[Mesa-dev] [PATCH] nir: Avoid an extra NIR op in integer divide lowering.

Eric Anholt eric at anholt.net
Mon Nov 7 20:28:34 UTC 2016


NIR bools are ~0 for true, so ((unsigned)a >> 31) != 0 -> ((int)a >> 31).
---
 src/compiler/nir/nir_lower_idiv.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/src/compiler/nir/nir_lower_idiv.c b/src/compiler/nir/nir_lower_idiv.c
index b1e7aeb03c8a..6726b718aaa5 100644
--- a/src/compiler/nir/nir_lower_idiv.c
+++ b/src/compiler/nir/nir_lower_idiv.c
@@ -101,8 +101,7 @@ convert_instr(nir_builder *bld, nir_alu_instr *alu)
    if (is_signed)  {
       /* fix the sign: */
       r = nir_ixor(bld, numer, denom);
-      r = nir_ushr(bld, r, nir_imm_int(bld, 31));
-      r = nir_i2b(bld, r);
+      r = nir_ishr(bld, r, nir_imm_int(bld, 31));
       b = nir_ineg(bld, q);
       q = nir_bcsel(bld, r, b, q);
    }
-- 
2.10.2



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