Minor loop-iv tweaks for doloops

[Bernd Schmidt <bernds_cb1 at t-online dot de>]

This allows us to generate slightly more hardware loops on the Blackfin.
 When walking through arrays on the stack, we often generate comparisons
based on the stack or frame pointer; we should treat these as invariant
everywhere.  Some earlier patches already went in that direction, this
one just converts a few more places.

Bootstrapped and regression tested on i686-linux.  Ok?

I'm also attaching a patch with three Blackfin-specific testcases which
verify that we're generating hardware loops as expected.


Bernd
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	* loop-iv.c (iv_analyze_op): Use function_invariant_p, not CONSTANT_P,
	to test for GRD_INVARIANT.
	(simple_rhs_p): Anything that's function_invariant_p is fine.

Index: loop-iv.c
===================================================================
--- loop-iv.c	(revision 152180)
+++ loop-iv.c	(working copy)
@@ -1120,7 +1120,7 @@ iv_analyze_op (rtx insn, rtx op, struct 
       print_rtl_single (dump_file, insn);
     }
 
-  if (CONSTANT_P (op))
+  if (function_invariant_p (op))
     res = GRD_INVARIANT;
   else if (GET_CODE (op) == SUBREG)
     {
@@ -1329,7 +1329,7 @@ simple_rhs_p (rtx rhs)
 {
   rtx op0, op1;
 
-  if (CONSTANT_P (rhs)
+  if (function_invariant_p (rhs)
       || (REG_P (rhs) && !HARD_REGISTER_P (rhs)))
     return true;
 

Index: testsuite/gcc.target/bfin/lsetup-1.c
===================================================================
--- testsuite/gcc.target/bfin/lsetup-1.c	(revision 0)
+++ testsuite/gcc.target/bfin/lsetup-1.c	(revision 0)
@@ -0,0 +1,45 @@
+/* { dg-do compile { target bfin-*-* } } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-times "LSETUP" 6 } } */
+
+#define SIZE 1024
+
+int foo (int (*x)[SIZE])
+{
+    int i, sum = 0;
+
+    for  (i = 0; i < SIZE; i++) {
+	int j;
+	for (j = 0; j < SIZE; j++)
+		sum += x[i][j];	
+    }
+
+    return sum;
+}
+
+int bar (int **x)
+{
+    int i, sum = 0;
+
+    for  (i = 0; i < SIZE; i++) {
+	int j;
+	for (j = 0; j < SIZE; j++)
+		sum += x[i][j];	
+    }
+
+    return sum;
+}
+
+int baz ()
+{
+    int i, sum = 0;
+    int x[SIZE][SIZE];
+    fill(x);
+    for  (i = 0; i < SIZE; i++) {
+	int j;
+	for (j = 0; j < SIZE; j++)
+		sum += x[i][j];	
+    }
+
+    return sum;
+}
Index: testsuite/gcc.target/bfin/lsetup-2.c
===================================================================
--- testsuite/gcc.target/bfin/lsetup-2.c	(revision 0)
+++ testsuite/gcc.target/bfin/lsetup-2.c	(revision 0)
@@ -0,0 +1,33 @@
+/* { dg-do compile { target bfin-*-* } } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler-times "LSETUP" 2 } } */
+
+#include <stdlib.h>
+#include <stdio.h>
+
+#define SIZE 1024
+
+void foo ()
+{
+    int index, sum = 0, *x;
+
+    x = malloc (SIZE);
+
+    for  (index = 0; index < SIZE ; index++) {
+	sum += x[index];
+    }
+
+    printf("%i",sum);
+}
+
+void bar ()
+{
+    int index, sum = 0, x[SIZE];
+
+    for  (index = 0; index < SIZE ; index++) {
+	sum += x[index];
+    }
+
+    printf("%i",sum);
+}
+
Index: testsuite/gcc.target/bfin/lsetup-3.c
===================================================================
--- testsuite/gcc.target/bfin/lsetup-3.c	(revision 0)
+++ testsuite/gcc.target/bfin/lsetup-3.c	(revision 0)
@@ -0,0 +1,13 @@
+/* { dg-do compile { target bfin-*-* } } */
+/* { dg-options "-O2" } */
+/* { dg-final { scan-assembler "LSETUP" } } */
+
+void test(unsigned int start, unsigned int end)
+{
+  unsigned int count;
+  start = start & -32;
+  end = end & -32;
+  for (count = (end - start); count; count -= 32)
+    __asm__ __volatile__("FLUSH[%0++];" :
+			 "+p"(start));
+}