[llvm] r254774 - [llc/opt] Add an option to run all passes twice
Justin Bogner via llvm-commits
llvm-commits at lists.llvm.org
Fri Dec 4 15:52:17 PST 2015
Keno Fischer via llvm-commits <llvm-commits at lists.llvm.org> writes:
> Author: kfischer
> Date: Fri Dec 4 15:56:46 2015
> New Revision: 254774
>
> URL: http://llvm.org/viewvc/llvm-project?rev=254774&view=rev
> Log:
> [llc/opt] Add an option to run all passes twice
>
> Summary: Lately, I have submitted a number of patches to fix bugs that
> only occurred when using the same pass manager to compile multiple
> modules (generally these bugs are failure to reset some persistent
> state). Unfortunately I don't think there is currently a way to test
> that from the command line. This adds a very simple flag to both llc
> and opt, under which the tools will simply re-run their respective
> pass pipelines using the same pass manager on (a clone of the same
> module). Additionally, we verify that both outputs are bitwise the
> same.
I'm getting a large number of Asan+Ubsan errors in opt calls from `ninja
check` after this change. See below.
> Reviewers: yaron.keren
>
> Subscribers: loladiro, yaron.keren, kcc, llvm-commits
>
> Differential Revision: http://reviews.llvm.org/D14965
>
> Added:
> llvm/trunk/test/MC/ELF/empty-twice.ll
> llvm/trunk/test/Other/opt-twice.ll
> Modified:
> llvm/trunk/tools/llc/llc.cpp
> llvm/trunk/tools/opt/opt.cpp
>
> Added: llvm/trunk/test/MC/ELF/empty-twice.ll
> URL:
> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/MC/ELF/empty-twice.ll?rev=254774&view=auto
> ==============================================================================
> --- llvm/trunk/test/MC/ELF/empty-twice.ll (added)
> +++ llvm/trunk/test/MC/ELF/empty-twice.ll Fri Dec 4 15:56:46 2015
> @@ -0,0 +1,6 @@
> +; Check that there is no persistent state in the ELF emitter that crashes us
> +; when we try to reuse the pass manager
> +; RUN: llc -compile-twice -filetype=obj %s -o -
> +
> +target datalayout = "e-p:32:32:32-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:32:64-f32:32:32-f64:32:64-v64:64:64-v128:128:128-a0:0:64-f80:32:32-n8:16:32"
> +target triple = "i386-pc-linux-gnu"
>
> Added: llvm/trunk/test/Other/opt-twice.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Other/opt-twice.ll?rev=254774&view=auto
> ==============================================================================
> --- llvm/trunk/test/Other/opt-twice.ll (added)
> +++ llvm/trunk/test/Other/opt-twice.ll Fri Dec 4 15:56:46 2015
> @@ -0,0 +1,14 @@
> +; The pass here doesn't matter (we use deadargelim), but test
> +; that the -run-twice options exists, generates output, and
> +; doesn't crash
> +; RUN: opt -run-twice -deadargelim -S < %s | FileCheck %s
> +
> +; CHECK: define internal void @test
> +define internal {} @test() {
> + ret {} undef
> +}
> +
> +define void @caller() {
> + call {} @test()
> + ret void
> +}
>
> Modified: llvm/trunk/tools/llc/llc.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/llc/llc.cpp?rev=254774&r1=254773&r2=254774&view=diff
> ==============================================================================
> --- llvm/trunk/tools/llc/llc.cpp (original)
> +++ llvm/trunk/tools/llc/llc.cpp Fri Dec 4 15:56:46 2015
> @@ -45,6 +45,7 @@
> #include "llvm/Support/ToolOutputFile.h"
> #include "llvm/Target/TargetMachine.h"
> #include "llvm/Target/TargetSubtargetInfo.h"
> +#include "llvm/Transforms/Utils/Cloning.h"
> #include <memory>
> using namespace llvm;
>
> @@ -96,6 +97,12 @@ static cl::opt<bool> AsmVerbose("asm-ver
> cl::desc("Add comments to directives."),
> cl::init(true));
>
> +static cl::opt<bool>
> + CompileTwice("compile-twice", cl::Hidden,
> + cl::desc("Run everything twice, re-using the same pass "
> + "manager and verify the the result is the same."),
> + cl::init(false));
> +
> static int compileModule(char **, LLVMContext &);
>
> static std::unique_ptr<tool_output_file>
> @@ -325,10 +332,15 @@ static int compileModule(char **argv, LL
>
> {
> raw_pwrite_stream *OS = &Out->os();
> - std::unique_ptr<buffer_ostream> BOS;
> - if (FileType != TargetMachine::CGFT_AssemblyFile &&
> - !Out->os().supportsSeeking()) {
> - BOS = make_unique<buffer_ostream>(*OS);
> +
> + // Manually do the buffering rather than using buffer_ostream,
> + // so we can memcmp the contents in CompileTwice mode
> + SmallVector<char, 0> Buffer;
> + std::unique_ptr<raw_svector_ostream> BOS;
> + if ((FileType != TargetMachine::CGFT_AssemblyFile &&
> + !Out->os().supportsSeeking()) ||
> + CompileTwice) {
> + BOS = make_unique<raw_svector_ostream>(Buffer);
> OS = BOS.get();
> }
>
> @@ -378,7 +390,39 @@ static int compileModule(char **argv, LL
> // Before executing passes, print the final values of the LLVM options.
