On Fri, Nov 3, 2017 at 9:38 AM, Uros Bizjak <ubiz...@gmail.com> wrote: >> * config/i386/i386.c (ix86_emit_restore_reg_using_pop): Prototype. >> (ix86_adjust_stack_and_probe_stack_clash): Use a push/pop sequence >> to probe at the start of a noreturn function. >> >> * gcc.target/i386/stack-check-12.c: New test > > - emit_stack_probe (plus_constant (Pmode, stack_pointer_rtx, > - -GET_MODE_SIZE (word_mode))); > + rtx_insn *insn = emit_insn (gen_push (gen_rtx_REG (word_mode, 0))); > > Please use AX_REG instead of 0. > > + RTX_FRAME_RELATED_P (insn) = 1; > + ix86_emit_restore_reg_using_pop (gen_rtx_REG (word_mode, 0)); > > Also here. > > emit_insn (gen_blockage ()); > > BTW: Could we use an unused register here, if available? %eax is used > to pass first argument in regparm functions on 32bit targets.
Can you push %[er]sp? What about partial reg stalls when using other registers (if the last set was a movb to it)? I guess [er]sp is safe here as was [re]ax due to the ABI? Richard. > Uros.
