ICE in clang on promoted vararg

[tkoenig1]

The code is doubious, a warning is expected. No ICE with x86_64.

$ cat Wcxx-compat-11.c 
/* { dg-do compile } */
/* { dg-options "-Wc++-compat" } */

#include <stdarg.h>

enum E { A };

extern void f2 (int);
void
f1 (int n, ...)
{
  va_list ap;

  va_start (ap, n);
  f2 (va_arg (ap, int));
  f2 (va_arg (ap, _Bool));      /* { dg-warning "promoted" } */
  f2 (va_arg (ap, enum E));     /* { dg-warning "promoted" } */
}

/* Match extra informative notes.  */
/* { dg-message "note:" "expected" { target *-*-* } 0 } */
$ 66 Wcxx-compat-11.c 
Wcxx-compat-11.c:16:19: warning: second argument to 'va_arg' is of promotable type '_Bool'; this va_arg has undefined behavior because arguments will be promoted to 'int' [-Wvarargs]
  f2 (va_arg (ap, _Bool));      /* { dg-warning "promoted" } */
                  ^~~~~
/home/asdf/lib/clang/15.0.0/include/stdarg.h:19:50: note: expanded from macro 'va_arg'
#define va_arg(ap, type)    __builtin_va_arg(ap, type)
                                                 ^~~~
clang: /home/asdf/llvm-my66000/llvm/lib/IR/Instructions.cpp:1488: void llvm::StoreInst::AssertOK(): Assertion `cast<PointerType>(getOperand(1)->getType()) ->isOpaqueOrPointeeTypeMatches(getOperand(0)->getType()) && "Ptr must be a pointer to Val type!"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: clang -fverbose-asm -c --target=my66000 -O3 -fno-vectorize -fno-slp-vectorize -emit-llvm -fno-unroll-loops Wcxx-compat-11.c
1.      <eof> parser at end of file
2.      Wcxx-compat-11.c:10:1: LLVM IR generation of declaration 'f1'
3.      Wcxx-compat-11.c:10:1: Generating code for declaration 'f1'

[bagel99]

Can not duplicate. Get the 2 warnings from clang and then things proceed normally.

[tkoenig1]

Can not duplicate. Get the 2 warnings from clang and then things proceed normally.

Here we go again...

reproducer.zip

I have attached the two reproducer files that clang generates. Maybe this will help (you will have to adjust the paths, obviously :-)

[bagel99]

Even with this new information, using your flags to clang, I cannot reproduce. May post the *.bc so we can see if the IR differs somehow.

[tkoenig1]

I cannot attach a .bc file because the error is in clang, no .bc is generated.

If you run the reproducer script file from the zip file, adjusting the path to clang, do you also not get the error?

But maybe it is just a clang error masked by some peculiarities in other implementations.

FWITW, here is a gdb session showing the occurence of the error on my system.

gdbsession.txt

However, I would not really classify this as a high-priority bug :-)

[bagel99]

OK. I think I know why we get different results. You are running a Debug version of clang, I am running a Release version. In the Debug version, asserts are enabled. They are not in the Release version. See if you get this assert when running clang for other targets.

[tkoenig1]

I just ran it on a machine where I have a Relase build enabled, and I do not see anything there.

I also checked a couple of other architectures, and the error is not there with the same Release compiler I use for my66000:

$ clang -S -O2 Wcxx-compat-11-409fb6.c 
Wcxx-compat-11.c:16:19: warning: second argument to 'va_arg' is of promotable type '_Bool'; this va_arg has undefined behavior because arguments will be promoted to 'int' [-Wvarargs]
  f2 (va_arg (ap, _Bool));      /* { dg-warning "promoted" } */
                  ^~~~~
/home/asdf/lib/clang/15.0.0/include/stdarg.h:19:50: note: expanded from macro 'va_arg'
#define va_arg(ap, type)    __builtin_va_arg(ap, type)
                                                 ^~~~
1 warning generated.
$ clang --target=powerpc64le-unknown-linux -S -O2 Wcxx-compat-11-409fb6.c 
Wcxx-compat-11.c:16:19: warning: second argument to 'va_arg' is of promotable type '_Bool'; this va_arg has undefined behavior because arguments will be promoted to 'int' [-Wvarargs]
  f2 (va_arg (ap, _Bool));      /* { dg-warning "promoted" } */
                  ^~~~~
/home/asdf/lib/clang/15.0.0/include/stdarg.h:19:50: note: expanded from macro 'va_arg'
#define va_arg(ap, type)    __builtin_va_arg(ap, type)
                                                 ^~~~
1 warning generated.
$ clang --target=my66000 -S -O2 Wcxx-compat-11-409fb6.c 
Wcxx-compat-11.c:16:19: warning: second argument to 'va_arg' is of promotable type '_Bool'; this va_arg has undefined behavior because arguments will be promoted to 'int' [-Wvarargs]
  f2 (va_arg (ap, _Bool));      /* { dg-warning "promoted" } */
                  ^~~~~
/home/asdf/lib/clang/15.0.0/include/stdarg.h:19:50: note: expanded from macro 'va_arg'
#define va_arg(ap, type)    __builtin_va_arg(ap, type)
                                                 ^~~~
clang: /home/asdf/llvm-my66000/llvm/lib/IR/Instructions.cpp:1488: void llvm::StoreInst::AssertOK(): Assertion `cast<PointerType>(getOperand(1)->getType()) ->isOpaqueOrPointeeTypeMatches(getOperand(0)->getType()) && "Ptr must be a pointer to Val type!"' failed.
PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace, preprocessed source, and associated run script.
Stack dump:
0.      Program arguments: clang --target=my66000 -S -O2 Wcxx-compat-11-409fb6.c
1.      <eof> parser at end of file
2.      Wcxx-compat-11.c:10:1: LLVM IR generation of declaration 'f1'
3.      Wcxx-compat-11.c:10:1: Generating code for declaration 'f1'
^C

[tkoenig1]

Seems fixed also in Debug mode with the current compiler, I cannot reproduce it any longer.