Improve debug info generated with enabled AddressSanitizer.
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. llvm-svn: 169984
This commit is contained in:
Alexey Samsonov
parent
9bd2e1bacc
commit
3d43b63a6e
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@ -635,6 +635,7 @@ namespace llvm {
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DIFile F = getFieldAs<DIFile>(3);
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return F.getCompileUnit();
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}
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DIFile getFile() const { return getFieldAs<DIFile>(3); }
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unsigned getLineNumber() const {
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return (getUnsignedField(4) << 8) >> 8;
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}
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@ -252,6 +252,11 @@ bool LowerDbgDeclare(Function &F);
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/// an alloca, if any.
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DbgDeclareInst *FindAllocaDbgDeclare(Value *V);
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/// replaceDbgDeclareForAlloca - Replaces llvm.dbg.declare instruction when
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/// alloca is replaced with a new value.
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bool replaceDbgDeclareForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
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DIBuilder &Builder);
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} // End llvm namespace
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#endif
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@ -25,6 +25,7 @@
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/ADT/Triple.h"
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#include "llvm/DataLayout.h"
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#include "llvm/DIBuilder.h"
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#include "llvm/Function.h"
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#include "llvm/IRBuilder.h"
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#include "llvm/InlineAsm.h"
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@ -38,6 +39,7 @@
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#include "llvm/Support/system_error.h"
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#include "llvm/Target/TargetMachine.h"
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#include "llvm/Transforms/Utils/BasicBlockUtils.h"
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#include "llvm/Transforms/Utils/Local.h"
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#include "llvm/Transforms/Utils/ModuleUtils.h"
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#include "llvm/Type.h"
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#include <algorithm>
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@ -1158,6 +1160,7 @@ bool AddressSanitizer::poisonStackInFunction(Function &F) {
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SmallVector<Instruction*, 8> RetVec;
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uint64_t TotalSize = 0;
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bool HavePoisonedAllocas = false;
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DIBuilder DIB(*F.getParent());
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// Filter out Alloca instructions we want (and can) handle.
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// Collect Ret instructions.
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@ -1228,6 +1231,7 @@ bool AddressSanitizer::poisonStackInFunction(Function &F) {
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Value *NewAllocaPtr = IRB.CreateIntToPtr(
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IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
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AI->getType());
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replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
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AI->replaceAllUsesWith(NewAllocaPtr);
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// Analyze lifetime intrinsics only for static allocas we handle.
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if (CheckLifetime)
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@ -928,3 +928,38 @@ DbgDeclareInst *llvm::FindAllocaDbgDeclare(Value *V) {
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return 0;
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}
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bool llvm::replaceDbgDeclareForAlloca(AllocaInst *AI, Value *NewAllocaAddress,
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DIBuilder &Builder) {
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DbgDeclareInst *DDI = FindAllocaDbgDeclare(AI);
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if (!DDI)
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return false;
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DIVariable DIVar(DDI->getVariable());
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if (!DIVar.Verify())
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return false;
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// Create a copy of the original DIDescriptor for user variable, appending
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// "deref" operation to a list of address elements, as new llvm.dbg.declare
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// will take a value storing address of the memory for variable, not
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// alloca itself.
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Type *Int64Ty = Type::getInt64Ty(AI->getContext());
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SmallVector<Value*, 4> NewDIVarAddress;
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if (DIVar.hasComplexAddress()) {
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for (unsigned i = 0, n = DIVar.getNumAddrElements(); i < n; ++i) {
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NewDIVarAddress.push_back(
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ConstantInt::get(Int64Ty, DIVar.getAddrElement(i)));
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}
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}
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NewDIVarAddress.push_back(ConstantInt::get(Int64Ty, DIBuilder::OpDeref));
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DIVariable NewDIVar = Builder.createComplexVariable(
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DIVar.getTag(), DIVar.getContext(), DIVar.getName(),
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DIVar.getFile(), DIVar.getLineNumber(), DIVar.getType(),
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NewDIVarAddress, DIVar.getArgNumber());
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// Insert llvm.dbg.declare in the same basic block as the original alloca,
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// and remove old llvm.dbg.declare.
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BasicBlock *BB = AI->getParent();
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Builder.insertDeclare(NewAllocaAddress, NewDIVar, BB);
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DDI->eraseFromParent();
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return true;
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}
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@ -0,0 +1,60 @@
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; RUN: opt < %s -asan -asan-module -S | FileCheck %s
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; Checks that llvm.dbg.declare instructions are updated
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; accordingly as we merge allocas.
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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"
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target triple = "x86_64-unknown-linux-gnu"
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define i32 @_Z3zzzi(i32 %p) nounwind uwtable address_safety {
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entry:
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%p.addr = alloca i32, align 4
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%r = alloca i32, align 4
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store i32 %p, i32* %p.addr, align 4
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call void @llvm.dbg.declare(metadata !{i32* %p.addr}, metadata !10), !dbg !11
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call void @llvm.dbg.declare(metadata !{i32* %r}, metadata !12), !dbg !14
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%0 = load i32* %p.addr, align 4, !dbg !14
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%add = add nsw i32 %0, 1, !dbg !14
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store i32 %add, i32* %r, align 4, !dbg !14
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%1 = load i32* %r, align 4, !dbg !15
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ret i32 %1, !dbg !15
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}
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; CHECK: define i32 @_Z3zzzi
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; CHECK: entry:
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; Verify that llvm.dbg.declare calls are in the entry basic block.
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; CHECK-NOT: %entry
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; CHECK: call void @llvm.dbg.declare(metadata {{.*}}, metadata ![[ARG_ID:[0-9]+]])
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; CHECK-NOT: %entry
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; CHECK: call void @llvm.dbg.declare(metadata {{.*}}, metadata ![[VAR_ID:[0-9]+]])
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declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
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!llvm.dbg.cu = !{!0}
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!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]
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!1 = metadata !{metadata !2}
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!2 = metadata !{i32 0}
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!3 = metadata !{metadata !4}
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!4 = metadata !{metadata !5}
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!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]
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!6 = metadata !{i32 786473, metadata !"a.cc", metadata !"/usr/local/google/llvm_cmake_clang/tmp/debuginfo", null} ; [ DW_TAG_file_type ]
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!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 ]
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!8 = metadata !{metadata !9, metadata !9}
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!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]
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!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]
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!11 = metadata !{i32 1, i32 0, metadata !5, null}
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!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]
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; Verify that debug descriptors for argument and local variable will be replaced
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; with descriptors that end with OpDeref (encoded as 2).
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; CHECK: ![[ARG_ID]] = metadata {{.*}} i64 2} ; [ DW_TAG_arg_variable ] [p] [line 1]
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; CHECK: ![[VAR_ID]] = metadata {{.*}} i64 2} ; [ DW_TAG_auto_variable ] [r] [line 2]
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; Verify that there are no more variable descriptors.
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; CHECK-NOT: DW_TAG_arg_variable
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; CHECK-NOT: DW_TAG_auto_variable
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!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]
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!14 = metadata !{i32 2, i32 0, metadata !13, null}
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!15 = metadata !{i32 3, i32 0, metadata !13, null}
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