https://gcc.gnu.org/g:1335fcb077113c83f9eb4b40b996be41bee80a74
commit 1335fcb077113c83f9eb4b40b996be41bee80a74
Author: Michael Meissner <meiss...@linux.ibm.com>
Date: Fri Jan 24 15:06:52 2025 -0500
Fix PR 118541, do not generate unordered fp cmoves.
2025-01-24 Michael Meissner <meiss...@linux.ibm.com>
gcc/
PR target/118541
* config/rs6000/rs6000-protos.h (REVERSE_COND_ORDERED_OK): New
macro.
(REVERSE_COND_NO_ORDERED): Likewise.
(rs6000_reverse_condition): Add argument.
* config/rs6000/rs6000.cc (rs6000_reverse_condition): Do not allow
ordered comparisons to be reversed for floating point cmoves.
(rs6000_emit_sCOND): Adjust rs6000_reverse_condition call.
* config/rs6000/rs6000.h (REVERSE_CONDITION): Likewise.
* config/rs6000/rs6000.md (reverse_branch_comparison): Name insn.
Adjust rs6000_reverse_condition call.
gcc/testsuite/
PR target/118541
* gcc.target/powerpc/pr118541.c: New test.
Diff:
---
gcc/config/rs6000/rs6000-protos.h | 6 ++++-
gcc/config/rs6000/rs6000.cc | 23 ++++++++++++----
gcc/config/rs6000/rs6000.h | 10 +++++--
gcc/config/rs6000/rs6000.md | 24 ++++++++++-------
gcc/testsuite/gcc.target/powerpc/pr118541.c | 42 +++++++++++++++++++++++++++++
5 files changed, 88 insertions(+), 17 deletions(-)
diff --git a/gcc/config/rs6000/rs6000-protos.h
b/gcc/config/rs6000/rs6000-protos.h
index 4619142d197b..112332660d3b 100644
--- a/gcc/config/rs6000/rs6000-protos.h
+++ b/gcc/config/rs6000/rs6000-protos.h
@@ -114,8 +114,12 @@ extern const char *rs6000_sibcall_template (rtx *,
unsigned int);
extern const char *rs6000_indirect_call_template (rtx *, unsigned int);
extern const char *rs6000_indirect_sibcall_template (rtx *, unsigned int);
extern const char *rs6000_pltseq_template (rtx *, int);
+
+#define REVERSE_COND_ORDERED_OK false
+#define REVERSE_COND_NO_ORDERED true
+
extern enum rtx_code rs6000_reverse_condition (machine_mode,
- enum rtx_code);
+ enum rtx_code, bool);
extern rtx rs6000_emit_eqne (machine_mode, rtx, rtx, rtx);
extern rtx rs6000_emit_fp_cror (rtx_code, machine_mode, rtx);
extern void rs6000_emit_sCOND (machine_mode, rtx[]);
diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
index f9f9a0b931db..eaf79435ec32 100644
--- a/gcc/config/rs6000/rs6000.cc
+++ b/gcc/config/rs6000/rs6000.cc
@@ -15360,15 +15360,25 @@ rs6000_print_patchable_function_entry (FILE *file,
}
enum rtx_code
-rs6000_reverse_condition (machine_mode mode, enum rtx_code code)
+rs6000_reverse_condition (machine_mode mode,
+ enum rtx_code code,
+ bool no_ordered)
{
/* Reversal of FP compares takes care -- an ordered compare
- becomes an unordered compare and vice versa. */
+ becomes an unordered compare and vice versa.
+
+ However, this is not safe for ordered comparisons (i.e. for isgreater,
+ etc.) starting with the power9 because ifcvt.cc will want to create a fp
+ cmove, and the x{s,v}cmp{eq,gt,ge}{dp,qp} instructions will trap if one of
+ the arguments is a signalling NaN. */
+
if (mode == CCFPmode
&& (!flag_finite_math_only
|| code == UNLT || code == UNLE || code == UNGT || code == UNGE
|| code == UNEQ || code == LTGT))
- return reverse_condition_maybe_unordered (code);
+ return (no_ordered
+ ? UNKNOWN
+ : reverse_condition_maybe_unordered (code));
else
return reverse_condition (code);
}
@@ -15980,11 +15990,14 @@ rs6000_emit_sCOND (machine_mode mode, rtx operands[])
rtx not_result = gen_reg_rtx (CCEQmode);
rtx not_op, rev_cond_rtx;
machine_mode cc_mode;
+ enum rtx_code rev;
cc_mode = GET_MODE (XEXP (condition_rtx, 0));
- rev_cond_rtx = gen_rtx_fmt_ee (rs6000_reverse_condition (cc_mode,
cond_code),
- SImode, XEXP (condition_rtx, 0),
const0_rtx);
+ rev = rs6000_reverse_condition (cc_mode, cond_code,
+ REVERSE_COND_ORDERED_OK);
+ rev_cond_rtx = gen_rtx_fmt_ee (rev, SImode, XEXP (condition_rtx, 0),
+ const0_rtx);
not_op = gen_rtx_COMPARE (CCEQmode, rev_cond_rtx, const0_rtx);
emit_insn (gen_rtx_SET (not_result, not_op));
condition_rtx = gen_rtx_EQ (VOIDmode, not_result, const0_rtx);
diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
index ec08c96d0f67..c595d7138bcd 100644
--- a/gcc/config/rs6000/rs6000.h
+++ b/gcc/config/rs6000/rs6000.h
@@ -1812,11 +1812,17 @@ extern scalar_int_mode rs6000_pmode;
/* Can the condition code MODE be safely reversed? This is safe in
all cases on this port, because at present it doesn't use the
- trapping FP comparisons (fcmpo). */
+ trapping FP comparisons (fcmpo).
