Add OpenMP IF clauses to filter templates, instead of modifying num_threads

(bzr r9508.1.37)

1 files changed, 14 insertions, 17 deletions

diff --git a/src/display/cairo-templates.h b/src/display/cairo-templates.h
index 900ca2d54..78fdff664 100644
--- a/src/display/cairo-templates.h
+++ b/src/display/cairo-templates.h
@@ -16,7 +16,7 @@
 #include <omp.h>
 #include "preferences.h"
 // single-threaded operation if the number of pixels is below this threshold
-#define OPENMP_THRESHOLD 2048
+static const int OPENMP_THRESHOLD = 2048;
 #endif
 
 #include <algorithm>
@@ -70,7 +70,6 @@ void ink_cairo_surface_blend(cairo_surface_t *in1, cairo_surface_t *in2, cairo_s
     #if HAVE_OPENMP
     Inkscape::Preferences *prefs = Inkscape::Preferences::get();
     int num_threads = prefs->getIntLimited("/options/threading/numthreads", omp_get_num_procs(), 1, 256);
-    if (limit < OPENMP_THRESHOLD) num_threads = 1; // do not spawn threads for very small surfaces
     #endif
 
     // The number of code paths here is evil.
@@ -78,14 +77,14 @@ void ink_cairo_surface_blend(cairo_surface_t *in1, cairo_surface_t *in2, cairo_s
         if (bpp2 == 4) {
             if (fast_path) {
                 #if HAVE_OPENMP
-                #pragma omp parallel for num_threads(num_threads)
+                #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
                 #endif
                 for (int i = 0; i < limit; ++i) {
                     *(out_data + i) = blend(*(in1_data + i), *(in2_data + i));
                 }
             } else {
                 #if HAVE_OPENMP
-                #pragma omp parallel for num_threads(num_threads)
+                #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
                 #endif
                 for (int i = 0; i < h; ++i) {
                     guint32 *in1_p = in1_data + i * stride1/4;
@@ -100,7 +99,7 @@ void ink_cairo_surface_blend(cairo_surface_t *in1, cairo_surface_t *in2, cairo_s
         } else {
             // bpp2 == 1
             #if HAVE_OPENMP
-            #pragma omp parallel for num_threads(num_threads)
+            #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
             #endif
             for (int i = 0; i < h; ++i) {
                 guint32 *in1_p = in1_data + i * stride1/4;
@@ -118,7 +117,7 @@ void ink_cairo_surface_blend(cairo_surface_t *in1, cairo_surface_t *in2, cairo_s
         if (bpp2 == 4) {
             // bpp1 == 1
             #if HAVE_OPENMP
-            #pragma omp parallel for num_threads(num_threads)
+            #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
             #endif
             for (int i = 0; i < h; ++i) {
                 guint8  *in1_p = reinterpret_cast<guint8*>(in1_data) + i * stride1;
@@ -135,7 +134,7 @@ void ink_cairo_surface_blend(cairo_surface_t *in1, cairo_surface_t *in2, cairo_s
             // bpp1 == 1 && bpp2 == 1
             if (fast_path) {
                 #if HAVE_OPENMP
-                #pragma omp parallel for num_threads(num_threads)
+                #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
                 #endif
                 for (int i = 0; i < limit; ++i) {
                     guint8 *in1_p = reinterpret_cast<guint8*>(in1_data) + i;
@@ -148,7 +147,7 @@ void ink_cairo_surface_blend(cairo_surface_t *in1, cairo_surface_t *in2, cairo_s
                 }
             } else {
                 #if HAVE_OPENMP
-                #pragma omp parallel for num_threads(num_threads)
+                #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
                 #endif
                 for (int i = 0; i < h; ++i) {
                     guint8 *in1_p = reinterpret_cast<guint8*>(in1_data) + i * stride1;
@@ -199,7 +198,6 @@ void ink_cairo_surface_filter(cairo_surface_t *in, cairo_surface_t *out, Filter
     #if HAVE_OPENMP
     Inkscape::Preferences *prefs = Inkscape::Preferences::get();
     int num_threads = prefs->getIntLimited("/options/threading/numthreads", omp_get_num_procs(), 1, 256);
-    if (limit < OPENMP_THRESHOLD) num_threads = 1; // do not spawn threads for very small surfaces
     #endif
 
     if (bppin == 4) {
@@ -207,14 +205,14 @@ void ink_cairo_surface_filter(cairo_surface_t *in, cairo_surface_t *out, Filter
             // bppin == 4, bppout == 4
             if (fast_path) {
                 #if HAVE_OPENMP
-                #pragma omp parallel for num_threads(num_threads)
+                #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
                 #endif
                 for (int i = 0; i < limit; ++i) {
                     *(out_data + i) = filter(*(in_data + i));
                 }
             } else {
                 #if HAVE_OPENMP
-                #pragma omp parallel for num_threads(num_threads)
+                #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
                 #endif
                 for (int i = 0; i < h; ++i) {
                     guint32 *in_p = in_data + i * stridein/4;
@@ -229,7 +227,7 @@ void ink_cairo_surface_filter(cairo_surface_t *in, cairo_surface_t *out, Filter
             // bppin == 4, bppout == 1
             // we use this path with COLORMATRIX_LUMINANCETOALPHA
             #if HAVE_OPENMP
-            #pragma omp parallel for num_threads(num_threads)
+            #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
             #endif
             for (int i = 0; i < h; ++i) {
                 guint32 *in_p = in_data + i * stridein/4;
@@ -246,7 +244,7 @@ void ink_cairo_surface_filter(cairo_surface_t *in, cairo_surface_t *out, Filter
         // Note: there is no path for bppin == 1, bppout == 4 because it is useless
         if (fast_path) {
             #if HAVE_OPENMP
-            #pragma omp parallel for num_threads(num_threads)
+            #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
             #endif
             for (int i = 0; i < limit; ++i) {
                 guint8 *in_p = reinterpret_cast<guint8*>(in_data) + i;
@@ -257,7 +255,7 @@ void ink_cairo_surface_filter(cairo_surface_t *in, cairo_surface_t *out, Filter
             }
         } else {
             #if HAVE_OPENMP
-            #pragma omp parallel for num_threads(num_threads)
+            #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
             #endif
             for (int i = 0; i < h; ++i) {
                 guint8 *in_p = reinterpret_cast<guint8*>(in_data) + i * stridein;
@@ -301,12 +299,11 @@ void ink_cairo_surface_synthesize(cairo_surface_t *out, cairo_rectangle_t const
     int limit = w * h;
     Inkscape::Preferences *prefs = Inkscape::Preferences::get();
     int num_threads = prefs->getIntLimited("/options/threading/numthreads", omp_get_num_procs(), 1, 256);
-    if (limit < OPENMP_THRESHOLD) num_threads = 1; // do not spawn threads for very small surfaces
     #endif
 
     if (bppout == 4) {
         #if HAVE_OPENMP
-        #pragma omp parallel for num_threads(num_threads)
+        #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
         #endif
         for (int i = out_area.y; i < h; ++i) {
             guint32 *out_p = reinterpret_cast<guint32*>(out_data + i * strideout);
@@ -318,7 +315,7 @@ void ink_cairo_surface_synthesize(cairo_surface_t *out, cairo_rectangle_t const
     } else {
         // bppout == 1
         #if HAVE_OPENMP
-        #pragma omp parallel for num_threads(num_threads)
+        #pragma omp parallel for if(limit > OPENMP_THRESHOLD) num_threads(num_threads)
         #endif
         for (int i = out_area.y; i < h; ++i) {
             guint8 *out_p = out_data + i * strideout;