Mesa (master): radv: Don't use a divide by index_size.

[Bas Nieuwenhuizen]

Module: Mesa
Branch: master
Commit: fe0b8d1e8b3343389b466cbd2b823716ead77399
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=fe0b8d1e8b3343389b466cbd2b823716ead77399

Author: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>
Date:   Tue Jun  6 18:22:23 2017 +0200

radv: Don't use a divide by index_size.

Divides are pretty slow, and this is in the hot path of a draw.

Signed-off-by: Bas Nieuwenhuizen <basni at google.com>
Reviewed-by: Dave Airlie <airlied at redhat.com>

---

 src/amd/vulkan/radv_cmd_buffer.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/src/amd/vulkan/radv_cmd_buffer.c b/src/amd/vulkan/radv_cmd_buffer.c
index c91c7b9188..ed0aa8020c 100644
--- a/src/amd/vulkan/radv_cmd_buffer.c
+++ b/src/amd/vulkan/radv_cmd_buffer.c
@@ -2643,6 +2643,12 @@ void radv_CmdDraw(
 	radv_cmd_buffer_trace_emit(cmd_buffer);
 }
 
+static
+uint32_t radv_get_max_index_count(struct radv_cmd_buffer *cmd_buffer) {
+	int index_size_shift = cmd_buffer->state.index_type ? 2 : 1;
+	return (cmd_buffer->state.index_buffer->size - cmd_buffer->state.index_offset) >> index_size_shift;
+}
+
 void radv_CmdDrawIndexed(
 	VkCommandBuffer                             commandBuffer,
 	uint32_t                                    indexCount,
@@ -2653,7 +2659,7 @@ void radv_CmdDrawIndexed(
 {
 	RADV_FROM_HANDLE(radv_cmd_buffer, cmd_buffer, commandBuffer);
 	int index_size = cmd_buffer->state.index_type ? 4 : 2;
-	uint32_t index_max_size = (cmd_buffer->state.index_buffer->size - cmd_buffer->state.index_offset) / index_size;
+	uint32_t index_max_size = radv_get_max_index_count(cmd_buffer);
 	uint64_t index_va;
 
 	radv_cmd_buffer_flush_state(cmd_buffer, true, (instanceCount > 1), false, indexCount);
@@ -2789,8 +2795,7 @@ radv_cmd_draw_indexed_indirect_count(
 	uint32_t                                    stride)
 {
 	RADV_FROM_HANDLE(radv_cmd_buffer, cmd_buffer, commandBuffer);
-	int index_size = cmd_buffer->state.index_type ? 4 : 2;
-	uint32_t index_max_size = (cmd_buffer->state.index_buffer->size - cmd_buffer->state.index_offset) / index_size;
+	uint32_t index_max_size = radv_get_max_index_count(cmd_buffer);
 	uint64_t index_va;
 	radv_cmd_buffer_flush_state(cmd_buffer, true, false, true, 0);