[CodeGen] Handle __func__ inside __finally

[smeenai]

Summary

When we enter a __finally block, the CGF's CurCodeDecl will be null
(because CodeGenFunction::StartFunction is given an empty GlobalDecl for
a __finally block), and so the dyn_cast here will result in an assertion
failure. Change it to dyn_cast_or_null to handle this case.

[smeenai]

test/CodeGen/exceptions-seh-finally.c

281 ↗

(On Diff #142025)

How stable is the mangling here? I included the complete call instruction because I wanted to ensure that the value of __func__ inside a __finally block reflects the parent function, not the outlined funclet, and both the [18 x i8] and the mangled string name are pretty good proxies for that. I can generalize it more if it'll make the test more reliable though.

[rnk]

lgtm, thanks!

test/CodeGen/exceptions-seh-finally.c

281 ↗

(On Diff #142025)

It's pretty stable.

cfe/trunk/lib/CodeGen/CGExpr.cpp

LValue CodeGenFunction::EmitPredefinedLValue(const PredefinedExpr *E) {
   auto SL = E->getFunctionName();
   assert(SL != nullptr && "No StringLiteral name in PredefinedExpr");
   StringRef FnName = CurFn->getName();
   if (FnName.startswith("\01"))
     FnName = FnName.substr(1);
   StringRef NameItems[] = {
       PredefinedExpr::getIdentTypeName(E->getIdentType()), FnName};
   std::string GVName = llvm::join(NameItems, NameItems + 2, ".");
-  if (auto *BD = dyn_cast<BlockDecl>(CurCodeDecl)) {
+  if (auto *BD = dyn_cast_or_null<BlockDecl>(CurCodeDecl)) {
     std::string Name = SL->getString();
     if (!Name.empty()) {
       unsigned Discriminator =
           CGM.getCXXABI().getMangleContext().getBlockId(BD, true);
       if (Discriminator)
         Name += "_" + Twine(Discriminator + 1).str();
       auto C = CGM.GetAddrOfConstantCString(Name, GVName.c_str());
       return MakeAddrLValue(C, E->getType(), AlignmentSource::Decl);

cfe/trunk/test/CodeGen/exceptions-seh-finally.c

 // CHECK: invoke void @might_crash(
 
 // CHECK: call void @"?fin$1@0@finally_within_finally@@"(
 // CHECK: call void @"?fin$1@0@finally_within_finally@@"({{.*}}) [ "funclet"(
 
 // CHECK-LABEL: define internal void @"?fin$1@0@finally_within_finally@@"({{[^)]*}})
 // CHECK-SAME: [[finally_attrs]]
 
+void cleanup_with_func(const char *);
+void finally_with_func() {
+  __try {
+    might_crash();
+  } __finally {
+    cleanup_with_func(__func__);
+  }
+}
+
+// CHECK-LABEL: define internal void @"?fin$0@0@finally_with_func@@"({{[^)]*}})
+// CHECK: call void @cleanup_with_func(i8* getelementptr inbounds ([18 x i8], [18 x i8]* @"??_C@_0BC@COAGBPGM@finally_with_func?$AA@", i32 0, i32 0))
+
 // Look for the absence of noinline. Enum attributes come first, so check that
 // a string attribute is the first to verify that no enum attributes are
 // present.
 // CHECK: attributes [[finally_attrs]] = { "{{.*}}" }