Mesa (master): mesa: check for no matrix change in _mesa_LoadMatrixf()

[Brian Paul]

Module: Mesa
Branch: master
Commit: 0d2eb8c14d8c791603cb60cb56ed468ee49543ad
URL:    http://cgit.freedesktop.org/mesa/mesa/commit/?id=0d2eb8c14d8c791603cb60cb56ed468ee49543ad

Author: Brian Paul <brianp at vmware.com>
Date:   Wed Sep 14 12:16:18 2016 -0600

mesa: check for no matrix change in _mesa_LoadMatrixf()

Some apps issue redundant glLoadMatrixf() calls with the same matrix.
Try to avoid setting dirty state in that situation.

This reduces the number of constant buffer updates by about half in
ET Quake Wars.

Tested with Piglit, ETQW, Sauerbraten, Google Earth, etc.

Reviewed-by: Charmaine Lee <charmainel at vmware.com>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>

---

 src/mesa/main/matrix.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/mesa/main/matrix.c b/src/mesa/main/matrix.c
index b30b983..83f081e 100644
--- a/src/mesa/main/matrix.c
+++ b/src/mesa/main/matrix.c
@@ -356,9 +356,11 @@ _mesa_LoadMatrixf( const GLfloat *m )
           m[2], m[6], m[10], m[14],
           m[3], m[7], m[11], m[15]);
 
-   FLUSH_VERTICES(ctx, 0);
-   _math_matrix_loadf( ctx->CurrentStack->Top, m );
-   ctx->NewState |= ctx->CurrentStack->DirtyFlag;
+   if (memcmp(m, ctx->CurrentStack->Top->m, 16 * sizeof(GLfloat)) != 0) {
+      FLUSH_VERTICES(ctx, 0);
+      _math_matrix_loadf( ctx->CurrentStack->Top, m );
+      ctx->NewState |= ctx->CurrentStack->DirtyFlag;
+   }
 }