clang13/trunk/strip-exception-specifications-in-CFI-type-names.patch

   1 From 0a14674f276b598d23353290635fc62f93e9ab30 Mon Sep 17 00:00:00 2001
   2 From: Peter Collingbourne <peter@pcc.me.uk>
   3 Date: Fri, 3 Dec 2021 14:48:57 -0500
   4 Subject: [PATCH] CodeGen: Strip exception specifications from function types
   5  in CFI type names.
   6
   7 With C++17 the exception specification has been made part of the
   8 function type, and therefore part of mangled type names.
   9
  10 However, it's valid to convert function pointers with an exception
  11 specification to function pointers with the same argument and return
  12 types but without an exception specification, which means that e.g. a
  13 function of type "void () noexcept" can be called through a pointer
  14 of type "void ()". We must therefore consider the two types to be
  15 compatible for CFI purposes.
  16
  17 We can do this by stripping the exception specification before mangling
  18 the type name, which is what this patch does.
  19
  20 Differential Revision: https://reviews.llvm.org/D115015
  21 ---
  22  clang/lib/CodeGen/CodeGenModule.cpp          |  5 +++++
  23  clang/test/CodeGenCXX/cfi-icall-noexcept.cpp | 11 +++++++++++
  24  2 files changed, 16 insertions(+)
  25  create mode 100644 clang/test/CodeGenCXX/cfi-icall-noexcept.cpp
  26
  27 diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
  28 index 9ba1a5c25e81a..39044617d6774 100644
  29 --- a/clang/lib/CodeGen/CodeGenModule.cpp
  30 +++ b/clang/lib/CodeGen/CodeGenModule.cpp
  31 @@ -6398,6 +6398,11 @@ void CodeGenModule::EmitOMPThreadPrivateDecl(const OMPThreadPrivateDecl *D) {
  32  llvm::Metadata *
  33  CodeGenModule::CreateMetadataIdentifierImpl(QualType T, MetadataTypeMap &Map,
  34                                              StringRef Suffix) {
  35 +  if (auto *FnType = T->getAs<FunctionProtoType>())
  36 +    T = getContext().getFunctionType(
  37 +        FnType->getReturnType(), FnType->getParamTypes(),
  38 +        FnType->getExtProtoInfo().withExceptionSpec(EST_None));
  39 +
  40    llvm::Metadata *&InternalId = Map[T.getCanonicalType()];
  41    if (InternalId)
  42      return InternalId;
  43 diff --git a/clang/test/CodeGenCXX/cfi-icall-noexcept.cpp b/clang/test/CodeGenCXX/cfi-icall-noexcept.cpp
  44 new file mode 100644
  45 index 0000000000000..eabc4862b4c52
  46 --- /dev/null
  47 +++ b/clang/test/CodeGenCXX/cfi-icall-noexcept.cpp
  48 @@ -0,0 +1,11 @@
  49 +// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-icall -emit-llvm -std=c++17 -o - %s | FileCheck %s
  50 +
  51 +// Tests that exception specifiers are stripped when forming the
  52 +// mangled CFI type name.
  53 +
  54 +void f() noexcept {}
  55 +
  56 +// CHECK: define{{.*}} void @_Z1fv({{.*}} !type [[TS1:![0-9]+]] !type [[TS2:![0-9]+]]
  57 +
  58 +// CHECK: [[TS1]] = !{i64 0, !"_ZTSFvvE"}
  59 +// CHECK: [[TS2]] = !{i64 0, !"_ZTSFvvE.generalized"}