i965: Split FS_OPCODE_DISCARD into two steps.

Having the single opcode write then read the reg meant that single
instruction opcodes had to consider their source regs to interfere
with their dest regs.

diff --git a/src/mesa/drivers/dri/i965/brw_fs.cpp b/src/mesa/drivers/dri/i965/brw_fs.cpp
index 11a5a4aceff928325506836d913ebbcd55c0d48a..f41e8783e6729d4fe6f122ca990dfebc996f58a3 100644 (file)
--- a/src/mesa/drivers/dri/i965/brw_fs.cpp
+++ b/src/mesa/drivers/dri/i965/brw_fs.cpp
@@ -73,7 +73,8 @@ enum fs_opcodes {
    FS_OPCODE_TEX,
    FS_OPCODE_TXB,
    FS_OPCODE_TXL,
-   FS_OPCODE_DISCARD,
+   FS_OPCODE_DISCARD_NOT,
+   FS_OPCODE_DISCARD_AND,
 };
 
 static int using_new_fs = -1;
@@ -475,7 +476,8 @@ public:
                         struct brw_reg *src);
    void generate_tex(fs_inst *inst, struct brw_reg dst, struct brw_reg src);
    void generate_math(fs_inst *inst, struct brw_reg dst, struct brw_reg *src);
-   void generate_discard(fs_inst *inst, struct brw_reg temp);
+   void generate_discard_not(fs_inst *inst, struct brw_reg temp);
+   void generate_discard_and(fs_inst *inst, struct brw_reg temp);
    void generate_ddx(fs_inst *inst, struct brw_reg dst, struct brw_reg src);
    void generate_ddy(fs_inst *inst, struct brw_reg dst, struct brw_reg src);
 
@@ -1548,7 +1550,8 @@ fs_visitor::visit(ir_discard *ir)
 
    assert(ir->condition == NULL); /* FINISHME */
 
-   emit(fs_inst(FS_OPCODE_DISCARD, temp, temp));
+   emit(fs_inst(FS_OPCODE_DISCARD_NOT, temp, reg_null));
+   emit(fs_inst(FS_OPCODE_DISCARD_AND, reg_null, temp));
    kill_emitted = true;
 }
 
@@ -2217,15 +2220,23 @@ fs_visitor::generate_ddy(fs_inst *inst, struct brw_reg dst, struct brw_reg src)
 }
 
 void
-fs_visitor::generate_discard(fs_inst *inst, struct brw_reg temp)
+fs_visitor::generate_discard_not(fs_inst *inst, struct brw_reg mask)
+{
+   brw_push_insn_state(p);
+   brw_set_mask_control(p, BRW_MASK_DISABLE);
+   brw_NOT(p, mask, brw_mask_reg(1)); /* IMASK */
+   brw_pop_insn_state(p);
+}
+
+void
+fs_visitor::generate_discard_and(fs_inst *inst, struct brw_reg mask)
 {
    struct brw_reg g0 = retype(brw_vec1_grf(0, 0), BRW_REGISTER_TYPE_UW);
-   temp = brw_uw1_reg(temp.file, temp.nr, 0);
+   mask = brw_uw1_reg(mask.file, mask.nr, 0);
 
    brw_push_insn_state(p);
    brw_set_mask_control(p, BRW_MASK_DISABLE);
-   brw_NOT(p, temp, brw_mask_reg(1)); /* IMASK */
-   brw_AND(p, g0, temp, g0);
+   brw_AND(p, g0, mask, g0);
    brw_pop_insn_state(p);
 }
 
@@ -3011,8 +3022,11 @@ fs_visitor::generate_code()
       case FS_OPCODE_TXL:
         generate_tex(inst, dst, src[0]);
         break;
-      case FS_OPCODE_DISCARD:
-        generate_discard(inst, dst /* src0 == dst */);
+      case FS_OPCODE_DISCARD_NOT:
+        generate_discard_not(inst, dst);
+        break;
+      case FS_OPCODE_DISCARD_AND:
+        generate_discard_and(inst, src[0]);
         break;
       case FS_OPCODE_DDX:
         generate_ddx(inst, dst, src[0]);