3 files changed, 20 insertions, 5 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);
                 }
diff --git a/src/gallium/drivers/vc4/vc4_qir.h b/src/gallium/drivers/vc4/vc4_qir.h
index 36652167595..4d41c427c10 100644
--- a/src/gallium/drivers/vc4/vc4_qir.h
+++ b/src/gallium/drivers/vc4/vc4_qir.h
@@ -195,6 +195,7 @@ struct qinst {
         struct qreg dst;
         struct qreg *src;
         bool sf;
+        bool cond_is_exec_mask;
         uint8_t cond;
 };
 
@@ -835,11 +836,13 @@ qir_ROT_MUL(struct vc4_compile *c, struct qreg val, uint32_t rot)
                                                 QPU_SMALL_IMM_MUL_ROT + rot)));
 }
 
-static inline void
+static inline struct qinst *
 qir_MOV_cond(struct vc4_compile *c, uint8_t cond,
              struct qreg dest, struct qreg src)
 {
-        qir_MOV_dest(c, dest, src)->cond = cond;
+        struct qinst *mov = qir_MOV_dest(c, dest, src);
+        mov->cond = cond;
+        return mov;
 }
 
 static inline struct qinst *
diff --git a/src/gallium/drivers/vc4/vc4_qir_live_variables.c b/src/gallium/drivers/vc4/vc4_qir_live_variables.c
index eac350ab852..beefb0d7f8a 100644
--- a/src/gallium/drivers/vc4/vc4_qir_live_variables.c
+++ b/src/gallium/drivers/vc4/vc4_qir_live_variables.c
@@ -113,8 +113,17 @@ qir_setup_def(struct vc4_compile *c, struct qblock *block, int ip,
         if (BITSET_TEST(block->use, var) || BITSET_TEST(block->def, var))
                 return;
 
-        /* Easy, common case: unconditional full register update. */
-        if (inst->cond == QPU_COND_ALWAYS && !inst->dst.pack) {
+        /* Easy, common case: unconditional full register update.
+         *
+         * We treat conditioning on the exec mask as the same as not being
+         * conditional.  This makes sure that if the register gets set on
+         * either side of an if, it is treated as being screened off before
+         * the if.  Otherwise, if there was no intervening def, its live
+         * interval doesn't extend back to the start of he program, and if too
+         * many registers did that we'd fail to register allocate.
+         */
+        if ((inst->cond == QPU_COND_ALWAYS ||
+             inst->cond_is_exec_mask) && !inst->dst.pack) {
                 BITSET_SET(block->def, var);
                 return;
         }