arm: don't vectorize fmaxf() unless unsafe math opts are enabled

This test has presumably been failing since vectorization was enabled
at -O2.  I suspect part of the reason this wasn't picked up sooner is
that the test is a hybrid execution/scan-assembler test and the
execution part requires appropriate hardware.

The problem is that we are vectorizing an expansion of fmaxf() when
the vector version of the instruction does not preserve denormal
values.  This means we should only apply this optimization when
-funsafe-math-optimizations is enabled.

This fix does a few things:

- Moves the expand pattern to vec-common.md.  Although I haven't changed
its behaviour (beyond fixing the bug), this should really be enabled for
MVE as well (but that will need to wait for gcc-16 since the MVE code
needs some additional changes first).
- Adds support for HF mode vectors.
- splits the test that was exposing the bug into two parts: an executable
test and a scan-assembler test.  The scan-assembler version is more
widely enabled, since it does not require a suitable executable environment.

gcc/ChangeLog:

	* config/arm/neon.md (<fmaxmin><mode>3): Move pattern from here...
	* config/arm/vec-common.md (<fmaxmin><mode>3): ... to here.  Convert
	to define_expand and disable the pattern when denormal values might
	get truncated to zero.  Iterate on VF to add V4HF and V8HF variants.

gcc/testsuite/ChangeLog:

	* gcc.target/arm/fmaxmin.c: Move scan-assembler checks to ...
	* gcc.target/arm/fmaxmin-2.c: ... here.  New test.

diff --git a/gcc/config/arm/neon.md b/gcc/config/arm/neon.md
index ef3310605cabf49918c1e845b7975bcaec1e3b7d..8446dd7f964bc4964ce6858c5fc273424240e5a5 100644 (file)
--- a/gcc/config/arm/neon.md
+++ b/gcc/config/arm/neon.md
@@ -2738,17 +2738,6 @@
   [(set_attr "type" "neon_fp_minmax_s<q>")]
 )
 
-;; Vector forms for the IEEE-754 fmax()/fmin() functions
-(define_insn "<fmaxmin><mode>3"
-  [(set (match_operand:VCVTF 0 "s_register_operand" "=w")
-       (unspec:VCVTF [(match_operand:VCVTF 1 "s_register_operand" "w")
-                      (match_operand:VCVTF 2 "s_register_operand" "w")]
-                      VMAXMINFNM))]
-  "TARGET_NEON && TARGET_VFP5"
-  "<fmaxmin_op>.<V_s_elem>\t%<V_reg>0, %<V_reg>1, %<V_reg>2"
-  [(set_attr "type" "neon_fp_minmax_s<q>")]
-)
-
 (define_expand "neon_vpadd<mode>"
   [(match_operand:VD 0 "s_register_operand")
    (match_operand:VD 1 "s_register_operand")

diff --git a/gcc/config/arm/vec-common.md b/gcc/config/arm/vec-common.md
index 204205cb0b77d68097f71111a0e0d89e0b47f6be..a485d057f0f1fa9e4ecf392479b34df4080f962e 100644 (file)
--- a/gcc/config/arm/vec-common.md
+++ b/gcc/config/arm/vec-common.md
@@ -137,6 +137,17 @@
    "ARM_HAVE_<MODE>_ARITH"
 )
 
+;; Vector forms for the IEEE-754 fmax()/fmin() functions
+;; Fixme: Should be enabled for MVE as well, but currently that uses an
+;; incompatible expasion.
+(define_expand "<fmaxmin><mode>3"
+  [(set (match_operand:VF 0 "s_register_operand" "")
+       (unspec:VF [(match_operand:VF 1 "s_register_operand")
+                   (match_operand:VF 2 "s_register_operand")]
+                  VMAXMINFNM))]
+  "TARGET_NEON && TARGET_VFP5 && ARM_HAVE_<MODE>_ARITH"
+)
+
 (define_expand "vec_perm<mode>"
   [(match_operand:VE 0 "s_register_operand")
    (match_operand:VE 1 "s_register_operand")

diff --git a/gcc/testsuite/gcc.target/arm/fmaxmin-2.c b/gcc/testsuite/gcc.target/arm/fmaxmin-2.c
new file mode 100644 (file)
index 0000000..a9990e1
--- /dev/null
+++ b/gcc/testsuite/gcc.target/arm/fmaxmin-2.c
@@ -0,0 +1,12 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target arm_arch_v8a_hard_ok } */
+/* { dg-options "-O2 -fno-inline" } */
+/* { dg-add-options arm_arch_v8a_hard } */
+
+#include "fmaxmin.x"
+
+/* { dg-final { scan-assembler-times "vmaxnm.f32\ts\[0-9\]+, s\[0-9\]+, s\[0-9\]+" 1 } } */
+/* { dg-final { scan-assembler-times "vminnm.f32\ts\[0-9\]+, s\[0-9\]+, s\[0-9\]+" 1 } } */
+
+/* { dg-final { scan-assembler-times "vmaxnm.f64\td\[0-9\]+, d\[0-9\]+, d\[0-9\]+" 1 } } */
+/* { dg-final { scan-assembler-times "vminnm.f64\td\[0-9\]+, d\[0-9\]+, d\[0-9\]+" 1 } } */

diff --git a/gcc/testsuite/gcc.target/arm/fmaxmin.c b/gcc/testsuite/gcc.target/arm/fmaxmin.c
index 5a6fb804e3d0993b9ce9e204dcae5a873994c0c6..7f30c1237ab35f4181cf38599b06a81cf0a29295 100644 (file)
--- a/gcc/testsuite/gcc.target/arm/fmaxmin.c
+++ b/gcc/testsuite/gcc.target/arm/fmaxmin.c
@@ -1,13 +1,6 @@
 /* { dg-do run } */
 /* { dg-require-effective-target arm_v8_neon_hw } */
-/* { dg-options "-O2 -fno-inline -march=armv8-a -save-temps" } */
+/* { dg-options "-O2 -fno-inline" } */
 /* { dg-add-options arm_v8_neon } */
 
 #include "fmaxmin.x"
-
-/* { dg-final { scan-assembler-times "vmaxnm.f32\ts\[0-9\]+, s\[0-9\]+, s\[0-9\]+" 1 } } */
-/* { dg-final { scan-assembler-times "vminnm.f32\ts\[0-9\]+, s\[0-9\]+, s\[0-9\]+" 1 } } */
-
-/* { dg-final { scan-assembler-times "vmaxnm.f64\td\[0-9\]+, d\[0-9\]+, d\[0-9\]+" 1 } } */
-/* { dg-final { scan-assembler-times "vminnm.f64\td\[0-9\]+, d\[0-9\]+, d\[0-9\]+" 1 } } */
-