r300/compiler: Fix vertex shader MAD instructions with constant swizzles

NOTE: This is a candidate for the 7.9 and 7.10 branches.

diff --git a/src/mesa/drivers/dri/r300/compiler/r3xx_vertprog.c b/src/mesa/drivers/dri/r300/compiler/r3xx_vertprog.c
index 8ad2175..654f9a0 100644 (file)
--- a/src/mesa/drivers/dri/r300/compiler/r3xx_vertprog.c
+++ b/src/mesa/drivers/dri/r300/compiler/r3xx_vertprog.c
@@ -273,6 +273,7 @@ static void ei_mad(struct r300_vertex_program_code *vp,
                                      struct rc_sub_instruction *vpi,
                                      unsigned int * inst)
 {
+       unsigned int i;
        /* Remarks about hardware limitations of MAD
         * (please preserve this comment, as this information is _NOT_
         * in the documentation provided by AMD).
@@ -318,6 +319,23 @@ static void ei_mad(struct r300_vertex_program_code *vp,
                                t_dst_index(vp, &vpi->DstReg),
                                t_dst_mask(vpi->DstReg.WriteMask),
                                t_dst_class(vpi->DstReg.File));
+
+               /* Arguments with constant swizzles still count as a unique
+                * temporary, so we should make sure these arguments share a
+                * register index with one of the other arguments. */
+               for (i = 0; i < 3; i++) {
+                       unsigned int j;
+                       if (vpi->SrcReg[i].File != RC_FILE_NONE)
+                               continue;
+
+                       for (j = 0; j < 3; j++) {
+                               if (i != j) {
+                                       vpi->SrcReg[i].Index =
+                                               vpi->SrcReg[j].Index;
+                                       break;
+                               }
+                       }
+               }
        }
        inst[1] = t_src(vp, &vpi->SrcReg[0]);
        inst[2] = t_src(vp, &vpi->SrcReg[1]);