Mesa (master): nir/lower_idiv: Use ilt instead of bit twiddling

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Module: Mesa
Branch: master
Commit: e17426058cd50d8302acd5155846871a2f39b408
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=e17426058cd50d8302acd5155846871a2f39b408

Author: Jason Ekstrand <jason.ekstrand at intel.com>
Date:   Sun Dec 16 00:42:01 2018 -0600

nir/lower_idiv: Use ilt instead of bit twiddling

The previous code was creating a boolean by doing an arithmetic right-
shift by 31 which produces a boolean which is true if the argument is
negative.  This is the same as the expression r < 0 which is much
simpler and doesn't depend on NIR's representation of booleans.

Reviewed-by: Eric Anholt <eric at anholt.net>

---

 src/compiler/nir/nir_lower_idiv.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/compiler/nir/nir_lower_idiv.c b/src/compiler/nir/nir_lower_idiv.c
index b2a0a3c189..4e7e2408ae 100644
--- a/src/compiler/nir/nir_lower_idiv.c
+++ b/src/compiler/nir/nir_lower_idiv.c
@@ -101,7 +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_ishr(bld, r, nir_imm_int(bld, 31));
+      r = nir_ilt(bld, r, nir_imm_int(bld, 0));
       b = nir_ineg(bld, q);
       q = nir_bcsel(bld, r, b, q);
    }