| Message ID | 87zi5nav7r.fsf_-_@linaro.org |
|---|---|
| State | New |
| Headers | show |
| Series | RFA: Expand vec_perm_indices::series_p comment | expand |
Ping Richard Sandiford <richard.sandiford@linaro.org> writes: > James Greenhalgh <james.greenhalgh@arm.com> writes: >> On Thu, Jan 04, 2018 at 11:27:56AM +0000, Richard Sandiford wrote: >>> Ping**2 >> >> This is OK. > > Thanks. > >> It took me a while to get the hang of the interface - a worked example >> in the comment in vec-perm-indices.c would probably have been helpful. >> It took until your code for REV for this to really make sense to me; so >> perhaps that make for a good example. > > Yeah, good idea. > > Is the following OK? Tested on aarch64-linux-gnu. > > Thanks, > Richard > > > 2018-01-09 Richard Sandiford <richard.sandiford@linaro.org> > > gcc/ > * vec-perm-indices.c (vec_perm_indices::series_p): Give examples > of usage. > > Index: gcc/vec-perm-indices.c > =================================================================== > --- gcc/vec-perm-indices.c 2018-01-03 11:12:55.709763763 +0000 > +++ gcc/vec-perm-indices.c 2018-01-09 15:46:40.004232873 +0000 > @@ -114,7 +114,18 @@ vec_perm_indices::rotate_inputs (int del > } > > /* Return true if index OUT_BASE + I * OUT_STEP selects input > - element IN_BASE + I * IN_STEP. */ > + element IN_BASE + I * IN_STEP. For example, the call to test > + whether a permute reverses a vector of N elements would be: > + > + series_p (0, 1, N - 1, -1) > + > + which would return true for { N - 1, N - 2, N - 3, ... }. > + The calls to test for an interleaving of elements starting > + at N1 and N2 would be: > + > + series_p (0, 2, N1, 1) && series_p (1, 2, N2, 1). > + > + which would return true for { N1, N2, N1 + 1, N2 + 1, ... }. */ > > bool > vec_perm_indices::series_p (unsigned int out_base, unsigned int out_step,
On 01/29/2018 01:38 PM, Richard Sandiford wrote: > Ping > > Richard Sandiford <richard.sandiford@linaro.org> writes: >> James Greenhalgh <james.greenhalgh@arm.com> writes: >>> On Thu, Jan 04, 2018 at 11:27:56AM +0000, Richard Sandiford wrote: >>>> Ping**2 >>> >>> This is OK. >> >> Thanks. >> >>> It took me a while to get the hang of the interface - a worked example >>> in the comment in vec-perm-indices.c would probably have been helpful. >>> It took until your code for REV for this to really make sense to me; so >>> perhaps that make for a good example. >> >> Yeah, good idea. >> >> Is the following OK? Tested on aarch64-linux-gnu. >> >> Thanks, >> Richard >> >> >> 2018-01-09 Richard Sandiford <richard.sandiford@linaro.org> >> >> gcc/ >> * vec-perm-indices.c (vec_perm_indices::series_p): Give examples >> of usage. OK jeff
Index: gcc/vec-perm-indices.c =================================================================== --- gcc/vec-perm-indices.c 2018-01-03 11:12:55.709763763 +0000 +++ gcc/vec-perm-indices.c 2018-01-09 15:46:40.004232873 +0000 @@ -114,7 +114,18 @@ vec_perm_indices::rotate_inputs (int del } /* Return true if index OUT_BASE + I * OUT_STEP selects input - element IN_BASE + I * IN_STEP. */ + element IN_BASE + I * IN_STEP. For example, the call to test + whether a permute reverses a vector of N elements would be: + + series_p (0, 1, N - 1, -1) + + which would return true for { N - 1, N - 2, N - 3, ... }. + The calls to test for an interleaving of elements starting + at N1 and N2 would be: + + series_p (0, 2, N1, 1) && series_p (1, 2, N2, 1). + + which would return true for { N1, N2, N1 + 1, N2 + 1, ... }. */ bool vec_perm_indices::series_p (unsigned int out_base, unsigned int out_step,