On Wed, Nov 4, 2020 at 9:16 PM Qing Zhao <qing.z...@oracle.com> wrote:
>
> As we discussed in the bug report, we should not zero stack registers when
> there is no x87 registers available.
>
> The following is the fix per Jakub’s suggestion.
>
> And I have tested it on X86.
>
> Okay for commit?
>
> thanks.
>
> Qing
>
> From 0080f104df2dc752969a1949981ba343f276e802 Mon Sep 17 00:00:00 2001
> From: qing zhao <qinz...@gcc.gnu.org>
> Date: Wed, 4 Nov 2020 20:46:15 +0100
> Subject: [PATCH] i386: Fix PR97715
>
> This change fixes a bug in the i386 backend when adding
> -fzero-call-used-regs=all on a target that has no x87
> registers.
>
> When there is no x87 registers available, we should not
> zero stack registers.
>
> gcc/Changelog:
>
> PR target/97715
> * config/i386/i386.c (zero_all_st_registers): Return
> earlier when the FPU is disabled.
>
> gcc/testsuite/ChnageLog:
>
> PR target/97715
> * gcc.target/i386/zero-scratch-regs-32.c: New test.
OK.
Thanks,
Uros.
> ---
> gcc/config/i386/i386.c | 5 +++++
> gcc/testsuite/gcc.target/i386/zero-scratch-regs-32.c | 11 +++++++++++
> 2 files changed, 16 insertions(+)
> create mode 100644 gcc/testsuite/gcc.target/i386/zero-scratch-regs-32.c
>
> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
> index 6fc6228a26e..789ef727cf8 100644
> --- a/gcc/config/i386/i386.c
> +++ b/gcc/config/i386/i386.c
> @@ -3640,6 +3640,11 @@ zero_all_vector_registers (HARD_REG_SET
> need_zeroed_hardregs)
> static bool
> zero_all_st_registers (HARD_REG_SET need_zeroed_hardregs)
> {
> +
> + /* If the FPU is disabled, no need to zero all st registers. */
> + if (! (TARGET_80387 || TARGET_FLOAT_RETURNS_IN_80387))
> + return false;
> +
> unsigned int num_of_st = 0;
> for (unsigned int regno = 0; regno < FIRST_PSEUDO_REGISTER; regno++)
> if ((STACK_REGNO_P (regno) || MMX_REGNO_P (regno))
> diff --git a/gcc/testsuite/gcc.target/i386/zero-scratch-regs-32.c
> b/gcc/testsuite/gcc.target/i386/zero-scratch-regs-32.c
> new file mode 100644
> index 00000000000..ca3261fe5ea
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/zero-scratch-regs-32.c
> @@ -0,0 +1,11 @@
> +/* { dg-do compile { target *-*-linux* } } */
> +/* { dg-options "-O2 -fzero-call-used-regs=all -mno-80387" } */
> +
> +int
> +foo (int x)
> +{
> + return (x + 1);
> +}
> +
> +/* { dg-final { scan-assembler-not "fldz" } } */
> +
> --
> 2.11.0
>
