[AddressSanitizer] Copy type metadata to prevent miscompilation

[ddcc]

Summary

When ASan and e.g. Dead Virtual Function Elimination are enabled, the
latter will rely on type metadata to determine if certain virtual calls can be
removed. However, ASan currently does not copy type metadata, which can cause
virtual function calls to be incorrectly removed.

[ddcc]

Fix optional regex

[aprantl]

llvm/test/Instrumentation/AddressSanitizer/debug_info.ll

11

Can you try to not hardcode !6 and instead use a placeholder like [[TYPE:[0-9]+]] and add a second CHECK for [[TYPE]] = ...?

[ddcc]

llvm/test/Instrumentation/AddressSanitizer/debug_info.ll

11

Ok, will do.

llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp

for (size_t i = 0; i < n; i++) {
     // Move null-terminated C strings to "__asan_cstring" section on Darwin.
     if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
         G->isConstant()) {
       auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
       if (Seq && Seq->isCString())
         NewGlobal->setSection("__TEXT,__asan_cstring,regular");
     }
 
-    // Transfer the debug info.  The payload starts at offset zero so we can
-    // copy the debug info over as is.
-    SmallVector<DIGlobalVariableExpression *, 1> GVs;
-    G->getDebugInfo(GVs);
-    for (auto *GV : GVs)
-      NewGlobal->addDebugInfo(GV);
+    // Transfer the debug info and type metadata.  The payload starts at offset
+    // zero so we can copy the metadata over as is.
+    NewGlobal->copyMetadata(G, 0);
 
     Value *Indices2[2];
     Indices2[0] = IRB.getInt32(0);
     Indices2[1] = IRB.getInt32(0);
 
     G->replaceAllUsesWith(
         ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
     NewGlobal->takeName(G);

llvm/test/Instrumentation/AddressSanitizer/debug_info.ll

 ; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=0 -S | FileCheck %s
 ; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=0 -S | FileCheck %s
 
-; Checks that llvm.dbg.declare instructions are updated 
+; 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 sanitize_address !dbg !5 {
+@G = global [32 x i8] zeroinitializer, align 32, !dbg !0, !type !6
+; CHECK: @G = global { [32 x i8], [32 x i8] } zeroinitializer{{(, comdat)?}}, align 32, !dbg !0, !type [[TYPE:![0-9]+]]
+
+define i32 @_Z3zzzi(i32 %p) nounwind uwtable sanitize_address !dbg !12 {
 entry:
   %p.addr = alloca i32, align 4
   %r = alloca i32, align 4
   store volatile i32 %p, i32* %p.addr, align 4
-  call void @llvm.dbg.declare(metadata i32* %p.addr, metadata !10, metadata !DIExpression()), !dbg !11
-  call void @llvm.dbg.declare(metadata i32* %r, metadata !12, metadata !DIExpression()), !dbg !14
-  %0 = load i32, i32* %p.addr, align 4, !dbg !14
-  %add = add nsw i32 %0, 1, !dbg !14
-  store volatile i32 %add, i32* %r, align 4, !dbg !14
-  %1 = load i32, i32* %r, align 4, !dbg !15
-  ret i32 %1, !dbg !15
+  call void @llvm.dbg.declare(metadata i32* %p.addr, metadata !17, metadata !DIExpression()), !dbg !18
+  call void @llvm.dbg.declare(metadata i32* %r, metadata !19, metadata !DIExpression()), !dbg !21
+  %0 = load i32, i32* %p.addr, align 4, !dbg !21
+  %add = add nsw i32 %0, 1, !dbg !21
+  store volatile i32 %add, i32* %r, align 4, !dbg !21
+  %1 = load i32, i32* %r, align 4, !dbg !22
+  ret i32 %1, !dbg !22
 }
 
 ;   CHECK: define i32 @_Z3zzzi
 ;   CHECK: [[MyAlloca:%.*]] = alloca i8, i64 64
 ; Note: these dbg.declares used to contain `ptrtoint` operands. The instruction
 ; selector would then decline to put the variable in the MachineFunction side
 ; table. Check that the dbg.declares have `alloca` operands.
 ;   CHECK: call void @llvm.dbg.declare(metadata i8* [[MyAlloca]], metadata ![[ARG_ID:[0-9]+]], metadata !DIExpression(DW_OP_plus_uconst, 32))
 ;   CHECK: call void @llvm.dbg.declare(metadata i8* [[MyAlloca]], metadata ![[VAR_ID:[0-9]+]], metadata !DIExpression(DW_OP_plus_uconst, 48))
 
 declare void @llvm.dbg.declare(metadata, metadata, metadata) nounwind readnone
 
-!llvm.dbg.cu = !{!0}
-!llvm.module.flags = !{!17}
+!llvm.dbg.cu = !{!7}
+!llvm.module.flags = !{!24}
 
