[STDCXX-861] [Sun C++ 5.9/x86_64] bad codegen on va_arg and long double

• Type: Bug
• Status: Open
• Priority: Major
• Resolution: Unresolved
• Component/s: External
• Severity: Runtime Error
• Assignee: Unassigned
• Reporter: Martin Sebor
• Created: 14/Apr/08 03:09
• Updated: 14/Apr/08 15:11

Description

Sun C++ 5.9 appears to generate incorrect code for x86_64 (but not for x86 or SPARC) the attached program involving va_arg() and long double.

$ cat t.cpp && CC -m64 -V t.cpp && ./a.out
#include <cassert>
#include <cstdarg>
#include <cstdio>
#include <cstring>

char buffer [80];
const char* a1;
int a2;
const char* a3;
int a4;
const char* a5;
long double a6;

void setargs (std::va_list va) {
    a1 = va_arg (va, const char*);
    a2 = va_arg (va, int);
    a3 = va_arg (va, const char*);
    a4 = va_arg (va, int);
    a5 = va_arg (va, const char*);
    a6 = va_arg (va, long double);
}

void foo (const char *fmt, ...) {
    std::va_list va;
    va_start (va, fmt);
    setargs (va);
    std::sprintf (buffer, "%s %x %Lg", a3, a4, a6);
    va_end (va);
}

void bar (char *buf, const char *fmt, ...) {
    std::va_list va;
    va_start (va, fmt);
    setargs (va);
    std::sprintf (buf, "%s %x %Lg", a3, a4, a6);
    va_end (va);
}

int main () {
    char buf [80];

    foo (     "", "", 1, "", 0x12345678, "%Lg", 1.0L);
    bar (buf, "", "", 1, "", 0x12345678, "%Lg", 1.0L);

    std::puts (buffer);
    std::puts (buf);

    assert (0 == std::strcmp (buf, buffer));
    assert (0 == std::strcmp (buf, " 12345678 1"));
}
CC: Sun C++ 5.9 SunOS_i386 Patch 124864-01 2007/07/25
/amd/packages/mdx/solaris/amd64/compilers/sun/C++5.9j1/prod/bin/c++filt: Sun C++ 5.9 SunOS_i386 2007/05/03
ccfe: Sun C++ 5.9 SunOS_i386 Patch 124864-01 2007/07/25
ld: Software Generation Utilities - Solaris Link Editors: 5.10-1.482
 12345678 1
 12345678 2.60544e-4932
Assertion failed: 0 == std::strcmp (buf, buffer), file t.cpp, line 48
Abort (core dumped)

Issue Links

• blocks: STDCXX-856 [Sun C++] data corruption in rw_printf() with "%{$VAR!:@}", "%A{*c}", and "%{@}"