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llvm-mirror/tools/opt/opt.cpp
Chandler Carruth 5c3f34f10b Introduce the "retpoline" x86 mitigation technique for variant #2 of the speculative execution vulnerabilities disclosed today, specifically identified by CVE-2017-5715, "Branch Target Injection", and is one of the two halves to Spectre.. 
Summary:
First, we need to explain the core of the vulnerability. Note that this
is a very incomplete description, please see the Project Zero blog post
for details:
https://googleprojectzero.blogspot.com/2018/01/reading-privileged-memory-with-side.html

The basis for branch target injection is to direct speculative execution
of the processor to some "gadget" of executable code by poisoning the
prediction of indirect branches with the address of that gadget. The
gadget in turn contains an operation that provides a side channel for
reading data. Most commonly, this will look like a load of secret data
followed by a branch on the loaded value and then a load of some
predictable cache line. The attacker then uses timing of the processors
cache to determine which direction the branch took *in the speculative
execution*, and in turn what one bit of the loaded value was. Due to the
nature of these timing side channels and the branch predictor on Intel
processors, this allows an attacker to leak data only accessible to
a privileged domain (like the kernel) back into an unprivileged domain.

The goal is simple: avoid generating code which contains an indirect
branch that could have its prediction poisoned by an attacker. In many
cases, the compiler can simply use directed conditional branches and
a small search tree. LLVM already has support for lowering switches in
this way and the first step of this patch is to disable jump-table
lowering of switches and introduce a pass to rewrite explicit indirectbr
sequences into a switch over integers.

However, there is no fully general alternative to indirect calls. We
introduce a new construct we call a "retpoline" to implement indirect
calls in a non-speculatable way. It can be thought of loosely as
a trampoline for indirect calls which uses the RET instruction on x86.
Further, we arrange for a specific call->ret sequence which ensures the
processor predicts the return to go to a controlled, known location. The
retpoline then "smashes" the return address pushed onto the stack by the
call with the desired target of the original indirect call. The result
is a predicted return to the next instruction after a call (which can be
used to trap speculative execution within an infinite loop) and an
actual indirect branch to an arbitrary address.

On 64-bit x86 ABIs, this is especially easily done in the compiler by
using a guaranteed scratch register to pass the target into this device.
For 32-bit ABIs there isn't a guaranteed scratch register and so several
different retpoline variants are introduced to use a scratch register if
one is available in the calling convention and to otherwise use direct
stack push/pop sequences to pass the target address.

This "retpoline" mitigation is fully described in the following blog
post: https://support.google.com/faqs/answer/7625886

We also support a target feature that disables emission of the retpoline
thunk by the compiler to allow for custom thunks if users want them.
These are particularly useful in environments like kernels that
routinely do hot-patching on boot and want to hot-patch their thunk to
different code sequences. They can write this custom thunk and use
`-mretpoline-external-thunk` *in addition* to `-mretpoline`. In this
case, on x86-64 thu thunk names must be:
```
  __llvm_external_retpoline_r11
```
or on 32-bit:
```
  __llvm_external_retpoline_eax
  __llvm_external_retpoline_ecx
  __llvm_external_retpoline_edx
  __llvm_external_retpoline_push
```
And the target of the retpoline is passed in the named register, or in
the case of the `push` suffix on the top of the stack via a `pushl`
instruction.

There is one other important source of indirect branches in x86 ELF
binaries: the PLT. These patches also include support for LLD to
generate PLT entries that perform a retpoline-style indirection.

The only other indirect branches remaining that we are aware of are from
precompiled runtimes (such as crt0.o and similar). The ones we have
found are not really attackable, and so we have not focused on them
here, but eventually these runtimes should also be replicated for
retpoline-ed configurations for completeness.

For kernels or other freestanding or fully static executables, the
compiler switch `-mretpoline` is sufficient to fully mitigate this
particular attack. For dynamic executables, you must compile *all*
libraries with `-mretpoline` and additionally link the dynamic
executable and all shared libraries with LLD and pass `-z retpolineplt`
(or use similar functionality from some other linker). We strongly
recommend also using `-z now` as non-lazy binding allows the
retpoline-mitigated PLT to be substantially smaller.

