Re: Use single-iteration epilogues when peeling for gaps

[James Greenhalgh <james.greenhalgh@arm.com>]

On Wed, Dec 13, 2017 at 04:42:02PM +0000, Jeff Law wrote:
> On 11/17/2017 08:38 AM, Richard Sandiford wrote:
> > This patch adds support for fully-masking loops that require peeling
> > for gaps.  It peels exactly one scalar iteration and uses the masked
> > loop to handle the rest.  Previously we would fall back on using a
> > standard unmasked loop instead.
> > 
> > Tested on aarch64-linux-gnu (with and without SVE), x86_64-linux-gnu
> > and powerpc64le-linux-gnu.  OK to install?
> > 
> > Richard
> > 
> > 
> > 2017-11-17  Richard Sandiford  <richard.sandiford@linaro.org>
> > 	    Alan Hayward  <alan.hayward@arm.com>
> > 	    David Sherwood  <david.sherwood@arm.com>
> > 
> > gcc/
> > 	* tree-vect-loop-manip.c (vect_gen_scalar_loop_niters): Replace
> > 	vfm1 with a bound_epilog parameter.
> > 	(vect_do_peeling): Update calls accordingly, and move the prologue
> > 	call earlier in the function.  Treat the base bound_epilog as 0 for
> > 	fully-masked loops and retain vf - 1 for other loops.  Add 1 to
> > 	this base when peeling for gaps.
> > 	* tree-vect-loop.c (vect_analyze_loop_2): Allow peeling for gaps
> > 	with fully-masked loops.
> > 	(vect_estimate_min_profitable_iters): Handle the single peeled
> > 	iteration in that case.
> > 
> > gcc/testsuite/
> > 	* gcc.target/aarch64/sve_struct_vect_18.c: Check the number
> > 	of branches.
> > 	* gcc.target/aarch64/sve_struct_vect_19.c: Likewise.
> > 	* gcc.target/aarch64/sve_struct_vect_20.c: New test.
> > 	* gcc.target/aarch64/sve_struct_vect_20_run.c: Likewise.
> > 	* gcc.target/aarch64/sve_struct_vect_21.c: Likewise.
> > 	* gcc.target/aarch64/sve_struct_vect_21_run.c: Likewise.
> > 	* gcc.target/aarch64/sve_struct_vect_22.c: Likewise.
> > 	* gcc.target/aarch64/sve_struct_vect_22_run.c: Likewise.
> > 	* gcc.target/aarch64/sve_struct_vect_23.c: Likewise.
> > 	* gcc.target/aarch64/sve_struct_vect_23_run.c: Likewise.
> OK.
> jeff

The AArch64 tests are OK.

Thanks,
James