i965/vec4: Don't set header_present if texel offsets are all 0.

In theory, a shader might use textureOffset() but set all the texel
offsets to zero.  In that case, we don't actually need to set up the
message header - zero is the implicit default.

By moving the texture_offset setup before the header_present setup, we
can easily only set header_present when there are non-zero texel offset
values.
Signed-off-by: Kenneth Graunke (AFK until mid-April)'s avatarKenneth Graunke <kenneth@whitecape.org>
Reviewed-by: Matt Turner's avatarMatt Turner <mattst88@gmail.com>
Reviewed-by: Chris Forbes's avatarChris Forbes <chrisf@ijw.co.nz>
parent 6943ac0b
......@@ -2363,10 +2363,16 @@ vec4_visitor::visit(ir_texture *ir)
assert(!"Unrecognized tex op");
}
bool use_texture_offset = ir->offset != NULL && ir->op != ir_txf;
if (ir->offset != NULL && ir->op != ir_txf)
inst->texture_offset = brw_texture_offset(ctx, ir->offset->as_constant());
/* Stuff the channel select bits in the top of the texture offset */
if (ir->op == ir_tg4)
inst->texture_offset |= gather_channel(ir, sampler) << 16;
/* Texel offsets go in the message header; Gen4 also requires headers. */
inst->header_present = use_texture_offset || brw->gen < 5 || ir->op == ir_tg4;
inst->header_present =
brw->gen < 5 || inst->texture_offset != 0 || ir->op == ir_tg4;
inst->base_mrf = 2;
inst->mlen = inst->header_present + 1; /* always at least one */
inst->sampler = sampler;
......@@ -2374,13 +2380,6 @@ vec4_visitor::visit(ir_texture *ir)
inst->dst.writemask = WRITEMASK_XYZW;
inst->shadow_compare = ir->shadow_comparitor != NULL;
if (use_texture_offset)
inst->texture_offset = brw_texture_offset(ctx, ir->offset->as_constant());
/* Stuff the channel select bits in the top of the texture offset */
if (ir->op == ir_tg4)
inst->texture_offset |= gather_channel(ir, sampler)<<16;
/* MRF for the first parameter */
int param_base = inst->base_mrf + inst->header_present;
......
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