mesa: Use bitmask/ffs to iterate enabled clip planes.

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 <[email protected]>
Signed-off-by: Mathias Fröhlich <[email protected]>

4 files changed, 87 insertions, 89 deletions

diff --git a/src/mesa/tnl/t_vb_cliptmp.h b/src/mesa/tnl/t_vb_cliptmp.h
index 12181f085bc..c6546668806 100644
--- a/src/mesa/tnl/t_vb_cliptmp.h
+++ b/src/mesa/tnl/t_vb_cliptmp.h
@@ -124,7 +124,6 @@ TAG(clip_line)( struct gl_context *ctx, GLuint v0, GLuint v1, GLubyte mask )
    GLuint newvert = VB->Count;
    GLfloat t0 = 0;
    GLfloat t1 = 0;
-   GLuint p;
    const GLuint v0_orig = v0;
 
    if (mask & CLIP_FRUSTUM_BITS) {
@@ -137,14 +136,14 @@ TAG(clip_line)( struct gl_context *ctx, GLuint v0, GLuint v1, GLubyte mask )
    }
 
    if (mask & CLIP_USER_BIT) {
-      for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
-	 if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
-            const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
-            const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
-            const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
-            const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
-	    LINE_CLIP( CLIP_USER_BIT, a, b, c, d );
-	 }
+      GLbitfield enabled = ctx->Transform.ClipPlanesEnabled;
+      while (enabled) {
+         const int p = u_bit_scan(&enabled);
+         const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
+         const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
+         const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
+         const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
+         LINE_CLIP( CLIP_USER_BIT, a, b, c, d );
       }
    }
 
@@ -194,7 +193,6 @@ TAG(clip_tri)( struct gl_context *ctx, GLuint v0, GLuint v1, GLuint v2, GLubyte
    GLuint pv = v2;
    GLuint vlist[2][MAX_CLIPPED_VERTICES];
    GLuint *inlist = vlist[0], *outlist = vlist[1];
-   GLuint p;
    GLuint n = 3;
 
    ASSIGN_3V(inlist, v2, v0, v1 ); /* pv rotated to slot zero */
@@ -226,14 +224,14 @@ TAG(clip_tri)( struct gl_context *ctx, GLuint v0, GLuint v1, GLuint v2, GLubyte
    }
 
    if (mask & CLIP_USER_BIT) {
-      for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
-         if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
-            const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
-            const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
-            const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
-            const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
-            POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
-         }
+      GLbitfield enabled = ctx->Transform.ClipPlanesEnabled;
+      while (enabled) {
+         const int p = u_bit_scan(&enabled);
+         const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
+         const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
+         const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
+         const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
+         POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
       }
    }
 
@@ -274,7 +272,6 @@ TAG(clip_quad)( struct gl_context *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint
    GLuint pv = v3;
    GLuint vlist[2][MAX_CLIPPED_VERTICES];
    GLuint *inlist = vlist[0], *outlist = vlist[1];
-   GLuint p;
    GLuint n = 4;
 
    ASSIGN_4V(inlist, v3, v0, v1, v2 ); /* pv rotated to slot zero */
@@ -289,14 +286,14 @@ TAG(clip_quad)( struct gl_context *ctx, GLuint v0, GLuint v1, GLuint v2, GLuint
    }
 
    if (mask & CLIP_USER_BIT) {
-      for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
-	 if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
-            const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
-            const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
-            const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
-            const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
-	    POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
-	 }
+      GLbitfield enabled = ctx->Transform.ClipPlanesEnabled;
+      while (enabled) {
+         const int p = u_bit_scan(&enabled);
+         const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
+         const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
+         const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
+         const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
+         POLY_CLIP( CLIP_USER_BIT, a, b, c, d );
       }
    }
 
diff --git a/src/mesa/tnl/t_vb_program.c b/src/mesa/tnl/t_vb_program.c
index 21fd6cd1a06..55c44d1845b 100644
--- a/src/mesa/tnl/t_vb_program.c
+++ b/src/mesa/tnl/t_vb_program.c
@@ -40,6 +40,7 @@
 #include "program/prog_statevars.h"
 #include "program/prog_execute.h"
 #include "swrast/s_context.h"
+#include "util/bitscan.h"
 
 #include "tnl/tnl.h"
 #include "tnl/t_context.h"
@@ -84,40 +85,38 @@ userclip( struct gl_context *ctx,
           GLubyte *clipormask,
           GLubyte *clipandmask )
 {
-   GLuint p;
-
-   for (p = 0; p < ctx->Const.MaxClipPlanes; p++) {
-      if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {
-	 GLuint nr, i;
-	 const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
-	 const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
-	 const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
-	 const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
-         GLfloat *coord = (GLfloat *)clip->data;
-         GLuint stride = clip->stride;
-         GLuint count = clip->count;
-
-	 for (nr = 0, i = 0 ; i < count ; i++) {
-	    GLfloat dp = (coord[0] * a + 
-			  coord[1] * b +
-			  coord[2] * c +
-			  coord[3] * d);
-
-	    if (dp < 0) {
-	       nr++;
-	       clipmask[i] |= CLIP_USER_BIT;
-	    }
-
-	    STRIDE_F(coord, stride);
-	 }
+   GLbitfield mask = ctx->Transform.ClipPlanesEnabled;
+   while (mask) {
+      const int p = u_bit_scan(&mask);
+      GLuint nr, i;
+      const GLfloat a = ctx->Transform._ClipUserPlane[p][0];
+      const GLfloat b = ctx->Transform._ClipUserPlane[p][1];
+      const GLfloat c = ctx->Transform._ClipUserPlane[p][2];
+      const GLfloat d = ctx->Transform._ClipUserPlane[p][3];
+      GLfloat *coord = (GLfloat *)clip->data;
+      GLuint stride = clip->stride;
+      GLuint count = clip->count;
+
+      for (nr = 0, i = 0 ; i < count ; i++) {
+         GLfloat dp = (coord[0] * a +
+                       coord[1] * b +
+                       coord[2] * c +
+                       coord[3] * d);
+
+         if (dp < 0) {
+            nr++;
+            clipmask[i] |= CLIP_USER_BIT;
+         }
+
+         STRIDE_F(coord, stride);
+      }
 
