commit 0a14674f276b598d23353290635fc62f93e9ab30
Author: Peter Collingbourne <peter@pcc.me.uk>
Date:   Fri Dec 3 14:48:57 2021 -0500

    CodeGen: Strip exception specifications from function types in CFI type names.
    
    With C++17 the exception specification has been made part of the
    function type, and therefore part of mangled type names.
    
    However, it's valid to convert function pointers with an exception
    specification to function pointers with the same argument and return
    types but without an exception specification, which means that e.g. a
    function of type "void () noexcept" can be called through a pointer
    of type "void ()". We must therefore consider the two types to be
    compatible for CFI purposes.
    
    We can do this by stripping the exception specification before mangling
    the type name, which is what this patch does.
    
    Differential Revision: https://reviews.llvm.org/D115015

diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 9ba1a5c25e81..39044617d677 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -6398,6 +6398,11 @@ void CodeGenModule::EmitOMPThreadPrivateDecl(const OMPThreadPrivateDecl *D) {
 llvm::Metadata *
 CodeGenModule::CreateMetadataIdentifierImpl(QualType T, MetadataTypeMap &Map,
                                             StringRef Suffix) {
+  if (auto *FnType = T->getAs<FunctionProtoType>())
+    T = getContext().getFunctionType(
+        FnType->getReturnType(), FnType->getParamTypes(),
+        FnType->getExtProtoInfo().withExceptionSpec(EST_None));
+
   llvm::Metadata *&InternalId = Map[T.getCanonicalType()];
   if (InternalId)
     return InternalId;
diff --git a/clang/test/CodeGenCXX/cfi-icall-noexcept.cpp b/clang/test/CodeGenCXX/cfi-icall-noexcept.cpp
new file mode 100644
index 000000000000..eabc4862b4c5
--- /dev/null
+++ b/clang/test/CodeGenCXX/cfi-icall-noexcept.cpp
@@ -0,0 +1,11 @@
+// RUN: %clang_cc1 -triple x86_64-unknown-linux -fsanitize=cfi-icall -emit-llvm -std=c++17 -o - %s | FileCheck %s
+
+// Tests that exception specifiers are stripped when forming the
+// mangled CFI type name.
+
+void f() noexcept {}
+
+// CHECK: define{{.*}} void @_Z1fv({{.*}} !type [[TS1:![0-9]+]] !type [[TS2:![0-9]+]]
+
+// CHECK: [[TS1]] = !{i64 0, !"_ZTSFvvE"}
+// CHECK: [[TS2]] = !{i64 0, !"_ZTSFvvE.generalized"}