[Mesa-dev] [PATCH 01/23] i965/fs: Refactor out guts of fs_visitor::try_opt_frontfacing_ternary

[Ian Romanick]

From: Ian Romanick <ian.d.romanick at intel.com>

The next patch will add a second user.

Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Cc: Abdiel Janulgue <abdiel.janulgue at intel.com>
---
 src/mesa/drivers/dri/i965/brw_fs_visitor.cpp | 105 +++++++++++++++------------
 1 file changed, 57 insertions(+), 48 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index 60a7a97..3388098 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -2800,6 +2800,62 @@ fs_visitor::emit_if_gen6(ir_if *ir)
    emit(IF(this->result, fs_reg(0), BRW_CONDITIONAL_NZ));
 }
 
+static void
+emit_frontfacing_to_float_one_neg_one(fs_visitor *v,
+                                      const fs_reg &dst,
+                                      ir_constant *then_rhs,
+                                      ir_constant *else_rhs)
+{
+   fs_reg tmp = v->vgrf(glsl_type::int_type);
+   if (v->brw->gen >= 6) {
+      /* Bit 15 of g0.0 is 0 if the polygon is front facing. */
+      fs_reg g0 = fs_reg(retype(brw_vec1_grf(0, 0), BRW_REGISTER_TYPE_W));
+
+      /* For (gl_FrontFacing ? 1.0 : -1.0), emit:
+       *
+       *    or(8)  tmp.1<2>W  g0.0<0,1,0>W  0x00003f80W
+       *    and(8) dst<1>D    tmp<8,8,1>D   0xbf800000D
+       *
+       * and negate g0.0<0,1,0>W for (gl_FrontFacing ? -1.0 : 1.0).
+       */
+
+      if (then_rhs->is_negative_one()) {
+         assert(else_rhs->is_one());
+         g0.negate = true;
+      }
+
+      tmp.type = BRW_REGISTER_TYPE_W;
+      tmp.subreg_offset = 2;
+      tmp.stride = 2;
+
+      fs_inst *or_inst = v->emit(v->OR(tmp, g0, fs_reg(0x3f80)));
+      or_inst->src[1].type = BRW_REGISTER_TYPE_UW;
+
+      tmp.type = BRW_REGISTER_TYPE_D;
+      tmp.subreg_offset = 0;
+      tmp.stride = 1;
+   } else {
+      /* Bit 31 of g1.6 is 0 if the polygon is front facing. */
+      fs_reg g1_6 = fs_reg(retype(brw_vec1_grf(1, 6), BRW_REGISTER_TYPE_D));
+
+      /* For (gl_FrontFacing ? 1.0 : -1.0), emit:
+       *
+       *    or(8)  tmp<1>D  g1.6<0,1,0>D  0x3f800000D
+       *    and(8) dst<1>D  tmp<8,8,1>D   0xbf800000D
+       *
+       * and negate g1.6<0,1,0>D for (gl_FrontFacing ? -1.0 : 1.0).
+       */
+
+      if (then_rhs->is_negative_one()) {
+         assert(else_rhs->is_one());
+         g1_6.negate = true;
+      }
+
+      v->emit(v->OR(tmp, g1_6, fs_reg(0x3f800000)));
+   }
+   v->emit(v->AND(dst, tmp, fs_reg(0xbf800000)));
+}
+
 bool
 fs_visitor::try_opt_frontfacing_ternary(ir_if *ir)
 {
@@ -2836,55 +2892,8 @@ fs_visitor::try_opt_frontfacing_ternary(ir_if *ir)
       then_assign->lhs->accept(this);
       fs_reg dst = this->result;
       dst.type = BRW_REGISTER_TYPE_D;
-      fs_reg tmp = vgrf(glsl_type::int_type);
-
-      if (brw->gen >= 6) {
-         /* Bit 15 of g0.0 is 0 if the polygon is front facing. */
-         fs_reg g0 = fs_reg(retype(brw_vec1_grf(0, 0), BRW_REGISTER_TYPE_W));
-
-         /* For (gl_FrontFacing ? 1.0 : -1.0), emit:
-          *
-          *    or(8)  tmp.1<2>W  g0.0<0,1,0>W  0x00003f80W
-          *    and(8) dst<1>D    tmp<8,8,1>D   0xbf800000D
-          *
-          * and negate g0.0<0,1,0>W for (gl_FrontFacing ? -1.0 : 1.0).
-          */
-
-         if (then_rhs->is_negative_one()) {
-            assert(else_rhs->is_one());
-            g0.negate = true;
-         }
-
-         tmp.type = BRW_REGISTER_TYPE_W;
-         tmp.subreg_offset = 2;
-         tmp.stride = 2;
 
-         fs_inst *or_inst = emit(OR(tmp, g0, fs_reg(0x3f80)));
-         or_inst->src[1].type = BRW_REGISTER_TYPE_UW;
-
-         tmp.type = BRW_REGISTER_TYPE_D;
-         tmp.subreg_offset = 0;
-         tmp.stride = 1;
-      } else {
-         /* Bit 31 of g1.6 is 0 if the polygon is front facing. */
-         fs_reg g1_6 = fs_reg(retype(brw_vec1_grf(1, 6), BRW_REGISTER_TYPE_D));
-
-         /* For (gl_FrontFacing ? 1.0 : -1.0), emit:
-          *
-          *    or(8)  tmp<1>D  g1.6<0,1,0>D  0x3f800000D
-          *    and(8) dst<1>D  tmp<8,8,1>D   0xbf800000D
-          *
-          * and negate g1.6<0,1,0>D for (gl_FrontFacing ? -1.0 : 1.0).
-          */
-
-         if (then_rhs->is_negative_one()) {
-            assert(else_rhs->is_one());
-            g1_6.negate = true;
-         }
-
-         emit(OR(tmp, g1_6, fs_reg(0x3f800000)));
-      }
-      emit(AND(dst, tmp, fs_reg(0xbf800000)));
+      emit_frontfacing_to_float_one_neg_one(this, dst, then_rhs, else_rhs);
       return true;
    }
 
-- 
2.1.0