When manually apply similar transformations to `-mretpoline` to the
Linux kernel we observed very small performance hits to applications
running typical workloads, and relatively minor hits (approximately 2%)
even for extremely syscall-heavy applications. This is largely due to
the small number of indirect branches that occur in performance
sensitive paths of the kernel.

When using these patches on statically linked applications, especially
C++ applications, you should expect to see a much more dramatic
performance hit. For microbenchmarks that are switch, indirect-, or
virtual-call heavy we have seen overheads ranging from 10% to 50%.

However, real-world workloads exhibit substantially lower performance
impact. Notably, techniques such as PGO and ThinLTO dramatically reduce
the impact of hot indirect calls (by speculatively promoting them to
direct calls) and allow optimized search trees to be used to lower
switches. If you need to deploy these techniques in C++ applications, we
*strongly* recommend that you ensure all hot call targets are statically
linked (avoiding PLT indirection) and use both PGO and ThinLTO. Well
tuned servers using all of these techniques saw 5% - 10% overhead from
the use of retpoline.

We will add detailed documentation covering these components in
subsequent patches, but wanted to make the core functionality available
as soon as possible. Happy for more code review, but we'd really like to
get these patches landed and backported ASAP for obvious reasons. We're
planning to backport this to both 6.0 and 5.0 release streams and get
a 5.0 release with just this cherry picked ASAP for distros and vendors.

This patch is the work of a number of people over the past month: Eric, Reid,
Rui, and myself. I'm mailing it out as a single commit due to the time
sensitive nature of landing this and the need to backport it. Huge thanks to
everyone who helped out here, and everyone at Intel who helped out in
discussions about how to craft this. Also, credit goes to Paul Turner (at
Google, but not an LLVM contributor) for much of the underlying retpoline
design.

Reviewers: echristo, rnk, ruiu, craig.topper, DavidKreitzer

Subscribers: sanjoy, emaste, mcrosier, mgorny, mehdi_amini, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D41723

