gallium/util: load s3tc on demand

This changes the S3TC function pointers to be initialized to stubs
that load the S3TC library and then delegate to the real functions.

If the S3TC library fails to load, the function pointers are replaced
with a "nop" function.

The code is also changed to attempt to load the library only one time.c

Note that unlike checking for a flag, this method has no performance
cost at all.

The use of the "nop" functions also allows to avoid most checks, that
are only preserved when the function does non-trivial work.

2 files changed, 151 insertions, 107 deletions

diff --git a/src/gallium/auxiliary/util/u_format_s3tc.c b/src/gallium/auxiliary/util/u_format_s3tc.c
index 268f0e8dfab..8a5e6f0c437 100644
--- a/src/gallium/auxiliary/util/u_format_s3tc.c
+++ b/src/gallium/auxiliary/util/u_format_s3tc.c
@@ -34,58 +34,118 @@
 #define DXTN_LIBNAME "libtxc_dxtn.so"
 #endif
 
+static void
+util_format_dxt1_rgb_fetch_stub( int src_stride,
+                             const uint8_t *src,
+                             int col, int row,
+                             uint8_t *dst )
+{
+   util_format_s3tc_init();
+   util_format_dxt1_rgb_fetch(src_stride, src, col, row, dst);
+}
 
-boolean util_format_s3tc_enabled = FALSE;
-
-util_format_dxtn_fetch_t util_format_dxt1_rgb_fetch = NULL;
-util_format_dxtn_fetch_t util_format_dxt1_rgba_fetch = NULL;
-util_format_dxtn_fetch_t util_format_dxt3_rgba_fetch = NULL;
-util_format_dxtn_fetch_t util_format_dxt5_rgba_fetch = NULL;
+static void
+util_format_dxt1_rgba_fetch_stub( int src_stride,
+                             const uint8_t *src,
+                             int col, int row,
+                             uint8_t *dst )
+{
+   util_format_s3tc_init();
+   util_format_dxt1_rgba_fetch(src_stride, src, col, row, dst);
+}
 
-util_format_dxtn_pack_t util_format_dxtn_pack = NULL;
+static void
+util_format_dxt3_rgba_fetch_stub( int src_stride,
+                             const uint8_t *src,
+                             int col, int row,
+                             uint8_t *dst )
+{
+   util_format_s3tc_init();
+   util_format_dxt3_rgba_fetch(src_stride, src, col, row, dst);
+}
 
+static void
+util_format_dxt5_rgba_fetch_stub( int src_stride,
+                             const uint8_t *src,
+                             int col, int row,
+                             uint8_t *dst )
+{
+   util_format_s3tc_init();
+   util_format_dxt5_rgba_fetch(src_stride, src, col, row, dst);
+}
 
-void
-util_format_s3tc_init(void)
+static
+void util_format_dxtn_pack_stub( int src_comps,
+                            int width, int height,
+                            const uint8_t *src,
+                            enum util_format_dxtn dst_format,
+                            uint8_t *dst,
+                            int dst_stride)
 {
-   static struct util_dl_library *
-   library = NULL;
+   util_format_s3tc_init();
+   util_format_dxtn_pack_stub(src_comps, width, height, src, dst_format, dst, dst_stride);
+}
 
-   if (util_format_s3tc_enabled)
-      return;
+boolean util_format_s3tc_enabled = FALSE;
+boolean util_format_s3tc_inited = FALSE;
 
