v3: Since the fs backend can emit saturate as a separate instruction, there is
no need to detect for min/max instructions and to rewrite the instruction
tree
accordingly. On the other hand, we don't need to emit a separate saturated
mov either when the expression generating src can do saturate directly.
v4: Add can_do_saturate() check before enabling saturate modifer (Ken)
Reviewed-by: Matt Turner <matts...@gmail.com>
Reviewed-by: Ian Romanick <ian.d.roman...@intel.com>
Signed-off-by: Abdiel Janulgue <abdiel.janul...@linux.intel.com>
---
src/mesa/drivers/dri/i965/brw_fs_visitor.cpp | 23 ++++++++---------------
1 file changed, 8 insertions(+), 15 deletions(-)
diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index 8af915b..fbf2112 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -267,17 +267,14 @@ fs_visitor::emit_minmax(enum brw_conditional_mod
conditionalmod, const fs_reg &d
}
}
-/* Instruction selection: Produce a MOV.sat instead of
- * MIN(MAX(val, 0), 1) when possible.
- */
bool
fs_visitor::try_emit_saturate(ir_expression *ir)
{
- ir_rvalue *sat_val = ir->as_rvalue_to_saturate();
-
- if (!sat_val)
+ if (ir->operation != ir_unop_saturate)
return false;
+ ir_rvalue *sat_val = ir->operands[0];
+
fs_inst *pre_inst = (fs_inst *) this->instructions.get_tail();
sat_val->accept(this);
@@ -285,21 +282,17 @@ fs_visitor::try_emit_saturate(ir_expression *ir)
fs_inst *last_inst = (fs_inst *) this->instructions.get_tail();
- /* If the last instruction from our accept() didn't generate our
- * src, generate a saturated MOV
+ /* If the last instruction from our accept() generated our
+ * src, just set the saturate flag instead of emmitting a separate mov.
*/
fs_inst *modify = get_instruction_generating_reg(pre_inst, last_inst, src);
- if (!modify || modify->regs_written != 1) {
- this->result = fs_reg(this, ir->type);
- fs_inst *inst = emit(MOV(this->result, src));
- inst->saturate = true;
- } else {
+ if (modify && modify->regs_written == 1 && modify->can_do_saturate()) {
modify->saturate = true;
this->result = src;
+ return true;
}
-
- return true;
+ return false;
}
bool
--
1.9.1
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