llvm-svn: 323155
2018-01-22 22:05:25 +00:00

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//===- opt.cpp - The LLVM Modular Optimizer -------------------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// Optimizations may be specified an arbitrary number of times on the command
// line, They are run in the order specified.
//
//===----------------------------------------------------------------------===//
#include "BreakpointPrinter.h"
#include "NewPMDriver.h"
#include "PassPrinters.h"
#include "llvm/ADT/Triple.h"
#include "llvm/Analysis/CallGraph.h"
#include "llvm/Analysis/CallGraphSCCPass.h"
#include "llvm/Analysis/LoopPass.h"
#include "llvm/Analysis/RegionPass.h"
#include "llvm/Analysis/TargetLibraryInfo.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Bitcode/BitcodeWriterPass.h"
#include "llvm/CodeGen/CommandFlags.def"
#include "llvm/CodeGen/TargetPassConfig.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfo.h"
#include "llvm/IR/IRPrintingPasses.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/LegacyPassManager.h"
#include "llvm/IR/LegacyPassNameParser.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/Verifier.h"
#include "llvm/IRReader/IRReader.h"
#include "llvm/InitializePasses.h"
#include "llvm/LinkAllIR.h"
#include "llvm/LinkAllPasses.h"
#include "llvm/MC/SubtargetFeature.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/FileSystem.h"
#include "llvm/Support/Host.h"
#include "llvm/Support/ManagedStatic.h"
#include "llvm/Support/PluginLoader.h"
#include "llvm/Support/PrettyStackTrace.h"
#include "llvm/Support/Signals.h"
#include "llvm/Support/SourceMgr.h"
#include "llvm/Support/SystemUtils.h"
#include "llvm/Support/TargetRegistry.h"
#include "llvm/Support/TargetSelect.h"
#include "llvm/Support/ToolOutputFile.h"
#include "llvm/Support/YAMLTraits.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/Coroutines.h"
#include "llvm/Transforms/IPO/AlwaysInliner.h"
#include "llvm/Transforms/IPO/PassManagerBuilder.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include <algorithm>
#include <memory>
using namespace llvm;
using namespace opt_tool;
// The OptimizationList is automatically populated with registered Passes by the
// PassNameParser.
//
static cl::list<const PassInfo*, bool, PassNameParser>
PassList(cl::desc("Optimizations available:"));
// This flag specifies a textual description of the optimization pass pipeline
// to run over the module. This flag switches opt to use the new pass manager
// infrastructure, completely disabling all of the flags specific to the old
// pass management.
static cl::opt<std::string> PassPipeline(
"passes",
cl::desc("A textual description of the pass pipeline for optimizing"),
cl::Hidden);
// Other command line options...
//
static cl::opt<std::string>
InputFilename(cl::Positional, cl::desc("<input bitcode file>"),
cl::init("-"), cl::value_desc("filename"));
static cl::opt<std::string>
OutputFilename("o", cl::desc("Override output filename"),
cl::value_desc("filename"));
static cl::opt<bool>
Force("f", cl::desc("Enable binary output on terminals"));
static cl::opt<bool>
PrintEachXForm("p", cl::desc("Print module after each transformation"));
static cl::opt<bool>
NoOutput("disable-output",
cl::desc("Do not write result bitcode file"), cl::Hidden);
static cl::opt<bool>
OutputAssembly("S", cl::desc("Write output as LLVM assembly"));
static cl::opt<bool>
OutputThinLTOBC("thinlto-bc",
cl::desc("Write output as ThinLTO-ready bitcode"));
static cl::opt<std::string> ThinLinkBitcodeFile(
"thin-link-bitcode-file", cl::value_desc("filename"),
cl::desc(
"A file in which to write minimized bitcode for the thin link only"));
static cl::opt<bool>
NoVerify("disable-verify", cl::desc("Do not run the verifier"), cl::Hidden);
static cl::opt<bool>
VerifyEach("verify-each", cl::desc("Verify after each transform"));
static cl::opt<bool>
