[llvm] 9544a32 - A new option -print-on-crash that prints the IR as it was upon entering the last pass when there is a crash.
Philip Reames via llvm-commits
llvm-commits at lists.llvm.org
Tue Mar 23 09:43:24 PDT 2021
This is awesome, and long overdue. Thanks!
Philip
On 3/23/21 6:30 AM, Jamie Schmeiser via llvm-commits wrote:
> Author: Jamie Schmeiser
> Date: 2021-03-23T09:29:17-04:00
> New Revision: 9544a32287eccb42a4367cff9b5888855d6b8756
>
> URL: https://github.com/llvm/llvm-project/commit/9544a32287eccb42a4367cff9b5888855d6b8756
> DIFF: https://github.com/llvm/llvm-project/commit/9544a32287eccb42a4367cff9b5888855d6b8756.diff
>
> LOG: A new option -print-on-crash that prints the IR as it was upon entering the last pass when there is a crash.
> Summary:
> The IR is saved in its print form before each pass is started and a
> signal handler is registered. If the compilation crashes, the signal
> handler will print the saved IR to dbgs(). This option
> can be modified using -print-module-scope to get the IR for the complete
> module. Note that this option only works with the new pass manager.
>
> Author: Jamie Schmeiser <schmeise at ca.ibm.com>
> Reviewed By: aeubanks (Arthur Eubanks) yrouban (Yevgeny Rouban)
> Differential Revision: https://reviews.llvm.org/D86657
>
> Added:
> llvm/test/Other/print-on-crash.ll
>
> Modified:
> llvm/include/llvm/Passes/StandardInstrumentations.h
> llvm/lib/Passes/PassBuilder.cpp
> llvm/lib/Passes/PassRegistry.def
> llvm/lib/Passes/StandardInstrumentations.cpp
>
> Removed:
>
>
>
> ################################################################################
> diff --git a/llvm/include/llvm/Passes/StandardInstrumentations.h b/llvm/include/llvm/Passes/StandardInstrumentations.h
> index f023a2924d8f..1717f09258e5 100644
> --- a/llvm/include/llvm/Passes/StandardInstrumentations.h
> +++ b/llvm/include/llvm/Passes/StandardInstrumentations.h
> @@ -15,6 +15,7 @@
> #ifndef LLVM_PASSES_STANDARDINSTRUMENTATIONS_H
> #define LLVM_PASSES_STANDARDINSTRUMENTATIONS_H
>
> +#include "llvm/ADT/DenseSet.h"
> #include "llvm/ADT/STLExtras.h"
> #include "llvm/ADT/SmallVector.h"
> #include "llvm/ADT/StringRef.h"
> @@ -25,6 +26,7 @@
> #include "llvm/Support/CommandLine.h"
> #include "llvm/Transforms/IPO/SampleProfileProbe.h"
>
> +#include <mutex>
> #include <string>
> #include <utility>
>
> @@ -390,6 +392,35 @@ class VerifyInstrumentation {
> void registerCallbacks(PassInstrumentationCallbacks &PIC);
> };
>
> +// Print IR on crash.
> +class PrintCrashIRInstrumentation {
> +public:
> + PrintCrashIRInstrumentation()
> + : SavedIR("*** Dump of IR Before Last Pass Unknown ***") {}
> + ~PrintCrashIRInstrumentation();
> + void registerCallbacks(PassInstrumentationCallbacks &PIC);
> + void reportCrashIR();
> +
> +protected:
> + std::string SavedIR;
> +
> +private:
> + // All of the crash reporters that will report on a crash.
> + static DenseSet<PrintCrashIRInstrumentation *> *CrashReporters;
> + // Crash handler registered when print-on-crash is specified.
> + static void SignalHandler(void *);
> + // Exception-safe locking
> + class MtxLock {
> + public:
> + MtxLock() { Mtx.lock(); }
> + ~MtxLock() { Mtx.unlock(); }
> +
> + protected:
> + // Avoid races when creating/destroying the crash IR printers.
> + static std::mutex Mtx;
> + };
> +};
> +
> /// This class provides an interface to register all the standard pass
> /// instrumentations and manages their state (if any).
