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Improve debug info generated with enabled AddressSanitizer.

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When ASan replaces <alloca instruction> with
<offset into a common large alloca>, it should also patch
llvm.dbg.declare calls and replace debug info descriptors to mark
that we've replaced alloca with a value that stores an address
of the user variable, not the user variable itself.

See PR11818 for more context.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169984 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Alexey Samsonov 2012-12-12 14:31:53 +00:00
parent cd5eb17be6
commit 1afbb51796
5 changed files with 105 additions and 0 deletions
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1
include/llvm/DebugInfo.h
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@ -635,6 +635,7 @@ namespace llvm {
DIFile F = getFieldAs<DIFile>(3); DIFile F = getFieldAs<DIFile>(3);
return F.getCompileUnit(); return F.getCompileUnit();
} }
DIFile getFile() const { return getFieldAs<DIFile>(3); }
unsigned getLineNumber() const { unsigned getLineNumber() const {
return (getUnsignedField(4) << 8) >> 8; return (getUnsignedField(4) << 8) >> 8;
} }

5
include/llvm/Transforms/Utils/Local.h
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@ -252,6 +252,11 @@ bool LowerDbgDeclare(Function &F);
/// an alloca, if any. /// an alloca, if any.
DbgDeclareInst *FindAllocaDbgDeclare(Value *V); DbgDeclareInst *FindAllocaDbgDeclare(Value *V);
/// replaceDbgDeclareForAlloca - Replaces llvm.dbg.declare instruction when
/// alloca is replaced with a new value.
bool replaceDbgDeclareForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
DIBuilder &Builder);
} // End llvm namespace } // End llvm namespace
#endif #endif

4
lib/Transforms/Instrumentation/AddressSanitizer.cpp
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@ -25,6 +25,7 @@
#include "llvm/ADT/StringExtras.h" #include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Triple.h" #include "llvm/ADT/Triple.h"
#include "llvm/DataLayout.h" #include "llvm/DataLayout.h"
#include "llvm/DIBuilder.h"
#include "llvm/Function.h" #include "llvm/Function.h"
#include "llvm/IRBuilder.h" #include "llvm/IRBuilder.h"
#include "llvm/InlineAsm.h" #include "llvm/InlineAsm.h"
@ -38,6 +39,7 @@
#include "llvm/Support/system_error.h" #include "llvm/Support/system_error.h"
#include "llvm/Target/TargetMachine.h" #include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h" #include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/ModuleUtils.h" #include "llvm/Transforms/Utils/ModuleUtils.h"
#include "llvm/Type.h" #include "llvm/Type.h"
#include <algorithm> #include <algorithm>
@ -1158,6 +1160,7 @@ bool AddressSanitizer::poisonStackInFunction(Function &F) {
SmallVector<Instruction*, 8> RetVec; SmallVector<Instruction*, 8> RetVec;
uint64_t TotalSize = 0; uint64_t TotalSize = 0;
bool HavePoisonedAllocas = false; bool HavePoisonedAllocas = false;
DIBuilder DIB(*F.getParent());
// Filter out Alloca instructions we want (and can) handle. // Filter out Alloca instructions we want (and can) handle.
// Collect Ret instructions. // Collect Ret instructions.
@ -1228,6 +1231,7 @@ bool AddressSanitizer::poisonStackInFunction(Function &F) {
Value *NewAllocaPtr = IRB.CreateIntToPtr( Value *NewAllocaPtr = IRB.CreateIntToPtr(
IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)), IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
AI->getType()); AI->getType());
replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
AI->replaceAllUsesWith(NewAllocaPtr); AI->replaceAllUsesWith(NewAllocaPtr);
// Analyze lifetime intrinsics only for static allocas we handle. // Analyze lifetime intrinsics only for static allocas we handle.
if (CheckLifetime) if (CheckLifetime)

35
lib/Transforms/Utils/Local.cpp
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@ -928,3 +928,38 @@ DbgDeclareInst *llvm::FindAllocaDbgDeclare(Value *V) {
return 0; return 0;
} }
bool llvm::replaceDbgDeclareForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
DIBuilder &Builder) {
DbgDeclareInst *DDI = FindAllocaDbgDeclare(AI);
if (!DDI)
return false;
DIVariable DIVar(DDI->getVariable());
if (!DIVar.Verify())
return false;
// Create a copy of the original DIDescriptor for user variable, appending
// "deref" operation to a list of address elements, as new llvm.dbg.declare
// will take a value storing address of the memory for variable, not
// alloca itself.
Type *Int64Ty = Type::getInt64Ty(AI->getContext());
SmallVector<Value*, 4> NewDIVarAddress;
if (DIVar.hasComplexAddress()) {
for (unsigned i = 0, n = DIVar.getNumAddrElements(); i < n; ++i) {
NewDIVarAddress.push_back(
ConstantInt::get(Int64Ty, DIVar.getAddrElement(i)));
}
}
NewDIVarAddress.push_back(ConstantInt::get(Int64Ty, DIBuilder::OpDeref));
DIVariable NewDIVar = Builder.createComplexVariable(
DIVar.getTag(), DIVar.getContext(), DIVar.getName(),
DIVar.getFile(), DIVar.getLineNumber(), DIVar.getType(),
NewDIVarAddress, DIVar.getArgNumber());
// Insert llvm.dbg.declare in the same basic block as the original alloca,
// and remove old llvm.dbg.declare.
BasicBlock *BB = AI->getParent();
Builder.insertDeclare(NewAllocaAddress, NewDIVar, BB);
DDI->eraseFromParent();
return true;
}

