[PATCH] arm: Fix up neon_vector_mem_operand [PR97528]

[Kyrylo Tkachov]

> -----Original Message-----
> From: Andre Vieira (lists) <andre.simoesdiasvieira@arm.com>
> Sent: 02 February 2021 17:27
> To: gcc-patches@gcc.gnu.org
> Cc: Kyrylo Tkachov <Kyrylo.Tkachov@arm.com>; jakub@redhat.com
> Subject: Re: [PATCH] arm: Fix up neon_vector_mem_operand [PR97528]
> 
> Hi,
> 
> This is a gcc-9 backport of the PR97528 fix that has been applied to
> trunk and gcc-10.
> Bootstraped on arm-linux-gnueabihf and regression tested.
> 
> OK for gcc-9 branch?

Ok.
Thanks,
Kyrill

> 
> 2021-02-02  Andre Vieira  <andre.simoesdiasvieira@arm.com>
> 
>      Backport from mainline
>      2020-11-20  Jakub Jelinek  <jakub@redhat.com>
> 
>      PR target/97528
>      * config/arm/arm.c (neon_vector_mem_operand): For POST_MODIFY,
> require
>      first POST_MODIFY operand is a REG and is equal to the first operand
>      of PLUS.
> 
>      * gcc.target/arm/pr97528.c: New test.
> 
> On 20/11/2020 11:25, Kyrylo Tkachov via Gcc-patches wrote:
> >
> >> -----Original Message-----
> >> From: Jakub Jelinek <jakub@redhat.com>
> >> Sent: 19 November 2020 18:57
> >> To: Richard Earnshaw <Richard.Earnshaw@arm.com>; Ramana
> >> Radhakrishnan <Ramana.Radhakrishnan@arm.com>; Kyrylo Tkachov
> >> <Kyrylo.Tkachov@arm.com>
> >> Cc: gcc-patches@gcc.gnu.org
> >> Subject: [PATCH] arm: Fix up neon_vector_mem_operand [PR97528]
> >>
> >> Hi!
> >>
> >> The documentation for POST_MODIFY says:
> >>     Currently, the compiler can only handle second operands of the
> >>     form (plus (reg) (reg)) and (plus (reg) (const_int)), where
> >>     the first operand of the PLUS has to be the same register as
> >>     the first operand of the *_MODIFY.
> >> The following testcase ICEs, because combine just attempts to simplify
> >> things and ends up with
> >> (post_modify (reg1) (plus (mult (reg2) (const_int 4)) (reg1))
> >> but the target predicates accept it, because they only verify
> >> that POST_MODIFY's second operand is PLUS and the second operand
> >> of the PLUS is a REG.
> >>
> >> The following patch fixes this by performing further verification that
> >> the POST_MODIFY is in the form it should be.
> >>
> >> Bootstrapped/regtested on armv7hl-linux-gnueabi, ok for trunk
> >> and release branches after a while?
> > Ok.
> > Thanks,
> > Kyrill
> >
> >> 2020-11-19  Jakub Jelinek  <jakub@redhat.com>
> >>
> >> 	PR target/97528
> >> 	* config/arm/arm.c (neon_vector_mem_operand): For
> >> POST_MODIFY, require
> >> 	first POST_MODIFY operand is a REG and is equal to the first operand
> >> 	of PLUS.
> >>
> >> 	* gcc.target/arm/pr97528.c: New test.
> >>
> >> --- gcc/config/arm/arm.c.jj	2020-11-13 19:00:46.729620560 +0100
> >> +++ gcc/config/arm/arm.c	2020-11-18 17:05:44.656867343 +0100
> >> @@ -13429,7 +13429,9 @@ neon_vector_mem_operand (rtx op, int typ
> >>     /* Allow post-increment by register for VLDn */
> >>     if (type == 2 && GET_CODE (ind) == POST_MODIFY
> >>         && GET_CODE (XEXP (ind, 1)) == PLUS
> >> -      && REG_P (XEXP (XEXP (ind, 1), 1)))
> >> +      && REG_P (XEXP (XEXP (ind, 1), 1))
> >> +      && REG_P (XEXP (ind, 0))
> >> +      && rtx_equal_p (XEXP (ind, 0), XEXP (XEXP (ind, 1), 0)))
> >>        return true;
> >>
> >>     /* Match:
> >> --- gcc/testsuite/gcc.target/arm/pr97528.c.jj	2020-11-18
> >> 17:09:58.195053288 +0100
> >> +++ gcc/testsuite/gcc.target/arm/pr97528.c	2020-11-18
> >> 17:09:47.839168237 +0100
> >> @@ -0,0 +1,28 @@
> >> +/* PR target/97528 */
> >> +/* { dg-do compile } */
> >> +/* { dg-require-effective-target arm_neon_ok } */
> >> +/* { dg-options "-O1" }  */
> >> +/* { dg-add-options arm_neon } */
> >> +
> >> +#include <arm_neon.h>
> >> +
> >> +typedef __simd64_int16_t T;
> >> +typedef __simd64_uint16_t U;
> >> +unsigned short c;
> >> +int d;
> >> +U e;
> >> +
> >> +void
> >> +foo (void)
> >> +{
> >> +  unsigned short *dst = &c;
> >> +  int g = d, b = 4;
> >> +  U dc = e;
> >> +  for (int h = 0; h < b; h++)
> >> +    {
> >> +      unsigned short *i = dst;
> >> +      U j = dc;
> >> +      vst1_s16 ((int16_t *) i, (T) j);
> >> +      dst += g;
> >> +    }
> >> +}
> >>
> >>
> >> 	Jakub