r214604 - [ASan] Use metadata to pass source-level information from Clang to ASan.
Alexey Samsonov
vonosmas at gmail.com
Fri Aug 1 17:35:51 PDT 2014
Author: samsonov
Date: Fri Aug 1 19:35:50 2014
New Revision: 214604
URL: http://llvm.org/viewvc/llvm-project?rev=214604&view=rev
Log:
[ASan] Use metadata to pass source-level information from Clang to ASan.
Instead of creating global variables for source locations and global names,
just create metadata nodes and strings. They will be transformed into actual
globals in the instrumentation pass (if necessary). This approach is more
flexible:
1) we don't have to ensure that our custom globals survive all the optimizations
2) if globals are discarded for some reason, we will simply ignore metadata for them
and won't have to erase corresponding globals
3) metadata for source locations can be reused for other purposes: e.g. we may
attach source location metadata to alloca instructions and provide better descriptions
for stack variables in ASan error reports.
No functionality change.
Modified:
cfe/trunk/lib/CodeGen/SanitizerMetadata.cpp
cfe/trunk/lib/CodeGen/SanitizerMetadata.h
cfe/trunk/test/CodeGen/asan-globals.cpp
Modified: cfe/trunk/lib/CodeGen/SanitizerMetadata.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/SanitizerMetadata.cpp?rev=214604&r1=214603&r2=214604&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/SanitizerMetadata.cpp (original)
+++ cfe/trunk/lib/CodeGen/SanitizerMetadata.cpp Fri Aug 1 19:35:50 2014
@@ -28,35 +28,15 @@ void SanitizerMetadata::reportGlobalToAS
IsDynInit &= !CGM.getSanitizerBlacklist().isIn(*GV, "init");
IsBlacklisted |= CGM.getSanitizerBlacklist().isIn(*GV);
- llvm::GlobalVariable *LocDescr = nullptr;
- llvm::GlobalVariable *GlobalName = nullptr;
+ llvm::Value *LocDescr = nullptr;
+ llvm::Value *GlobalName = nullptr;
llvm::LLVMContext &VMContext = CGM.getLLVMContext();
if (!IsBlacklisted) {
// Don't generate source location and global name if it is blacklisted -
// it won't be instrumented anyway.
- PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc);
- if (PLoc.isValid()) {
- llvm::Constant *LocData[] = {
- CGM.GetAddrOfConstantCString(PLoc.getFilename()),
- llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
- PLoc.getLine()),
- llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
- PLoc.getColumn()),
- };
- auto LocStruct = llvm::ConstantStruct::getAnon(LocData);
- LocDescr = new llvm::GlobalVariable(
- CGM.getModule(), LocStruct->getType(), true,
- llvm::GlobalValue::PrivateLinkage, LocStruct, ".asan_loc_descr");
- LocDescr->setUnnamedAddr(true);
- // Add LocDescr to llvm.compiler.used, so that it won't be removed by
- // the optimizer before the ASan instrumentation pass.
- CGM.addCompilerUsedGlobal(LocDescr);
- }
- if (!Name.empty()) {
- GlobalName = CGM.GetAddrOfConstantCString(Name);
- // GlobalName shouldn't be removed by the optimizer.
- CGM.addCompilerUsedGlobal(GlobalName);
- }
+ LocDescr = getLocationMetadata(Loc);
+ if (!Name.empty())
+ GlobalName = llvm::MDString::get(VMContext, Name);
}
llvm::Value *GlobalMetadata[] = {
@@ -86,3 +66,17 @@ void SanitizerMetadata::disableSanitizer
if (CGM.getLangOpts().Sanitize.Address)
reportGlobalToASan(GV, SourceLocation(), "", false, true);
}
+
+llvm::MDNode *SanitizerMetadata::getLocationMetadata(SourceLocation Loc) {
+ PresumedLoc PLoc = CGM.getContext().getSourceManager().getPresumedLoc(Loc);
+ if (!PLoc.isValid())
+ return nullptr;
+ llvm::LLVMContext &VMContext = CGM.getLLVMContext();
+ llvm::Value *LocMetadata[] = {
+ llvm::MDString::get(VMContext, PLoc.getFilename()),
+ llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext), PLoc.getLine()),
+ llvm::ConstantInt::get(llvm::Type::getInt32Ty(VMContext),
+ PLoc.getColumn()),
+ };
+ return llvm::MDNode::get(VMContext, LocMetadata);
+}
