Mesa (master): nir: Optimize out discard_ifs with a constant 0 argument.
Eric Anholt
anholt at kemper.freedesktop.org
Wed Sep 28 15:41:12 UTC 2016
Module: Mesa
Branch: master
Commit: 1aa8a0392f256a1be8f8d2774a4f7d3e03b3aac3
URL: http://cgit.freedesktop.org/mesa/mesa/commit/?id=1aa8a0392f256a1be8f8d2774a4f7d3e03b3aac3
Author: Eric Anholt <eric at anholt.net>
Date: Tue Mar 15 18:32:19 2016 -0700
nir: Optimize out discard_ifs with a constant 0 argument.
I found this in a shader that was doing an alpha test when alpha is fixed
at 1.0.
v2: Rebase on master (now the const value is "u32" not "u").
Reviewed-by: Jason Ekstrand <jason at jlekstrand.net> (v1)
---
src/compiler/nir/nir_opt_constant_folding.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/src/compiler/nir/nir_opt_constant_folding.c b/src/compiler/nir/nir_opt_constant_folding.c
index 8f04061..d6be807 100644
--- a/src/compiler/nir/nir_opt_constant_folding.c
+++ b/src/compiler/nir/nir_opt_constant_folding.c
@@ -155,6 +155,14 @@ constant_fold_intrinsic_instr(nir_intrinsic_instr *instr)
progress |= constant_fold_deref(&instr->instr, instr->variables[i]);
}
+ if (instr->intrinsic == nir_intrinsic_discard_if) {
+ nir_const_value *src_val = nir_src_as_const_value(instr->src[0]);
+ if (src_val && src_val->u32[0] == 0) {
+ nir_instr_remove(&instr->instr);
+ progress = true;
+ }
+ }
+
return progress;
}
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