> class StandardInstrumentations {
> @@ -402,6 +433,7 @@ class StandardInstrumentations {
> IRChangedPrinter PrintChangedIR;
> PseudoProbeVerifier PseudoProbeVerification;
> InLineChangePrinter PrintChangedDiff;
> + PrintCrashIRInstrumentation PrintCrashIR;
> VerifyInstrumentation Verify;
>
> bool VerifyEach;
> @@ -419,7 +451,6 @@ extern template class TextChangeReporter<std::string>;
>
> extern template class ChangeReporter<ChangedIRData>;
> extern template class TextChangeReporter<ChangedIRData>;
> -
> } // namespace llvm
>
> #endif
>
> diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
> index 3a325277e370..3119445da738 100644
> --- a/llvm/lib/Passes/PassBuilder.cpp
> +++ b/llvm/lib/Passes/PassBuilder.cpp
> @@ -438,6 +438,18 @@ bool shouldPopulateClassToPassNames() {
> return !printBeforePasses().empty() || !printAfterPasses().empty();
> }
>
> +// A pass for testing -print-on-crash.
> +// DO NOT USE THIS EXCEPT FOR TESTING!
> +class TriggerCrashPass : public PassInfoMixin<TriggerCrashPass> {
> +public:
> + PreservedAnalyses run(Function &F, FunctionAnalysisManager &FAM);
> +};
> +
> +// DO NOT USE THIS EXCEPT FOR TESTING!
> +PreservedAnalyses TriggerCrashPass::run(Function &, FunctionAnalysisManager &) {
> + __builtin_trap();
> +}
> +
> } // namespace
>
> PassBuilder::PassBuilder(bool DebugLogging, TargetMachine *TM,
>
> diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
> index 579143d3c1c8..ca3ed7f19bf6 100644
> --- a/llvm/lib/Passes/PassRegistry.def
> +++ b/llvm/lib/Passes/PassRegistry.def
> @@ -311,6 +311,7 @@ FUNCTION_PASS("sroa", SROA())
> FUNCTION_PASS("strip-gc-relocates", StripGCRelocates())
> FUNCTION_PASS("structurizecfg", StructurizeCFGPass())
> FUNCTION_PASS("tailcallelim", TailCallElimPass())
> +FUNCTION_PASS("trigger-crash", TriggerCrashPass())
> FUNCTION_PASS("unify-loop-exits", UnifyLoopExitsPass())
> FUNCTION_PASS("vector-combine", VectorCombinePass())
> FUNCTION_PASS("verify", VerifierPass())
>
> diff --git a/llvm/lib/Passes/StandardInstrumentations.cpp b/llvm/lib/Passes/StandardInstrumentations.cpp
> index 601957034489..ff2a014f8453 100644
> --- a/llvm/lib/Passes/StandardInstrumentations.cpp
> +++ b/llvm/lib/Passes/StandardInstrumentations.cpp
> @@ -15,6 +15,7 @@
> #include "llvm/Passes/StandardInstrumentations.h"
> #include "llvm/ADT/Any.h"
> #include "llvm/ADT/Optional.h"
> +#include "llvm/ADT/SmallString.h"
> #include "llvm/ADT/StringRef.h"
> #include "llvm/Analysis/CallGraphSCCPass.h"
> #include "llvm/Analysis/LazyCallGraph.h"
> @@ -25,10 +26,12 @@
> #include "llvm/IR/PrintPasses.h"
> #include "llvm/IR/Verifier.h"
> #include "llvm/Support/CommandLine.h"
> +#include "llvm/Support/CrashRecoveryContext.h"
> #include "llvm/Support/Debug.h"
> #include "llvm/Support/FormatVariadic.h"
> #include "llvm/Support/MemoryBuffer.h"
> #include "llvm/Support/Program.h"
> +#include "llvm/Support/Signals.h"
> #include "llvm/Support/raw_ostream.h"
> #include <unordered_set>
> #include <vector>
> @@ -117,6 +120,12 @@ static cl::opt<std::string>
> DiffBinary("print-changed-
> diff -path", cl::Hidden, cl::init("
> diff "),
> cl::desc("system
> diff used by change reporters"));
>
> +// An option to print the IR that was being processed when a pass crashes.
> +static cl::opt<bool>
> + PrintCrashIR("print-on-crash",
> + cl::desc("Print the last form of the IR before crash"),
> + cl::init(false), cl::Hidden);
> +
> namespace {
>
> // Perform a system based
> diff between \p Before and \p After, using
> @@ -1153,6 +1162,68 @@ StandardInstrumentations::StandardInstrumentations(bool DebugLogging,
> PrintChangedDiff(PrintChanged == ChangePrinter::PrintChangedDiffVerbose),
> Verify(DebugLogging), VerifyEach(VerifyEach) {}
>
> +std::mutex PrintCrashIRInstrumentation::MtxLock::Mtx;
> +DenseSet<PrintCrashIRInstrumentation *>
> + *PrintCrashIRInstrumentation::CrashReporters = nullptr;
> +
> +void PrintCrashIRInstrumentation::reportCrashIR() { dbgs() << SavedIR; }
> +
> +void PrintCrashIRInstrumentation::SignalHandler(void *) {
> + // Called by signal handlers so do not lock here
> + // Are any of PrintCrashIRInstrumentation objects still alive?
