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Recommit "[HardwareLoops] Optimisation remarks" 

With a few things fixed:
- initialisaiton of the optimisation remark pass (this was causing the buildbot
  failures on PPC),
- a test case.

Differential Revision: https://reviews.llvm.org/D69660
This commit is contained in:
Sjoerd Meijer 2019-11-05 08:56:14 +00:00
parent edfb8eea57
commit 92164cf25d
3 changed files with 112 additions and 31 deletions
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115
llvm/lib/CodeGen/HardwareLoops.cpp
View File

@ -21,6 +21,7 @@
#include "llvm/ADT/Statistic.h"
#include "llvm/Analysis/AssumptionCache.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/ScalarEvolutionExpander.h"
#include "llvm/Analysis/TargetTransformInfo.h"
@ -75,8 +76,44 @@ ForceGuardLoopEntry(
STATISTIC(NumHWLoops, "Number of loops converted to hardware loops");
#ifndef NDEBUG
static void debugHWLoopFailure(const StringRef DebugMsg,
Instruction *I) {
dbgs() << "HWLoops: " << DebugMsg;
if (I)
dbgs() << ' ' << *I;
else
dbgs() << '.';
dbgs() << '\n';
}
#endif
static OptimizationRemarkAnalysis
createHWLoopAnalysis(StringRef RemarkName, Loop *L, Instruction *I) {
Value *CodeRegion = L->getHeader();
DebugLoc DL = L->getStartLoc();
if (I) {
CodeRegion = I->getParent();
// If there is no debug location attached to the instruction, revert back to
// using the loop's.
if (I->getDebugLoc())
DL = I->getDebugLoc();
}
OptimizationRemarkAnalysis R(DEBUG_TYPE, RemarkName, DL, CodeRegion);
R << "hardware-loop not created: ";
return R;
}
namespace {
void reportHWLoopFailure(const StringRef Msg, const StringRef ORETag,
OptimizationRemarkEmitter *ORE, Loop *TheLoop, Instruction *I = nullptr) {
LLVM_DEBUG(debugHWLoopFailure(Msg, I));
ORE->emit(createHWLoopAnalysis(ORETag, TheLoop, I) << Msg);
}
using TTI = TargetTransformInfo;
class HardwareLoops : public FunctionPass {
@ -97,6 +134,7 @@ namespace {
AU.addRequired<ScalarEvolutionWrapperPass>();
AU.addRequired<AssumptionCacheTracker>();
AU.addRequired<TargetTransformInfoWrapperPass>();
AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
}
// Try to convert the given Loop into a hardware loop.
@ -110,6 +148,7 @@ namespace {
ScalarEvolution *SE = nullptr;
LoopInfo *LI = nullptr;
const DataLayout *DL = nullptr;
OptimizationRemarkEmitter *ORE = nullptr;
const TargetTransformInfo *TTI = nullptr;
DominatorTree *DT = nullptr;
bool PreserveLCSSA = false;
@ -143,8 +182,9 @@ namespace {
public:
HardwareLoop(HardwareLoopInfo &Info, ScalarEvolution &SE,
const DataLayout &DL) :
SE(SE), DL(DL), L(Info.L), M(L->getHeader()->getModule()),
const DataLayout &DL,
OptimizationRemarkEmitter *ORE) :
SE(SE), DL(DL), ORE(ORE), L(Info.L), M(L->getHeader()->getModule()),
ExitCount(Info.ExitCount),
CountType(Info.CountType),
ExitBranch(Info.ExitBranch),
@ -157,6 +197,7 @@ namespace {
private:
ScalarEvolution &SE;
const DataLayout &DL;
OptimizationRemarkEmitter *ORE = nullptr;
Loop *L = nullptr;
Module *M = nullptr;
const SCEV *ExitCount = nullptr;
@ -182,6 +223,7 @@ bool HardwareLoops::runOnFunction(Function &F) {
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
TTI = &getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
DL = &F.getParent()->getDataLayout();
ORE = &getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE();
auto *TLIP = getAnalysisIfAvailable<TargetLibraryInfoWrapperPass>();
LibInfo = TLIP ? &TLIP->getTLI(F) : nullptr;
PreserveLCSSA = mustPreserveAnalysisID(LCSSAID);
@ -201,31 +243,39 @@ bool HardwareLoops::runOnFunction(Function &F) {