-   if (!library) {
-      library = util_dl_open(DXTN_LIBNAME);
-      if (!library) {
-	 debug_printf("couldn't open " DXTN_LIBNAME ", software DXTn "
-	    "compression/decompression unavailable");
-      }
-      else {
-         util_format_dxt1_rgb_fetch = (util_format_dxtn_fetch_t)
-            util_dl_get_proc_address(library, "fetch_2d_texel_rgb_dxt1");
-         util_format_dxt1_rgba_fetch = (util_format_dxtn_fetch_t)
-            util_dl_get_proc_address(library, "fetch_2d_texel_rgba_dxt1");
-         util_format_dxt3_rgba_fetch = (util_format_dxtn_fetch_t)
-            util_dl_get_proc_address(library, "fetch_2d_texel_rgba_dxt3");
-         util_format_dxt5_rgba_fetch = (util_format_dxtn_fetch_t)
-            util_dl_get_proc_address(library, "fetch_2d_texel_rgba_dxt5");
-         util_format_dxtn_pack = (util_format_dxtn_pack_t)
-            util_dl_get_proc_address(library, "tx_compress_dxtn");
-
-         if (util_format_dxt1_rgb_fetch ||
-             util_format_dxt1_rgba_fetch ||
-             util_format_dxt3_rgba_fetch ||
-             util_format_dxt5_rgba_fetch ||
-             util_format_dxtn_pack) {
-            util_format_s3tc_enabled = TRUE;
-            debug_printf("software DXTn compression/decompression available");
-
-         } else {
-	    debug_printf("couldn't reference all symbols in "
-	       DXTN_LIBNAME ", software DXTn compression/decompression "
-	       "unavailable");
-         }
-      }
+util_format_dxtn_fetch_t util_format_dxt1_rgb_fetch = util_format_dxt1_rgb_fetch_stub;
+util_format_dxtn_fetch_t util_format_dxt1_rgba_fetch = util_format_dxt1_rgba_fetch_stub;
+util_format_dxtn_fetch_t util_format_dxt3_rgba_fetch = util_format_dxt3_rgba_fetch_stub;
+util_format_dxtn_fetch_t util_format_dxt5_rgba_fetch = util_format_dxt5_rgba_fetch_stub;
+
+util_format_dxtn_pack_t util_format_dxtn_pack = util_format_dxtn_pack_stub;
+
+static void
+nop(void)
+{}
+
+#define is_nop(f) ((void*)(f) == (void*)nop)
+
+static util_dl_proc
+get_proc_address_or_nop(struct util_dl_library *library,
+                         const char *procname)
+{
+   if(library) {
+      util_dl_proc proc = util_dl_get_proc_address(library, procname);
+      if(proc)
+         return proc;
+   }
+   return (util_dl_proc)nop;
+}
+
+void
+util_format_s3tc_do_init(void)
+{
+   struct util_dl_library *library;
+
+   library = util_dl_open(DXTN_LIBNAME);
+   util_format_dxt1_rgb_fetch = (util_format_dxtn_fetch_t)
+      get_proc_address_or_nop(library, "fetch_2d_texel_rgb_dxt1");
+   util_format_dxt1_rgba_fetch = (util_format_dxtn_fetch_t)
+      get_proc_address_or_nop(library, "fetch_2d_texel_rgba_dxt1");
+   util_format_dxt3_rgba_fetch = (util_format_dxtn_fetch_t)
+      get_proc_address_or_nop(library, "fetch_2d_texel_rgba_dxt3");
+   util_format_dxt5_rgba_fetch = (util_format_dxtn_fetch_t)
+      get_proc_address_or_nop(library, "fetch_2d_texel_rgba_dxt5");
+   util_format_dxtn_pack = (util_format_dxtn_pack_t)
+      get_proc_address_or_nop(library, "tx_compress_dxtn");
+
+   if (!library)
+      debug_printf("couldn't open " DXTN_LIBNAME ", software DXTn "
+         "compression/decompression unavailable");
+   else {
+      if (!is_nop(util_format_dxt1_rgb_fetch) &&
+         !is_nop(util_format_dxt1_rgba_fetch) &&
+         !is_nop(util_format_dxt3_rgba_fetch) &&
+         !is_nop(util_format_dxt5_rgba_fetch) &&
+         !is_nop(util_format_dxtn_pack)) {
+         debug_printf("software DXTn compression/decompression available");
+         util_format_s3tc_enabled = TRUE;
+      } else
+         debug_printf("couldn't reference all symbols in "
+            DXTN_LIBNAME ", software DXTn compression/decompression "
+            "unavailable");
    }
 }
 
