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i965: Move 3-src subnr swizzle handling into the vec4 backend.

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While most align16 instructions only support a SubRegNum of 0 or 4
(using swizzling to control the other channels), 3-src instructions
actually support arbitrary SubRegNums.  When the RepCtrl bit is set,
we believe it ignores the swizzle and uses the equivalent of a <0,1,0>
region from the subnr.

In the past, we adopted a vec4-centric approach of specifying subnr of
0 or 4 and a swizzle, then having brw_eu_emit.c convert that to a proper
SubRegNum.  This isn't a great fit for the scalar backend, where we
don't set swizzles at all, and happily set subnrs in the range [0, 7].

This patch changes brw_eu_emit.c to use subnr and swizzle directly,
relying on the higher levels to set them sensibly.

This should fix problems where scalar sources get copy propagated into
3-src instructions in the FS backend.  I've only observed this with
TES push model inputs, but I suppose it could happen in other cases.

Signed-off-by: Kenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner <mattst88@gmail.com>
This commit is contained in:
Kenneth Graunke 2015-12-31 12:47:19 -08:00
parent 64253fdb2e
commit 53a9b6223f
2 changed files with 18 additions and 6 deletions
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11
src/mesa/drivers/dri/i965/brw_eu_emit.c
View file

@ -847,12 +847,11 @@ brw_alu2(struct brw_codegen *p, unsigned opcode,
static int
get_3src_subreg_nr(struct brw_reg reg)
{
if (reg.vstride == BRW_VERTICAL_STRIDE_0) {
assert(brw_is_single_value_swizzle(reg.swizzle));
return reg.subnr / 4 + BRW_GET_SWZ(reg.swizzle, 0);
} else {
return reg.subnr / 4;
}
/* Normally, SubRegNum is in bytes (0..31). However, 3-src instructions
* use 32-bit units (components 0..7). Since they only support F/D/UD
* types, this doesn't lose any flexibility, but uses fewer bits.
*/
return reg.subnr / 4;
}
static brw_inst *

13
src/mesa/drivers/dri/i965/brw_vec4.cpp
View file

@ -1784,9 +1784,22 @@ vec4_visitor::convert_to_hw_regs()
case ATTR:
unreachable("not reached");
}
src = reg;
}
if (inst->is_3src()) {
/* 3-src instructions with scalar sources support arbitrary subnr,
* but don't actually use swizzles. Convert swizzle into subnr.
*/
for (int i = 0; i < 3; i++) {
if (inst->src[i].vstride == BRW_VERTICAL_STRIDE_0) {
assert(brw_is_single_value_swizzle(inst->src[i].swizzle));
inst->src[i].subnr += 4 * BRW_GET_SWZ(inst->src[i].swizzle, 0);
}
}
}
dst_reg &dst = inst->dst;
struct brw_reg reg;