i965: Respect CondSwizzle in OPCODE_IF.

Fixes piglit glsl-vs-if-bool and progs/glsl/twoside, and will likely be
useful for the looping code.

Bug #18992
(cherry picked from commit 78c022acd0)
(cherry picked from commit 63d7a2f53f)

src/mesa/drivers/dri/i965/brw_vs_emit.c

@@ -1190,6 +1190,23 @@ post_vs_emit( struct brw_vs_compile *c,
    brw_set_src1(end_inst, brw_imm_d(offset * 16));
 }
 
+static uint32_t
+get_predicate(uint32_t swizzle)
+{
+   switch (swizzle) {
+   case SWIZZLE_XXXX:
+      return BRW_PREDICATE_ALIGN16_REPLICATE_X;
+   case SWIZZLE_YYYY:
+      return BRW_PREDICATE_ALIGN16_REPLICATE_Y;
+   case SWIZZLE_ZZZZ:
+      return BRW_PREDICATE_ALIGN16_REPLICATE_Z;
+   case SWIZZLE_WWWW:
+      return BRW_PREDICATE_ALIGN16_REPLICATE_W;
+   default:
+      _mesa_problem(NULL, "Unexpected predicate: 0x%08x\n", swizzle);
+      return BRW_PREDICATE_NORMAL;
+   }
+}
 
 /* Emit the vertex program instructions here.
  */
@@ -1394,7 +1411,10 @@ void brw_vs_emit(struct brw_vs_compile *c )
 	 break;
       case OPCODE_IF:
 	 assert(if_depth < MAX_IF_DEPTH);
-         if_inst[if_depth++] = brw_IF(p, BRW_EXECUTE_8);
+	 if_inst[if_depth] = brw_IF(p, BRW_EXECUTE_8);
+	 if_inst[if_depth]->header.predicate_control =
+	    get_predicate(inst->DstReg.CondSwizzle);
+	 if_depth++;
 	 break;
       case OPCODE_ELSE:
 	 if_inst[if_depth-1] = brw_ELSE(p, if_inst[if_depth-1]);