DisableDITypeMap("disable-debug-info-type-map",
cl::desc("Don't use a uniquing type map for debug info"));
static cl::opt<bool>
StripDebug("strip-debug",
cl::desc("Strip debugger symbol info from translation unit"));
static cl::opt<bool>
DisableInline("disable-inlining", cl::desc("Do not run the inliner pass"));
static cl::opt<bool>
DisableOptimizations("disable-opt",
cl::desc("Do not run any optimization passes"));
static cl::opt<bool>
StandardLinkOpts("std-link-opts",
cl::desc("Include the standard link time optimizations"));
static cl::opt<bool>
OptLevelO0("O0",
cl::desc("Optimization level 0. Similar to clang -O0"));
static cl::opt<bool>
OptLevelO1("O1",
cl::desc("Optimization level 1. Similar to clang -O1"));
static cl::opt<bool>
OptLevelO2("O2",
cl::desc("Optimization level 2. Similar to clang -O2"));
static cl::opt<bool>
OptLevelOs("Os",
cl::desc("Like -O2 with extra optimizations for size. Similar to clang -Os"));
static cl::opt<bool>
OptLevelOz("Oz",
cl::desc("Like -Os but reduces code size further. Similar to clang -Oz"));
static cl::opt<bool>
OptLevelO3("O3",
cl::desc("Optimization level 3. Similar to clang -O3"));
static cl::opt<unsigned>
CodeGenOptLevel("codegen-opt-level",
cl::desc("Override optimization level for codegen hooks"));
static cl::opt<std::string>
TargetTriple("mtriple", cl::desc("Override target triple for module"));
static cl::opt<bool>
UnitAtATime("funit-at-a-time",
cl::desc("Enable IPO. This corresponds to gcc's -funit-at-a-time"),
cl::init(true));
static cl::opt<bool>
DisableLoopUnrolling("disable-loop-unrolling",
cl::desc("Disable loop unrolling in all relevant passes"),
cl::init(false));
static cl::opt<bool>
DisableLoopVectorization("disable-loop-vectorization",
cl::desc("Disable the loop vectorization pass"),
cl::init(false));
static cl::opt<bool>
DisableSLPVectorization("disable-slp-vectorization",
cl::desc("Disable the slp vectorization pass"),
cl::init(false));
static cl::opt<bool> EmitSummaryIndex("module-summary",
cl::desc("Emit module summary index"),
cl::init(false));
static cl::opt<bool> EmitModuleHash("module-hash", cl::desc("Emit module hash"),
cl::init(false));
static cl::opt<bool>
DisableSimplifyLibCalls("disable-simplify-libcalls",
cl::desc("Disable simplify-libcalls"));
static cl::opt<bool>
Quiet("q", cl::desc("Obsolete option"), cl::Hidden);
static cl::alias
QuietA("quiet", cl::desc("Alias for -q"), cl::aliasopt(Quiet));
static cl::opt<bool>
AnalyzeOnly("analyze", cl::desc("Only perform analysis, no optimization"));
static cl::opt<bool>
PrintBreakpoints("print-breakpoints-for-testing",
cl::desc("Print select breakpoints location for testing"));
static cl::opt<std::string> ClDataLayout("data-layout",
cl::desc("data layout string to use"),
cl::value_desc("layout-string"),
cl::init(""));
static cl::opt<bool> PreserveBitcodeUseListOrder(
"preserve-bc-uselistorder",
cl::desc("Preserve use-list order when writing LLVM bitcode."),
cl::init(true), cl::Hidden);
static cl::opt<bool> PreserveAssemblyUseListOrder(
"preserve-ll-uselistorder",
cl::desc("Preserve use-list order when writing LLVM assembly."),
cl::init(false), cl::Hidden);
static cl::opt<bool>
RunTwice("run-twice",
cl::desc("Run all passes twice, re-using the same pass manager."),
cl::init(false), cl::Hidden);
static cl::opt<bool> DiscardValueNames(
"discard-value-names",
cl::desc("Discard names from Value (other than GlobalValue)."),
cl::init(false), cl::Hidden);
static cl::opt<bool> Coroutines(
"enable-coroutines",
cl::desc("Enable coroutine passes."),
cl::init(false), cl::Hidden);
static cl::opt<bool> PassRemarksWithHotness(
"pass-remarks-with-hotness",
cl::desc("With PGO, include profile count in optimization remarks"),
cl::Hidden);
static cl::opt<unsigned> PassRemarksHotnessThreshold(
"pass-remarks-hotness-threshold",
cl::desc("Minimum profile count required for an optimization remark to be output"),
cl::Hidden);
static cl::opt<std::string>
