Re: [MIPS] Implement static stack checking

[Eric Botcazou <ebotcazou at adacore dot com>]

> This function doesn't work with MIPS16 mode.  Maybe just:
> 
>   if (TARGET_MIPS16)
>     sorry ("MIPS16 stack probes");
> 
> (We can't test TARGET_MIPS16 in something like STACK_CHECK_STATIC_BUILTIN
> because MIPS16ness is a per-function property.)

I put

  if (TARGET_MIPS16)
    sorry ("-fstack-check=specific not implemented for MIPS16");

> Please use MIPS_PROLOGUE_TEMP for r3 (and probably rename r3).
> I suppose GP_REG_FIRST + 12 should be MIPS_PROLOGUE_TEMP2, probably as:
> 
> #define MIPS_PROLOGUE_TEMP2_REGNUM \
>   (TARGET_MIPS16 ? gcc_unreachable () \
>    cfun->machine->interrupt_handler_p ? K1_REG_NUM : GP_REG_FIRST + 12)
> 
> #define MIPS_PROLOGUE_TEMP2(MODE) \
>   gen_rtx_REG (MODE, MIPS_PROLOGUE_TEMP2_REGNUM)
> 
> and update the block comment above the MIPS_PROLOGUE_TEMP_REGNUM definition.

Done.

> I Might Be Wrong, but it looks like this won't probe at FIRST + SIZE
> in the case where SIZE == ROUNDED_SIZE, because the loop exits on that
> value without probing it.  Should the last line be unconditional,
> or does the loop need to be a do-while instead?  (I suppose the latter,
> so that there isn't a hole bigger than PROBE_INTERVAL in the
> SIZE != ROUNDED_SIZE case?)

The loop probes at FIRST + N * PROBE_INTERVAL for values of N from 1 until it 
is equal to ROUNDED_SIZE, inclusive, so FIRST + SIZE is always probed.

> This only works in noreorder mode.  If there's an asm in the function,
> or something else that forces reorder mode (e.g. a -mfix-* option),
> the addition won't be put in the delay slot.
> 
> "%(%<beq\t%0,%1," and "daddiu\t%0,%0,%1%>%)" should work.  (Note that
> our MIPS asm output doesn't have a space before the delay slot; there's
> a blank line after it instead.  That's all handled by output_asm_insn
> though.)

Thanks for the incantation!

> OK with those changes, thanks.

I'll retest with the changes tomorrow.  Thanks for the review.

-- 
Eric Botcazou