// converted and the parent loop doesn't support containing a hardware loop.
bool HardwareLoops::TryConvertLoop(Loop *L) {
// Process nested loops first.
for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I)
if (TryConvertLoop(*I))
for (Loop::iterator I = L->begin(), E = L->end(); I != E; ++I) {
if (TryConvertLoop(*I)) {
reportHWLoopFailure("nested hardware-loops not supported", "HWLoopNested",
ORE, L);
return true; // Stop search.
HardwareLoopInfo HWLoopInfo(L);
if (!HWLoopInfo.canAnalyze(*LI))
return false;
if (TTI->isHardwareLoopProfitable(L, *SE, *AC, LibInfo, HWLoopInfo) ||
ForceHardwareLoops) {
// Allow overriding of the counter width and loop decrement value.
if (CounterBitWidth.getNumOccurrences())
HWLoopInfo.CountType =
IntegerType::get(M->getContext(), CounterBitWidth);
if (LoopDecrement.getNumOccurrences())
HWLoopInfo.LoopDecrement =
ConstantInt::get(HWLoopInfo.CountType, LoopDecrement);
MadeChange |= TryConvertLoop(HWLoopInfo);
return MadeChange && (!HWLoopInfo.IsNestingLegal && !ForceNestedLoop);
}
}
return false;
HardwareLoopInfo HWLoopInfo(L);
if (!HWLoopInfo.canAnalyze(*LI)) {
reportHWLoopFailure("cannot analyze loop, irreducible control flow",
"HWLoopCannotAnalyze", ORE, L);
return false;
}
if (!ForceHardwareLoops &&
!TTI->isHardwareLoopProfitable(L, *SE, *AC, LibInfo, HWLoopInfo)) {
reportHWLoopFailure("it's not profitable to create a hardware-loop",
"HWLoopNotProfitable", ORE, L);
return false;
}
// Allow overriding of the counter width and loop decrement value.
if (CounterBitWidth.getNumOccurrences())
HWLoopInfo.CountType =
IntegerType::get(M->getContext(), CounterBitWidth);
if (LoopDecrement.getNumOccurrences())
HWLoopInfo.LoopDecrement =
ConstantInt::get(HWLoopInfo.CountType, LoopDecrement);
MadeChange |= TryConvertLoop(HWLoopInfo);
return MadeChange && (!HWLoopInfo.IsNestingLegal && !ForceNestedLoop);
}
bool HardwareLoops::TryConvertLoop(HardwareLoopInfo &HWLoopInfo) {
@ -234,8 +284,13 @@ bool HardwareLoops::TryConvertLoop(HardwareLoopInfo &HWLoopInfo) {
LLVM_DEBUG(dbgs() << "HWLoops: Try to convert profitable loop: " << *L);
if (!HWLoopInfo.isHardwareLoopCandidate(*SE, *LI, *DT, ForceNestedLoop,
ForceHardwareLoopPHI))
ForceHardwareLoopPHI)) {
// TODO: there can be many reasons a loop is not considered a
// candidate, so we should let isHardwareLoopCandidate fill in the
// reason and then report a better message here.
reportHWLoopFailure("loop is not a candidate", "HWLoopNoCandidate", ORE, L);
return false;
}
assert(
(HWLoopInfo.ExitBlock && HWLoopInfo.ExitBranch && HWLoopInfo.ExitCount) &&
@ -249,7 +304,7 @@ bool HardwareLoops::TryConvertLoop(HardwareLoopInfo &HWLoopInfo) {
if (!Preheader)
return false;
HardwareLoop HWLoop(HWLoopInfo, *SE, *DL);
HardwareLoop HWLoop(HWLoopInfo, *SE, *DL, ORE);
HWLoop.Create();
++NumHWLoops;
return true;
@ -257,10 +312,13 @@ bool HardwareLoops::TryConvertLoop(HardwareLoopInfo &HWLoopInfo) {
void HardwareLoop::Create() {
LLVM_DEBUG(dbgs() << "HWLoops: Converting loop..\n");
Value *LoopCountInit = InitLoopCount();
if (!LoopCountInit)
if (!LoopCountInit) {
reportHWLoopFailure("could not safely create a loop count expression",
"HWLoopNotSafe", ORE, L);
return;
}
InsertIterationSetup(LoopCountInit);
@ -458,6 +516,7 @@ INITIALIZE_PASS_BEGIN(HardwareLoops, DEBUG_TYPE, HW_LOOPS_NAME, false, false)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(ScalarEvolutionWrapperPass)
INITIALIZE_PASS_DEPENDENCY(OptimizationRemarkEmitterWrapperPass)
INITIALIZE_PASS_END(HardwareLoops, DEBUG_TYPE, HW_LOOPS_NAME, false, false)
FunctionPass *llvm::createHardwareLoopsPass() { return new HardwareLoops(); }