+
+ However, this is not safe for ordered comparisons (i.e. for isgreater, etc.)
+ starting with the power9 because ifcvt.cc will want to create a fp cmove,
+ and the x{s,v}cmp{eq,gt,ge}{dp,qp} instructions will trap if one of the
+ arguments is a signalling NaN. */
#define REVERSIBLE_CC_MODE(MODE) 1
/* Given a condition code and a mode, return the inverse condition. */
-#define REVERSE_CONDITION(CODE, MODE) rs6000_reverse_condition (MODE, CODE)
+#define REVERSE_CONDITION(CODE, MODE) \
+ rs6000_reverse_condition (MODE, CODE, REVERSE_COND_NO_ORDERED)
/* Target cpu costs. */
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 65da0c653304..5f7ff36617da 100644
--- a/gcc/config/rs6000/rs6000.md
+++ b/gcc/config/rs6000/rs6000.md
@@ -13497,7 +13497,7 @@
;; If we are comparing the result of two comparisons, this can be done
;; using creqv or crxor.
-(define_insn_and_split ""
+(define_insn_and_split "*reverse_branch_comparison"
[(set (match_operand:CCEQ 0 "cc_reg_operand" "=y")
(compare:CCEQ (match_operator 1 "branch_comparison_operator"
[(match_operand 2 "cc_reg_operand" "y")
@@ -13519,19 +13519,25 @@
GET_MODE (operands[3]));
if (! positive_1)
- operands[1] = gen_rtx_fmt_ee (rs6000_reverse_condition (GET_MODE
(operands[2]),
- GET_CODE
(operands[1])),
- SImode,
- operands[2], const0_rtx);
+ {
+ enum rtx_code rev = rs6000_reverse_condition (GET_MODE (operands[2]),
+ GET_CODE (operands[1]),
+ REVERSE_COND_ORDERED_OK);
+ gcc_assert (rev != UNKNOWN);
+ operands[1] = gen_rtx_fmt_ee (rev, SImode, operands[2], const0_rtx);
+ }
else if (GET_MODE (operands[1]) != SImode)
operands[1] = gen_rtx_fmt_ee (GET_CODE (operands[1]), SImode,
operands[2], const0_rtx);
if (! positive_2)
- operands[3] = gen_rtx_fmt_ee (rs6000_reverse_condition (GET_MODE
(operands[4]),
- GET_CODE
(operands[3])),
- SImode,
- operands[4], const0_rtx);
+ {
+ enum rtx_code rev = rs6000_reverse_condition (GET_MODE (operands[4]),
+ GET_CODE (operands[3]),
+ REVERSE_COND_ORDERED_OK);
+ gcc_assert (rev != UNKNOWN);
+ operands[3] = gen_rtx_fmt_ee (rev, SImode, operands[4], const0_rtx);
+ }
else if (GET_MODE (operands[3]) != SImode)
operands[3] = gen_rtx_fmt_ee (GET_CODE (operands[3]), SImode,
operands[4], const0_rtx);
diff --git a/gcc/testsuite/gcc.target/powerpc/pr118541.c
b/gcc/testsuite/gcc.target/powerpc/pr118541.c
new file mode 100644
index 000000000000..a89224020fdb
--- /dev/null
+++ b/gcc/testsuite/gcc.target/powerpc/pr118541.c
@@ -0,0 +1,42 @@
+/* { dg-do compile } */
+/* { dg-options "-mdejagnu-cpu=power9 -O2" } */
+
+/* PR target/118541 says that the ordered comparison functions like isgreater
+ should not optimize floating point conditional moves to use
+ x{s,v}cmp{eq,gt,ge}{dp,qp} and xxsel since that instruction can cause traps
+ if one of the arguments is a signaling NaN. */
+
+/* Verify isgreater does not generate xscmpgtdp. */
+
+double
+ordered_compare (double a, double b, double c, double d)
+{
+ /*
+ * fcmpu 0,1,2
+ * fmr 1,4
+ * bnglr 0
+ * fmr 1,3
+ * blr
+ */
+
+ return __builtin_isgreater (a, b) ? c : d;
+}
+
+/* Verify normal > does generate xscmpgtdp. */
+
+double
+normal_compare (double a, double b, double c, double d)
+{
+ /*
+ * xscmpgtdp 1,1,2
+ * xxsel 1,4,3,1
+ * blr
+ */
+
+ return a > b ? c : d;
+}
+
+/* { dg-final { scan-assembler-times {\mxscmpg[te]dp\M} } 1 } */
+/* { dg-final { scan-assembler-times {\mxxsel} } 1 } */
+/* { dg-final { scan-assembler-times {\mxscmpudp\|fcmpu\M} 1 } */
+
