https://gcc.gnu.org/g:bba9b39a793faf48f2e6cf04289b1e48190b127f
commit bba9b39a793faf48f2e6cf04289b1e48190b127f
Author: Michael Meissner <meiss...@linux.ibm.com>
Date: Fri Jan 24 10:50:35 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 (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): Likewise.
Diff:
---
gcc/config/rs6000/rs6000-protos.h | 2 +-
gcc/config/rs6000/rs6000.cc | 19 +++++++++++++++----
gcc/config/rs6000/rs6000.h | 10 ++++++++--
gcc/config/rs6000/rs6000.md | 24 +++++++++++++++---------
4 files changed, 39 insertions(+), 16 deletions(-)
diff --git a/gcc/config/rs6000/rs6000-protos.h
b/gcc/config/rs6000/rs6000-protos.h
index 4619142d197b..8f790d261d9a 100644
--- a/gcc/config/rs6000/rs6000-protos.h
+++ b/gcc/config/rs6000/rs6000-protos.h
@@ -115,7 +115,7 @@ 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);
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..276e2f886acc 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);
}
@@ -15983,7 +15993,8 @@ rs6000_emit_sCOND (machine_mode mode, rtx operands[])
cc_mode = GET_MODE (XEXP (condition_rtx, 0));
- rev_cond_rtx = gen_rtx_fmt_ee (rs6000_reverse_condition (cc_mode,
cond_code),
+ rev_cond_rtx = gen_rtx_fmt_ee (rs6000_reverse_condition (cc_mode,
cond_code,
+ false),
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));
diff --git a/gcc/config/rs6000/rs6000.h b/gcc/config/rs6000/rs6000.h
index ec08c96d0f67..98228ee5ac16 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, true)
/* Target cpu costs. */
diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
index 65da0c653304..cf4b10257903 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]),
+ false);
+ 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]),
+ false);
+ 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);