-	 if (nr > 0) {
-	    *clipormask |= CLIP_USER_BIT;
-	    if (nr == count) {
-	       *clipandmask |= CLIP_USER_BIT;
-	       return;
-	    }
-	 }
+      if (nr > 0) {
+         *clipormask |= CLIP_USER_BIT;
+         if (nr == count) {
+            *clipandmask |= CLIP_USER_BIT;
+            return;
+         }
       }
    }
 }
diff --git a/src/mesa/tnl/t_vb_render.c b/src/mesa/tnl/t_vb_render.c
index 03e8fcfa196..9ff1f18f53b 100644
--- a/src/mesa/tnl/t_vb_render.c
+++ b/src/mesa/tnl/t_vb_render.c
@@ -46,6 +46,7 @@
 #include "main/imports.h"
 #include "main/mtypes.h"
 #include "math/m_xform.h"
+#include "util/bitscan.h"
 
 #include "t_pipeline.h"
 
diff --git a/src/mesa/tnl/t_vb_vertex.c b/src/mesa/tnl/t_vb_vertex.c
index b56d6803c99..71a32b49528 100644
--- a/src/mesa/tnl/t_vb_vertex.c
+++ b/src/mesa/tnl/t_vb_vertex.c
@@ -33,6 +33,8 @@
 
 #include "math/m_xform.h"
 
+#include "util/bitscan.h"
+
 #include "t_context.h"
 #include "t_pipeline.h"
 
@@ -63,40 +65,39 @@ static void NAME( struct gl_context *ctx,				\
 		  GLubyte *clipormask,				\
 		  GLubyte *clipandmask )			\
 {								\
-   GLuint p;							\
-								\
-   for (p = 0; p < ctx->Const.MaxClipPlanes; p++)		\
-      if (ctx->Transform.ClipPlanesEnabled & (1 << p)) {	\
-	 GLuint nr, i;						\
-	 const GLfloat a = ctx->Transform._ClipUserPlane[p][0];	\
-	 const GLfloat b = ctx->Transform._ClipUserPlane[p][1];	\
-	 const GLfloat c = ctx->Transform._ClipUserPlane[p][2];	\
-	 const GLfloat d = ctx->Transform._ClipUserPlane[p][3];	\
-         GLfloat *coord = (GLfloat *)clip->data;		\
-         GLuint stride = clip->stride;				\
-         GLuint count = clip->count;				\
+   GLbitfield mask = ctx->Transform.ClipPlanesEnabled;          \
+   while (mask) {                                               \
+      const int p = u_bit_scan(&mask);                          \
+      GLuint nr, i;						\
+      const GLfloat a = ctx->Transform._ClipUserPlane[p][0];	\
+      const GLfloat b = ctx->Transform._ClipUserPlane[p][1];	\
+      const GLfloat c = ctx->Transform._ClipUserPlane[p][2];	\
+      const GLfloat d = ctx->Transform._ClipUserPlane[p][3];	\
+      GLfloat *coord = (GLfloat *)clip->data;                   \
+      GLuint stride = clip->stride;				\
+      GLuint count = clip->count;				\
 								\
-	 for (nr = 0, i = 0 ; i < count ; i++) {		\
-	    GLfloat dp = coord[0] * a + coord[1] * b;		\
-	    if (SZ > 2) dp += coord[2] * c;			\
-	    if (SZ > 3) dp += coord[3] * d; else dp += d;	\
+      for (nr = 0, i = 0 ; i < count ; i++) {                   \
+         GLfloat dp = coord[0] * a + coord[1] * b;		\
+         if (SZ > 2) dp += coord[2] * c;			\
+         if (SZ > 3) dp += coord[3] * d; else dp += d;          \
 								\
-	    if (dp < 0) {					\
-	       nr++;						\
-	       clipmask[i] |= CLIP_USER_BIT;			\
-	    }							\
+         if (dp < 0) {                                          \
+            nr++;						\
+            clipmask[i] |= CLIP_USER_BIT;			\
+         }							\
 								\
-	    STRIDE_F(coord, stride);				\
-	 }							\
+         STRIDE_F(coord, stride);				\
+      }                                                         \
 								\
-	 if (nr > 0) {						\
-	    *clipormask |= CLIP_USER_BIT;			\
-	    if (nr == count) {					\
-	       *clipandmask |= CLIP_USER_BIT;			\
-	       return;						\
-	    }							\
-	 }							\
+      if (nr > 0) {						\
+         *clipormask |= CLIP_USER_BIT;                          \
+         if (nr == count) {					\
+            *clipandmask |= CLIP_USER_BIT;			\
+            return;						\
+         }							\
       }								\
+   }								\
 }