On 30/11/17 16:01, Sudakshina Das wrote:
Hi
This patch is the fix for gcc-7 for the same issue as mentioned in:
https://gcc.gnu.org/ml/gcc-patches/2017-11/msg02209.html
For the following test case:
__fp16
test_select (__fp16 a, __fp16 b, __fp16 c)
{
return (a < b) ? b : c;
}
when compiled with -O2 -mfpu=fp-armv8 -march=armv8.2-a+fp16 -marm
-mfloat-abi=hard generates wrong code:
test_select:
@ args = 0, pretend = 0, frame = 0
@ frame_needed = 0, uses_anonymous_args = 0
@ link register save eliminated.
vcvtb.f32.f16 s0, s0
vcvtb.f32.f16 s15, s1
vmov.f16 r3, s2 @ __fp16
vcmpe.f32 s0, s15
vmrs APSR_nzcv, FPSCR
// <------ No conditional branch
vmov.f16 r3, s1 @ __fp16
.L1:
vmov.f16 s0, r3 @ __fp16
bx lr
There should have been a conditional branch there to skip one of the VMOVs.
This patch fixes this problem by making *movhf_vfp_fp16 unconditional.
Testing done: Add a new test case and checked for regressions on
bootstrapped arm-none-linux-gnueabihf.
Is this ok for gcc-7?
Sudi
ChangeLog entry are as follow:
*** gcc/ChangeLog ***
2017-11-30 Sudakshina Das <sudi....@arm.com>
* config/arm/vfp.md (*movhf_vfp_fp16): Add conds attribute.
*** gcc/testsuite/ChangeLog ***
2017-11-30 Sudakshina Das <sudi....@arm.com>
* gcc.target/arm/armv8_2-fp16-move-2.c: New test.
As per the trunk thread for this
(https://gcc.gnu.org/ml/gcc-patches/2017-11/msg02209.html) committed as
r255536 on gcc-7-branch for the backport.
Thanks
Sudi