RemarksFilename("pass-remarks-output",
cl::desc("YAML output filename for pass remarks"),
cl::value_desc("filename"));
static inline void addPass(legacy::PassManagerBase &PM, Pass *P) {
// Add the pass to the pass manager...
PM.add(P);
// If we are verifying all of the intermediate steps, add the verifier...
if (VerifyEach)
PM.add(createVerifierPass());
}
/// This routine adds optimization passes based on selected optimization level,
/// OptLevel.
///
/// OptLevel - Optimization Level
static void AddOptimizationPasses(legacy::PassManagerBase &MPM,
legacy::FunctionPassManager &FPM,
TargetMachine *TM, unsigned OptLevel,
unsigned SizeLevel) {
if (!NoVerify || VerifyEach)
FPM.add(createVerifierPass()); // Verify that input is correct
PassManagerBuilder Builder;
Builder.OptLevel = OptLevel;
Builder.SizeLevel = SizeLevel;
if (DisableInline) {
// No inlining pass
} else if (OptLevel > 1) {
Builder.Inliner = createFunctionInliningPass(OptLevel, SizeLevel, false);
} else {
Builder.Inliner = createAlwaysInlinerLegacyPass();
}
Builder.DisableUnitAtATime = !UnitAtATime;
Builder.DisableUnrollLoops = (DisableLoopUnrolling.getNumOccurrences() > 0) ?
DisableLoopUnrolling : OptLevel == 0;
// This is final, unless there is a #pragma vectorize enable
if (DisableLoopVectorization)
Builder.LoopVectorize = false;
// If option wasn't forced via cmd line (-vectorize-loops, -loop-vectorize)
else if (!Builder.LoopVectorize)
Builder.LoopVectorize = OptLevel > 1 && SizeLevel < 2;
// When #pragma vectorize is on for SLP, do the same as above
Builder.SLPVectorize =
DisableSLPVectorization ? false : OptLevel > 1 && SizeLevel < 2;
if (TM)
TM->adjustPassManager(Builder);
if (Coroutines)
addCoroutinePassesToExtensionPoints(Builder);
Builder.populateFunctionPassManager(FPM);
Builder.populateModulePassManager(MPM);
}
static void AddStandardLinkPasses(legacy::PassManagerBase &PM) {
PassManagerBuilder Builder;
Builder.VerifyInput = true;
if (DisableOptimizations)
Builder.OptLevel = 0;
if (!DisableInline)
Builder.Inliner = createFunctionInliningPass();
Builder.populateLTOPassManager(PM);
}
//===----------------------------------------------------------------------===//
// CodeGen-related helper functions.
//
static CodeGenOpt::Level GetCodeGenOptLevel() {
if (CodeGenOptLevel.getNumOccurrences())
return static_cast<CodeGenOpt::Level>(unsigned(CodeGenOptLevel));
if (OptLevelO1)
return CodeGenOpt::Less;
if (OptLevelO2)
return CodeGenOpt::Default;
if (OptLevelO3)
return CodeGenOpt::Aggressive;
return CodeGenOpt::None;
}
// Returns the TargetMachine instance or zero if no triple is provided.
static TargetMachine* GetTargetMachine(Triple TheTriple, StringRef CPUStr,
StringRef FeaturesStr,
const TargetOptions &Options) {
std::string Error;
const Target *TheTarget = TargetRegistry::lookupTarget(MArch, TheTriple,
Error);
// Some modules don't specify a triple, and this is okay.
if (!TheTarget) {
return nullptr;
}
return TheTarget->createTargetMachine(TheTriple.getTriple(), CPUStr,
FeaturesStr, Options, getRelocModel(),
getCodeModel(), GetCodeGenOptLevel());
}
#ifdef LINK_POLLY_INTO_TOOLS
namespace polly {
void initializePollyPasses(llvm::PassRegistry &Registry);
}
#endif
//===----------------------------------------------------------------------===//
// main for opt
//
int main(int argc, char **argv) {
sys::PrintStackTraceOnErrorSignal(argv[0]);
llvm::PrettyStackTraceProgram X(argc, argv);
// Enable debug stream buffering.
EnableDebugBuffering = true;
llvm_shutdown_obj Y; // Call llvm_shutdown() on exit.
LLVMContext Context;
InitializeAllTargets();
InitializeAllTargetMCs();
InitializeAllAsmPrinters();
InitializeAllAsmParsers();
// Initialize passes
PassRegistry &Registry = *PassRegistry::getPassRegistry();
initializeCore(Registry);
initializeCoroutines(Registry);
initializeScalarOpts(Registry);
initializeObjCARCOpts(Registry);
initializeVectorization(Registry);
