On Tue, Jul 11, 2023 at 12:24 AM Alexander Monakov via Gcc-patches
wrote:
>
>
> On Mon, 10 Jul 2023, liuhongt via Gcc-patches wrote:
>
> > False dependency happens when destination is only updated by
> > pternlog. There is no false dependency when destination is also used
> > in source. So either
On Mon, 10 Jul 2023, liuhongt via Gcc-patches wrote:
> False dependency happens when destination is only updated by
> pternlog. There is no false dependency when destination is also used
> in source. So either a pxor should be inserted, or input operand
> should be set with constraint '0'.
>
>
False dependency happens when destination is only updated by
pternlog. There is no false dependency when destination is also used
in source. So either a pxor should be inserted, or input operand
should be set with constraint '0'.
Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
Ready to p
On Thu, Jul 6, 2023 at 11:46 PM wrote:
>
> > +; False dependency happens on destination register which is not really
> > +; used when moving all ones to vector register
> > +(define_split
> > + [(set (match_operand:VMOVE 0 "register_operand")
> > + (match_operand:VMOVE 1 "int_float_vector_all
+; False dependency happens on destination register which is not really
+; used when moving all ones to vector register
+(define_split
+ [(set (match_operand:VMOVE 0 "register_operand")
+ (match_operand:VMOVE 1 "int_float_vector_all_ones_operand"))]
+ "TARGET_AVX512F && reload_completed
+
vpternlog is also used for optimization which doesn't need any valid
input operand, in that case, the destination is used as input in the
instruction and that creates a false dependence.
Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
Ready to push to trunk.
gcc/ChangeLog:
PR t
