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Revert "Re-commit : [LICM] Allow sinking when foldable in loop" 

This reverts commit r320833.

llvm-svn: 320836
This commit is contained in:
Jun Bum Lim 2017-12-15 18:12:49 +00:00
parent d3ddf28e7f
commit 5efd4d8b5e
3 changed files with 31 additions and 231 deletions
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5
llvm/include/llvm/Transforms/Utils/LoopUtils.h
View File

@ -436,9 +436,8 @@ bool formLCSSARecursively(Loop &L, DominatorTree &DT, LoopInfo *LI,
/// instructions of the loop and loop safety information as
/// arguments. Diagnostics is emitted via \p ORE. It returns changed status.
bool sinkRegion(DomTreeNode *, AliasAnalysis *, LoopInfo *, DominatorTree *,
TargetLibraryInfo *, TargetTransformInfo *, Loop *,
AliasSetTracker *, LoopSafetyInfo *,
OptimizationRemarkEmitter *ORE);
TargetLibraryInfo *, Loop *, AliasSetTracker *,
LoopSafetyInfo *, OptimizationRemarkEmitter *ORE);
/// \brief Walk the specified region of the CFG (defined by all blocks
/// dominated by the specified block, and that are in the current loop) in depth

107
llvm/lib/Transforms/Scalar/LICM.cpp
View File

@ -90,15 +90,14 @@ static cl::opt<uint32_t> MaxNumUsesTraversed(
"invariance in loop using invariant start (default = 8)"));
static bool inSubLoop(BasicBlock *BB, Loop *CurLoop, LoopInfo *LI);
static bool isNotUsedOrFreeInLoop(const Instruction &I, const Loop *CurLoop,
const LoopSafetyInfo *SafetyInfo,
TargetTransformInfo *TTI, bool &FreeInLoop);
static bool isNotUsedInLoop(const Instruction &I, const Loop *CurLoop,
const LoopSafetyInfo *SafetyInfo);
static bool hoist(Instruction &I, const DominatorTree *DT, const Loop *CurLoop,
const LoopSafetyInfo *SafetyInfo,
OptimizationRemarkEmitter *ORE);
static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
const Loop *CurLoop, const LoopSafetyInfo *SafetyInfo,
OptimizationRemarkEmitter *ORE, bool FreeInLoop);
OptimizationRemarkEmitter *ORE);
static bool isSafeToExecuteUnconditionally(Instruction &Inst,
const DominatorTree *DT,
const Loop *CurLoop,
@ -116,8 +115,7 @@ CloneInstructionInExitBlock(Instruction &I, BasicBlock &ExitBlock, PHINode &PN,
namespace {
struct LoopInvariantCodeMotion {
bool runOnLoop(Loop *L, AliasAnalysis *AA, LoopInfo *LI, DominatorTree *DT,
TargetLibraryInfo *TLI, TargetTransformInfo *TTI,
ScalarEvolution *SE, MemorySSA *MSSA,
TargetLibraryInfo *TLI, ScalarEvolution *SE, MemorySSA *MSSA,
OptimizationRemarkEmitter *ORE, bool DeleteAST);
DenseMap<Loop *, AliasSetTracker *> &getLoopToAliasSetMap() {
@ -161,8 +159,6 @@ struct LegacyLICMPass : public LoopPass {
&getAnalysis<LoopInfoWrapperPass>().getLoopInfo(),
&getAnalysis<DominatorTreeWrapperPass>().getDomTree(),
&getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(),
&getAnalysis<TargetTransformInfoWrapperPass>().getTTI(
