i965: Add support for the CMP opcode in the GLSL path.

This would be triggered by use of sqrt() along with control flow.
Fixes piglit-fs-sqrt-branch and a bug in Yo Frankie!.
(cherry picked from commit 48dca99feb)

src/mesa/drivers/dri/i965/brw_wm.h

@@ -328,6 +328,12 @@ void emit_cinterp(struct brw_compile *p,
 		  const struct brw_reg *dst,
 		  GLuint mask,
 		  const struct brw_reg *arg0);
+void emit_cmp(struct brw_compile *p,
+	      const struct brw_reg *dst,
+	      GLuint mask,
+	      const struct brw_reg *arg0,
+	      const struct brw_reg *arg1,
+	      const struct brw_reg *arg2);
 void emit_ddxy(struct brw_compile *p,
 	       const struct brw_reg *dst,
 	       GLuint mask,

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

@@ -566,12 +566,12 @@ static void emit_sne( struct brw_compile *p,
    emit_sop(p, dst, mask, BRW_CONDITIONAL_NEQ, arg0, arg1);
 }
 
-static void emit_cmp( struct brw_compile *p, 
-		      const struct brw_reg *dst,
-		      GLuint mask,
-		      const struct brw_reg *arg0,
-		      const struct brw_reg *arg1,
-		      const struct brw_reg *arg2 )
+void emit_cmp(struct brw_compile *p,
+	      const struct brw_reg *dst,
+	      GLuint mask,
+	      const struct brw_reg *arg0,
+	      const struct brw_reg *arg1,
+	      const struct brw_reg *arg2)
 {
    GLuint i;
 

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

@@ -1960,6 +1960,9 @@ static void brw_wm_emit_glsl(struct brw_context *brw, struct brw_wm_compile *c)
 	    case OPCODE_LG2:
 		emit_math1(c, BRW_MATH_FUNCTION_LOG, dst, dst_flags, args[0]);
 		break;
+	    case OPCODE_CMP:
+		emit_cmp(p, dst, dst_flags, args[0], args[1], args[2]);
+		break;
 	    case OPCODE_MIN:	
 		unalias2(c, emit_min, dst, dst_flags, args[0], args[1]);
 		break;