1 files changed, 27 insertions, 14 deletions

diff --git a/mesalib/src/mesa/state_tracker/st_glsl_to_tgsi.cpp b/mesalib/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
index 460bafb38..d7a1ba80e 100644
--- a/mesalib/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
+++ b/mesalib/src/mesa/state_tracker/st_glsl_to_tgsi.cpp
@@ -949,8 +949,6 @@ st_src_reg
 glsl_to_tgsi_visitor::get_temp(const glsl_type *type)
 {
    st_src_reg src;
-   int swizzle[4];
-   int i;
 
    src.type = glsl_version >= 130 ? type->base_type : GLSL_TYPE_FLOAT;
    src.file = PROGRAM_TEMPORARY;
@@ -961,12 +959,7 @@ glsl_to_tgsi_visitor::get_temp(const glsl_type *type)
    if (type->is_array() || type->is_record()) {
       src.swizzle = SWIZZLE_NOOP;
    } else {
-      for (i = 0; i < type->vector_elements; i++)
-         swizzle[i] = i;
-      for (; i < 4; i++)
-         swizzle[i] = type->vector_elements - 1;
-      src.swizzle = MAKE_SWIZZLE4(swizzle[0], swizzle[1],
-        			  swizzle[2], swizzle[3]);
+      src.swizzle = swizzle_for_size(type->vector_elements);
    }
    src.negate = 0;
 
@@ -1232,12 +1225,32 @@ glsl_to_tgsi_visitor::try_emit_sat(ir_expression *ir)
    sat_src->accept(this);
    st_src_reg src = this->result;
 
-   this->result = get_temp(ir->type);
-   st_dst_reg result_dst = st_dst_reg(this->result);
-   result_dst.writemask = (1 << ir->type->vector_elements) - 1;
-   glsl_to_tgsi_instruction *inst;
-   inst = emit(ir, TGSI_OPCODE_MOV, result_dst, src);
-   inst->saturate = true;
+   /* If we generated an expression instruction into a temporary in
+    * processing the saturate's operand, apply the saturate to that
+    * instruction.  Otherwise, generate a MOV to do the saturate.
+    *
+    * Note that we have to be careful to only do this optimization if
+    * the instruction in question was what generated src->result.  For
+    * example, ir_dereference_array might generate a MUL instruction
+    * to create the reladdr, and return us a src reg using that
+    * reladdr.  That MUL result is not the value we're trying to
+    * saturate.
+    */
+   ir_expression *sat_src_expr = sat_src->as_expression();
+   if (sat_src_expr && (sat_src_expr->operation == ir_binop_mul ||
+			sat_src_expr->operation == ir_binop_add ||
+			sat_src_expr->operation == ir_binop_dot)) {
+      glsl_to_tgsi_instruction *new_inst;
+      new_inst = (glsl_to_tgsi_instruction *)this->instructions.get_tail();
+      new_inst->saturate = true;
+   } else {
+      this->result = get_temp(ir->type);
+      st_dst_reg result_dst = st_dst_reg(this->result);
+      result_dst.writemask = (1 << ir->type->vector_elements) - 1;
+      glsl_to_tgsi_instruction *inst;
+      inst = emit(ir, TGSI_OPCODE_MOV, result_dst, src);
+      inst->saturate = true;
+   }
 
    return true;
 }