[WebAssembly] Lower ASan constructor priority on Emscripten
Summary:
This change gives Emscripten the ability to use more than one constructor
priorities that runs before ASan. By convention, constructor priorites 0-100
are reserved for use by the system. ASan on Emscripten now uses priority 50,
leaving plenty of room for use by Emscripten before and after ASan.
This change is done in response to:
https://github.com/emscripten-core/emscripten/pull/9076#discussion_r310323723
Reviewers: kripken, tlively, aheejin
Reviewed By: tlively
Subscribers: cfe-commits, dschuff, sbc100, jgravelle-google, hiraditya, sunfish, llvm-commits
Tags: #llvm, #clang
Differential Revision: https://reviews.llvm.org/D65684
llvm-svn: 368101
diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index 164d1a5..62c542a 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -129,6 +129,8 @@
static const char *const kAsanModuleCtorName = "asan.module_ctor";
static const char *const kAsanModuleDtorName = "asan.module_dtor";
static const uint64_t kAsanCtorAndDtorPriority = 1;
+// On Emscripten, the system needs more than one priorities for constructors.
+static const uint64_t kAsanEmscriptenCtorAndDtorPriority = 50;
static const char *const kAsanReportErrorTemplate = "__asan_report_";
static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
static const char *const kAsanUnregisterGlobalsName =
@@ -530,6 +532,14 @@
return std::max(32U, 1U << MappingScale);
}
+static uint64_t GetCtorAndDtorPriority(Triple &TargetTriple) {
+ if (TargetTriple.isOSEmscripten()) {
+ return kAsanEmscriptenCtorAndDtorPriority;
+ } else {
+ return kAsanCtorAndDtorPriority;
+ }
+}
+
namespace {
/// Module analysis for getting various metadata about the module.
@@ -1777,7 +1787,8 @@
if (F->getName() == kAsanModuleCtorName) continue;
ConstantInt *Priority = dyn_cast<ConstantInt>(CS->getOperand(0));
// Don't instrument CTORs that will run before asan.module_ctor.
- if (Priority->getLimitedValue() <= kAsanCtorAndDtorPriority) continue;
+ if (Priority->getLimitedValue() <= GetCtorAndDtorPriority(TargetTriple))
+ continue;
poisonOneInitializer(*F, ModuleName);
}
}
@@ -2429,22 +2440,22 @@
Changed |= InstrumentGlobals(IRB, M, &CtorComdat);
}
+ const uint64_t Priority = GetCtorAndDtorPriority(TargetTriple);
+
// Put the constructor and destructor in comdat if both
// (1) global instrumentation is not TU-specific
// (2) target is ELF.
if (UseCtorComdat && TargetTriple.isOSBinFormatELF() && CtorComdat) {
AsanCtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleCtorName));
- appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority,
- AsanCtorFunction);
+ appendToGlobalCtors(M, AsanCtorFunction, Priority, AsanCtorFunction);
if (AsanDtorFunction) {
AsanDtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleDtorName));
- appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority,
- AsanDtorFunction);
+ appendToGlobalDtors(M, AsanDtorFunction, Priority, AsanDtorFunction);
}
} else {
- appendToGlobalCtors(M, AsanCtorFunction, kAsanCtorAndDtorPriority);
+ appendToGlobalCtors(M, AsanCtorFunction, Priority);
if (AsanDtorFunction)
- appendToGlobalDtors(M, AsanDtorFunction, kAsanCtorAndDtorPriority);
+ appendToGlobalDtors(M, AsanDtorFunction, Priority);
}
return Changed;