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[g-arc-opts] Teach the arc optimizer how to recognize more trap BBs in the stdlib.

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This reduces the number of retain, release operations in the dylib from 38512 to
16041. That is a reduction of 60%. Most of the code paths affected by this were
in the cocoa part of the stdlib so when I measured the perf test suite I did not
see a huge boost in perf.

rdar://18327670

Swift SVN r21934
This commit is contained in:
Michael Gottesman
2014-09-13 01:42:24 +00:00
parent 8eb7bf2c31
commit 1bfdd9e3bf
2 changed files with 70 additions and 18 deletions
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52
lib/SILAnalysis/GlobalARCSequenceDataflow.cpp
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@@ -19,6 +19,7 @@
#include "swift/SIL/SILFunction.h"
#include "swift/SIL/SILSuccessor.h"
#include "swift/SIL/CFG.h"
#include "swift/SIL/SILModule.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringSwitch.h"
@@ -792,27 +793,35 @@ bool swift::arc::ARCSequenceDataflowEvaluator::run() {
return NestingDetected;
}
/// Match a call to int_trap.
static bool matchTrappingUnreachableBB(SILBasicBlock *BB) {
auto II = BB->begin();
auto *BFRI = dyn_cast<BuiltinFunctionRefInst>(&*II);
if (!BFRI || !BFRI->getName().str().equals("int_trap"))
return false;
++II;
static bool ignoreableApplyInstInUnreachableBlock(ApplyInst *AI) {
if (auto *BFRI = dyn_cast<BuiltinFunctionRefInst>(AI->getCallee())) {
const BuiltinInfo &BInfo = BFRI->getBuiltinInfo();
if (BInfo.ID == BuiltinValueKind::CondUnreachable)
return true;
auto *AI = dyn_cast<ApplyInst>(&*II);
if (!AI || AI->getCallee() != SILValue(BFRI))
const IntrinsicInfo &IInfo = BFRI->getIntrinsicInfo();
if (IInfo.ID == llvm::Intrinsic::trap)
return true;
}
const char *fatalName =
"_TFSs18_fatalErrorMessageFTVSs12StaticStringS_S_Su_T_";
auto *FRI = dyn_cast<FunctionRefInst>(AI->getCallee());
if (!FRI || !FRI->getReferencedFunction()->getName().equals(fatalName))
return false;
++II;
return true;
}
/// Match a call to a BB with no ARC relevant side effects.
static bool matchNoSideEffectUnreachableBB(SILBasicBlock *BB) {
auto II = BB->begin();
while (true) {
// Ignore any literal insts.
if (isa<LiteralInst>(II)) {
auto II = BB->begin(), IE = BB->end();
while (II != IE) {
if (isa<UnreachableInst>(&*II))
return true;
// Ignore any instructions without side effects.
if (!II->mayHaveSideEffects()) {
++II;
continue;
}
@@ -823,11 +832,20 @@ static bool matchNoSideEffectUnreachableBB(SILBasicBlock *BB) {
continue;
}
return isa<UnreachableInst>(&*II);
// Check for apply insts that we can ignore.
if (auto *AI = dyn_cast<ApplyInst>(&*II)) {
if (ignoreableApplyInstInUnreachableBlock(AI)) {
++II;
continue;
}
}
return false;
}
return false;
}
void swift::arc::ARCBBState::initializeTrapStatus() {
IsTrapBB = matchTrappingUnreachableBB(BB) ||
matchNoSideEffectUnreachableBB(BB);
IsTrapBB = matchNoSideEffectUnreachableBB(BB);
}