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[SYCL] resolve double free in CleanupSYCLMetadataFromLLVMUsed Pass #22016

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[SYCL] resolve double free in CleanupSYCLMetadataFromLLVMUsed Pass #22016

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2 changes: 2 additions & 0 deletions llvm/lib/Passes/PassRegistry.def
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Original file line number Diff line number Diff line change
Expand Up @@ -200,6 +200,8 @@ MODULE_PASS("sycl-add-opt-level-attribute", SYCLAddOptLevelAttributePass())
MODULE_PASS("compile-time-properties", CompileTimePropertiesPass())
MODULE_PASS("sycl-remangle-libspirv", SYCLRemangleLibspirvPass())
MODULE_PASS("cleanup-sycl-metadata", CleanupSYCLMetadataPass())
MODULE_PASS("cleanup-sycl-metadata-from-llvm-used", CleanupSYCLMetadataFromLLVMUsed())
MODULE_PASS("remove-device-global-from-llvm-compiler-used", RemoveDeviceGlobalFromLLVMCompilerUsed())
MODULE_PASS("sycl-create-nvvm-annotations", SYCLCreateNVVMAnnotationsPass())
MODULE_PASS("lower-slm-reservation-calls", ESIMDLowerSLMReservationCalls())
MODULE_PASS("record-sycl-aspect-names", RecordSYCLAspectNamesPass())
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18 changes: 10 additions & 8 deletions llvm/lib/SYCLLowerIR/CleanupSYCLMetadata.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//

#include "llvm/SYCLLowerIR/CleanupSYCLMetadata.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/IR/Constants.h"
Expand All @@ -34,18 +35,18 @@ void cleanupSYCLCompilerModuleMetadata(const Module &M, llvm::StringRef MD) {
}

// GV is supposed to be either llvm.compiler.used or llvm.used.
SmallVector<Constant *>
eraseGlobalVariableAndReturnOperands(GlobalVariable *GV) {
SmallPtrSet<Constant *, 0>
eraseGlobalVariableAndReturnUniqueOperands(GlobalVariable *GV) {
assert(GV->user_empty() && "Users aren't expected");
Constant *Initializer = GV->getInitializer();
GV->setInitializer(nullptr);
GV->eraseFromParent();

// Destroy the initializer and save operands.
SmallVector<Constant *> Operands;
Operands.resize(0);
SmallPtrSet<Constant *, 0> Operands;
Operands.reserve(Initializer->getNumOperands());
for (auto &Op : Initializer->operands())
Operands.push_back(cast<Constant>(Op));
Operands.insert(cast<Constant>(Op));

assert(isSafeToDestroyConstant(Initializer) &&
"Cannot remove initializer of the given GV");
Expand Down Expand Up @@ -81,8 +82,8 @@ CleanupSYCLMetadataFromLLVMUsed::run(Module &M, ModuleAnalysisManager &) {
if (!GV)
return PreservedAnalyses::all();

SmallVector<Constant *, 8> IOperands =
eraseGlobalVariableAndReturnOperands(GV);
SmallPtrSet<Constant *, 0> IOperands =
eraseGlobalVariableAndReturnUniqueOperands(GV);
// Erase all operands.
for (auto *Op : IOperands) {
auto StrippedOp = Op->stripPointerCasts();
Expand Down Expand Up @@ -113,7 +114,8 @@ RemoveDeviceGlobalFromLLVMCompilerUsed::run(Module &M,

const auto *VAT = cast<ArrayType>(GV->getValueType());
// Destroy the initializer. Keep the operands so we keep the ones we need.
SmallVector<Constant *> IOperands = eraseGlobalVariableAndReturnOperands(GV);
SmallPtrSet<Constant *, 0> IOperands =
eraseGlobalVariableAndReturnUniqueOperands(GV);

// Iterate through all operands. If they are device_global then we drop them
// and erase them if they have no uses afterwards. All other values are kept.
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10 changes: 10 additions & 0 deletions llvm/test/SYCLLowerIR/CleanupSYCLCompilerInternalMetadata/repetative_values_in_llvm_used.ll
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Original file line number Diff line number Diff line change
@@ -0,0 +1,10 @@
; RUN: opt --passes=cleanup-sycl-metadata-from-llvm-used %s

; Check that CleanupSYCLMetadataFromLLVMUsed pass considers the case
; when llvm.used has one value more than once. It used to perform a double free
; due to llvm::isSafeToDestroyConstant(C) for the provided @C returns true.

@C = linkonce_odr hidden addrspace(1) constant <{i64}> <{i64 0}>

@llvm.used = appending global [2 x ptr addrspace(2)] [ptr addrspace(2) addrspacecast (ptr addrspace(1) @C to ptr addrspace(2)), ptr addrspace(2) addrspacecast (ptr addrspace(1) @C to ptr addrspace(2))], section "llvm.metadata"

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