Splitters are not allowed to use data flow routines depending on
REG_DEAD notes since these are not recomputed by the split pass and
might therefore be outdated. The splitter we have for load and test
FP turns a potentially stale REG_DEAD note into a clobber of that
register. This then leads to wrong code being generated. This patch
just removes that splitter until I can come up with a better solution.
Regression tested on GCC 8 and mainline.
The 2 load and test FP testcases fail now due to that change:
load-and-test-fp-1.c and load-and-test-fp-2.c
I'll leave it that way to remind me to fix that.
Committed to mainline, GCC 8, and GCC 7.
Andreas
gcc/ChangeLog:
2019-02-05 Andreas Krebbel <kreb...@linux.ibm.com>
PR target/88856
* config/s390/s390.md: Remove load and test FP splitter.
---
gcc/config/s390/s390.md | 21 +++------------------
1 file changed, 3 insertions(+), 18 deletions(-)
diff --git a/gcc/config/s390/s390.md b/gcc/config/s390/s390.md
index 722d924..9033672 100644
--- a/gcc/config/s390/s390.md
+++ b/gcc/config/s390/s390.md
@@ -1357,10 +1357,11 @@
; (TF|DF|SF|TD|DD|SD) instructions
-; load and test instructions turn SNaN into QNaN what is not
+; FIXME: load and test instructions turn SNaN into QNaN what is not
; acceptable if the target will be used afterwards. On the other hand
; they are quite convenient for implementing comparisons with 0.0. So
-; try to enable them via splitter if the value isn't needed anymore.
+; try to enable them via splitter/peephole if the value isn't needed anymore.
+; See testcases: load-and-test-fp-1.c and load-and-test-fp-2.c
; ltxbr, ltdbr, ltebr, ltxtr, ltdtr
(define_insn "*cmp<mode>_ccs_0"
@@ -1373,22 +1374,6 @@
[(set_attr "op_type" "RRE")
(set_attr "type" "fsimp<mode>")])
-(define_split
- [(set (match_operand 0 "cc_reg_operand")
- (compare (match_operand:FP 1 "register_operand")
- (match_operand:FP 2 "const0_operand")))]
- "TARGET_HARD_FLOAT && REG_P (operands[1]) && dead_or_set_p (insn,
operands[1])"
- [(parallel
- [(set (match_dup 0) (match_dup 3))
- (clobber (match_dup 1))])]
- {
- /* s390_match_ccmode requires the compare to have the same CC mode
- as the CC destination register. */
- operands[3] = gen_rtx_COMPARE (GET_MODE (operands[0]),
- operands[1], operands[2]);
- })
-
-
; VX: TFmode in FPR pairs: use cxbr instead of wfcxb
; cxtr, cdtr, cxbr, cdbr, cebr, cdb, ceb, wfcsb, wfcdb
(define_insn "*cmp<mode>_ccs"
--
2.7.4
