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i965/fs: Stop using the LOAD_PAYLOAD instruction in lower_simd_width.

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Instead of using the LOAD_PAYLOAD instruction (emitted through the
emit_transpose() helper that is no longer useful and this commit
removes) which had to be marked force_writemask_all in some cases,
emit a series of moves to apply proper channel enable signals to the
destination.  Until now lower_simd_width() had mainly been used to
lower things that invariably had a basic block-local temporary as
destination so it didn't seem like a big deal, but I found it to be
the reason for several Piglit regressions in my SIMD32 branch and
Igalia discovered the same issue independently while working on FP64
support.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>
This commit is contained in:
Francisco Jerez 2016-05-03 21:26:13 -07:00 • committed by Samuel Iglesias Gonsálvez
parent 9149fd6817
commit 4d9c461e53
1 changed files with 18 additions and 40 deletions
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58
src/mesa/drivers/dri/i965/brw_fs.cpp
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@ -4681,29 +4681,6 @@ get_lowered_simd_width(const struct brw_device_info *devinfo,
}
}
/**
* The \p rows array of registers represents a \p num_rows by \p num_columns
* matrix in row-major order, write it in column-major order into the register
* passed as destination. \p stride gives the separation between matrix
* elements in the input in fs_builder::dispatch_width() units.
*/
static void
emit_transpose(const fs_builder &bld,
const fs_reg &dst, const fs_reg *rows,
unsigned num_rows, unsigned num_columns, unsigned stride)
{
fs_reg *const components = new fs_reg[num_rows * num_columns];
for (unsigned i = 0; i < num_columns; ++i) {
for (unsigned j = 0; j < num_rows; ++j)
components[num_rows * i + j] = offset(rows[j], bld, stride * i);
}
bld.LOAD_PAYLOAD(dst, components, num_rows * num_columns, 0);
delete[] components;
}
bool
fs_visitor::lower_simd_width()
{
@ -4754,16 +4731,19 @@ fs_visitor::lower_simd_width()
if (inst->src[j].file != BAD_FILE &&
!is_uniform(inst->src[j])) {
/* Get the i-th copy_width-wide chunk of the source. */
const fs_reg src = horiz_offset(inst->src[j], copy_width * i);
const fs_builder cbld = lbld.group(copy_width, 0);
const fs_reg src = offset(inst->src[j], cbld, i);
const unsigned src_size = inst->components_read(j);
/* Use a trivial transposition to copy one every n
* copy_width-wide components of the register into a
* temporary passed as source to the lowered instruction.
/* Copy one every n copy_width-wide components of the
* register into a temporary passed as source to the lowered
* instruction.
*/
split_inst.src[j] = lbld.vgrf(inst->src[j].type, src_size);
emit_transpose(lbld.group(copy_width, 0),
split_inst.src[j], &src, 1, src_size, n);
for (unsigned k = 0; k < src_size; ++k)
cbld.MOV(offset(split_inst.src[j], lbld, k),
offset(src, cbld, n * k));
}
}
@ -4782,20 +4762,18 @@ fs_visitor::lower_simd_width()
}
if (inst->regs_written) {
/* Distance between useful channels in the temporaries, skipping
* garbage if the lowered instruction is wider than the original.
*/
const unsigned m = lower_width / copy_width;
const fs_builder lbld = ibld.group(lower_width, 0);
/* Interleave the components of the result from the lowered
* instructions. We need to set exec_all() when copying more than
* one half per component, because LOAD_PAYLOAD (in terms of which
* emit_transpose is implemented) can only use the same channel
* enable signals for all of its non-header sources.
* instructions.
*/
emit_transpose(ibld.exec_all(inst->exec_size > copy_width)
.group(copy_width, 0),
inst->dst, dsts, n, dst_size, m);
for (unsigned i = 0; i < dst_size; ++i) {
for (unsigned j = 0; j < n; ++j) {
const fs_builder cbld = ibld.group(copy_width, j);
cbld.MOV(offset(inst->dst, cbld, n * i + j),
offset(dsts[j], lbld, i));
}
}
}
inst->remove(block);