*L->getHeader()->getParent()),
SE ? &SE->getSE() : nullptr, MSSA, &ORE, false);
}
@ -174,7 +170,6 @@ struct LegacyLICMPass : public LoopPass {
AU.addRequired<TargetLibraryInfoWrapperPass>();
if (EnableMSSALoopDependency)
AU.addRequired<MemorySSAWrapperPass>();
AU.addRequired<TargetTransformInfoWrapperPass>();
getLoopAnalysisUsage(AU);
}
@ -215,8 +210,8 @@ PreservedAnalyses LICMPass::run(Loop &L, LoopAnalysisManager &AM,
"cached at a higher level");
LoopInvariantCodeMotion LICM;
if (!LICM.runOnLoop(&L, &AR.AA, &AR.LI, &AR.DT, &AR.TLI, &AR.TTI, &AR.SE,
AR.MSSA, ORE, true))
if (!LICM.runOnLoop(&L, &AR.AA, &AR.LI, &AR.DT, &AR.TLI, &AR.SE, AR.MSSA, ORE,
true))
return PreservedAnalyses::all();
auto PA = getLoopPassPreservedAnalyses();
@ -229,7 +224,6 @@ INITIALIZE_PASS_BEGIN(LegacyLICMPass, "licm", "Loop Invariant Code Motion",
false, false)
INITIALIZE_PASS_DEPENDENCY(LoopPass)
INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)
INITIALIZE_PASS_END(LegacyLICMPass, "licm", "Loop Invariant Code Motion", false,
false)
@ -242,10 +236,12 @@ Pass *llvm::createLICMPass() { return new LegacyLICMPass(); }
/// We should delete AST for inner loops in the new pass manager to avoid
/// memory leak.
///
bool LoopInvariantCodeMotion::runOnLoop(
Loop *L, AliasAnalysis *AA, LoopInfo *LI, DominatorTree *DT,
TargetLibraryInfo *TLI, TargetTransformInfo *TTI, ScalarEvolution *SE,
MemorySSA *MSSA, OptimizationRemarkEmitter *ORE, bool DeleteAST) {
bool LoopInvariantCodeMotion::runOnLoop(Loop *L, AliasAnalysis *AA,
LoopInfo *LI, DominatorTree *DT,
TargetLibraryInfo *TLI,
ScalarEvolution *SE, MemorySSA *MSSA,
OptimizationRemarkEmitter *ORE,
bool DeleteAST) {
bool Changed = false;
assert(L->isLCSSAForm(*DT) && "Loop is not in LCSSA form.");
@ -270,7 +266,7 @@ bool LoopInvariantCodeMotion::runOnLoop(
// instructions, we perform another pass to hoist them out of the loop.
//
if (L->hasDedicatedExits())
Changed |= sinkRegion(DT->getNode(L->getHeader()), AA, LI, DT, TLI, TTI, L,
Changed |= sinkRegion(DT->getNode(L->getHeader()), AA, LI, DT, TLI, L,
CurAST, &SafetyInfo, ORE);
if (Preheader)
Changed |= hoistRegion(DT->getNode(L->getHeader()), AA, LI, DT, TLI, L,
@ -363,8 +359,7 @@ bool LoopInvariantCodeMotion::runOnLoop(
/// definitions, allowing us to sink a loop body in one pass without iteration.
///
bool llvm::sinkRegion(DomTreeNode *N, AliasAnalysis *AA, LoopInfo *LI,
DominatorTree *DT, TargetLibraryInfo *TLI,
TargetTransformInfo *TTI, Loop *CurLoop,
DominatorTree *DT, TargetLibraryInfo *TLI, Loop *CurLoop,
AliasSetTracker *CurAST, LoopSafetyInfo *SafetyInfo,
OptimizationRemarkEmitter *ORE) {
@ -405,15 +400,12 @@ bool llvm::sinkRegion(DomTreeNode *N, AliasAnalysis *AA, LoopInfo *LI,
// outside of the loop. In this case, it doesn't even matter if the
// operands of the instruction are loop invariant.
