Fix PR tree-optimization/101626

[Eric Botcazou]

This is a regression present on the mainline, caused by an oversight of mine 
in an earlier fix for SRA, whereby I forgot to exclude cases for reverse SSO.

Tested on x86-64/Linux, applied on the mainline as obvious.


2021-08-05  Eric Botcazuo  <ebotca...@adacore.com>

        PR tree-optimization/101626
        * tree-sra.c (propagate_subaccesses_from_rhs): Do not set the
        reverse scalar storage order on a pointer or vector component.


2021-08-05  Eric Botcazuo  <ebotca...@adacore.com>

        * gcc.dg/sso-15.c: New test.

-- 
Eric Botcazou
diff --git a/gcc/tree-sra.c b/gcc/tree-sra.c
index c05d22f3e8f..3a9e14f50a0 100644
--- a/gcc/tree-sra.c
+++ b/gcc/tree-sra.c
@@ -2790,7 +2790,10 @@ propagate_subaccesses_from_rhs (struct access *lacc, struct access *racc)
 	{
 	  /* We are about to change the access type from aggregate to scalar,
 	     so we need to put the reverse flag onto the access, if any.  */
-	  const bool reverse = TYPE_REVERSE_STORAGE_ORDER (lacc->type);
+	  const bool reverse
+	    = TYPE_REVERSE_STORAGE_ORDER (lacc->type)
+	      && !POINTER_TYPE_P (racc->type)
+	      && !VECTOR_TYPE_P (racc->type);
 	  tree t = lacc->base;
 
 	  lacc->type = racc->type;

/* { dg-do compile } */
/* { dg-options "-O2" } */

#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
#define REV_ENDIANNESS __attribute__((scalar_storage_order("big-endian")))
#else
#define REV_ENDIANNESS __attribute__((scalar_storage_order("little-endian")))
#endif

struct X { int *p; } REV_ENDIANNESS;

struct X x;

struct X __attribute__((noinline)) foo (int *p)
{
  struct X x;
  x.p = p;
  return x;
}

void __attribute((noinline)) bar (void)
{
  *x.p = 1;
}

extern void abort (void);

int main (void)
{
  int i = 0;
  x = foo(&i);
  bar();
  if (i != 1)
    abort ();
  return 0;
}