Re: [PATCH] regcprop: Determine subreg offset depending on endianness [PR101260]

[Stefan Schulze Frielinghaus <stefansf@linux.ibm.com>]

[-- Attachment #1: Type: text/plain, Size: 1716 bytes --]

On Mon, Oct 11, 2021 at 09:38:36AM +0200, Richard Biener wrote:
> On Fri, Oct 8, 2021 at 1:31 PM Stefan Schulze Frielinghaus via
> Gcc-patches <gcc-patches@gcc.gnu.org> wrote:
> >
> > gcc/ChangeLog:
> >
> >         * regcprop.c (maybe_mode_change): Determine offset relative to
> >         high or low part depending on endianness.
> >
> > Bootstrapped and regtested on IBM Z. Ok for mainline and gcc-{11,10,9}?
> 
> Is there a testcase to add?

I've updated the patch and added the testcase from the PR.

> 
> > ---
> >  gcc/regcprop.c | 11 ++++++++---
> >  1 file changed, 8 insertions(+), 3 deletions(-)
> >
> > diff --git a/gcc/regcprop.c b/gcc/regcprop.c
> > index d2a01130fe1..0e1ac12458a 100644
> > --- a/gcc/regcprop.c
> > +++ b/gcc/regcprop.c
> > @@ -414,9 +414,14 @@ maybe_mode_change (machine_mode orig_mode, machine_mode copy_mode,
> >                             copy_nregs, &bytes_per_reg))
> >         return NULL_RTX;
> >        poly_uint64 copy_offset = bytes_per_reg * (copy_nregs - use_nregs);
> > -      poly_uint64 offset
> > -       = subreg_size_lowpart_offset (GET_MODE_SIZE (new_mode) + copy_offset,
> > -                                     GET_MODE_SIZE (orig_mode));
> > +      poly_uint64 offset =
> > +#if WORDS_BIG_ENDIAN
> > +       subreg_size_highpart_offset
> > +#else
> > +       subreg_size_lowpart_offset
> > +#endif
> > +                                   (GET_MODE_SIZE (new_mode) + copy_offset,
> > +                                    GET_MODE_SIZE (orig_mode));
> >        regno += subreg_regno_offset (regno, orig_mode, offset, new_mode);
> >        if (targetm.hard_regno_mode_ok (regno, new_mode))
> >         return gen_raw_REG (new_mode, regno);
> > --
> > 2.31.1
> >

[-- Attachment #2: 0001-regcprop-Determine-subreg-offset-depending-on-endian.patch --]
[-- Type: text/plain, Size: 2556 bytes --]

From 299959788321e21c27f0d4a6d437a586c5f6c92e Mon Sep 17 00:00:00 2001
From: Stefan Schulze Frielinghaus <stefansf@linux.ibm.com>
Date: Mon, 4 Oct 2021 09:36:21 +0200
Subject: [PATCH] regcprop: Determine subreg offset depending on endianness
 [PR101260]

gcc/ChangeLog:

	* regcprop.c (maybe_mode_change): Determine offset relative to
	high or low part depending on endianness.

gcc/testsuite/ChangeLog:

	* gcc.dg/pr101260.c: New test.
---
 gcc/regcprop.c                  | 11 ++++++--
 gcc/testsuite/gcc.dg/pr101260.c | 49 +++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+), 3 deletions(-)
 create mode 100644 gcc/testsuite/gcc.dg/pr101260.c

diff --git a/gcc/regcprop.c b/gcc/regcprop.c
index d2a01130fe1..0e1ac12458a 100644
--- a/gcc/regcprop.c
+++ b/gcc/regcprop.c
@@ -414,9 +414,14 @@ maybe_mode_change (machine_mode orig_mode, machine_mode copy_mode,
 			    copy_nregs, &bytes_per_reg))
 	return NULL_RTX;
       poly_uint64 copy_offset = bytes_per_reg * (copy_nregs - use_nregs);
-      poly_uint64 offset
-	= subreg_size_lowpart_offset (GET_MODE_SIZE (new_mode) + copy_offset,
-				      GET_MODE_SIZE (orig_mode));
+      poly_uint64 offset =
+#if WORDS_BIG_ENDIAN
+	subreg_size_highpart_offset
+#else
+	subreg_size_lowpart_offset
+#endif
+				    (GET_MODE_SIZE (new_mode) + copy_offset,
+				     GET_MODE_SIZE (orig_mode));
       regno += subreg_regno_offset (regno, orig_mode, offset, new_mode);
       if (targetm.hard_regno_mode_ok (regno, new_mode))
 	return gen_raw_REG (new_mode, regno);
diff --git a/gcc/testsuite/gcc.dg/pr101260.c b/gcc/testsuite/gcc.dg/pr101260.c
new file mode 100644
index 00000000000..0e9ec4e203a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr101260.c
@@ -0,0 +1,49 @@
+/* PR rtl-optimization/101260 */
+/* { dg-do run } */
+/* { dg-options -O1 } */
+struct a {
+  unsigned b : 7;
+  int c;
+  int d;
+  short e;
+} p, *q = &p;
+int f, g, h, i, r, s;
+static short j[8][1][6] = {0};
+char k[7];
+short l, m;
+int *n;
+int **o = &n;
+void t() {
+  for (; f;)
+    ;
+}
+static struct a u(int x) {
+  struct a a = {4, 8, 5, 4};
+  for (; i <= 6; i++) {
+    struct a v = {0};
+    for (; l; l++)
+      h = 0;
+    for (; h >= 0; h--) {
+      struct a *w;
+      j[i];
+      w = &p;
+      s = 0;
+      for (; s < 3; s++) {
+        r ^= x;
+        m = j[i][g][h] == (k[g] = g);
+        *w = v;
+      }
+      r = 2;
+      for (; r; r--)
+        *o = &r;
+    }
+  }
+  t();
+  return a;
+}
+int main() {
+  *q = u(636);
+  if (p.b != 4)
+    __builtin_abort ();
+  return 0;
+}
-- 
2.31.1