On 24/07/15 12:27, Kyrill Tkachov wrote:
On 24/07/15 12:10, Szabolcs Nagy wrote:
(-a)*b should not be compiled to vnmul a,b with -frounding-math.
Added a new -(a*b) pattern for vnmul and the old one is only
used if !flag_rounding_math. Updated the costs too.
This is the ARM version of
https://gcc.gnu.org/ml/gcc-patches/2015-07/msg00300.html
Tested with arm-none-linux-gnueabihf cross compiler.
is this OK?
gcc/Changelog:
2015-07-20 Szabolcs Nagy <szabolcs.nagy@arm.com>
PR target/66731
* config/arm/arm.md (muldf3negdf_vfp): Handle -frounding-math.
(mulsf3negsf_vfp): Likewise.
This entry is misleading. You disable two existing patterns
for flag_rounding_math and you add two new patterns. The
entry should reflect that.
..
Can you give the new pattern a different name to reflect that
the neg is on the outside? Something like *negmulsf3_vfp.
..
+/* { dg-options "-O2 -mfpu=vfp -mfloat-abi=hard" } */
Can you please add an explicit -fno-rounding-math here? That way we get a hint as to
why these tests exist. Alternatively, you can rename the tests to be pr66731_1.c,
pr66731_2.c etc. That way in the future we'll know what issue they're testing for.
..
+float
+foo_s (float a, float b)
+{
+ /* { dg-final { scan-assembler "vneg\.f32" } } */
+ /* { dg-final { scan-assembler "vmul\.f32" } } */
+ return -a * b;
+}
I'd prefer if you just do a scan-assembler not "vnmul", which is what this
patch really fixes. Whether the midend decides to use a pair of vneg+vmul
is tangential to this patch, it's the vnmul that we're trying to avoid.
[v2]:
- used different names for the new patterns
- fixed change log accordingly
- used explicit -fno-rounding-math in tests
- used scan-assembler-not "vnmul"
(I havent changed the names of the tests to be
consistent with the aarch64 patches but if ppl
prefer pr<N>.c name I can do that.)
gcc/Changelog:
2015-07-28 Szabolcs Nagy <szabolcs.nagy@arm.com>
PR target/66731
* config/arm/arm.md (negmuldf3_vfp): Add new pattern.
(negmulsf3_vfp): Likewise.
(muldf3negdf_vfp): Disable for -frounding-math.
(mulsf3negsf_vfp): Likewise.
* config/arm/arm.c (arm_new_rtx_costs): Fix NEG cost for VNMUL,
fix MULT cost with -frounding-math.
gcc/testsuite/Changelog:
2015-07-28 Szabolcs Nagy <szabolcs.nagy@arm.com>
PR target/66731
* gcc.target/arm/vnmul-1.c: New.
* gcc.target/arm/vnmul-2.c: New.
* gcc.target/arm/vnmul-3.c: New.
* gcc.target/arm/vnmul-4.c: New.