> cl::PrintOptionValues();
>
> + // If requested, run the pass manager over the same module again,
> + // to catch any bugs due to persistent state in the passes. Note that
> + // opt has the same functionality, so it may be worth abstracting this out
> + // in the future.
> + SmallVector<char, 0> CompileTwiceBuffer;
> + if (CompileTwice) {
> + std::unique_ptr<Module> M2(llvm::CloneModule(M.get()));
> + PM.run(*M2);
> + CompileTwiceBuffer = Buffer;
> + Buffer.clear();
> + }
> +
> PM.run(*M);
> +
> + // Compare the two outputs and make sure they're the same
> + if (CompileTwice) {
> + 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() << Buffer;
> + Out->keep();
> + return 1;
> + }
> + }
> +
> + if (BOS) {
> + Out->os() << Buffer;
> + }
> }
>
> // Declare success.
>
> Modified: llvm/trunk/tools/opt/opt.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/opt/opt.cpp?rev=254774&r1=254773&r2=254774&view=diff
> ==============================================================================
> --- llvm/trunk/tools/opt/opt.cpp (original)
> +++ llvm/trunk/tools/opt/opt.cpp Fri Dec 4 15:56:46 2015
> @@ -28,6 +28,7 @@
> #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"
> @@ -36,7 +37,6 @@
> #include "llvm/LinkAllIR.h"
> #include "llvm/LinkAllPasses.h"
> #include "llvm/MC/SubtargetFeature.h"
> -#include "llvm/IR/LegacyPassManager.h"
> #include "llvm/Support/Debug.h"
> #include "llvm/Support/FileSystem.h"
> #include "llvm/Support/Host.h"
> @@ -51,6 +51,7 @@
> #include "llvm/Support/ToolOutputFile.h"
> #include "llvm/Target/TargetMachine.h"
> #include "llvm/Transforms/IPO/PassManagerBuilder.h"
> +#include "llvm/Transforms/Utils/Cloning.h"
> #include <algorithm>
> #include <memory>
> using namespace llvm;
> @@ -190,6 +191,11 @@ static cl::opt<bool> PreserveAssemblyUse
> 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 inline void addPass(legacy::PassManagerBase &PM, Pass *P) {
> // Add the pass to the pass manager...
> PM.add(P);
> @@ -582,14 +588,25 @@ int main(int argc, char **argv) {
> 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 = &Out->os();
Apparently `Out` is sometimes (often?) null here. If you want/need to
investigate without having to build with sanitizers, just throw an
assert(Out) here.
> + if (RunTwice) {
> + BOS = make_unique<raw_svector_ostream>(Buffer);
> + OS = BOS.get();
> + }
> +
> // Write bitcode or assembly to the output as the last step...
> if (!NoOutput && !AnalyzeOnly) {
> if (OutputAssembly)
> - Passes.add(
> - createPrintModulePass(Out->os(), "", PreserveAssemblyUseListOrder));
> + Passes.add(createPrintModulePass(*OS, "", PreserveAssemblyUseListOrder));
> else
> - Passes.add(
> - createBitcodeWriterPass(Out->os(), PreserveBitcodeUseListOrder));
> + Passes.add(createBitcodeWriterPass(*OS, PreserveBitcodeUseListOrder));
> }
>
> // Before executing passes, print the final values of the LLVM options.
> @@ -598,6 +615,27 @@ int main(int argc, char **argv) {
> // Now that we have all of the passes ready, run them.
> Passes.run(*M);
>
> + // If requested, run all passes again with the same pass manager to catch
> + // bugs caused by persistent state in the passes
> + if (RunTwice) {
> + CompileTwiceBuffer = Buffer;
> + Buffer.clear();
> + std::unique_ptr<Module> M2(CloneModule(M.get()));
> + Passes.run(*M2);
> + 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."
> + "To generate the one-run comparison binary, just run without\n"
> + "the compile-twice option\n";
> + Out->os() << BOS->str();
> + Out->keep();
> + return 1;
> + }
> + Out->os() << BOS->str();
> + }
> +
> // Declare success.
> if (!NoOutput || PrintBreakpoints)
> Out->keep();
>
>
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