On Mon, 13 Oct 2025 at 21:00, Matt Parks <[email protected]> wrote:
>
> This patch fixes PR117366:
> arm thumb1 epilogue size optimizer violates -ffixed-r4.
>
> gcc/ChangeLog:
> PR target/117366
> * arm.cc (thumb1_extra_regs_pushed): Take fixed regs into account.
>
Thanks for the update.
I think Richard has some worries / comments?
Christophe
Christophe
> ---
> gcc/config/arm/arm.cc | 5 +++--
> gcc/testsuite/gcc.target/arm/pr117366.c | 14 ++++++++++++++
> 2 files changed, 17 insertions(+), 2 deletions(-)
> create mode 100644 gcc/testsuite/gcc.target/arm/pr117366.c
>
> diff --git a/gcc/config/arm/arm.cc b/gcc/config/arm/arm.cc
> index bde06f3fa86..6c3000f0d25 100644
> --- a/gcc/config/arm/arm.cc
> +++ b/gcc/config/arm/arm.cc
> @@ -26746,8 +26746,9 @@ thumb1_extra_regs_pushed (arm_stack_offsets *offsets,
> bool for_prologue)
> live_regs_mask >>= reg_base;
> }
>
> - while (reg_base + n_free < 8 && !(live_regs_mask & 1)
> - && (for_prologue || call_used_or_fixed_reg_p (reg_base + n_free)))
> + while (reg_base + n_free <= LAST_LO_REGNUM && !(live_regs_mask & 1)
> + && (for_prologue || (call_used_or_fixed_reg_p (reg_base + n_free)
> + && !fixed_regs[reg_base + n_free])))
> {
> live_regs_mask >>= 1;
> n_free++;
> diff --git a/gcc/testsuite/gcc.target/arm/pr117366.c
> b/gcc/testsuite/gcc.target/arm/pr117366.c
> new file mode 100644
> index 00000000000..b23d114381b
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/arm/pr117366.c
> @@ -0,0 +1,14 @@
> +
> +/* { dg-do compile } */
> +/* { dg-options "-Os -ffixed-r4 -ffixed-r5 -ffixed-r6 -ffixed-r7" } */
> +/* { dg-require-effective-target arm_arch_v5t_thumb_ok } */
> +/* { dg-add-options arm_arch_v5t_thumb } */
> +void func(void *, void *, void *, int, int);
> +
> +int bad_func(void) {
> + int a, b, c;
> + func(&a, &b, &c, 1, 2);
> + return b;
> +}
> +
> +/* { dg-final { scan-assembler-not "pop.*r\[4567\]" } } */
> --
> 2.34.1
