Mesa (master): i965/fs: Fix Sandybridge regressions from SEL optimization.

[Kenneth Graunke]

Module: Mesa
Branch: master
Commit: 90129da82c91b731c7c65e8e3adbde58d8c62840
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=90129da82c91b731c7c65e8e3adbde58d8c62840

Author: Kenneth Graunke <kenneth at whitecape.org>
Date:   Tue Aug 13 16:07:56 2013 -0700

i965/fs: Fix Sandybridge regressions from SEL optimization.

Sandybridge is the only platform that supports an IF instruction
with an embedded comparison.  In this case, we need to emit a CMP
to go along with the SEL.

Fixes regressions in Piglit's glsl-fs-atan-3, fs-unpackHalf2x16,
fs-faceforward-float-float-float, isinf-and-isnan fs_basic, and
isinf-and-isnan fs_fbo.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=68086
Signed-off-by: Kenneth Graunke <kenneth at whitecape.org>
Reviewed-by: Matt Turner <mattst88 at gmail.com>
Reviewed-by: Anuj Phogat <anuj.phogat at gmail.com>
Tested-by: lu hua <huax.lu at intel.com>

---

 src/mesa/drivers/dri/i965/brw_fs_visitor.cpp |   17 +++++++++++++----
 1 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index a36c248..984b08a 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -1911,10 +1911,19 @@ fs_visitor::try_replace_with_sel()
          emit(MOV(src0, then_mov->src[0]));
       }
 
-      fs_inst *sel = emit(BRW_OPCODE_SEL, then_mov->dst, src0, else_mov->src[0]);
-      sel->predicate = if_inst->predicate;
-      sel->predicate_inverse = if_inst->predicate_inverse;
-      sel->conditional_mod = if_inst->conditional_mod;
+      fs_inst *sel;
+      if (if_inst->conditional_mod) {
+         /* Sandybridge-specific IF with embedded comparison */
+         emit(CMP(reg_null_d, if_inst->src[0], if_inst->src[1],
+                  if_inst->conditional_mod));
+         sel = emit(BRW_OPCODE_SEL, then_mov->dst, src0, else_mov->src[0]);
+         sel->predicate = BRW_PREDICATE_NORMAL;
+      } else {
+         /* Separate CMP and IF instructions */
+         sel = emit(BRW_OPCODE_SEL, then_mov->dst, src0, else_mov->src[0]);
+         sel->predicate = if_inst->predicate;
+         sel->predicate_inverse = if_inst->predicate_inverse;
+      }
    }
 }