60
test/Instrumentation/AddressSanitizer/debug_info.ll Normal file
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@ -0,0 +1,60 @@
; RUN: opt < %s -asan -asan-module -S | FileCheck %s
; Checks that llvm.dbg.declare instructions are updated
; accordingly as we merge allocas.
target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
target triple = "x86_64-unknown-linux-gnu"
define i32 @_Z3zzzi(i32 %p) nounwind uwtable address_safety {
entry:
%p.addr = alloca i32, align 4
%r = alloca i32, align 4
store i32 %p, i32* %p.addr, align 4
call void @llvm.dbg.declare(metadata !{i32* %p.addr}, metadata !10), !dbg !11
call void @llvm.dbg.declare(metadata !{i32* %r}, metadata !12), !dbg !14
%0 = load i32* %p.addr, align 4, !dbg !14
%add = add nsw i32 %0, 1, !dbg !14
store i32 %add, i32* %r, align 4, !dbg !14
%1 = load i32* %r, align 4, !dbg !15
ret i32 %1, !dbg !15
}
; CHECK: define i32 @_Z3zzzi
; CHECK: entry:
; Verify that llvm.dbg.declare calls are in the entry basic block.
; CHECK-NOT: %entry
; CHECK: call void @llvm.dbg.declare(metadata {{.*}}, metadata ![[ARG_ID:[0-9]+]])
; CHECK-NOT: %entry
; CHECK: call void @llvm.dbg.declare(metadata {{.*}}, metadata ![[VAR_ID:[0-9]+]])
declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
!llvm.dbg.cu = !{!0}
!0 = metadata !{i32 786449, i32 0, i32 4, metadata !"a.cc", metadata !"/usr/local/google/llvm_cmake_clang/tmp/debuginfo", metadata !"clang version 3.3 (trunk 169314)", i1 true, i1 false, metadata !"", i32 0, metadata !1, metadata !1, metadata !3, metadata !1} ; [ DW_TAG_compile_unit ] [/usr/local/google/llvm_cmake_clang/tmp/debuginfo/a.cc] [DW_LANG_C_plus_plus]
!1 = metadata !{metadata !2}
!2 = metadata !{i32 0}
!3 = metadata !{metadata !4}
!4 = metadata !{metadata !5}
!5 = metadata !{i32 786478, i32 0, metadata !6, metadata !"zzz", metadata !"zzz", metadata !"_Z3zzzi", metadata !6, i32 1, metadata !7, i1 false, i1 true, i32 0, i32 0, null, i32 256, i1 false, i32 (i32)* @_Z3zzzi, null, null, metadata !1, i32 1} ; [ DW_TAG_subprogram ] [line 1] [def] [zzz]
!6 = metadata !{i32 786473, metadata !"a.cc", metadata !"/usr/local/google/llvm_cmake_clang/tmp/debuginfo", null} ; [ DW_TAG_file_type ]
!7 = metadata !{i32 786453, i32 0, metadata !"", i32 0, i32 0, i64 0, i64 0, i64 0, i32 0, null, metadata !8, i32 0, i32 0} ; [ DW_TAG_subroutine_type ] [line 0, size 0, align 0, offset 0] [from ]
!8 = metadata !{metadata !9, metadata !9}
!9 = metadata !{i32 786468, null, metadata !"int", null, i32 0, i64 32, i64 32, i64 0, i32 0, i32 5} ; [ DW_TAG_base_type ] [int] [line 0, size 32, align 32, offset 0, enc DW_ATE_signed]
!10 = metadata !{i32 786689, metadata !5, metadata !"p", metadata !6, i32 16777217, metadata !9, i32 0, i32 0} ; [ DW_TAG_arg_variable ] [p] [line 1]
!11 = metadata !{i32 1, i32 0, metadata !5, null}
!12 = metadata !{i32 786688, metadata !13, metadata !"r", metadata !6, i32 2, metadata !9, i32 0, i32 0} ; [ DW_TAG_auto_variable ] [r] [line 2]
; Verify that debug descriptors for argument and local variable will be replaced
; with descriptors that end with OpDeref (encoded as 2).
; CHECK: ![[ARG_ID]] = metadata {{.*}} i64 2} ; [ DW_TAG_arg_variable ] [p] [line 1]
; CHECK: ![[VAR_ID]] = metadata {{.*}} i64 2} ; [ DW_TAG_auto_variable ] [r] [line 2]
; Verify that there are no more variable descriptors.
; CHECK-NOT: DW_TAG_arg_variable
; CHECK-NOT: DW_TAG_auto_variable
!13 = metadata !{i32 786443, metadata !5, i32 1, i32 0, metadata !6, i32 0} ; [ DW_TAG_lexical_block ] [/usr/local/google/llvm_cmake_clang/tmp/debuginfo/a.cc]
!14 = metadata !{i32 2, i32 0, metadata !13, null}
!15 = metadata !{i32 3, i32 0, metadata !13, null}