[patch committed] Defaulting to -fno-ira-share-spill-slots on SH

[Kaz Kojima <kkojima at rr dot iij4u dot or dot jp>]

Hi,

PR 37514 is a wrong-code problem on SH which is a 4.4 regression
started after the IRA merge.  IRA makes spill slots shared if
possible when flag_ira_share_spill_slots set.  In the above PR,
it causes a wrong sharing of slots on SH.  I've been trying to
see why this sharing occurs but it's a hard problem for me.
With -fno-ira-share-spill-slots, the problem goes away, though
it increases the code sizes of several tests in CSiBE by ~10%.
Although this code size regression isn't ignorable, I think
that the wrong code problem is far bigger than that.  I'd like
to work around this PR by defaulting to -fno-ira-share-spill-slots
on this target.  The attached patch is for this.  The patch also
adds a new target specific test to remember that the PR isn't fixed
yet.  It's tested with bootstrap and the top level "make -k check"
on sh4-unknown-linux-gnu.  The testsuite change is tested also
on i686-pc-linux-gnu.

Regards,
	kaz
--
[gcc/ChangeLog]
2008-11-10  Kaz Kojima  <kkojima@gcc.gnu.org>

	PR rtl-optimization/37514
	* config/sh/sh.h (OPTIMIZATION_OPTIONS): Set
	flag_ira_share_spill_slots to 2 if it's already non-zero.
	(OVERRIDE_OPTIONS): Clear flag_ira_share_spill_slots if
        flag_ira_share_spill_slots is 2.

[gcc/testsuite/ChangeLog]
2008-11-10  Kaz Kojima  <kkojima@gcc.gnu.org>

	* gcc.target/sh/pr37514.c: New test.

diff -uprN ORIG/trunk/gcc/config/sh/sh.h LOCAL/trunk/gcc/config/sh/sh.h
--- ORIG/trunk/gcc/config/sh/sh.h	2008-10-22 09:11:15.000000000 +0900
+++ LOCAL/trunk/gcc/config/sh/sh.h	2008-11-08 07:59:02.000000000 +0900
@@ -496,6 +496,9 @@ do {									\
      the user explicitly requested this to be on or off.  */		\
   if (flag_schedule_insns > 0)						\
     flag_schedule_insns = 2;						\
+  /* Likewise for flag_ira_share_spill_slots.  */			\
+  if (flag_ira_share_spill_slots > 0)					\
+    flag_ira_share_spill_slots = 2;					\
 									\
   set_param_value ("simultaneous-prefetches", 2);			\
 } while (0)
@@ -730,6 +733,12 @@ do {									\
 	}								\
     }									\
 									\
+  /* FIXME.  Currently -fira-share-spill-slots causes a wrong code	\
+     problem PR 37514, though the compiler generates lengthy codes	\
+     in some cases without it.  */					\
+  if (flag_ira_share_spill_slots == 2)					\
+    flag_ira_share_spill_slots = 0;					\
+									\
   if (align_loops == 0)							\
     align_loops =  1 << (TARGET_SH5 ? 3 : 2);				\
   if (align_jumps == 0)							\
diff -uprN ORIG/trunk/gcc/testsuite/gcc.target/sh/pr37514.c LOCAL/trunk/gcc/testsuite/gcc.target/sh/pr37514.c
--- ORIG/trunk/gcc/testsuite/gcc.target/sh/pr37514.c	1970-01-01 09:00:00.000000000 +0900
+++ LOCAL/trunk/gcc/testsuite/gcc.target/sh/pr37514.c	2008-11-08 08:02:27.000000000 +0900
@@ -0,0 +1,65 @@
+/* This is essentially gcc.c-torture/execute/20021120-1.c run with
+   -O3 -fomit-frame-pointer -fira-share-spill-slots.  */
+/* { dg-do run { target "sh*-*-*" } } */
+/* { dg-options "-O3 -fomit-frame-pointer -fira-share-spill-slots" } */
+
+/* Macros to emit "L Nxx R" for each octal number xx between 000 and 037.  */
+#define OP1(L, N, R, I, J) L N##I##J R
+#define OP2(L, N, R, I) \
+    OP1(L, N, R, 0, I), OP1(L, N, R, 1, I), \
+    OP1(L, N, R, 2, I), OP1(L, N, R, 3, I)
+#define OP(L, N, R) \
+    OP2(L, N, R, 0), OP2(L, N, R, 1), OP2(L, N, R, 2), OP2(L, N, R, 3), \
+    OP2(L, N, R, 4), OP2(L, N, R, 5), OP2(L, N, R, 6), OP2(L, N, R, 7)
+
+/* Declare 32 unique variables with prefix N.  */
+#define DECLARE(N) OP (, N,)
+
+/* Copy 32 variables with prefix N from the array at ADDR.
+   Leave ADDR pointing to the end of the array.  */
+#define COPYIN(N, ADDR) OP (, N, = *(ADDR++))
+
+/* Likewise, but copy the other way.  */
+#define COPYOUT(N, ADDR) OP (*(ADDR++) =, N,)
+
+/* Add the contents of the array at ADDR to 32 variables with prefix N.
+   Leave ADDR pointing to the end of the array.  */
+#define ADD(N, ADDR) OP (, N, += *(ADDR++))
+
+volatile double gd[32];
+volatile float gf[32];
+
+extern void abort (void);
+
+static void foo (int n)
+{
+  double DECLARE(d);
+  float DECLARE(f);
+  volatile double *pd;
+  volatile float *pf;
+  int i;
+
+  pd = gd; COPYIN (d, pd);
+  for (i = 0; i < n; i++)
+    {
+      pf = gf; COPYIN (f, pf);
+      pd = gd; ADD (d, pd);
+      pd = gd; ADD (d, pd);
+      pd = gd; ADD (d, pd);
+      pf = gf; COPYOUT (f, pf);
+    }
+  pd = gd; COPYOUT (d, pd);
+}
+
+int main ()
+{
+  int i;
+
+  for (i = 0; i < 32; i++)
+    gd[i] = i, gf[i] = i;
+  foo (1);
+  for (i = 0; i < 32; i++)
+    if (gd[i] != i * 4 || gf[i] != i)
+      abort ();
+  return 0;
+}