On Friday, August 23, 2019, Alexandre Oliva <ol...@adacore.com> wrote:
> This test uses a call-saved register as a global variable. It
> attempts to preserve its value across main, but only the lower int
> part is preserved, which is not good enough for x86_64, when the
> runtime that calls main() happens to hold something in the chosen
> register that is not a zero-extension from the 32-bit value, and
> rightfully expects the full register to remain unchanged when main()
> returns.
>
> Tested on x86_64-linux-gnu, both -m64 and -m32. Ok to install?
>
>
> for gcc/testsuite/ChangeLog
>
> * gcc.target/i386/20020616-1.c: Preserve full register across
> main.
> ---
> gcc/testsuite/gcc.target/i386/20020616-1.c | 14 +++++++++-----
> 1 file changed, 9 insertions(+), 5 deletions(-)
>
> diff --git a/gcc/testsuite/gcc.target/i386/20020616-1.c
b/gcc/testsuite/gcc.target/i386/20020616-1.c
> index 5641826b4837..3b8cf8e41783 100644
> --- a/gcc/testsuite/gcc.target/i386/20020616-1.c
> +++ b/gcc/testsuite/gcc.target/i386/20020616-1.c
> @@ -2,12 +2,16 @@
> /* { dg-do run } */
> /* { dg-options "-O2" } */
>
> +/* We need this type to be as wide as the register chosen below, so
> + that, when we preserve it across main, we preserve all of it. */
> +typedef long reg_type;
Can __attribute__ ((mode (__word__))) be used here?
Otherwise OK.
Thanks,
Uros.
> #if !__PIC__
> -register int k asm("%ebx");
> +register reg_type k asm("%ebx");
> #elif __amd64
> -register int k asm("%r12");
> +register reg_type k asm("%r12");
> #else
> -register int k asm("%esi");
> +register reg_type k asm("%esi");
> #endif
>
> void __attribute__((noinline))
> @@ -18,7 +22,7 @@ foo()
>
> void test()
> {
> - int i;
> + reg_type i;
> for (i = 0; i < 10; i += k)
> {
> k = 0;
> @@ -28,7 +32,7 @@ void test()
>
> int main()
> {
> - int old = k;
> + reg_type old = k;
> test();
> k = old;
> return 0;
>
> --
> Alexandre Oliva, freedom fighter he/him https://FSFLA.org/blogs/lxo
> Be the change, be Free! FSF Latin America board member
> GNU Toolchain Engineer Free Software Evangelist
> Hay que enGNUrecerse, pero sin perder la terGNUra jamás - Che GNUevara
>
