* [x86 testsuite] preserve full register across main
@ 2019-08-23 19:23 Alexandre Oliva
2019-08-24 19:02 ` Uros Bizjak
0 siblings, 1 reply; 3+ messages in thread
From: Alexandre Oliva @ 2019-08-23 19:23 UTC (permalink / raw)
To: gcc-patches; +Cc: Rainer Orth, Mike Stump, Jan Hubicka, Uros Bizjak
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;
+
#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
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [x86 testsuite] preserve full register across main
2019-08-23 19:23 [x86 testsuite] preserve full register across main Alexandre Oliva
@ 2019-08-24 19:02 ` Uros Bizjak
2019-09-03 5:36 ` Alexandre Oliva
0 siblings, 1 reply; 3+ messages in thread
From: Uros Bizjak @ 2019-08-24 19:02 UTC (permalink / raw)
To: Alexandre Oliva; +Cc: gcc-patches, Rainer Orth, Mike Stump, Jan Hubicka
On Friday, August 23, 2019, Alexandre Oliva <oliva@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
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [x86 testsuite] preserve full register across main
2019-08-24 19:02 ` Uros Bizjak
@ 2019-09-03 5:36 ` Alexandre Oliva
0 siblings, 0 replies; 3+ messages in thread
From: Alexandre Oliva @ 2019-09-03 5:36 UTC (permalink / raw)
To: Uros Bizjak; +Cc: gcc-patches, Rainer Orth, Mike Stump, Jan Hubicka
On Aug 24, 2019, Uros Bizjak <ubizjak@gmail.com> wrote:
> Can __attribute__ ((mode (__word__))) be used here?
Oh, nice, yes, thanks!
> Otherwise OK.
Here's what I'm installing.
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 5641826b4837c..48dea27956ce2 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 int __attribute__ ((mode (__word__))) reg_type;
+
#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.org & FSF Latin America board member
GNU Toolchain Engineer Free Software Evangelist
Hay que enGNUrecerse, pero sin perder la terGNUra jamás - Che GNUevara
^ permalink raw reply [flat|nested] 3+ messages in thread
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2019-08-23 19:23 [x86 testsuite] preserve full register across main Alexandre Oliva
2019-08-24 19:02 ` Uros Bizjak
2019-09-03 5:36 ` Alexandre Oliva
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