[Bug target/64785] [5 Regression][SH] and|or|xor #imm not used

[olegendo at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=64785

Oleg Endo <olegendo at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2015-01-27
                 CC|                            |kkojima at gcc dot gnu.org
     Ever confirmed|0                           |1

--- Comment #1 from Oleg Endo <olegendo at gcc dot gnu.org> ---
It seems that hardregs in insn operands are kind of sticky.  Combine propagates
the function arg in r5 into the and insn and this doesn't get changed to r0.

Disallowing combine to do that seems to fix the problem, although I haven't
checked for any other side effects of that change.  Probably some code will get
worse for insns that really use hardregs (e.g. libfuncs).

Index: gcc/config/sh/sh.c
===================================================================
--- gcc/config/sh/sh.c    (revision 220144)
+++ gcc/config/sh/sh.c    (working copy)
@@ -2066,6 +2066,26 @@
       && MEM_P (XEXP (XEXP (p, 1), 0)))
       return false;

+  subrtx_iterator::array_type array;
+  FOR_EACH_SUBRTX (i, array, p, ALL)
+    {
+      if (*i == NULL)
+    continue;
+      int regno = -1;
+      for (const_rtx x = *i; regno == -1; )
+    {
+      if (REG_P (x))
+        regno = REGNO (x);
+      else if (SUBREG_P (x))
+        x = SUBREG_REG (x);
+      else
+        break;
+    }
+
+      if (regno != -1 && regno >= R0_REG && regno <= R0_REG + 15)
+    return false;
+    }
+
   return true;
 }


Another more radical approach could be to insert an RTL pass that pre-allocates
the R0 reg for those insns that have "z" constraint alternatives, similar to
what Kaz did with the mov.{b|w} patterns in prepare_move_operands for LRA.