-!0 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.3 (trunk 169314)", isOptimized: true, emissionKind: FullDebug, file: !16, enums: !1, retainedTypes: !1, globals: !1)
-!1 = !{}
-!5 = distinct !DISubprogram(name: "zzz", linkageName: "_Z3zzzi", line: 1, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !0, scopeLine: 1, file: !16, scope: !6, type: !7, retainedNodes: !1)
-!6 = !DIFile(filename: "a.cc", directory: "/usr/local/google/llvm_cmake_clang/tmp/debuginfo")
-!7 = !DISubroutineType(types: !8)
-!8 = !{!9, !9}
-!9 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
-!10 = !DILocalVariable(name: "p", line: 1, arg: 1, scope: !5, file: !6, type: !9)
-!11 = !DILocation(line: 1, scope: !5)
-!12 = !DILocalVariable(name: "r", line: 2, scope: !13, file: !6, type: !9)
+!0 = !DIGlobalVariableExpression(var: !1, expr: !DIExpression())
+!1 = distinct !DIGlobalVariable(name: "G", type: !2, isLocal: false, isDefinition: true)
+!2 = !DICompositeType(tag: DW_TAG_array_type, baseType: !3, size: 256, elements: !4)
+!3 = !DIBasicType(name: "unsigned char", size: 8, encoding: DW_ATE_unsigned_char)
+!4 = !{!5}
+!5 = !DISubrange(count: 32)
+!6 = !{i64 0, !"G"}
+; CHECK: [[TYPE]] = !{i64 0, !"G"}
+
+!7 = distinct !DICompileUnit(language: DW_LANG_C_plus_plus, producer: "clang version 3.3 (trunk 169314)", isOptimized: true, emissionKind: FullDebug, file: !23, enums: !8, retainedTypes: !8, globals: !8)
+!8 = !{}
+!12 = distinct !DISubprogram(name: "zzz", linkageName: "_Z3zzzi", line: 1, isLocal: false, isDefinition: true, virtualIndex: 6, flags: DIFlagPrototyped, isOptimized: false, unit: !7, scopeLine: 1, file: !23, scope: !13, type: !14, retainedNodes: !8)
+!13 = !DIFile(filename: "a.cc", directory: "/usr/local/google/llvm_cmake_clang/tmp/debuginfo")
+!14 = !DISubroutineType(types: !15)
+!15 = !{!16, !16}
+!16 = !DIBasicType(tag: DW_TAG_base_type, name: "int", size: 32, align: 32, encoding: DW_ATE_signed)
+!17 = !DILocalVariable(name: "p", line: 1, arg: 1, scope: !12, file: !13, type: !16)
+!18 = !DILocation(line: 1, scope: !12)
+!19 = !DILocalVariable(name: "r", line: 2, scope: !20, file: !13, type: !16)
 
 ; Verify that debug descriptors for argument and local variable will be replaced
 ; with descriptors that end with OpDeref (encoded as 2).
 ;   CHECK: ![[ARG_ID]] = !DILocalVariable(name: "p", arg: 1,{{.*}} line: 1
 ;   CHECK: ![[VAR_ID]] = !DILocalVariable(name: "r",{{.*}} line: 2
 ; Verify that there are no more variable descriptors.
 ;   CHECK-NOT: !DILocalVariable(tag: DW_TAG_arg_variable
 ;   CHECK-NOT: !DILocalVariable(tag: DW_TAG_auto_variable
 
 
-!13 = distinct !DILexicalBlock(line: 1, column: 0, file: !16, scope: !5)
-!14 = !DILocation(line: 2, scope: !13)
-!15 = !DILocation(line: 3, scope: !13)
-!16 = !DIFile(filename: "a.cc", directory: "/usr/local/google/llvm_cmake_clang/tmp/debuginfo")
-!17 = !{i32 1, !"Debug Info Version", i32 3}
+!20 = distinct !DILexicalBlock(line: 1, column: 0, file: !23, scope: !12)
+!21 = !DILocation(line: 2, scope: !20)
+!22 = !DILocation(line: 3, scope: !20)
+!23 = !DIFile(filename: "a.cc", directory: "/usr/local/google/llvm_cmake_clang/tmp/debuginfo")
+!24 = !{i32 1, !"Debug Info Version", i32 3}