Today I committed a patch
https://gcc.gnu.org/ml/gcc-patches/2018-11/msg01945.html
But it makes gcc.target/powerpc/pr70669.c to fail. Here is the patch
to fix the failure. The expected code assumes that variable r should
get a general reg. I suspect the expectation is wrong. There are three
possible choices for r: a general reg, a vsx reg, and memory.
The cost of move of vsx to/from mem is 4, the cost of move of general
reg of this mode to/from mem is 8, and the cost of move of general reg
to/from vsx is 12.
So approximately if r is assigned memory we have cost 8 * 2 (asm) + 4
* 2 (plus) = 24 (when we use memory at *q), if r is assigned to vsx the
cost is 12*2(asm) + 4(r=*q) = 28, and if r is assigned a general reg the
cost is 12 * 2 (plus) + 8 (r = *q) = 32.
ira-costs should choose mem although it chose a general reg before my
patch (it is a big topic why it chose a general reg. In brief, it is
because some inherent drawbacks of the current cost calculation
algorithm). The patch I recently submitted solves some drawbacks and
memory is chosen for r.
To generate the expected code with r in a general reg, I just decrease
the number of getting r value into vsx reg by changing r + r onto -r.
Is the following patch ok for trunk?
Index: testsuite/ChangeLog
===================================================================
--- testsuite/ChangeLog (revision 266318)
+++ testsuite/ChangeLog (working copy)
@@ -1,3 +1,8 @@
+2018-11-22 Vladimir Makarov <vmaka...@redhat.com>
+
+ * gcc.target/powerpc/pr70669.c: Use unary minus instead of
+ addition.
+
2018-11-20 Jan Hubicka <hubi...@ucw.cz>
PR ipa/87706
Index: testsuite/gcc.target/powerpc/pr70669.c
===================================================================
--- testsuite/gcc.target/powerpc/pr70669.c (revision 266318)
+++ testsuite/gcc.target/powerpc/pr70669.c (working copy)
@@ -13,7 +13,7 @@ void foo (TYPE *p, TYPE *q)
#ifndef NO_ASM
__asm__ (" # %0" : "+r" (r));
#endif
- *p = r + r;
+ *p = -r;
}
/* { dg-final { scan-assembler "mfvsrd" } } */
