tgsi: fix SSE code emit for XPD

Rearrange things so that the writes to the dest registers happen
after we've fetched/used all src registers.

The problematic instruction was:  XPD TEMP[2].xyz, TEMP[0], TEMP[2];
Note that the dst reg is also a src reg.

This fixes bad shading with progs/glsl/bump.c since Eric's changes to the
Mesa program optimizer in commit d6690ce15fb8c7c6abf1bc0d847c1d2da2c33904.
The optimizer rearranges some registers so we occasionally wind up with
something like the above.

1 files changed, 30 insertions, 20 deletions

diff --git a/src/gallium/auxiliary/tgsi/tgsi_sse2.c b/src/gallium/auxiliary/tgsi/tgsi_sse2.c
index a96fc94c7a..2c39defde5 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_sse2.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_sse2.c
@@ -2142,40 +2142,50 @@ emit_instruction(
       break;
 
    case TGSI_OPCODE_XPD:
+      /* Note: we do all stores after all operands have been fetched
+       * to avoid src/dst register aliasing issues for an instruction
+       * such as:  XPD TEMP[2].xyz, TEMP[0], TEMP[2];
+       */
       if( IS_DST0_CHANNEL_ENABLED( *inst, CHAN_X ) ||
           IS_DST0_CHANNEL_ENABLED( *inst, CHAN_Y ) ) {
-         FETCH( func, *inst, 1, 1, CHAN_Z );
-         FETCH( func, *inst, 3, 0, CHAN_Z );
+         FETCH( func, *inst, 1, 1, CHAN_Z ); /* xmm[1] = src[1].z */
+         FETCH( func, *inst, 3, 0, CHAN_Z ); /* xmm[3] = src[0].z */
       }
       if( IS_DST0_CHANNEL_ENABLED( *inst, CHAN_X ) ||
           IS_DST0_CHANNEL_ENABLED( *inst, CHAN_Z ) ) {
-         FETCH( func, *inst, 0, 0, CHAN_Y );
-         FETCH( func, *inst, 4, 1, CHAN_Y );
+         FETCH( func, *inst, 0, 0, CHAN_Y ); /* xmm[0] = src[0].y */
+         FETCH( func, *inst, 4, 1, CHAN_Y ); /* xmm[4] = src[1].y */
       }
       IF_IS_DST0_CHANNEL_ENABLED( *inst, CHAN_X ) {
-         emit_MOV( func, 2, 0 );
-         emit_mul( func, 2, 1 );
-         emit_MOV( func, 5, 3 );
-         emit_mul( func, 5, 4 );
-         emit_sub( func, 2, 5 );
-         STORE( func, *inst, 2, 0, CHAN_X );
+         emit_MOV( func, 7, 0 );  /* xmm[7] = xmm[0] */
+         emit_mul( func, 7, 1 );  /* xmm[7] = xmm[2] * xmm[1] */
+         emit_MOV( func, 5, 3 );  /* xmm[5] = xmm[3] */
+         emit_mul( func, 5, 4 );  /* xmm[5] = xmm[5] * xmm[4] */
+         emit_sub( func, 7, 5 );  /* xmm[7] = xmm[2] - xmm[5] */
+         /* store xmm[7] in dst.x below */
       }
       if( IS_DST0_CHANNEL_ENABLED( *inst, CHAN_Y ) ||
           IS_DST0_CHANNEL_ENABLED( *inst, CHAN_Z ) ) {
-         FETCH( func, *inst, 2, 1, CHAN_X );
-         FETCH( func, *inst, 5, 0, CHAN_X );
+         FETCH( func, *inst, 2, 1, CHAN_X ); /* xmm[2] = src[1].x */
+         FETCH( func, *inst, 5, 0, CHAN_X ); /* xmm[5] = src[0].x */
       }
       IF_IS_DST0_CHANNEL_ENABLED( *inst, CHAN_Y ) {
-         emit_mul( func, 3, 2 );
-         emit_mul( func, 1, 5 );
-         emit_sub( func, 3, 1 );
-         STORE( func, *inst, 3, 0, CHAN_Y );
+         emit_mul( func, 3, 2 );  /* xmm[3] = xmm[3] * xmm[2] */
+         emit_mul( func, 1, 5 );  /* xmm[1] = xmm[1] * xmm[5] */
+         emit_sub( func, 3, 1 );  /* xmm[3] = xmm[3] - xmm[1] */
+         /* store xmm[3] in dst.y below */
       }
       IF_IS_DST0_CHANNEL_ENABLED( *inst, CHAN_Z ) {
-         emit_mul( func, 5, 4 );
-         emit_mul( func, 0, 2 );
-         emit_sub( func, 5, 0 );
-         STORE( func, *inst, 5, 0, CHAN_Z );
+         emit_mul( func, 5, 4 );  /* xmm[5] = xmm[5] * xmm[4] */
+         emit_mul( func, 0, 2 );  /* xmm[0] = xmm[0] * xmm[2] */
+         emit_sub( func, 5, 0 );  /* xmm[5] = xmm[5] - xmm[0] */
+         STORE( func, *inst, 5, 0, CHAN_Z ); /* dst.z = xmm[5] */
+      }
+      IF_IS_DST0_CHANNEL_ENABLED( *inst, CHAN_X ) {
+         STORE( func, *inst, 7, 0, CHAN_X ); /* dst.x = xmm[7] */
+      }
+      IF_IS_DST0_CHANNEL_ENABLED( *inst, CHAN_Y ) {
+         STORE( func, *inst, 3, 0, CHAN_Y ); /* dst.y = xmm[3] */
       }
       IF_IS_DST0_CHANNEL_ENABLED( *inst, CHAN_W ) {
 	 emit_tempf(