initializeIPO(Registry);
initializeAnalysis(Registry);
initializeTransformUtils(Registry);
initializeInstCombine(Registry);
initializeInstrumentation(Registry);
initializeTarget(Registry);
// For codegen passes, only passes that do IR to IR transformation are
// supported.
initializeExpandMemCmpPassPass(Registry);
initializeScalarizeMaskedMemIntrinPass(Registry);
initializeCodeGenPreparePass(Registry);
initializeAtomicExpandPass(Registry);
initializeRewriteSymbolsLegacyPassPass(Registry);
initializeWinEHPreparePass(Registry);
initializeDwarfEHPreparePass(Registry);
initializeSafeStackLegacyPassPass(Registry);
initializeSjLjEHPreparePass(Registry);
initializePreISelIntrinsicLoweringLegacyPassPass(Registry);
initializeGlobalMergePass(Registry);
initializeIndirectBrExpandPassPass(Registry);
initializeInterleavedAccessPass(Registry);
initializeEntryExitInstrumenterPass(Registry);
initializePostInlineEntryExitInstrumenterPass(Registry);
initializeUnreachableBlockElimLegacyPassPass(Registry);
initializeExpandReductionsPass(Registry);
initializeWriteBitcodePassPass(Registry);
#ifdef LINK_POLLY_INTO_TOOLS
polly::initializePollyPasses(Registry);
#endif
cl::ParseCommandLineOptions(argc, argv,
"llvm .bc -> .bc modular optimizer and analysis printer\n");
if (AnalyzeOnly && NoOutput) {
errs() << argv[0] << ": analyze mode conflicts with no-output mode.\n";
return 1;
}
SMDiagnostic Err;
Context.setDiscardValueNames(DiscardValueNames);
if (!DisableDITypeMap)
Context.enableDebugTypeODRUniquing();
if (PassRemarksWithHotness)
Context.setDiagnosticsHotnessRequested(true);
if (PassRemarksHotnessThreshold)
Context.setDiagnosticsHotnessThreshold(PassRemarksHotnessThreshold);
std::unique_ptr<ToolOutputFile> OptRemarkFile;
if (RemarksFilename != "") {
std::error_code EC;
OptRemarkFile =
llvm::make_unique<ToolOutputFile>(RemarksFilename, EC, sys::fs::F_None);
if (EC) {
errs() << EC.message() << '\n';
return 1;
}
Context.setDiagnosticsOutputFile(
llvm::make_unique<yaml::Output>(OptRemarkFile->os()));
}
// Load the input module...
std::unique_ptr<Module> M =
parseIRFile(InputFilename, Err, Context, !NoVerify);
if (!M) {
Err.print(argv[0], errs());
return 1;
}
// Strip debug info before running the verifier.
if (StripDebug)
StripDebugInfo(*M);
// Immediately run the verifier to catch any problems before starting up the
// pass pipelines. Otherwise we can crash on broken code during
// doInitialization().
if (!NoVerify && verifyModule(*M, &errs())) {
errs() << argv[0] << ": " << InputFilename
<< ": error: input module is broken!\n";
return 1;
}
// If we are supposed to override the target triple or data layout, do so now.
if (!TargetTriple.empty())
M->setTargetTriple(Triple::normalize(TargetTriple));
if (!ClDataLayout.empty())
M->setDataLayout(ClDataLayout);
// Figure out what stream we are supposed to write to...
std::unique_ptr<ToolOutputFile> Out;
std::unique_ptr<ToolOutputFile> ThinLinkOut;
if (NoOutput) {
if (!OutputFilename.empty())
errs() << "WARNING: The -o (output filename) option is ignored when\n"
"the --disable-output option is used.\n";
} else {
// Default to standard output.
if (OutputFilename.empty())
OutputFilename = "-";
std::error_code EC;
Out.reset(new ToolOutputFile(OutputFilename, EC, sys::fs::F_None));
if (EC) {
errs() << EC.message() << '\n';
return 1;
}
if (!ThinLinkBitcodeFile.empty()) {
ThinLinkOut.reset(
new ToolOutputFile(ThinLinkBitcodeFile, EC, sys::fs::F_None));
if (EC) {
errs() << EC.message() << '\n';
return 1;
}
}
}
Triple ModuleTriple(M->getTargetTriple());
std::string CPUStr, FeaturesStr;
TargetMachine *Machine = nullptr;
const TargetOptions Options = InitTargetOptionsFromCodeGenFlags();
if (ModuleTriple.getArch()) {
CPUStr = getCPUStr();
FeaturesStr = getFeaturesStr();
Machine = GetTargetMachine(ModuleTriple, CPUStr, FeaturesStr, Options);
}
std::unique_ptr<TargetMachine> TM(Machine);