@@ -97,85 +157,69 @@ util_format_s3tc_init(void)
 void
 util_format_dxt1_rgb_fetch_8unorm(uint8_t *dst, const uint8_t *src, unsigned i, unsigned j)
 {
-   if (util_format_dxt1_rgb_fetch) {
-      util_format_dxt1_rgb_fetch(0, src, i, j, dst);
-   }
+   util_format_dxt1_rgb_fetch(0, src, i, j, dst);
 }
 
 void
 util_format_dxt1_rgba_fetch_8unorm(uint8_t *dst, const uint8_t *src, unsigned i, unsigned j)
 {
-   if (util_format_dxt1_rgba_fetch) {
-      util_format_dxt1_rgba_fetch(0, src, i, j, dst);
-   }
+   util_format_dxt1_rgba_fetch(0, src, i, j, dst);
 }
 
 void
 util_format_dxt3_rgba_fetch_8unorm(uint8_t *dst, const uint8_t *src, unsigned i, unsigned j)
 {
-   if (util_format_dxt3_rgba_fetch) {
-      util_format_dxt3_rgba_fetch(0, src, i, j, dst);
-   }
+   util_format_dxt3_rgba_fetch(0, src, i, j, dst);
 }
 
 void
 util_format_dxt5_rgba_fetch_8unorm(uint8_t *dst, const uint8_t *src, unsigned i, unsigned j)
 {
-   if (util_format_dxt5_rgba_fetch) {
-      util_format_dxt5_rgba_fetch(0, src, i, j, dst);
-   }
+   util_format_dxt5_rgba_fetch(0, src, i, j, dst);
 }
 
 void
 util_format_dxt1_rgb_fetch_float(float *dst, const uint8_t *src, unsigned i, unsigned j)
 {
-   if (util_format_dxt1_rgb_fetch) {
-      uint8_t tmp[4];
-      util_format_dxt1_rgb_fetch(0, src, i, j, tmp);
-      dst[0] = ubyte_to_float(tmp[0]);
-      dst[1] = ubyte_to_float(tmp[1]);
-      dst[2] = ubyte_to_float(tmp[2]);
-      dst[3] = 1.0;
-   }
+   uint8_t tmp[4];
+   util_format_dxt1_rgb_fetch(0, src, i, j, tmp);
+   dst[0] = ubyte_to_float(tmp[0]);
+   dst[1] = ubyte_to_float(tmp[1]);
+   dst[2] = ubyte_to_float(tmp[2]);
+   dst[3] = 1.0;
 }
 
 void
 util_format_dxt1_rgba_fetch_float(float *dst, const uint8_t *src, unsigned i, unsigned j)
 {
-   if (util_format_dxt1_rgba_fetch) {
-      uint8_t tmp[4];
-      util_format_dxt1_rgba_fetch(0, src, i, j, tmp);
-      dst[0] = ubyte_to_float(tmp[0]);
-      dst[1] = ubyte_to_float(tmp[1]);
-      dst[2] = ubyte_to_float(tmp[2]);
-      dst[3] = ubyte_to_float(tmp[3]);
-   }
+   uint8_t tmp[4];
+   util_format_dxt1_rgba_fetch(0, src, i, j, tmp);
+   dst[0] = ubyte_to_float(tmp[0]);
+   dst[1] = ubyte_to_float(tmp[1]);
+   dst[2] = ubyte_to_float(tmp[2]);
+   dst[3] = ubyte_to_float(tmp[3]);
 }
 
