[Mesa-dev] [PATCH 2/3] i965: Convert reloc.target_handle into an index for I915_EXEC_HANDLE_LUT

[Chris Wilson]

Passing the index of the target buffer via the reloc.target_handle is
marginally more efficient for the kernel (it can avoid some allocations,
and can use a direct lookup rather than a hash or search). It is also
useful for ourselves as we can use the index into our exec_bos for other
tasks.

Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
Cc: Kenneth Graunke <kenneth at whitecape.org>
Cc: Jason Ekstrand <jason.ekstrand at intel.com>
---
 src/mesa/drivers/dri/i965/intel_batchbuffer.c | 30 ++++++++++++++++++---------
 1 file changed, 20 insertions(+), 10 deletions(-)

diff --git a/src/mesa/drivers/dri/i965/intel_batchbuffer.c b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
index 752e9b389b..2e10d165c7 100644
--- a/src/mesa/drivers/dri/i965/intel_batchbuffer.c
+++ b/src/mesa/drivers/dri/i965/intel_batchbuffer.c
@@ -518,19 +518,19 @@ throttle(struct brw_context *brw)
 
 #define READ_ONCE(x) (*(volatile __typeof__(x) *)&(x))
 
-static void
+static unsigned int
 add_exec_bo(struct intel_batchbuffer *batch, struct brw_bo *bo)
 {
    if (bo != batch->bo) {
       unsigned int index = READ_ONCE(bo->index);
 
       if (index < batch->exec_count && batch->exec_bos[index] == bo)
-         return;
+         return index;
 
       /* May have been shared between multiple active batches */
       for (index = 0; index < batch->exec_count; index++) {
          if (batch->exec_bos[index] == bo)
-            return;
+            return index;
       }
 
       brw_bo_reference(bo);
@@ -564,8 +564,9 @@ add_exec_bo(struct intel_batchbuffer *batch, struct brw_bo *bo)
 
    bo->index = batch->exec_count;
    batch->exec_bos[batch->exec_count] = bo;
-   batch->exec_count++;
    batch->aperture_space += bo->size;
+
+   return batch->exec_count++;
 }
 
 static int
@@ -643,21 +644,28 @@ do_flush_locked(struct brw_context *brw, int in_fence_fd, int *out_fence_fd)
    }
 
    if (!brw->screen->no_hw) {
-      int flags;
+      unsigned int flags;
 
+      flags = I915_EXEC_HANDLE_LUT;
       if (brw->gen >= 6 && batch->ring == BLT_RING) {
-         flags = I915_EXEC_BLT;
+         flags |= I915_EXEC_BLT;
       } else {
-         flags = I915_EXEC_RENDER;
+         flags |= I915_EXEC_RENDER;
       }
       if (batch->needs_sol_reset)
 	 flags |= I915_EXEC_GEN7_SOL_RESET;
 
       if (ret == 0) {
          uint32_t hw_ctx = batch->ring == RENDER_RING ? brw->hw_ctx : 0;
+         unsigned int index;
 
          /* Add the batch itself to the end of the validation list */
-         add_exec_bo(batch, batch->bo);
+         index = add_exec_bo(batch, batch->bo);
+         for (unsigned int i = 0; i < batch->reloc_count; i++) {
+            struct drm_i915_gem_relocation_entry *reloc = &batch->relocs[i];
+            if (reloc->target_handle == -1)
+               reloc->target_handle = index;
+         }
 
          ret = execbuffer(dri_screen->fd, batch, hw_ctx,
                           4 * USED_BATCH(*batch),
@@ -768,6 +776,7 @@ brw_emit_reloc(struct intel_batchbuffer *batch, uint32_t batch_offset,
                uint32_t read_domains, uint32_t write_domain)
 {
    uint64_t offset64;
+   unsigned int index;
 
    if (batch->reloc_count == batch->reloc_array_size) {
       batch->reloc_array_size *= 2;
@@ -780,8 +789,9 @@ brw_emit_reloc(struct intel_batchbuffer *batch, uint32_t batch_offset,
    assert(batch_offset <= BATCH_SZ - sizeof(uint32_t));
    assert(_mesa_bitcount(write_domain) <= 1);
 
+   index = -1; /* to be fixed up later when the index of the batch is known */
    if (target != batch->bo)
-      add_exec_bo(batch, target);
+      index = add_exec_bo(batch, target);
 
    struct drm_i915_gem_relocation_entry *reloc =
       &batch->relocs[batch->reloc_count];
@@ -792,7 +802,7 @@ brw_emit_reloc(struct intel_batchbuffer *batch, uint32_t batch_offset,
    offset64 = *((volatile uint64_t *)&target->offset64);
    reloc->offset = batch_offset;
    reloc->delta = target_offset;
-   reloc->target_handle = target->gem_handle;
+   reloc->target_handle = index;
    reloc->read_domains = read_domains;
    reloc->write_domain = write_domain;
    reloc->presumed_offset = offset64;
-- 
2.11.0