[PATCH] arm: Fix REVERSIBLE_CC_MODE [PR110796...]

[Christophe Lyon]

Since we have vcmp and vcmpe instructions (vcmpe raises an "Invalid
Operation" exception in presence of a NaN operand), we need to tell
the compiler it is not safe to reverse comparisons of floating-point
arguments.

On armv8-m.main+dsp+fp (cortex-m33):
PASS: gcc.dg/torture/builtin-iseqsig-1.c
at -O1, -O2, -O3, -Os

On armv8.1-m.main+mve.fp+fp.dp (cortex-m55):
PASS: gcc.dg/torture/builtin-iseqsig-1.c
PASS: gcc.dg/torture/builtin-iseqsig-2.c
PASS: gcc.dg/torture/builtin-iseqsig-3.c
at -O1, -O2, -O3, -Os

On armv7e-m+fp.dp (cortex-m7):
PASS: gcc.dg/torture/builtin-iseqsig-1.c
PASS: gcc.dg/torture/builtin-iseqsig-2.c
PASS: gcc.dg/torture/builtin-iseqsig-3.c
PASS: gcc.dg/torture/pr82692.c
at -O1, -O2, -O3, -Os

On armv8-a+simd:
PASS: gcc.dg/torture/builtin-iseqsig-1.c
PASS: gcc.dg/torture/builtin-iseqsig-2.c
PASS: gcc.dg/torture/builtin-iseqsig-3.c
PASS: gfortran.dg/ieee/comparisons_3.F90
at -Os (they already passed at other optimization levels)

	gcc/
	PR target/110796
	PR target/118446
	* config/arm/arm.h (REVERSIBLE_CC_MODE): Take floating-point modes
	into account.
---
 gcc/config/arm/arm.h | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/gcc/config/arm/arm.h b/gcc/config/arm/arm.h
index 8472b756127..3c9c7c795cb 100644
--- a/gcc/config/arm/arm.h
+++ b/gcc/config/arm/arm.h
@@ -2257,7 +2257,10 @@ extern int making_const_table;
 
 #define SELECT_CC_MODE(OP, X, Y)  arm_select_cc_mode (OP, X, Y)
 
-#define REVERSIBLE_CC_MODE(MODE) 1
+/* Having an integer comparison mode guarantees that we can use
+   reverse_condition, but the usual restrictions apply to floating-point
+   comparisons.  */
+#define REVERSIBLE_CC_MODE(MODE) ((MODE) != CCFPmode && (MODE) != CCFPEmode)
 
 #define REVERSE_CONDITION(CODE,MODE) \
   (((MODE) == CCFPmode || (MODE) == CCFPEmode) \
-- 
2.34.1