[llvm] 297a183 - [asan] Don't demangle __odr_asan_gen_* symbols

[Fangrui Song via llvm-commits]

Author: Fangrui Song
Date: 2022-11-22T16:47:33-08:00
New Revision: 297a1830228a0cdc61fa2a0014ace3817497982e

URL: https://github.com/llvm/llvm-project/commit/297a1830228a0cdc61fa2a0014ace3817497982e
DIFF: https://github.com/llvm/llvm-project/commit/297a1830228a0cdc61fa2a0014ace3817497982e.diff

LOG: [asan] Don't demangle __odr_asan_gen_* symbols

This relands the ODR indicator part of D138095 (reverted by 06c74b5e7367b41e9b4ea3d74c971aace5681fb8):
a `__odr_asan_gen_*` symbol should use a mangled name as its associated symbol does.

Added: 
    

Modified: 
    llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
    llvm/test/Instrumentation/AddressSanitizer/local_alias.ll

Removed: 
    


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diff  --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
index ff05454aa920e..a4d4cc73c4828 100644
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -2264,11 +2264,12 @@ bool ModuleAddressSanitizer::InstrumentGlobals(IRBuilder<> &IRB, Module &M,
     if (G->hasSanitizerMetadata())
       MD = G->getSanitizerMetadata();
 
-    // TODO: Symbol names in the descriptor can be demangled by the runtime
-    // library. This could save ~0.4% of VM size for a private large binary.
-    std::string NameForGlobal = llvm::demangle(G->getName().str());
+    // The runtime library tries demangling symbol names in the descriptor but
+    // functionality like __cxa_demangle may be unavailable (e.g.
+    // -static-libstdc++). So we demangle the symbol names here.
+    std::string NameForGlobal = G->getName().str();
     GlobalVariable *Name =
-        createPrivateGlobalForString(M, NameForGlobal,
+        createPrivateGlobalForString(M, llvm::demangle(NameForGlobal),
                                      /*AllowMerging*/ true, kAsanGenPrefix);
 
     Type *Ty = G->getValueType();

diff  --git a/llvm/test/Instrumentation/AddressSanitizer/local_alias.ll b/llvm/test/Instrumentation/AddressSanitizer/local_alias.ll
index b772d5c76167c..ada8120155e5e 100644
--- a/llvm/test/Instrumentation/AddressSanitizer/local_alias.ll
+++ b/llvm/test/Instrumentation/AddressSanitizer/local_alias.ll
@@ -13,17 +13,20 @@ target triple = "x86_64-unknown-linux-gnu"
 @a = dso_local global [2 x i32] zeroinitializer, align 4
 @b = private global [2 x i32] zeroinitializer, align 4
 @c = internal global [2 x i32] zeroinitializer, align 4
- at d = unnamed_addr global [2 x i32] zeroinitializer, align 4
+ at _ZL1d = unnamed_addr global [2 x i32] zeroinitializer, align 4
 
 ; Check that we generate internal alias and odr indicator symbols for global to be protected.
 ; CHECK-NOINDICATOR-NOT: __odr_asan_gen_a
 ; CHECK-NOALIAS-NOT: private alias
+; CHECK-INDICATOR: @___asan_gen_.1 = private unnamed_addr constant [2 x i8] c"a\00", align 1
 ; CHECK-INDICATOR: @__odr_asan_gen_a = global i8 0, align 1
+; CHECK-INDICATOR: @___asan_gen_.4 = private unnamed_addr constant [2 x i8] c"d\00", align 1
+; CHECK-INDICATOR: @__odr_asan_gen__ZL1d = global i8 0, align 1
 ; CHECK-ALIAS: @0 = private alias { [2 x i32], [24 x i8] }, ptr @a
 
 ; CHECK-ALIAS: @1 = private alias { [2 x i32], [24 x i8] }, ptr @b
 ; CHECK-ALIAS: @2 = private alias { [2 x i32], [24 x i8] }, ptr @c
-; CHECK-ALIAS: @3 = private alias { [2 x i32], [24 x i8] }, ptr @d
+; CHECK-ALIAS: @3 = private alias { [2 x i32], [24 x i8] }, ptr @_ZL1d
 
 ; Function Attrs: nounwind sanitize_address uwtable
 define i32 @foo(i32 %M) #0 {