//
bool FreeInLoop = false;
if (isNotUsedOrFreeInLoop(I, CurLoop, SafetyInfo, TTI, FreeInLoop) &&
if (isNotUsedInLoop(I, CurLoop, SafetyInfo) &&
canSinkOrHoistInst(I, AA, DT, CurLoop, CurAST, SafetyInfo, ORE)) {
if (sink(I, LI, DT, CurLoop, SafetyInfo, ORE, FreeInLoop)) {
if (!FreeInLoop) {
++II;
CurAST->deleteValue(&I);
I.eraseFromParent();
}
if (sink(I, LI, DT, CurLoop, SafetyInfo, ORE)) {
++II;
CurAST->deleteValue(&I);
I.eraseFromParent();
Changed = true;
}
}
@ -716,39 +708,13 @@ static bool isTriviallyReplacablePHI(const PHINode &PN, const Instruction &I) {
return true;
}
/// Return true if the instruction is free in the loop.
static bool isFreeInLoop(const Instruction &I, const Loop *CurLoop,
const TargetTransformInfo *TTI) {
if (const GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(&I)) {
if (TTI->getUserCost(&I) != TargetTransformInfo::TCC_Free)
return false;
// For a GEP, we cannot simply use getUserCost because currently it
// optimistically assume that a GEP will fold into addressing mode
// regardless of its users.
const BasicBlock *BB = I.getParent();
for (const User *U : I.users()) {
const Instruction *UI = cast<Instruction>(U);
if (CurLoop->contains(UI) &&
(BB != UI->getParent() ||
(!isa<StoreInst>(UI) && !isa<LoadInst>(UI))))
return false;
}
return true;
} else
return TTI->getUserCost(&I) == TargetTransformInfo::TCC_Free;
}
/// Return true if the only users of this instruction are outside of
/// the loop. If this is true, we can sink the instruction to the exit
/// blocks of the loop.
///
/// We also return true if the instruction could be folded away in lowering.
/// (e.g., a GEP can be folded into a load as an addressing mode in the loop).
static bool isNotUsedOrFreeInLoop(const Instruction &I, const Loop *CurLoop,
const LoopSafetyInfo *SafetyInfo,
TargetTransformInfo *TTI, bool &FreeInLoop) {
static bool isNotUsedInLoop(const Instruction &I, const Loop *CurLoop,
const LoopSafetyInfo *SafetyInfo) {
const auto &BlockColors = SafetyInfo->BlockColors;
bool IsFree = isFreeInLoop(I, CurLoop, TTI);
for (const User *U : I.users()) {
const Instruction *UI = cast<Instruction>(U);
if (const PHINode *PN = dyn_cast<PHINode>(UI)) {
@ -765,13 +731,8 @@ static bool isNotUsedOrFreeInLoop(const Instruction &I, const Loop *CurLoop,
return false;
}
if (CurLoop->contains(UI)) {
if (IsFree) {
FreeInLoop = true;
continue;
}
if (CurLoop->contains(UI))
return false;
}
}
return true;
}
@ -927,7 +888,7 @@ static void splitPredecessorsOfLoopExit(PHINode *PN, DominatorTree *DT,
///
static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
const Loop *CurLoop, const LoopSafetyInfo *SafetyInfo,
OptimizationRemarkEmitter *ORE, bool FreeInLoop) {
OptimizationRemarkEmitter *ORE) {
DEBUG(dbgs() << "LICM sinking instruction: " << I << "\n");
ORE->emit([&]() {
return OptimizationRemark(DEBUG_TYPE, "InstSunk", &I)
@ -939,6 +900,7 @@ static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
else if (isa<CallInst>(I))
++NumMovedCalls;
++NumSunk;
Changed = true;
// Iterate over users to be ready for actual sinking. Replace users via
// unrechable blocks with undef and make all user PHIs trivially replcable.
@ -948,12 +910,11 @@ static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
Use &U = UI.getUse();
++UI;
if (VisitedUsers.count(User) || CurLoop->contains(User))
if (VisitedUsers.count(User))
continue;
if (!DT->isReachableFromEntry(User->getParent())) {
U = UndefValue::get(I.getType());
Changed = true;
continue;
}
@ -966,7 +927,6 @@ static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
BasicBlock *BB = PN->getIncomingBlock(U);
if (!DT->isReachableFromEntry(BB)) {
U = UndefValue::get(I.getType());
Changed = true;
continue;
}
@ -975,7 +935,7 @@ static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
continue;
if (!canSplitPredecessors(PN))
return Changed;
return false;
// Split predecessors of the PHI so that we can make users trivially
// replacable.
