tgsi: make SSE ADD instruction SOA-safe

To properly execute an instruction such as "ADD tmp, tmp.wzyx, foo;"
with SOA we (sometimes) need to put the results into temporaries before
writing the results to the destination register.

This patch fixes the ADD instruction but this needs to be done for
many more instructions.

Helps to fix piglit fp-long-alu test (fd.o bug 27989).

1 files changed, 13 insertions, 5 deletions

diff --git a/src/gallium/auxiliary/tgsi/tgsi_sse2.c b/src/gallium/auxiliary/tgsi/tgsi_sse2.c
index 0820a4137e7..01b4a960129 100644
--- a/src/gallium/auxiliary/tgsi/tgsi_sse2.c
+++ b/src/gallium/auxiliary/tgsi/tgsi_sse2.c
@@ -1938,11 +1938,17 @@ emit_instruction(
       break;
 
    case TGSI_OPCODE_ADD:
+      /* do all fetches and adds, storing results in temp regs */
       FOR_EACH_DST0_ENABLED_CHANNEL( *inst, chan_index ) {
-         FETCH( func, *inst, 0, 0, chan_index );
-         FETCH( func, *inst, 1, 1, chan_index );
-         emit_add( func, 0, 1 );
-         STORE( func, *inst, 0, 0, chan_index );
+         int r = chan_index + 1;
+         FETCH( func, *inst, 0, 0, chan_index ); /* load xmm[0] */
+         FETCH( func, *inst, r, 1, chan_index ); /* load xmm[r] */
+         emit_add( func, r, 0 );   /* xmm[r] = xmm[r] + xmm[0] */
+      }
+      /* do all stores of the temp regs */
+      FOR_EACH_DST0_ENABLED_CHANNEL( *inst, chan_index ) {
+         int r = chan_index + 1;
+         STORE( func, *inst, r, 0, chan_index ); /* store xmm[r] */
       }
       break;
 
@@ -2825,8 +2831,10 @@ static void
 check_soa_dependencies(const struct tgsi_full_instruction *inst)
 {
    switch (inst->Instruction.Opcode) {
+   case TGSI_OPCODE_ADD:
+   case TGSI_OPCODE_MOV:
    case TGSI_OPCODE_XPD:
-      /* OK */
+      /* OK - these opcodes correctly handle SOA dependencies */
       break;
    default:
       if (tgsi_check_soa_dependencies(inst)) {