3
llvm/test/CodeGen/ARM/O3-pipeline.ll
View File

@ -52,6 +52,9 @@
; CHECK-NEXT: Dominator Tree Construction
; CHECK-NEXT: Natural Loop Information
; CHECK-NEXT: Scalar Evolution Analysis
; CHECK-NEXT: Lazy Branch Probability Analysis
; CHECK-NEXT: Lazy Block Frequency Analysis
; CHECK-NEXT: Optimization Remark Emitter
; CHECK-NEXT: Hardware Loop Insertion
; CHECK-NEXT: Scalar Evolution Analysis
; CHECK-NEXT: Loop Pass Manager

25
llvm/test/Transforms/HardwareLoops/ARM/structure.ll
View File

@ -1,6 +1,25 @@
; RUN: opt -mtriple=thumbv8.1m.main-arm-none-eabi -hardware-loops %s -S -o - | FileCheck %s
; RUN: llc -mtriple=thumbv8.1m.main-arm-none-eabi %s -o - | FileCheck %s --check-prefix=CHECK-LLC
; RUN: opt -mtriple=thumbv8.1m.main -loop-unroll -unroll-remainder=false -S < %s | llc -mtriple=thumbv8.1m.main | FileCheck %s --check-prefix=CHECK-UNROLL
; RUN: opt -mtriple=thumbv8.1m.main-arm-none-eabi -hardware-loops %s -S -o - | \
; RUN: FileCheck %s
; RUN: llc -mtriple=thumbv8.1m.main-arm-none-eabi %s -o - | \
; RUN: FileCheck %s --check-prefix=CHECK-LLC
; RUN: opt -mtriple=thumbv8.1m.main -loop-unroll -unroll-remainder=false -S < %s | \
; RUN: llc -mtriple=thumbv8.1m.main | FileCheck %s --check-prefix=CHECK-UNROLL
; RUN: opt -mtriple=thumbv8.1m.main-arm-none-eabi -hardware-loops \
; RUN: -pass-remarks-analysis=hardware-loops %s -S -o - 2>&1 | \
; RUN: FileCheck %s --check-prefix=CHECK-REMARKS
; CHECK-REMARKS: remark: <unknown>:0:0: hardware-loop not created: it's not profitable to create a hardware-loop
; CHECK-REMARKS: remark: <unknown>:0:0: hardware-loop not created: nested hardware-loops not supported
; CHECK-REMARKS: remark: <unknown>:0:0: hardware-loop not created: it's not profitable to create a hardware-loop
; CHECK-REMARKS: remark: <unknown>:0:0: hardware-loop not created: it's not profitable to create a hardware-loop
; CHECK-REMARKS: remark: <unknown>:0:0: hardware-loop not created: it's not profitable to create a hardware-loop
; CHECK-REMARKS: remark: <unknown>:0:0: hardware-loop not created: it's not profitable to create a hardware-loop
; CHECK-REMARKS: remark: <unknown>:0:0: hardware-loop not created: loop is not a candidate
; CHECK-REMARKS: remark: <unknown>:0:0: hardware-loop not created: nested hardware-loops not supported
; CHECK-REMARKS: remark: <unknown>:0:0: hardware-loop not created: it's not profitable to create a hardware-loop
; CHECK-REMARKS: remark: <unknown>:0:0: hardware-loop not created: it's not profitable to create a hardware-loop
; CHECK-LABEL: early_exit
; CHECK-NOT: llvm.set.loop.iterations