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[asan] Don't overalign global metadata.

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Other than on COFF with incremental linking, global metadata should
not need any extra alignment.

Differential Revision: https://reviews.llvm.org/D28628

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@291859 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Evgeniy Stepanov 2017-01-12 23:26:20 +00:00
parent dad67dd505
commit e2cae83d96
2 changed files with 13 additions and 12 deletions
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23
lib/Transforms/Instrumentation/AddressSanitizer.cpp
View File

@ -1609,22 +1609,12 @@ void AddressSanitizerModule::SetComdatForGlobalMetadata(
GlobalVariable *
AddressSanitizerModule::CreateMetadataGlobal(Module &M, Constant *Initializer,
StringRef OriginalName) {
auto &DL = M.getDataLayout();
GlobalVariable *Metadata =
new GlobalVariable(M, Initializer->getType(), false,
GlobalVariable::InternalLinkage, Initializer,
Twine("__asan_global_") +
GlobalValue::getRealLinkageName(OriginalName));
Metadata->setSection(getGlobalMetadataSection());
// We don't want any padding, but we also need a reasonable alignment.
// The MSVC linker always inserts padding when linking incrementally. We
// cope with that by aligning each struct to its size, which must be a power
// of two.
unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType());
assert(isPowerOf2_32(SizeOfGlobalStruct) &&
"global metadata will not be padded appropriately");
Metadata->setAlignment(SizeOfGlobalStruct);
return Metadata;
}
@ -1642,11 +1632,22 @@ void AddressSanitizerModule::InstrumentGlobalsCOFF(
IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
ArrayRef<Constant *> MetadataInitializers) {
assert(ExtendedGlobals.size() == MetadataInitializers.size());
auto &DL = M.getDataLayout();
for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
Constant *Initializer = MetadataInitializers[i];
GlobalVariable *G = ExtendedGlobals[i];
GlobalVariable *Metadata =
CreateMetadataGlobal(M, MetadataInitializers[i], G->getName());
CreateMetadataGlobal(M, Initializer, G->getName());
// The MSVC linker always inserts padding when linking incrementally. We
// cope with that by aligning each struct to its size, which must be a power
// of two.
unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType());
assert(isPowerOf2_32(SizeOfGlobalStruct) &&
"global metadata will not be padded appropriately");
Metadata->setAlignment(SizeOfGlobalStruct);
SetComdatForGlobalMetadata(G, Metadata);
}
}

2
test/Instrumentation/AddressSanitizer/global_metadata_darwin.ll
View File

@ -16,7 +16,7 @@ target triple = "x86_64-apple-macosx10.11.0"
; Find the metadata for @global:
; CHECK: [[METADATA:@.+]] = internal global {{.*}} @global {{.*}} section "__DATA,__asan_globals,regular", align 64
; CHECK: [[METADATA:@.+]] = internal global {{.*}} @global {{.*}} section "__DATA,__asan_globals,regular"
; Find the liveness binder for @global and its metadata:
; CHECK: @__asan_binder_global = internal global {{.*}} @global {{.*}} [[METADATA]] {{.*}} section "__DATA,__asan_liveness,regular,live_support"