[gcc(refs/vendors/redhat/heads/gcc-8-branch)] arm: Fix up neon_vector_mem_operand [PR97528]

[Jakub Jelinek <jakub@gcc.gnu.org>]

https://gcc.gnu.org/g:315d26684c204dc355f0e450908c81dee12f632d

commit 315d26684c204dc355f0e450908c81dee12f632d
Author: Jakub Jelinek <jakub@redhat.com>
Date:   Fri Nov 20 12:26:58 2020 +0100

    arm: Fix up neon_vector_mem_operand [PR97528]
    
    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.
    
    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.
    
    (cherry picked from commit 410b8f6f41920dad200cd709f9f3de8b840a995c)

Diff:
---
 gcc/config/arm/arm.c                   |  4 +++-
 gcc/testsuite/gcc.target/arm/pr97528.c | 28 ++++++++++++++++++++++++++++
 2 files changed, 31 insertions(+), 1 deletion(-)

diff --git a/gcc/config/arm/arm.c b/gcc/config/arm/arm.c
index eefe3d99548..55e54c9c319 100644
--- a/gcc/config/arm/arm.c
+++ b/gcc/config/arm/arm.c
@@ -12619,7 +12619,9 @@ neon_vector_mem_operand (rtx op, int type, bool strict)
   /* 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:
diff --git a/gcc/testsuite/gcc.target/arm/pr97528.c b/gcc/testsuite/gcc.target/arm/pr97528.c
new file mode 100644
index 00000000000..6cc59f2158c
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/pr97528.c
@@ -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;
+    }
+}