vc4: Fix live intervals analysis for screening defs in if statements.

If a conditional assignment is only conditioned on the exec mask, that's
still screening off the value in the executed channels (and, since we're
not storing to the unexcuted channels, we don't care what's in there).

Fixes a bunch of extra register pressure on Processing's Ribbons demo,
which is failing to allocate.

1 files changed, 4 insertions, 1 deletions

diff --git a/src/gallium/drivers/vc4/vc4_program.c b/src/gallium/drivers/vc4/vc4_program.c
index a91e6200e8a..81ac070d463 100644
--- a/src/gallium/drivers/vc4/vc4_program.c
+++ b/src/gallium/drivers/vc4/vc4_program.c
@@ -169,8 +169,11 @@ ntq_store_dest(struct vc4_compile *c, nir_dest *dest, int chan,
                  * channel is active.
                  */
                 if (c->execute.file != QFILE_NULL) {
+                        struct qinst *mov;
+
                         qir_SF(c, c->execute);
-                        qir_MOV_cond(c, QPU_COND_ZS, qregs[chan], result);
+                        mov = qir_MOV_cond(c, QPU_COND_ZS, qregs[chan], result);
+                        mov->cond_is_exec_mask = true;
                 } else {
                         qir_MOV_dest(c, qregs[chan], result);
                 }