[llvm] 06cad82 - PrintStackTrace: don't symbolize if LLVM_DISABLE_SYMBOLIZATION is set
Fangrui Song via llvm-commits
llvm-commits at lists.llvm.org
Fri Aug 21 11:27:22 PDT 2020
Author: Fangrui Song
Date: 2020-08-21T11:27:13-07:00
New Revision: 06cad825cdd4c819e88eac8179a06d196304e78e
URL: https://github.com/llvm/llvm-project/commit/06cad825cdd4c819e88eac8179a06d196304e78e
DIFF: https://github.com/llvm/llvm-project/commit/06cad825cdd4c819e88eac8179a06d196304e78e.diff
LOG: PrintStackTrace: don't symbolize if LLVM_DISABLE_SYMBOLIZATION is set
See http://lists.llvm.org/pipermail/llvm-dev/2017-June/113975.html for a related previous discussion.
Many tools install signal handlers to print stack traces and optionally
symbolize the addresses with an external program 'llvm-symbolizer' (when
searching for 'llvm-symbolizer', the directory containg the executable
is preferred over PATH).
'llvm-symbolizer' can be slow if the executable is large and/or if
llvm-symbolizer' itself is under-optimized. For example, my 'llvm-lto2' from a
-DCMAKE_BUILD_TYPE=Debug build is 443MiB. The 'llvm-symbolizer' from the same
build takes ~2s to symbolize it. (An optimized 'llvm-symbolizer' takes 0.34s).
A crashed clang may take more than 5s to symbolize a stack trace.
If a test file has several `not --crash` RUN lines. It can be very slow in a Debug build.
This patch makes `not --crash` set an environment variable to suppress symbolization.
This is similar to D33804 which uses a command line option.
I pick 'symbolization' instead of 'symbolication' because the former is
used much more commonly and its stem matches 'llvm-symbolizer'.
Also set LLVM_DISABLE_CRASH_REPORT=1, which is currently only applicable on
`__APPLE__`.
Reviewed By: dblaikie, aganea
Differential Revision: https://reviews.llvm.org/D86170
Added:
llvm/test/tools/not/disable-symbolization.test
Modified:
llvm/lib/Support/Signals.cpp
llvm/utils/not/not.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Support/Signals.cpp b/llvm/lib/Support/Signals.cpp
index 2cfdf2d42a4a..83a606b59df3 100644
--- a/llvm/lib/Support/Signals.cpp
+++ b/llvm/lib/Support/Signals.cpp
@@ -44,6 +44,8 @@ static cl::opt<bool, true>
cl::desc("Disable symbolizing crash backtraces."),
cl::location(DisableSymbolicationFlag), cl::Hidden);
+constexpr char DisableSymbolizationEnv[] = "LLVM_DISABLE_SYMBOLIZATION";
+
// Callbacks to run in signal handler must be lock-free because a signal handler
// could be running as we add new callbacks. We don't add unbounded numbers of
// callbacks, an array is therefore sufficient.
@@ -105,7 +107,7 @@ static FormattedNumber format_ptr(void *PC) {
LLVM_ATTRIBUTE_USED
static bool printSymbolizedStackTrace(StringRef Argv0, void **StackTrace,
int Depth, llvm::raw_ostream &OS) {
- if (DisableSymbolicationFlag)
+ if (DisableSymbolicationFlag || getenv(DisableSymbolizationEnv))
return false;
// Don't recursively invoke the llvm-symbolizer binary.
diff --git a/llvm/test/tools/not/disable-symbolization.test b/llvm/test/tools/not/disable-symbolization.test
new file mode 100644
index 000000000000..05dbf9db053e
--- /dev/null
+++ b/llvm/test/tools/not/disable-symbolization.test
@@ -0,0 +1,5 @@
+# RUN: not --crash printenv > %t || true
+# RUN: FileCheck %s < %t
+
+# CHECK-DAG: LLVM_DISABLE_CRASH_REPORT=1
+# CHECK-DAG: LLVM_DISABLE_SYMBOLIZATION=1
diff --git a/llvm/utils/not/not.cpp b/llvm/utils/not/not.cpp
index f00b9c8dde42..4454035b079e 100644
--- a/llvm/utils/not/not.cpp
+++ b/llvm/utils/not/not.cpp
@@ -15,6 +15,10 @@
#include "llvm/Support/WithColor.h"
#include "llvm/Support/raw_ostream.h"
+#ifdef _WIN32
+#include <windows.h>
+#endif
+
using namespace llvm;
int main(int argc, const char **argv) {
@@ -27,6 +31,16 @@ int main(int argc, const char **argv) {
++argv;
--argc;
ExpectCrash = true;
+
+ // Crash is expected, so disable crash report and symbolization to reduce
+ // output and avoid potentially slow symbolization.
+#ifdef _WIN32
+ SetEnvironmentVariableA("LLVM_DISABLE_CRASH_REPORT", "1");
+ SetEnvironmentVariableA("LLVM_DISABLE_SYMBOLIZATION", "1");
+#else
+ setenv("LLVM_DISABLE_CRASH_REPORT", "1", 0);
+ setenv("LLVM_DISABLE_SYMBOLIZATION", "1", 0);
+#endif
}
if (argc == 0)
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