[Mesa-dev] [PATCH 27/29] mesa: Use bitmask/ffs to iterate the active_samplers bitmask.

[Mathias.Froehlich at gmx.net]

From: Mathias Fröhlich <mathias.froehlich at web.de>

Replaces an iterate and test bit in a bitmask loop by a
loop only iterating over the bits set in the bitmask.

v2: Use _mesa_bit_scan{,64} instead of open coding.
v3: Use u_bit_scan{,64} instead of _mesa_bit_scan{,64}.

Reviewed-by: Brian Paul <brianp at vmware.com>
Signed-off-by: Mathias Fröhlich <Mathias.Froehlich at web.de>
---
 src/mesa/main/uniform_query.cpp | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/mesa/main/uniform_query.cpp b/src/mesa/main/uniform_query.cpp
index eea611b..127f097 100644
--- a/src/mesa/main/uniform_query.cpp
+++ b/src/mesa/main/uniform_query.cpp
@@ -36,6 +36,7 @@
 #include "compiler/glsl/glsl_parser_extras.h"
 #include "compiler/glsl/program.h"
 #include "program/hash_table.h"
+#include "util/bitscan.h"
 
 
 extern "C" void GLAPIENTRY
@@ -843,9 +844,10 @@ _mesa_uniform(struct gl_context *ctx, struct gl_shader_program *shProg,
 	  * been modified.
 	  */
 	 bool changed = false;
-	 for (unsigned j = 0; j < ARRAY_SIZE(prog->SamplerUnits); j++) {
-	    if ((sh->active_samplers & (1U << j)) != 0
-		&& (prog->SamplerUnits[j] != sh->SamplerUnits[j])) {
+	 GLbitfield mask = sh->active_samplers;
+	 while (mask) {
+	    const int j = u_bit_scan(&mask);
+	    if (prog->SamplerUnits[j] != sh->SamplerUnits[j]) {
 	       changed = true;
 	       break;
 	    }
-- 
2.5.5