Re: [PATCH] PR67305, tighten neon_vector_mem_operand on eliminable registers

[Ramana Radhakrishnan <ramana.radhakrishnan@foss.arm.com>]

On 04/11/15 09:45, Jiong Wang wrote:
> As discussed at the bugzilla
> 
>   https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67305
> 
> neon_vector_mem_operand is broken.  As the comments says
> "/* Reject eliminable registers.  */", the code block at the head
> of this function which checks eliminable registers is designed to do
> early reject only, there shouldn't be any early accept.
> 
> If this code hunk doesn't reject the incoming rtx, then the rtx pattern
> should still go through all default checks below. All other similar
> functions, thumb1_legitimate_address_p, arm_coproc_mem_operand,
> neon_struct_mem_operand etc are exactly follow this check flow.
> 
> So as Jim Wilson commented on the bugzilla, instead of "return !strict",
> we need to only do the check if strict be true, and only does rejection
> which means return FALSE, for all other cases, we need to go through
> those normal checks below.
> 
> neon_vector_mem_operand is only used by several misalign pattern, I
> guess that's why this bug is not exposed for long time.
> 
> boostrap & regression OK on armv8 aarch32, ok for trunk?
> 
> 2015-11-04  Jiong Wang  <jiong.wang@arm.com>
>             Jim Wilson  <wilson@gcc.gnu.org>
> 
> gcc/
>   PR target/67305
>   * config/arm/arm.md (neon_vector_mem_operand): Return FALSE if strict
>   be true and eliminable registers mentioned.
> 


This has been lurking for a long time ...  Sorry about the delay in reviewing. This is OK for trunk

regards
Ramana

> 
> neon-mem.patch
> 
> 
> diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
> index 87e55e9..7fbf897 100644
> --- a/gcc/config/arm/arm.c
> +++ b/gcc/config/arm/arm.c
> @@ -12957,14 +12957,14 @@ neon_vector_mem_operand (rtx op, int type, bool strict)
>    rtx ind;
>  
>    /* Reject eliminable registers.  */
> -  if (! (reload_in_progress || reload_completed)
> -      && (   reg_mentioned_p (frame_pointer_rtx, op)
> +  if (strict && ! (reload_in_progress || reload_completed)
> +      && (reg_mentioned_p (frame_pointer_rtx, op)
>  	  || reg_mentioned_p (arg_pointer_rtx, op)
>  	  || reg_mentioned_p (virtual_incoming_args_rtx, op)
>  	  || reg_mentioned_p (virtual_outgoing_args_rtx, op)
>  	  || reg_mentioned_p (virtual_stack_dynamic_rtx, op)
>  	  || reg_mentioned_p (virtual_stack_vars_rtx, op)))
> -    return !strict;
> +    return FALSE;
>  
>    /* Constants are converted into offsets from labels.  */
>    if (!MEM_P (op))
>