// Override function attributes based on CPUStr, FeaturesStr, and command line
// flags.
setFunctionAttributes(CPUStr, FeaturesStr, *M);
// If the output is set to be emitted to standard out, and standard out is a
// console, print out a warning message and refuse to do it. We don't
// impress anyone by spewing tons of binary goo to a terminal.
if (!Force && !NoOutput && !AnalyzeOnly && !OutputAssembly)
if (CheckBitcodeOutputToConsole(Out->os(), !Quiet))
NoOutput = true;
if (PassPipeline.getNumOccurrences() > 0) {
OutputKind OK = OK_NoOutput;
if (!NoOutput)
OK = OutputAssembly
? OK_OutputAssembly
: (OutputThinLTOBC ? OK_OutputThinLTOBitcode : OK_OutputBitcode);
VerifierKind VK = VK_VerifyInAndOut;
if (NoVerify)
VK = VK_NoVerifier;
else if (VerifyEach)
VK = VK_VerifyEachPass;
// The user has asked to use the new pass manager and provided a pipeline
// string. Hand off the rest of the functionality to the new code for that
// layer.
return runPassPipeline(argv[0], *M, TM.get(), Out.get(), ThinLinkOut.get(),
OptRemarkFile.get(), PassPipeline, OK, VK,
PreserveAssemblyUseListOrder,
PreserveBitcodeUseListOrder, EmitSummaryIndex,
EmitModuleHash)
? 0
: 1;
}
// Create a PassManager to hold and optimize the collection of passes we are
// about to build.
//
legacy::PassManager Passes;
// Add an appropriate TargetLibraryInfo pass for the module's triple.
TargetLibraryInfoImpl TLII(ModuleTriple);
// The -disable-simplify-libcalls flag actually disables all builtin optzns.
if (DisableSimplifyLibCalls)
TLII.disableAllFunctions();
Passes.add(new TargetLibraryInfoWrapperPass(TLII));
// Add internal analysis passes from the target machine.
Passes.add(createTargetTransformInfoWrapperPass(TM ? TM->getTargetIRAnalysis()
: TargetIRAnalysis()));
std::unique_ptr<legacy::FunctionPassManager> FPasses;
if (OptLevelO0 || OptLevelO1 || OptLevelO2 || OptLevelOs || OptLevelOz ||
OptLevelO3) {
FPasses.reset(new legacy::FunctionPassManager(M.get()));
FPasses->add(createTargetTransformInfoWrapperPass(
TM ? TM->getTargetIRAnalysis() : TargetIRAnalysis()));
}
if (PrintBreakpoints) {
// Default to standard output.
if (!Out) {
if (OutputFilename.empty())
OutputFilename = "-";
std::error_code EC;
Out = llvm::make_unique<ToolOutputFile>(OutputFilename, EC,
sys::fs::F_None);
if (EC) {
errs() << EC.message() << '\n';
return 1;
}
}
Passes.add(createBreakpointPrinter(Out->os()));
NoOutput = true;
}
if (TM) {
// FIXME: We should dyn_cast this when supported.
auto &LTM = static_cast<LLVMTargetMachine &>(*TM);
Pass *TPC = LTM.createPassConfig(Passes);
Passes.add(TPC);
}
// Create a new optimization pass for each one specified on the command line
for (unsigned i = 0; i < PassList.size(); ++i) {
if (StandardLinkOpts &&
StandardLinkOpts.getPosition() < PassList.getPosition(i)) {
AddStandardLinkPasses(Passes);
StandardLinkOpts = false;
}
if (OptLevelO0 && OptLevelO0.getPosition() < PassList.getPosition(i)) {
AddOptimizationPasses(Passes, *FPasses, TM.get(), 0, 0);
OptLevelO0 = false;
}
if (OptLevelO1 && OptLevelO1.getPosition() < PassList.getPosition(i)) {
AddOptimizationPasses(Passes, *FPasses, TM.get(), 1, 0);
OptLevelO1 = false;
}
if (OptLevelO2 && OptLevelO2.getPosition() < PassList.getPosition(i)) {
AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 0);
OptLevelO2 = false;
}
if (OptLevelOs && OptLevelOs.getPosition() < PassList.getPosition(i)) {
AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 1);
OptLevelOs = false;
}
if (OptLevelOz && OptLevelOz.getPosition() < PassList.getPosition(i)) {
AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 2);
OptLevelOz = false;
}
if (OptLevelO3 && OptLevelO3.getPosition() < PassList.getPosition(i)) {
AddOptimizationPasses(Passes, *FPasses, TM.get(), 3, 0);
OptLevelO3 = false;
}
const PassInfo *PassInf = PassList[i];
Pass *P = nullptr;
if (PassInf->getNormalCtor())
P = PassInf->getNormalCtor()();
else
