llvm-project/clang/lib/StaticAnalyzer/Core/AnalyzerOptions.cpp
Anna Zaks d53182b0df [analyzer] Implement "do not inline large functions many times"
performance heuristic

After inlining a function with more than 13 basic blocks 32 times, we
are not going to inline it anymore. The idea is that inlining large
functions leads to drastic performance implications. Since the function
has already been inlined, we know that we've analyzed it in many
contexts. 

The following metrics are used:
 - Large function is a function with more than 13 basic blocks (we
should switch to another metric, like cyclomatic complexity)
 - We consider that we've inlined a function many times if it's been
inlined 32 times. This number is configurable with -analyzer-config
max-times-inline-large=xx

This heuristic addresses a performance regression introduced with
inlining on one benchmark. The analyzer on this benchmark became 60
times slower with inlining turned on. The heuristic allows us to analyze
it in 24% of the time. The performance improvements on the other
benchmarks I've tested with are much lower - under 10%, which is
expected.

llvm-svn: 170361
2012-12-17 20:08:51 +00:00

145 lines
4.8 KiB
C++

//===-- AnalyzerOptions.cpp - Analysis Engine Options -----------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains special accessors for analyzer configuration options
// with string representations.
//
//===----------------------------------------------------------------------===//
#include "clang/StaticAnalyzer/Core/AnalyzerOptions.h"
#include "llvm/ADT/SmallString.h"
#include "llvm/ADT/StringSwitch.h"
#include "llvm/Support/raw_ostream.h"
using namespace clang;
using namespace llvm;
bool
AnalyzerOptions::mayInlineCXXMemberFunction(CXXInlineableMemberKind K) {
if (IPAMode < Inlining)
return false;
if (!CXXMemberInliningMode) {
static const char *ModeKey = "c++-inlining";
StringRef ModeStr(Config.GetOrCreateValue(ModeKey,
"methods").getValue());
CXXInlineableMemberKind &MutableMode =
const_cast<CXXInlineableMemberKind &>(CXXMemberInliningMode);
MutableMode = llvm::StringSwitch<CXXInlineableMemberKind>(ModeStr)
.Case("constructors", CIMK_Constructors)
.Case("destructors", CIMK_Destructors)
.Case("none", CIMK_None)
.Case("methods", CIMK_MemberFunctions)
.Default(CXXInlineableMemberKind());
if (!MutableMode) {
// FIXME: We should emit a warning here about an unknown inlining kind,
// but the AnalyzerOptions doesn't have access to a diagnostic engine.
MutableMode = CIMK_None;
}
}
return CXXMemberInliningMode >= K;
}
static StringRef toString(bool b) { return b ? "true" : "false"; }
bool AnalyzerOptions::getBooleanOption(StringRef Name, bool DefaultVal) {
// FIXME: We should emit a warning here if the value is something other than
// "true", "false", or the empty string (meaning the default value),
// but the AnalyzerOptions doesn't have access to a diagnostic engine.
StringRef V(Config.GetOrCreateValue(Name, toString(DefaultVal)).getValue());
return llvm::StringSwitch<bool>(V)
.Case("true", true)
.Case("false", false)
.Default(DefaultVal);
}
bool AnalyzerOptions::getBooleanOption(llvm::Optional<bool> &V,
StringRef Name,
bool DefaultVal) {
if (!V.hasValue())
V = getBooleanOption(Name, DefaultVal);
return V.getValue();
}
bool AnalyzerOptions::includeTemporaryDtorsInCFG() {
return getBooleanOption(IncludeTemporaryDtorsInCFG,
"cfg-temporary-dtors",
/* Default = */ false);
}
bool AnalyzerOptions::mayInlineCXXStandardLibrary() {
return getBooleanOption(InlineCXXStandardLibrary,
"c++-stdlib-inlining",
/*Default=*/true);
}
bool AnalyzerOptions::mayInlineTemplateFunctions() {
return getBooleanOption(InlineTemplateFunctions,
"c++-template-inlining",
/*Default=*/true);
}
bool AnalyzerOptions::mayInlineObjCMethod() {
return getBooleanOption(ObjCInliningMode,
"objc-inlining",
/* Default = */ true);
}
bool AnalyzerOptions::shouldPruneNullReturnPaths() {
return getBooleanOption(PruneNullReturnPaths,
"suppress-null-return-paths",
/* Default = */ true);
}
bool AnalyzerOptions::shouldAvoidSuppressingNullArgumentPaths() {
return getBooleanOption(AvoidSuppressingNullArgumentPaths,
"avoid-suppressing-null-argument-paths",
/* Default = */ false);
}
int AnalyzerOptions::getOptionAsInteger(StringRef Name, int DefaultVal) {
llvm::SmallString<10> StrBuf;
llvm::raw_svector_ostream OS(StrBuf);
OS << DefaultVal;
StringRef V(Config.GetOrCreateValue(Name, OS.str()).getValue());
int Res = DefaultVal;
bool b = V.getAsInteger(10, Res);
assert(!b && "analyzer-config option should be numeric");
(void) b;
return Res;
}
unsigned AnalyzerOptions::getAlwaysInlineSize() {
if (!AlwaysInlineSize.hasValue())
AlwaysInlineSize = getOptionAsInteger("ipa-always-inline-size", 3);
return AlwaysInlineSize.getValue();
}
unsigned AnalyzerOptions::getGraphTrimInterval() {
if (!GraphTrimInterval.hasValue())
GraphTrimInterval = getOptionAsInteger("graph-trim-interval", 1000);
return GraphTrimInterval.getValue();
}
unsigned AnalyzerOptions::getMaxTimesInlineLarge() {
if (!MaxTimesInlineLarge.hasValue())
MaxTimesInlineLarge = getOptionAsInteger("max-times-inline-large", 32);
return MaxTimesInlineLarge.getValue();
}
bool AnalyzerOptions::shouldSynthesizeBodies() {
return getBooleanOption("faux-bodies", true);
}