@ -987,9 +947,6 @@ static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
UE = I.user_end();
}
if (VisitedUsers.empty())
return Changed;
#ifndef NDEBUG
SmallVector<BasicBlock *, 32> ExitBlocks;
CurLoop->getUniqueExitBlocks(ExitBlocks);
@ -1003,14 +960,9 @@ static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
// If this instruction is only used outside of the loop, then all users are
// PHI nodes in exit blocks due to LCSSA form. Just RAUW them with clones of
// the instruction.
SmallSetVector<User*, 8> Users(I.user_begin(), I.user_end());
for (auto *UI : Users) {
auto *User = cast<Instruction>(UI);
if (CurLoop->contains(User))
continue;
PHINode *PN = cast<PHINode>(User);
while (!I.use_empty()) {
Value::user_iterator UI = I.user_begin();
PHINode *PN = cast<PHINode>(*UI);
assert(ExitBlockSet.count(PN->getParent()) &&
"The LCSSA PHI is not in an exit block!");
// The PHI must be trivially replacable.
@ -1018,7 +970,6 @@ static bool sink(Instruction &I, LoopInfo *LI, DominatorTree *DT,
SafetyInfo, CurLoop);
PN->replaceAllUsesWith(New);
PN->eraseFromParent();
Changed = true;
}
return Changed;
}

150
llvm/test/Transforms/LICM/sink-foldable.ll
View File

@ -1,150 +0,0 @@
; REQUIRES: aarch64-registered-target
; RUN: opt < %s -licm -S | FileCheck %s
target triple = "aarch64--linux-gnueabi"
; CHECK-LABEL:@test1
; CHECK-LABEL:loopexit1:
; CHECK: %[[PHI:.+]] = phi i8** [ %arrayidx0, %if.end ]
; CHECK: getelementptr inbounds i8*, i8** %[[PHI]], i64 1
define i8** @test1(i32 %j, i8** readonly %P, i8* readnone %Q) {
entry:
%cmp0 = icmp slt i32 0, %j
br i1 %cmp0, label %for.body.lr.ph, label %return
for.body.lr.ph:
br label %for.body
for.body:
%P.addr = phi i8** [ %P, %for.body.lr.ph ], [ %arrayidx0, %if.end ]
%i0 = phi i32 [ 0, %for.body.lr.ph ], [ %i.add, %if.end]
%i0.ext = sext i32 %i0 to i64
%arrayidx0 = getelementptr inbounds i8*, i8** %P.addr, i64 %i0.ext
%l0 = load i8*, i8** %arrayidx0, align 8
%cmp1 = icmp ugt i8* %l0, %Q
br i1 %cmp1, label %loopexit0, label %if.end
if.end: ; preds = %for.body
%arrayidx1 = getelementptr inbounds i8*, i8** %arrayidx0, i64 1
%l1 = load i8*, i8** %arrayidx1, align 8
%cmp4 = icmp ugt i8* %l1, %Q
%i.add = add nsw i32 %i0, 2
br i1 %cmp4, label %loopexit1, label %for.body
loopexit0:
%p1 = phi i8** [%arrayidx0, %for.body]
br label %return
loopexit1:
%p2 = phi i8** [%arrayidx1, %if.end]
br label %return
return:
%retval.0 = phi i8** [ %p1, %loopexit0 ], [%p2, %loopexit1], [ null, %entry ]
ret i8** %retval.0
}
; CHECK-LABEL: @test2
; CHECK-LABEL: loopexit2:
; CHECK: %[[PHI:.*]] = phi i8** [ %add.ptr, %if.end ]
; CHECK: getelementptr inbounds i8*, i8** %[[PHI]]
