[Mesa-dev] [PATCH v2 1/9] vc4: Do all uniform loads with byte offsets

[Jason Ekstrand]

Previously, we lowered direct uniform loads to dword offsets and indirect
loads to byte offsets in vc4_nir_lower_io.  However, it simplifies things a
bit if we just use byte offsets for everything and then divide by 4 when we
handle the direct uniform load.

Cc: Eric Anholt <eric at anholt.net>
---
 src/gallium/drivers/vc4/vc4_nir_lower_io.c | 17 +++++------------
 src/gallium/drivers/vc4/vc4_program.c      | 11 +++++++----
 2 files changed, 12 insertions(+), 16 deletions(-)

diff --git a/src/gallium/drivers/vc4/vc4_nir_lower_io.c b/src/gallium/drivers/vc4/vc4_nir_lower_io.c
index 1afe52a..e2581c8 100644
--- a/src/gallium/drivers/vc4/vc4_nir_lower_io.c
+++ b/src/gallium/drivers/vc4/vc4_nir_lower_io.c
@@ -338,8 +338,8 @@ static void
 vc4_nir_lower_uniform(struct vc4_compile *c, nir_builder *b,
                       nir_intrinsic_instr *intr)
 {
-        /* All TGSI-to-NIR uniform loads are vec4, but we may create dword
-         * loads in our lowering passes.
+        /* All TGSI-to-NIR uniform loads are vec4, but we need byte offsets
+         * byte offsets in the backend.
          */
         if (intr->num_components == 1)
                 return;
@@ -355,6 +355,9 @@ vc4_nir_lower_uniform(struct vc4_compile *c, nir_builder *b,
                 intr_comp->num_components = 1;
                 nir_ssa_dest_init(&intr_comp->instr, &intr_comp->dest, 1, NULL);
 
+                /* Convert the base offset to bytes and add the component */
+                intr_comp->const_index[0] = (intr->const_index[0] * 16 + i * 4);
+
                 if (intr->intrinsic == nir_intrinsic_load_uniform_indirect) {
                         /* Convert the variable TGSI register index to a byte
                          * offset.
@@ -363,16 +366,6 @@ vc4_nir_lower_uniform(struct vc4_compile *c, nir_builder *b,
                                 nir_src_for_ssa(nir_ishl(b,
                                                          intr->src[0].ssa,
                                                          nir_imm_int(b, 4)));
-
-                        /* Convert the offset to be a byte index, too. */
-                        intr_comp->const_index[0] = (intr->const_index[0] * 16 +
-                                                     i * 4);
-                } else {
-                        /* We want a dword index for non-indirect uniform
-                         * loads.
-                         */
-                        intr_comp->const_index[0] = (intr->const_index[0] * 4 +
-                                                     i);
                 }
 
                 dests[i] = &intr_comp->dest.ssa;
diff --git a/src/gallium/drivers/vc4/vc4_program.c b/src/gallium/drivers/vc4/vc4_program.c
index 197577b..1a45bac 100644
--- a/src/gallium/drivers/vc4/vc4_program.c
+++ b/src/gallium/drivers/vc4/vc4_program.c
@@ -1433,6 +1433,7 @@ static void
 ntq_emit_intrinsic(struct vc4_compile *c, nir_intrinsic_instr *instr)
 {
         const nir_intrinsic_info *info = &nir_intrinsic_infos[instr->intrinsic];
+        int dword_offset;
         struct qreg *dest = NULL;
 
         if (info->has_dest) {
@@ -1442,11 +1443,13 @@ ntq_emit_intrinsic(struct vc4_compile *c, nir_intrinsic_instr *instr)
         switch (instr->intrinsic) {
         case nir_intrinsic_load_uniform:
                 assert(instr->num_components == 1);
-                if (instr->const_index[0] < VC4_NIR_STATE_UNIFORM_OFFSET) {
-                        *dest = qir_uniform(c, QUNIFORM_UNIFORM,
-                                            instr->const_index[0]);
+                /* The offset is in bytes, but we need dwords */
+                assert(instr->const_index[0] % 4 == 0);
+                dword_offset = instr->const_index[0] / 4;
+                if (dword_offset < VC4_NIR_STATE_UNIFORM_OFFSET) {
+                        *dest = qir_uniform(c, QUNIFORM_UNIFORM, dword_offset);
                 } else {
-                        *dest = qir_uniform(c, instr->const_index[0] -
+                        *dest = qir_uniform(c, dword_offset -
                                             VC4_NIR_STATE_UNIFORM_OFFSET,
                                             0);
                 }
-- 
2.5.0.400.gff86faf