT,
+ bool ExpensiveCombines = true,
LoopInfo *LI = nullptr) {
auto &DL = F.getParent()->getDataLayout();
+ ExpensiveCombines |= EnableExpensiveCombines;
/// Builder - This is an IRBuilder that automatically inserts new
/// instructions into the worklist when they are created.
@@ -3064,8 +3070,8 @@ combineInstructionsOverFunction(Function
bool Changed = prepareICWorklistFromFunction(F, DL, &TLI, Worklist);
- InstCombiner IC(Worklist, &Builder, F.optForMinSize(), AA, &AC, &TLI, &DT,
- DL, LI);
+ InstCombiner IC(Worklist, &Builder, F.optForMinSize(), ExpensiveCombines,
+ AA, &AC, &TLI, &DT, DL, LI);
Changed |= IC.run();
if (!Changed)
@@ -3084,7 +3090,8 @@ PreservedAnalyses InstCombinePass::run(F
auto *LI = AM->getCachedResult<LoopAnalysis>(F);
// FIXME: The AliasAnalysis is not yet supported in the new pass manager
- if (!combineInstructionsOverFunction(F, Worklist, nullptr, AC, TLI, DT, LI))
+ if (!combineInstructionsOverFunction(F, Worklist, nullptr, AC, TLI, DT,
+ ExpensiveCombines, LI))
// No changes, all analyses are preserved.
return PreservedAnalyses::all();
@@ -3121,7 +3128,8 @@ bool InstructionCombiningPass::runOnFunc
auto *LIWP = getAnalysisIfAvailable<LoopInfoWrapperPass>();
auto *LI = LIWP ? &LIWP->getLoopInfo() : nullptr;
- return combineInstructionsOverFunction(F, Worklist, AA, AC, TLI, DT, LI);
+ return combineInstructionsOverFunction(F, Worklist, AA, AC, TLI, DT,
+ ExpensiveCombines, LI);
}
char InstructionCombiningPass::ID = 0;
@@ -3144,6 +3152,6 @@ void LLVMInitializeInstCombine(LLVMPassR
initializeInstructionCombiningPassPass(*unwrap(R));
}
-FunctionPass *llvm::createInstructionCombiningPass() {
- return new InstructionCombiningPass();
+FunctionPass *llvm::createInstructionCombiningPass(bool ExpensiveCombines) {
+ return new InstructionCombiningPass(ExpensiveCombines);
}
Modified: llvm/trunk/test/Analysis/ValueTracking/known-bits-from-range-md.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Analysis/ValueTracking/known-bits-from-range-md.ll?rev=263047&r1=263046&r2=263047&view=diff
==============================================================================
--- llvm/trunk/test/Analysis/ValueTracking/known-bits-from-range-md.ll (original)
+++ llvm/trunk/test/Analysis/ValueTracking/known-bits-from-range-md.ll Wed Mar 9 12:47:11 2016
@@ -1,4 +1,4 @@
-; RUN: opt -S -instsimplify < %s | FileCheck %s
+; RUN: opt -S -instsimplify -instcombine < %s | FileCheck %s
define i1 @test0(i8* %ptr) {
; CHECK-LABEL: @test0(
@@ -23,10 +23,10 @@ define i1 @test1(i8* %ptr) {
define i1 @test2(i8* %ptr) {
; CHECK-LABEL: @test2(
entry:
-; CHECK: load
-; CHECK: and
-; CHECK: icmp eq
-; CHECK: ret
+; CHECK: %val = load i8
+; CHECK: %and = and i8 %val
+; CHECK: %is.eq = icmp ne i8 %and, 0
+; CHECK: ret i1 %is.eq
%val = load i8, i8* %ptr, !range !{i8 64, i8 129}
%and = and i8 %val, 64
%is.eq = icmp eq i8 %and, 64
Modified: llvm/trunk/test/Transforms/InstCombine/all-bits-shift.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/InstCombine/all-bits-shift.ll?rev=263047&r1=263046&r2=263047&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/InstCombine/all-bits-shift.ll (original)
+++ llvm/trunk/test/Transforms/InstCombine/all-bits-shift.ll Wed Mar 9 12:47:11 2016
@@ -1,5 +1,4 @@
-; RUN: opt -S -instcombine < %s | FileCheck %s
-; RUN: opt -S -instsimplify < %s | FileCheck %s
+; RUN: opt -S -instcombine -expensive-combines < %s | FileCheck %s
target datalayout = "E-m:e-i64:64-n32:64"
target triple = "powerpc64-unknown-linux-gnu"
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