> + if (!CrashReporters)
> + return;
> +
> + assert(PrintCrashIR && "Did not expect to get here without option set.");
> + for (auto I : *CrashReporters)
> + I->reportCrashIR();
> +}
> +
> +PrintCrashIRInstrumentation::~PrintCrashIRInstrumentation() {
> + if (!PrintCrashIR)
> + return;
> +
> + MtxLock Lock;
> + assert(CrashReporters && "Expected CrashReporters to be set");
> +
> + // Was this registered?
> + DenseSet<PrintCrashIRInstrumentation *>::iterator I =
> + CrashReporters->find(this);
> + if (I == CrashReporters->end())
> + return;
> + CrashReporters->erase(I);
> + if (!CrashReporters->empty())
> + return;
> + delete CrashReporters;
> + CrashReporters = nullptr;
> +}
> +
> +void PrintCrashIRInstrumentation::registerCallbacks(
> + PassInstrumentationCallbacks &PIC) {
> + if (!PrintCrashIR)
> + return;
> +
> + {
> + MtxLock Lock;
> + if (!CrashReporters) {
> + CrashReporters = new DenseSet<PrintCrashIRInstrumentation *>();
> + sys::AddSignalHandler(SignalHandler, nullptr);
> + }
> + CrashReporters->insert(this);
> + }
> + PIC.registerBeforeNonSkippedPassCallback([this](StringRef PassID, Any IR) {
> + assert((MtxLock(), CrashReporters && CrashReporters->find(this) !=
> + CrashReporters->end()) &&
> + "Expected CrashReporters to be set and containing this");
> + SavedIR.clear();
> + SmallString<80> Banner =
> + formatv("*** Dump of {0}IR Before Last Pass {1} Started ***",
> + llvm::forcePrintModuleIR() ? "Module " : "", PassID);
> + raw_string_ostream OS(SavedIR);
> + unwrapAndPrint(OS, IR, Banner, llvm::forcePrintModuleIR());
> + });
> +}
> +
> void StandardInstrumentations::registerCallbacks(
> PassInstrumentationCallbacks &PIC) {
> PrintIR.registerCallbacks(PIC);
> @@ -1166,6 +1237,7 @@ void StandardInstrumentations::registerCallbacks(
> if (VerifyEach)
> Verify.registerCallbacks(PIC);
> PrintChangedDiff.registerCallbacks(PIC);
> + PrintCrashIR.registerCallbacks(PIC);
> }
>
> namespace llvm {
>
> diff --git a/llvm/test/Other/print-on-crash.ll b/llvm/test/Other/print-on-crash.ll
> new file mode 100644
> index 000000000000..42da46237432
> --- /dev/null
> +++ b/llvm/test/Other/print-on-crash.ll
> @@ -0,0 +1,28 @@
> +; A test that the hidden option -print-on-crash properly sets a signal handler
> +; which gets called when a pass crashes. The trigger-crash pass calls
> +; __builtin_trap.
> +
> +; RUN: not --crash opt -print-on-crash -passes=trigger-crash < %s 2>&1 | FileCheck %s --check-prefix=CHECK_SIMPLE
> +
> +; A test that the signal handler set by the hidden option -print-on-crash
> +; is not called when no pass crashes.
> +
> +; RUN: opt -print-on-crash -passes="default<O2>" < %s 2>&1 | FileCheck %s --check-prefix=CHECK_NO_CRASH
> +
> +; RUN: not --crash opt -print-on-crash -print-module-scope -passes=trigger-crash < %s 2>&1 | FileCheck %s --check-prefix=CHECK_MODULE
> +
> +; The input corresponds to "int main() { return 0; }" but is irrelevant.
> +
> +; CHECK_SIMPLE: *** Dump of IR Before Last Pass {{.*}} Started ***
> +; CHECK_SIMPLE: @main
> +; CHECK_SIMPLE: entry:
> +; CHECK_NO_CRASH-NOT: *** Dump of IR
> +; CHECK_MODULE: *** Dump of Module IR Before Last Pass {{.*}} Started ***
> +; CHECK_MODULE: ; ModuleID = {{.*}}
> +
> +define i32 @main() {
> +entry:
> + %retval = alloca i32, align 4
> + store i32 0, i32* %retval, align 4
> + ret i32 0
> +}
>
>
>
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