From mboxrd@z Thu Jan  1 00:00:00 1970
From: Dibyendu Majumdar <mobile@majumdar.org.uk>
Subject: Potential issue with handling of va_arg()
Date: Fri, 31 Mar 2017 14:47:44 +0100
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To: Linux-Sparse <linux-sparse@vger.kernel.org>

Hi,

I am investigating a failure in this test:

#include <stdarg.h>
#include <stdlib.h>
#include <stdio.h>

void error_message(const char *fmt, ...) {
va_list argp;
va_start(argp, fmt);
vfprintf(stdout, fmt, argp);
va_end(argp);
}

int main(void)
{
error_message("%s\n", "hello world");
return 0;
}


The linearized output for error_message() is:

rror_message:
.L0:
<entry-point>
store.64    %arg1 -> 0[fmt]
cast.64     %r2 <- (64) fmt
load.64     %r3 <- 0[stdout]
call.32     %r6 <- vfprintf, %r3, %arg1, %r2
ret

Above seems incorrect to me, as %r2 should be pointing to [8]fmt presumably?

Thanks and Regards
Dibyendu