errs() << argv[0] << ": cannot create pass: "
<< PassInf->getPassName() << "\n";
if (P) {
PassKind Kind = P->getPassKind();
addPass(Passes, P);
if (AnalyzeOnly) {
switch (Kind) {
case PT_BasicBlock:
Passes.add(createBasicBlockPassPrinter(PassInf, Out->os(), Quiet));
break;
case PT_Region:
Passes.add(createRegionPassPrinter(PassInf, Out->os(), Quiet));
break;
case PT_Loop:
Passes.add(createLoopPassPrinter(PassInf, Out->os(), Quiet));
break;
case PT_Function:
Passes.add(createFunctionPassPrinter(PassInf, Out->os(), Quiet));
break;
case PT_CallGraphSCC:
Passes.add(createCallGraphPassPrinter(PassInf, Out->os(), Quiet));
break;
default:
Passes.add(createModulePassPrinter(PassInf, Out->os(), Quiet));
break;
}
}
}
if (PrintEachXForm)
Passes.add(
createPrintModulePass(errs(), "", PreserveAssemblyUseListOrder));
}
if (StandardLinkOpts) {
AddStandardLinkPasses(Passes);
StandardLinkOpts = false;
}
if (OptLevelO0)
AddOptimizationPasses(Passes, *FPasses, TM.get(), 0, 0);
if (OptLevelO1)
AddOptimizationPasses(Passes, *FPasses, TM.get(), 1, 0);
if (OptLevelO2)
AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 0);
if (OptLevelOs)
AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 1);
if (OptLevelOz)
AddOptimizationPasses(Passes, *FPasses, TM.get(), 2, 2);
if (OptLevelO3)
AddOptimizationPasses(Passes, *FPasses, TM.get(), 3, 0);
if (FPasses) {
FPasses->doInitialization();
for (Function &F : *M)
FPasses->run(F);
FPasses->doFinalization();
}
// Check that the module is well formed on completion of optimization
if (!NoVerify && !VerifyEach)
Passes.add(createVerifierPass());
// In run twice mode, we want to make sure the output is bit-by-bit
// equivalent if we run the pass manager again, so setup two buffers and
// a stream to write to them. Note that llc does something similar and it
// may be worth to abstract this out in the future.
SmallVector<char, 0> Buffer;
SmallVector<char, 0> CompileTwiceBuffer;
std::unique_ptr<raw_svector_ostream> BOS;
raw_ostream *OS = nullptr;
// Write bitcode or assembly to the output as the last step...
if (!NoOutput && !AnalyzeOnly) {
assert(Out);
OS = &Out->os();
if (RunTwice) {
BOS = make_unique<raw_svector_ostream>(Buffer);
OS = BOS.get();
}
if (OutputAssembly) {
if (EmitSummaryIndex)
report_fatal_error("Text output is incompatible with -module-summary");
if (EmitModuleHash)
report_fatal_error("Text output is incompatible with -module-hash");
Passes.add(createPrintModulePass(*OS, "", PreserveAssemblyUseListOrder));
} else if (OutputThinLTOBC)
Passes.add(createWriteThinLTOBitcodePass(
*OS, ThinLinkOut ? &ThinLinkOut->os() : nullptr));
else
Passes.add(createBitcodeWriterPass(*OS, PreserveBitcodeUseListOrder,
EmitSummaryIndex, EmitModuleHash));
}
// Before executing passes, print the final values of the LLVM options.
cl::PrintOptionValues();
// If requested, run all passes again with the same pass manager to catch
// bugs caused by persistent state in the passes
if (RunTwice) {
std::unique_ptr<Module> M2(CloneModule(M.get()));
Passes.run(*M2);
CompileTwiceBuffer = Buffer;
Buffer.clear();
}
// Now that we have all of the passes ready, run them.
Passes.run(*M);
// Compare the two outputs and make sure they're the same
if (RunTwice) {
assert(Out);
if (Buffer.size() != CompileTwiceBuffer.size() ||
(memcmp(Buffer.data(), CompileTwiceBuffer.data(), Buffer.size()) !=
0)) {
errs() << "Running the pass manager twice changed the output.\n"
"Writing the result of the second run to the specified output.\n"
"To generate the one-run comparison binary, just run without\n"
"the compile-twice option\n";
Out->os() << BOS->str();
Out->keep();
if (OptRemarkFile)
OptRemarkFile->keep();
return 1;
}
Out->os() << BOS->str();
}
// Declare success.
if (!NoOutput || PrintBreakpoints)
Out->keep();
if (OptRemarkFile)
OptRemarkFile->keep();
if (ThinLinkOut)
ThinLinkOut->keep();
return 0;
}
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