[llvm] r305056 - bugpoint: disabling symbolication of bugpoint-executed programs
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Sun Jun 11 18:15:44 PDT 2017
On 06/09/2017 12:29 AM, David Blaikie via llvm-commits wrote:
> Author: dblaikie
> Date: Fri Jun 9 02:29:03 2017
> New Revision: 305056
>
> URL: http://llvm.org/viewvc/llvm-project?rev=305056&view=rev
> Log:
> bugpoint: disabling symbolication of bugpoint-executed programs
>
> Initial implementation - needs similar work/testing for other tools
> bugpoint invokes (llc, lli I think, maybe more).
>
> Alternatively (as suggested by chandlerc@) an environment variable could
> be used. This would allow the option to pass transparently through user
> scripts, pass to compilers if they happened to be LLVM-ish, etc.
>
> I worry a bit about using cl::opt in the crash handling code - LLVM
> might crash early, perhaps before the cl::opt is properly initialized?
> Or at least before arguments have been parsed?
>
> - should be OK since it defaults to "pretty", so if the crash is very
> early in opt parsing, etc, then crash reports will still be symbolized.
>
> I shyed away from doing this with an environment variable when I
> realized that would require copying the existing environment and
> appending the env variable of interest. But it seems there's no existing
> LLVM API for accessing the environment (even the Support tests for
> process launching have their own ifdefs for getting the environment). It
> could be added, but seemed like a higher bar/untested codepath to
> actually add environment variables.
>
> Most importantly, this reduces the runtime of test/BugPoint/metadata.ll
> in a split-dwarf Debug build from 1m34s to 6.5s by avoiding a lot of
> symbolication. (this wasn't a problem for non-split-dwarf builds only
> because the executable was too large to map into memory (due to bugpoint
> setting a 400MB memory (including address space - not sure why? Going to
> remove that) limit on the child process) so symbolication would fail
> fast & wouldn't spend all that time parsing DWARF, etc)
The 400MB limit is probably to catch out of memory conditions in the
sub-process. (i.e. some bugs show up as huge bogus allocation attempts
and we want to be able to reduce those too.) It can probably be fine
tuned, but having some limit is definitely useful.
>
> Reviewers: chandlerc, dannyb
>
> Differential Revision: https://reviews.llvm.org/D33804
>
> Added:
> llvm/trunk/test/BugPoint/unsymbolized.ll
> Modified:
> llvm/trunk/lib/Support/Signals.cpp
> llvm/trunk/tools/bugpoint/OptimizerDriver.cpp
>
> Modified: llvm/trunk/lib/Support/Signals.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Support/Signals.cpp?rev=305056&r1=305055&r2=305056&view=diff
> ==============================================================================
> --- llvm/trunk/lib/Support/Signals.cpp (original)
> +++ llvm/trunk/lib/Support/Signals.cpp Fri Jun 9 02:29:03 2017
> @@ -26,15 +26,21 @@
> #include "llvm/Support/Program.h"
> #include "llvm/Support/StringSaver.h"
> #include "llvm/Support/raw_ostream.h"
> +#include "llvm/Support/Options.h"
> #include <vector>
>
> -namespace llvm {
> -
> //===----------------------------------------------------------------------===//
> //=== WARNING: Implementation here must contain only TRULY operating system
> //=== independent code.
> //===----------------------------------------------------------------------===//
>
> +using namespace llvm;
> +
> +static cl::opt<bool>
> + DisableSymbolication("disable-symbolication",
> + cl::desc("Disable symbolizing crash backtraces."),
> + cl::init(false), cl::Hidden);
> +
> static ManagedStatic<std::vector<std::pair<void (*)(void *), void *>>>
> CallBacksToRun;
> void sys::RunSignalHandlers() {
> @@ -44,9 +50,6 @@ void sys::RunSignalHandlers() {
> I.first(I.second);
> CallBacksToRun->clear();
> }
> -}
> -
> -using namespace llvm;
>
> static bool findModulesAndOffsets(void **StackTrace, int Depth,
> const char **Modules, intptr_t *Offsets,
> @@ -70,6 +73,9 @@ static bool printSymbolizedStackTrace(St
> static bool printSymbolizedStackTrace(StringRef Argv0,
> void **StackTrace, int Depth,
> llvm::raw_ostream &OS) {
> + if (DisableSymbolication)
> + return false;
> +
> // Don't recursively invoke the llvm-symbolizer binary.
> if (Argv0.find("llvm-symbolizer") != std::string::npos)
> return false;
>
> Added: llvm/trunk/test/BugPoint/unsymbolized.ll
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/BugPoint/unsymbolized.ll?rev=305056&view=auto
> ==============================================================================
> --- llvm/trunk/test/BugPoint/unsymbolized.ll (added)
> +++ llvm/trunk/test/BugPoint/unsymbolized.ll Fri Jun 9 02:29:03 2017
> @@ -0,0 +1,21 @@
> +; REQUIRES: loadable_module
> +; RUN: echo "import sys" > %t.py
> +; RUN: echo "print('args = ' + str(sys.argv))" >> %t.py
> +; RUN: echo "exit(1)" >> %t.py
> +; RUN: not bugpoint -load %llvmshlibdir/BugpointPasses%shlibext %s -output-prefix %t -bugpoint-crashcalls -opt-command="%python" -opt-args %t.py | FileCheck %s
> +; RUN: not --crash opt -load %llvmshlibdir/BugpointPasses%shlibext %s -bugpoint-crashcalls -disable-symbolication 2>&1 | FileCheck --check-prefix=CRASH %s
> +
> +; Test that bugpoint disables symbolication on the opt tool to reduce runtime overhead when opt crashes
> +; CHECK: args = {{.*}}'-disable-symbolication'
> +
> +; Test that opt, when it crashes & is passed -disable-symbolication, doesn't symbolicate.
> +; In theory this test should maybe be in test/tools/opt or
> +; test/Transforms, but since there doesn't seem to be another convenient way to
> +; crash opt, apart from the BugpointPasses dynamic plugin, this is the spot for
> +; now.
> +; CRASH-NOT: Signals.inc
> +
> +define void @f() {
> + call void @f()
> + ret void
> +}
>
> Modified: llvm/trunk/tools/bugpoint/OptimizerDriver.cpp
> URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/tools/bugpoint/OptimizerDriver.cpp?rev=305056&r1=305055&r2=305056&view=diff
> ==============================================================================
> --- llvm/trunk/tools/bugpoint/OptimizerDriver.cpp (original)
> +++ llvm/trunk/tools/bugpoint/OptimizerDriver.cpp Fri Jun 9 02:29:03 2017
> @@ -202,10 +202,11 @@ bool BugDriver::runPasses(Module *Progra
> } else
> Args.push_back(tool.c_str());
>
> - Args.push_back("-o");
> - Args.push_back(OutputFilename.c_str());
> for (unsigned i = 0, e = OptArgs.size(); i != e; ++i)
> Args.push_back(OptArgs[i].c_str());
> + Args.push_back("-disable-symbolication");
> + Args.push_back("-o");
> + Args.push_back(OutputFilename.c_str());
> std::vector<std::string> pass_args;
> for (unsigned i = 0, e = PluginLoader::getNumPlugins(); i != e; ++i) {
> pass_args.push_back(std::string("-load"));
>
>
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