[llvm-commits] [PATCH] Add transformation that replaces llvm.dbg.declare() call if we replace its alloca argument. Use this transformation in ASan.
Alexey Samsonov
samsonov at google.com
Tue Dec 4 18:09:18 PST 2012
Hi echristo,
This patch significantly improves debug info generated by ASan.
When ASan replaces alloca instructions with offsets into one common large
alloca, it should also patch llvm.dbg.declare calls and replace debug
info descriptors to mark that we've replaced alloca not with a value holder,
but with a value that stores an address of the memory.
http://llvm-reviews.chandlerc.com/D168
Files:
lib/Transforms/Utils/Local.cpp
lib/Transforms/Instrumentation/AddressSanitizer.cpp
test/Instrumentation/AddressSanitizer/debug_info.ll
include/llvm/DebugInfo.h
include/llvm/Transforms/Utils/Local.h
Index: lib/Transforms/Utils/Local.cpp
===================================================================
--- lib/Transforms/Utils/Local.cpp
+++ lib/Transforms/Utils/Local.cpp
@@ -928,3 +928,38 @@
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;
+}
Index: lib/Transforms/Instrumentation/AddressSanitizer.cpp
===================================================================
--- lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -25,6 +25,7 @@
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/Triple.h"
#include "llvm/DataLayout.h"
+#include "llvm/DIBuilder.h"
#include "llvm/Function.h"
#include "llvm/IRBuilder.h"
#include "llvm/InlineAsm.h"
@@ -38,6 +39,7 @@
#include "llvm/Support/system_error.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/ModuleUtils.h"
#include "llvm/Type.h"
#include <algorithm>
@@ -1158,6 +1160,7 @@
SmallVector<Instruction*, 8> RetVec;
uint64_t TotalSize = 0;
bool HavePoisonedAllocas = false;
+ DIBuilder DIB(*F.getParent());
// Filter out Alloca instructions we want (and can) handle.
// Collect Ret instructions.
@@ -1228,6 +1231,7 @@
Value *NewAllocaPtr = IRB.CreateIntToPtr(
IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Pos)),
AI->getType());
+ replaceDbgDeclareForAlloca(AI, NewAllocaPtr, DIB);
AI->replaceAllUsesWith(NewAllocaPtr);
// Analyze lifetime intrinsics only for static allocas we handle.
if (CheckLifetime)
Index: test/Instrumentation/AddressSanitizer/debug_info.ll
===================================================================
--- /dev/null
+++ test/Instrumentation/AddressSanitizer/debug_info.ll
@@ -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}
Index: include/llvm/DebugInfo.h
===================================================================
--- include/llvm/DebugInfo.h
+++ include/llvm/DebugInfo.h
@@ -635,6 +635,7 @@
DIFile F = getFieldAs<DIFile>(3);
return F.getCompileUnit();
}
+ DIFile getFile() const { return getFieldAs<DIFile>(3); }
unsigned getLineNumber() const {
return (getUnsignedField(4) << 8) >> 8;
}
Index: include/llvm/Transforms/Utils/Local.h
===================================================================
--- include/llvm/Transforms/Utils/Local.h
+++ include/llvm/Transforms/Utils/Local.h
@@ -252,6 +252,11 @@
/// an alloca, if any.
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
#endif
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