define i8** @test2(i32 %j, i8** readonly %P, i8* readnone %Q) {
entry:
br label %for.body
for.cond:
%i.addr.0 = phi i32 [ %add, %if.end ]
%P.addr.0 = phi i8** [ %add.ptr, %if.end ]
%cmp = icmp slt i32 %i.addr.0, %j
br i1 %cmp, label %for.body, label %loopexit0
for.body:
%P.addr = phi i8** [ %P, %entry ], [ %P.addr.0, %for.cond ]
%i.addr = phi i32 [ 0, %entry ], [ %i.addr.0, %for.cond ]
%idx.ext = sext i32 %i.addr to i64
%add.ptr = getelementptr inbounds i8*, i8** %P.addr, i64 %idx.ext
%l0 = load i8*, i8** %add.ptr, align 8
%cmp1 = icmp ugt i8* %l0, %Q
br i1 %cmp1, label %loopexit1, label %if.end
if.end:
%add.i = add i32 %i.addr, 1
%idx2.ext = sext i32 %add.i to i64
%arrayidx2 = getelementptr inbounds i8*, i8** %add.ptr, i64 %idx2.ext
%l1 = load i8*, i8** %arrayidx2, align 8
%cmp2 = icmp ugt i8* %l1, %Q
%add = add nsw i32 %add.i, 1
br i1 %cmp2, label %loopexit2, label %for.cond
loopexit0:
%p0 = phi i8** [ null, %for.cond ]
br label %return
loopexit1:
%p1 = phi i8** [ %add.ptr, %for.body ]
br label %return
loopexit2:
%p2 = phi i8** [ %arrayidx2, %if.end ]
br label %return
return:
%retval.0 = phi i8** [ %p1, %loopexit1 ], [ %p2, %loopexit2 ], [ %p0, %loopexit0 ]
ret i8** %retval.0
}
; CHECK-LABEL: @test3
; CHECK-LABEL: loopexit1:
; CHECK: %[[ADD:.*]] = phi i64 [ %add, %if.end ]
; CHECK: %[[ADDR:.*]] = phi i8** [ %P.addr, %if.end ]
; CHECK: %[[TRUNC:.*]] = trunc i64 %[[ADD]] to i32
; CHECK: getelementptr inbounds i8*, i8** %[[ADDR]], i32 %[[TRUNC]]
; CHECK: call void @dummy(i32 %[[TRUNC]])
define i8** @test3(i64 %j, i8** readonly %P, i8* readnone %Q) {
entry:
%cmp0 = icmp slt i64 0, %j
br i1 %cmp0, label %for.body.lr.ph, label %return
for.body.lr.ph:
br label %for.body
for.body:
%P.addr = phi i8** [ %P, %for.body.lr.ph ], [ %arrayidx0, %if.end ]
%i0 = phi i32 [ 0, %for.body.lr.ph ], [ %i.add, %if.end]
%i0.ext = sext i32 %i0 to i64
%arrayidx0 = getelementptr inbounds i8*, i8** %P.addr, i64 %i0.ext
%l0 = load i8*, i8** %arrayidx0, align 8
%cmp1 = icmp ugt i8* %l0, %Q
br i1 %cmp1, label %loopexit0, label %if.end
if.end: ; preds = %for.body
%add = add i64 %i0.ext, 1
%trunc = trunc i64 %add to i32
%arrayidx1 = getelementptr inbounds i8*, i8** %P.addr, i32 %trunc
%l1 = load i8*, i8** %arrayidx1, align 8
%cmp4 = icmp ugt i8* %l1, %Q
%i.add = add nsw i32 %i0, 2
br i1 %cmp4, label %loopexit1, label %for.body
loopexit0:
%p1 = phi i8** [%arrayidx0, %for.body]
br label %return
loopexit1:
%p2 = phi i8** [%arrayidx1, %if.end]
call void @dummy(i32 %trunc)
br label %return
return:
%retval.0 = phi i8** [ %p1, %loopexit0 ], [%p2, %loopexit1], [ null, %entry ]
ret i8** %retval.0
}
declare void @dummy(i32)