[PATCH] D54539: [CodeGen] Replace '@' characters in block descriptors' symbol names with '\1' on ELF targets.

[Akira Hatanaka via Phabricator via cfe-commits]

ahatanak created this revision.
ahatanak added reviewers: theraven, rjmccall.
ahatanak added a project: clang.
Herald added subscribers: dexonsmith, jkorous.

This fixes a bug introduced in r340041 (see the discussion in https://reviews.llvm.org/D50783).

'@' can't be used in block descriptors' symbol names since it is reserved on ELF platforms as a separator between symbol names and symbol versions.

I don't know of any forbidden symbols on Windows PE/COFF symbols, but if there are, I can make changes similar to the ones I made in this patch.


Repository:
  rC Clang

https://reviews.llvm.org/D54539

Files:
  lib/CodeGen/CGBlocks.cpp
  lib/CodeGen/CGObjCGNU.cpp
  lib/CodeGen/CGObjCRuntime.cpp
  lib/CodeGen/CGObjCRuntime.h
  test/CodeGenObjC/gnu-block-desc-str.m


Index: test/CodeGenObjC/gnu-block-desc-str.m
===================================================================
--- /dev/null
+++ test/CodeGenObjC/gnu-block-desc-str.m
@@ -0,0 +1,14 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-freebsd -emit-llvm -fobjc-runtime=gnustep-1.7 -fblocks -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple x86_64-pc-linux-gnu -emit-llvm -fobjc-runtime=gcc -fblocks -o - %s | FileCheck %s
+
+// Test that descriptor symbol names don't include '@', which is reserved on ELF
+// platforms as a separator between symbol name and symbol version.
+
+// CHECK: @[[STR:.*]] = private unnamed_addr constant [6 x i8] c"v8@?0\00"
+// CHECK: @"__block_descriptor_40_8_32o_e5_v8\01?0l" = linkonce_odr hidden unnamed_addr constant { i64, i64, i8*, i8*, i8*, i8* } { i64 0, i64 40, i8* bitcast ({{.*}} to i8*), i8* bitcast ({{.*}} to i8*), i8* getelementptr inbounds ([6 x i8], [6 x i8]* @[[STR]], i32 0, i32 0), i8* null }, align 8
+
+typedef void (^BlockTy)(void);
+
+void test(id a) {
+  BlockTy b = ^{ (void)a; };
+}
Index: lib/CodeGen/CGObjCRuntime.h
===================================================================
--- lib/CodeGen/CGObjCRuntime.h
+++ lib/CodeGen/CGObjCRuntime.h
@@ -283,6 +283,10 @@
     return {};
   }
 
+  /// Return the block's type encoding string that is used in the block
+  /// descriptor's symbol name.
+  virtual std::string getObjCEncodingForBlock(const BlockExpr *BE) const;
+
   /// Returns an i8* which points to the byref layout information.
   virtual llvm::Constant *BuildByrefLayout(CodeGen::CodeGenModule &CGM,
                                            QualType T) = 0;
Index: lib/CodeGen/CGObjCRuntime.cpp
===================================================================
--- lib/CodeGen/CGObjCRuntime.cpp
+++ lib/CodeGen/CGObjCRuntime.cpp
@@ -352,6 +352,10 @@
   CGF.EmitStmt(S.getSynchBody());
 }
 
+std::string CGObjCRuntime::getObjCEncodingForBlock(const BlockExpr *BE) const {
+  return CGM.getContext().getObjCEncodingForBlock(BE);
+}
+
 /// Compute the pointer-to-function type to which a message send
 /// should be casted in order to correctly call the given method
 /// with the given arguments.
Index: lib/CodeGen/CGObjCGNU.cpp
===================================================================
--- lib/CodeGen/CGObjCGNU.cpp
+++ lib/CodeGen/CGObjCGNU.cpp
@@ -662,6 +662,14 @@
   llvm::Constant *BuildByrefLayout(CodeGenModule &CGM, QualType T) override {
     return NULLPtr;
   }
+
+  /// Replace occurrences of '@' with '\1'. '@' is reserved on ELF platforms as
+  /// a separator between symbol name and symbol version.
+  std::string getObjCEncodingForBlock(const BlockExpr *BE) const override {
+    std::string Str = CGM.getContext().getObjCEncodingForBlock(BE);
+    std::replace(Str.begin(), Str.end(), '@', '\1');
+    return Str;
+  }
 };
 
 /// Class representing the legacy GCC Objective-C ABI.  This is the default when
Index: lib/CodeGen/CGBlocks.cpp
===================================================================
--- lib/CodeGen/CGBlocks.cpp
+++ lib/CodeGen/CGBlocks.cpp
@@ -160,7 +160,7 @@
   }
 
   std::string TypeAtEncoding =
-      CGM.getContext().getObjCEncodingForBlock(BlockInfo.getBlockExpr());
+      CGM.getObjCRuntime().getObjCEncodingForBlock(BlockInfo.getBlockExpr());
   Name += "e" + llvm::to_string(TypeAtEncoding.size()) + "_" + TypeAtEncoding;
   Name += "l" + CGM.getObjCRuntime().getRCBlockLayoutStr(CGM, BlockInfo);
   return Name;


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