iris: Fix DrawTransformFeedback math when there's a buffer offset

We need to subtract the starting offset from the final offset before
dividing by the stride.  See src/intel/vulkan/genX_cmd_buffer.c:3142.

Not known to fix anything.

3 files changed, 14 insertions, 0 deletions

diff --git a/src/gallium/drivers/iris/iris_context.h b/src/gallium/drivers/iris/iris_context.h
index ab70fc58718..f660c9ae251 100644
--- a/src/gallium/drivers/iris/iris_context.h
+++ b/src/gallium/drivers/iris/iris_context.h
@@ -782,6 +782,9 @@ bool iris_blorp_upload_shader(struct blorp_batch *blorp_batch,
 void iris_math_div32_gpr0(struct iris_context *ice,
                           struct iris_batch *batch,
                           uint32_t D);
+void iris_math_add32_gpr0(struct iris_context *ice,
+                          struct iris_batch *batch,
+                          uint32_t x);
 
 uint64_t iris_timebase_scale(const struct gen_device_info *devinfo,
                              uint64_t gpu_timestamp);
diff --git a/src/gallium/drivers/iris/iris_query.c b/src/gallium/drivers/iris/iris_query.c
index 904feba39cc..eace45c64ed 100644
--- a/src/gallium/drivers/iris/iris_query.c
+++ b/src/gallium/drivers/iris/iris_query.c
@@ -503,6 +503,15 @@ iris_math_div32_gpr0(struct iris_context *ice,
    }
 }
 
+void
+iris_math_add32_gpr0(struct iris_context *ice,
+                     struct iris_batch *batch,
+                     uint32_t x)
+{
+   emit_lri32(batch, CS_GPR(1), x);
+   emit_alu_add(batch, MI_ALU_R0, MI_ALU_R0, MI_ALU_R1);
+}
+
 /*
  * GPR0 = (GPR0 == 0) ? 0 : 1;
  */
diff --git a/src/gallium/drivers/iris/iris_state.c b/src/gallium/drivers/iris/iris_state.c
index 55ed7be647a..f4d7c698a6c 100644
--- a/src/gallium/drivers/iris/iris_state.c
+++ b/src/gallium/drivers/iris/iris_state.c
@@ -5203,6 +5203,8 @@ iris_upload_render_state(struct iris_context *ice,
          lrm.MemoryAddress =
             ro_bo(iris_resource_bo(so->offset.res), so->offset.offset);
       }
+      if (so->base.buffer_offset)
+         iris_math_add32_gpr0(ice, batch, -so->base.buffer_offset);
       iris_math_div32_gpr0(ice, batch, so->stride);
       _iris_emit_lrr(batch, _3DPRIM_VERTEX_COUNT, CS_GPR(0));