[Mesa-dev] [PATCH 2/4] i965: Use greater-equal cmod to implement maximum.

[Matt Turner]

The docs specifically call out SEL with .l and .ge as the
implementations of MIN and MAX respectively. Among other things, SEL
with these conditional mods are commutative.
---
 src/mesa/drivers/dri/i965/brw_fs_visitor.cpp      | 5 ++++-
 src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp    | 6 +++---
 src/mesa/drivers/dri/i965/brw_vec4_vp.cpp         | 4 ++--
 src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp | 2 +-
 4 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
index 6cddcf5..bca2139 100644
--- a/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs_visitor.cpp
@@ -322,6 +322,9 @@ void
 fs_visitor::emit_minmax(enum brw_conditional_mod conditionalmod, const fs_reg &dst,
                         const fs_reg &src0, const fs_reg &src1)
 {
+   assert(conditionalmod == BRW_CONDITIONAL_GE ||
+          conditionalmod == BRW_CONDITIONAL_L);
+
    fs_inst *inst;
 
    if (brw->gen >= 6) {
@@ -1948,7 +1951,7 @@ fs_visitor::rescale_texcoord(fs_reg coordinate, int coord_components,
 	    chan = offset(chan, i);
 
 	    inst = emit(BRW_OPCODE_SEL, chan, chan, fs_reg(0.0f));
-	    inst->conditional_mod = BRW_CONDITIONAL_G;
+	    inst->conditional_mod = BRW_CONDITIONAL_GE;
 
 	    /* Our parameter comes in as 1.0/width or 1.0/height,
 	     * because that's what people normally want for doing
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
index e6a7ed0..d13c716 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_visitor.cpp
@@ -513,7 +513,7 @@ vec4_visitor::emit_unpack_snorm_4x8(const dst_reg &dst, src_reg src0)
    emit(MUL(scaled, src_reg(f), src_reg(1.0f / 127.0f)));
 
    dst_reg max(this, glsl_type::vec4_type);
-   emit_minmax(BRW_CONDITIONAL_G, max, src_reg(scaled), src_reg(-1.0f));
+   emit_minmax(BRW_CONDITIONAL_GE, max, src_reg(scaled), src_reg(-1.0f));
    emit_minmax(BRW_CONDITIONAL_L, dst, src_reg(max), src_reg(1.0f));
 }
 
@@ -541,7 +541,7 @@ void
 vec4_visitor::emit_pack_snorm_4x8(const dst_reg &dst, const src_reg &src0)
 {
    dst_reg max(this, glsl_type::vec4_type);
-   emit_minmax(BRW_CONDITIONAL_G, max, src0, src_reg(-1.0f));
+   emit_minmax(BRW_CONDITIONAL_GE, max, src0, src_reg(-1.0f));
 
    dst_reg min(this, glsl_type::vec4_type);
    emit_minmax(BRW_CONDITIONAL_L, min, src_reg(max), src_reg(1.0f));
@@ -1673,7 +1673,7 @@ vec4_visitor::visit(ir_expression *ir)
       emit_minmax(BRW_CONDITIONAL_L, result_dst, op[0], op[1]);
       break;
    case ir_binop_max:
-      emit_minmax(BRW_CONDITIONAL_G, result_dst, op[0], op[1]);
+      emit_minmax(BRW_CONDITIONAL_GE, result_dst, op[0], op[1]);
       break;
 
    case ir_binop_pow:
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_vp.cpp b/src/mesa/drivers/dri/i965/brw_vec4_vp.cpp
index 434f032..e2d4b7c 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_vp.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_vp.cpp
@@ -227,7 +227,7 @@ vec4_vs_visitor::emit_program_code()
                /* if (tmp.y < 0) tmp.y = 0; */
                src_reg tmp_y = swizzle(src[0], BRW_SWIZZLE_YYYY);
                result.writemask = WRITEMASK_Z;
-               emit_minmax(BRW_CONDITIONAL_G, result, tmp_y, src_reg(0.0f));
+               emit_minmax(BRW_CONDITIONAL_GE, result, tmp_y, src_reg(0.0f));
 
                src_reg clamped_y(result);
                clamped_y.swizzle = BRW_SWIZZLE_ZZZZ;
@@ -314,7 +314,7 @@ vec4_vs_visitor::emit_program_code()
       }
 
       case OPCODE_MAX:
-         emit_minmax(BRW_CONDITIONAL_G, dst, src[0], src[1]);
+         emit_minmax(BRW_CONDITIONAL_GE, dst, src[0], src[1]);
          break;
 
       case OPCODE_MIN:
diff --git a/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp b/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp
index 72b6ef0..a48b730 100644
--- a/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp
+++ b/src/mesa/drivers/dri/i965/brw_vec4_vs_visitor.cpp
@@ -97,7 +97,7 @@ vec4_vs_visitor::emit_prolog()
                dst.type = brw_type_for_base_type(glsl_type::vec4_type);
                emit(MOV(dst, src_reg(reg_d)));
                emit(MUL(dst, src_reg(dst), src_reg(es3_normalize_factor)));
-               emit_minmax(BRW_CONDITIONAL_G, dst, src_reg(dst), src_reg(-1.0f));
+               emit_minmax(BRW_CONDITIONAL_GE, dst, src_reg(dst), src_reg(-1.0f));
             } else {
                /* The following equations are from the OpenGL 3.2 specification:
                 *
-- 
2.0.5