Modified: cfe/trunk/lib/CodeGen/SanitizerMetadata.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/SanitizerMetadata.h?rev=214604&r1=214603&r2=214604&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/SanitizerMetadata.h (original)
+++ cfe/trunk/lib/CodeGen/SanitizerMetadata.h Fri Aug 1 19:35:50 2014
@@ -18,6 +18,7 @@
namespace llvm {
class GlobalVariable;
+class MDNode;
}
namespace clang {
@@ -40,6 +41,8 @@ public:
StringRef Name, bool IsDynInit = false,
bool IsBlacklisted = false);
void disableSanitizerForGlobal(llvm::GlobalVariable *GV);
+private:
+ llvm::MDNode *getLocationMetadata(SourceLocation Loc);
};
} // end namespace CodeGen
} // end namespace clang
Modified: cfe/trunk/test/CodeGen/asan-globals.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGen/asan-globals.cpp?rev=214604&r1=214603&r2=214604&view=diff
==============================================================================
--- cfe/trunk/test/CodeGen/asan-globals.cpp (original)
+++ cfe/trunk/test/CodeGen/asan-globals.cpp Fri Aug 1 19:35:50 2014
@@ -5,28 +5,24 @@
// REQUIRES: shell
int global;
-// CHECK: [[GLOBAL_LOC:@.asan_loc_descr[0-9]*]] = private unnamed_addr constant {{.*}} i32 [[@LINE-1]], i32 5
-// CHECK: [[GLOBAL_NAME:@.str[0-9]+]] = private unnamed_addr constant {{.*}} c"global\00"
int dyn_init_global = global;
-// CHECK: [[DYN_INIT_LOC:@.asan_loc_descr[0-9]*]] = {{.*}} i32 [[@LINE-1]], i32 5
-// CHECK: [[DYN_INIT_NAME:@.str[0-9]+]] = private unnamed_addr constant {{.*}} c"dyn_init_global\00"
int blacklisted_global;
void func() {
static int static_var = 0;
- // CHECK: [[STATIC_LOC:@.asan_loc_descr[0-9]*]] = {{.*}} i32 [[@LINE-1]], i32 14
- // CHECK: [[STATIC_NAME:@.str[0-9]+]] = private unnamed_addr constant {{.*}} c"static_var\00"
const char *literal = "Hello, world!";
- // CHECK: [[LITERAL_LOC:@.asan_loc_descr[0-9]*]] = {{.*}} i32 [[@LINE-1]], i32 25
- // CHECK: [[LITERAL_NAME:@.str[0-9]+]] = private unnamed_addr constant {{.*}} c"<string literal>\00"
}
// CHECK: !llvm.asan.globals = !{![[GLOBAL:[0-9]+]], ![[DYN_INIT_GLOBAL:[0-9]+]], ![[BLACKLISTED_GLOBAL:[0-9]+]], ![[STATIC_VAR:[0-9]+]], ![[LITERAL:[0-9]+]]}
-// CHECK: ![[GLOBAL]] = metadata !{{{.*}} [[GLOBAL_LOC]], {{.*}} [[GLOBAL_NAME]], i1 false, i1 false}
-// CHECK: ![[DYN_INIT_GLOBAL]] = metadata !{{{.*}} [[DYN_INIT_LOC]], {{.*}} [[DYN_INIT_NAME]], i1 true, i1 false}
+// CHECK: ![[GLOBAL]] = metadata !{{{.*}} metadata ![[GLOBAL_LOC:[0-9]+]], metadata !"global", i1 false, i1 false}
+// CHECK: ![[GLOBAL_LOC]] = metadata !{metadata !"{{.*}}asan-globals.cpp", i32 7, i32 5}
+// CHECK: ![[DYN_INIT_GLOBAL]] = metadata !{{{.*}} metadata ![[DYN_INIT_LOC:[0-9]+]], metadata !"dyn_init_global", i1 true, i1 false}
+// CHECK: ![[DYN_INIT_LOC]] = metadata !{metadata !"{{.*}}asan-globals.cpp", i32 8, i32 5}
// CHECK: ![[BLACKLISTED_GLOBAL]] = metadata !{{{.*}}, null, null, i1 false, i1 true}
-// CHECK: ![[STATIC_VAR]] = metadata !{{{.*}} [[STATIC_LOC]], {{.*}} [[STATIC_NAME]], i1 false, i1 false}
-// CHECK: ![[LITERAL]] = metadata !{{{.*}} [[LITERAL_LOC]], {{.*}} [[LITERAL_NAME]], i1 false, i1 false}
+// CHECK: ![[STATIC_VAR]] = metadata !{{{.*}} metadata ![[STATIC_LOC:[0-9]+]], metadata !"static_var", i1 false, i1 false}
+// CHECK: ![[STATIC_LOC]] = metadata !{metadata !"{{.*}}asan-globals.cpp", i32 12, i32 14}
+// CHECK: ![[LITERAL]] = metadata !{{{.*}} metadata ![[LITERAL_LOC:[0-9]+]], metadata !"<string literal>", i1 false, i1 false}
+// CHECK: ![[LITERAL_LOC]] = metadata !{metadata !"{{.*}}asan-globals.cpp", i32 13, i32 25}
// BLACKLIST-SRC: !llvm.asan.globals = !{![[GLOBAL:[0-9]+]], ![[DYN_INIT_GLOBAL:[0-9]+]], ![[BLACKLISTED_GLOBAL:[0-9]+]], ![[STATIC_VAR:[0-9]+]], ![[LITERAL:[0-9]+]]}
// BLACKLIST-SRC: ![[GLOBAL]] = metadata !{{{.*}} null, null, i1 false, i1 true}
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