Committed: fix for PR38016 -fno-ivopts exposes CRIS port bug

[Hans-Peter Nilsson <hans-peter.nilsson@axis.com>]

Not so much a new bug as the fix for PR25947 being incomplete.
This was exposed by local patch, that I consider committing here
too for OPTIMIZATION_OPTIONS (but properly commenting the cause
for each, to enable simple re-testing and removal):

Index: cris.h
===================================================================
--- cris.h	(revision 22658)
+++ cris.h	(working copy)
@@ -335,6 +335,9 @@ extern int target_flags;
     {						\
       if ((OPTIMIZE) >= 2 || (SIZE))		\
 	flag_omit_frame_pointer = 1;		\
+      flag_gcse = 0;				\
+      flag_ivopts = 0;				\
+      flag_tree_reassoc = 0;			\
     }						\
   while (0)
 

My benchmarks say those passes don't do any good on average for
CRIS.  I'd be interesting to hear what -fno-tree-reassoc does
for peoples benchmarks as it seems what good it does is negated
by far by the higher register pressure for all architectures,
see PR37916.

I understand this testsuite change is preferred to adding a
special reduced version of fp-cmp-8 (whether in the generic
parts or gcc.target/cris) or extending TORTURE_OPTIONS with
-fno-ivopts (and/or -fno-gcse).  Only the former option is
needed to expose the bug, but the latter makes the test fail for
more iterations.  (Actually, -fno-gcse exposes a bug too,
PR38026.)  Yes, gcc.c-torture/execute/ieee still needs .x files,
it doesn't understand dg- annotations.

Tested cross to cris-axis-elf on trunk and 4.3 branch, committed
to both.

gcc:
	PR target/38016
	* config/cris/cris.c (cris_order_for_addsi3): Test for !REG_P, not
	just MEM_P.

gcc/testsuite:
	PR target/38016
	* gcc.c-torture/execute/ieee/pr38016.c,
	gcc.c-torture/execute/ieee/pr38016.c: New test.

Index: gcc.c-torture/execute/ieee/pr38016.c
===================================================================
--- gcc.c-torture/execute/ieee/pr38016.c	(revision 0)
+++ gcc.c-torture/execute/ieee/pr38016.c	(revision 0)
@@ -0,0 +1 @@
+#include "fp-cmp-8.c"
Index: gcc.c-torture/execute/ieee/pr38016.x
===================================================================
--- gcc.c-torture/execute/ieee/pr38016.x	(revision 0)
+++ gcc.c-torture/execute/ieee/pr38016.x	(revision 0)
@@ -0,0 +1,2 @@
+lappend additional_flags "-fno-ivopts" "-fno-gcse"
+return 0
Index: config/cris/cris.c
===================================================================
--- config/cris/cris.c	(revision 141613)
+++ config/cris/cris.c	(working copy)
@@ -3565,14 +3565,15 @@ cris_expand_pic_call_address (rtx *opp)
 }
 
 /* Make sure operands are in the right order for an addsi3 insn as
-   generated by a define_split.  A MEM as the first operand isn't
-   recognized by addsi3 after reload.  OPERANDS contains the operands,
-   with the first at OPERANDS[N] and the second at OPERANDS[N+1].  */
+   generated by a define_split.  Nothing but REG_P as the first
+   operand is recognized by addsi3 after reload.  OPERANDS contains
+   the operands, with the first at OPERANDS[N] and the second at
+   OPERANDS[N+1].  */
 
 void
 cris_order_for_addsi3 (rtx *operands, int n)
 {
-  if (MEM_P (operands[n]))
+  if (!REG_P (operands[n]))
     {
       rtx tem = operands[n];
       operands[n] = operands[n + 1];

brgds, H-P