Disable sanitizer's on ifunc resolvers.

Resolvers are running before the module is initialised which leads to
crashes due to the santizer is not yet initialised.

Fixes #40287

Reviewed By: hctim

Differential Revision: https://reviews.llvm.org/D150262

clang/lib/CodeGen/CodeGenModule.cpp

@@ -5832,7 +5832,9 @@ void CodeGenModule::emitIFuncDefinition(GlobalDecl GD) {
     Entry->eraseFromParent();
   } else
     GIF->setName(MangledName);
-
+  if (auto *F = dyn_cast<llvm::Function>(Resolver)) {
+    F->addFnAttr(llvm::Attribute::DisableSanitizerInstrumentation);
+  }
   SetCommonAttributes(GD, GIF);
 }
 

clang/test/CodeGen/ifunc.c

@@ -1,5 +1,8 @@
 // RUN: %clang_cc1 -triple i386-unknown-linux-gnu -emit-llvm -o - %s | FileCheck %s
 // RUN: %clang_cc1 -triple i386-unknown-linux-gnu -O2 -emit-llvm -o - %s | FileCheck %s
+// RUN: %clang_cc1 -triple i386-unknown-linux-gnu -fsanitize=thread -O2 -emit-llvm -o - %s | FileCheck %s --check-prefix=SAN
+// RUN: %clang_cc1 -triple i386-unknown-linux-gnu -fsanitize=address -O2 -emit-llvm -o - %s | FileCheck %s --check-prefix=SAN
+// RUN: %clang_cc1 -triple i386-unknown-linux-gnu -fsanitize=memory -O2 -emit-llvm -o - %s | FileCheck %s --check-prefix=SAN
 
 int foo(int) __attribute__ ((ifunc("foo_ifunc")));
 
@@ -39,3 +42,11 @@ void* goo_ifunc(void) {
 
 // CHECK: call i32 @foo(i32
 // CHECK: call void @goo()
+
+// SAN: define internal nonnull ptr @foo_ifunc() #[[#FOO_IFUNC:]] {
+
+// SAN: define dso_local noalias ptr @goo_ifunc() #[[#GOO_IFUNC:]] {
+
+// SAN-DAG: attributes #[[#FOO_IFUNC]] = {{{.*}} disable_sanitizer_instrumentation {{.*}}
+
+// SAN-DAG: attributes #[[#GOO_IFUNC]] = {{{.*}} disable_sanitizer_instrumentation {{.*}}