 void
 util_format_dxt3_rgba_fetch_float(float *dst, const uint8_t *src, unsigned i, unsigned j)
 {
-   if (util_format_dxt3_rgba_fetch) {
-      uint8_t tmp[4];
-      util_format_dxt3_rgba_fetch(0, src, i, j, tmp);
-      dst[0] = ubyte_to_float(tmp[0]);
-      dst[1] = ubyte_to_float(tmp[1]);
-      dst[2] = ubyte_to_float(tmp[2]);
-      dst[3] = ubyte_to_float(tmp[3]);
-   }
+   uint8_t tmp[4];
+   util_format_dxt3_rgba_fetch(0, src, i, j, tmp);
+   dst[0] = ubyte_to_float(tmp[0]);
+   dst[1] = ubyte_to_float(tmp[1]);
+   dst[2] = ubyte_to_float(tmp[2]);
+   dst[3] = ubyte_to_float(tmp[3]);
 }
 
 void
 util_format_dxt5_rgba_fetch_float(float *dst, const uint8_t *src, unsigned i, unsigned j)
 {
-   if (util_format_dxt5_rgba_fetch) {
-      uint8_t tmp[4];
-      util_format_dxt5_rgba_fetch(0, src, i, j, tmp);
-      dst[0] = ubyte_to_float(tmp[0]);
-      dst[1] = ubyte_to_float(tmp[1]);
-      dst[2] = ubyte_to_float(tmp[2]);
-      dst[3] = ubyte_to_float(tmp[3]);
-   }
+   uint8_t tmp[4];
+   util_format_dxt5_rgba_fetch(0, src, i, j, tmp);
+   dst[0] = ubyte_to_float(tmp[0]);
+   dst[1] = ubyte_to_float(tmp[1]);
+   dst[2] = ubyte_to_float(tmp[2]);
+   dst[3] = ubyte_to_float(tmp[3]);
 }
 
 
@@ -186,7 +230,7 @@ util_format_dxt5_rgba_fetch_float(float *dst, const uint8_t *src, unsigned i, un
 void
 util_format_dxt1_rgb_unpack_8unorm(uint8_t *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxt1_rgb_fetch) {
+   if (!is_nop(util_format_dxt1_rgb_fetch)) {
       unsigned x, y, i, j;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -207,7 +251,7 @@ util_format_dxt1_rgb_unpack_8unorm(uint8_t *dst_row, unsigned dst_stride, const
 void
 util_format_dxt1_rgba_unpack_8unorm(uint8_t *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxt1_rgba_fetch) {
+   if (!is_nop(util_format_dxt1_rgba_fetch)) {
       unsigned x, y, i, j;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -228,7 +272,7 @@ util_format_dxt1_rgba_unpack_8unorm(uint8_t *dst_row, unsigned dst_stride, const
 void
 util_format_dxt3_rgba_unpack_8unorm(uint8_t *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxt3_rgba_fetch) {
+   if (!is_nop(util_format_dxt3_rgba_fetch)) {
       unsigned x, y, i, j;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -249,7 +293,7 @@ util_format_dxt3_rgba_unpack_8unorm(uint8_t *dst_row, unsigned dst_stride, const
 void
 util_format_dxt5_rgba_unpack_8unorm(uint8_t *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxt5_rgba_fetch) {
+   if (is_nop(util_format_dxt5_rgba_fetch)) {
       unsigned x, y, i, j;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -270,7 +314,7 @@ util_format_dxt5_rgba_unpack_8unorm(uint8_t *dst_row, unsigned dst_stride, const
 void
 util_format_dxt1_rgb_unpack_float(float *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxt1_rgb_fetch) {
+   if (is_nop(util_format_dxt1_rgb_fetch)) {
       unsigned x, y, i, j;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -296,7 +340,7 @@ util_format_dxt1_rgb_unpack_float(float *dst_row, unsigned dst_stride, const uin
 void
 util_format_dxt1_rgba_unpack_float(float *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxt1_rgba_fetch) {
+   if (!is_nop(util_format_dxt1_rgba_fetch)) {
       unsigned x, y, i, j;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -322,7 +366,7 @@ util_format_dxt1_rgba_unpack_float(float *dst_row, unsigned dst_stride, const ui
 void
 util_format_dxt3_rgba_unpack_float(float *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxt3_rgba_fetch) {
+   if (!is_nop(util_format_dxt3_rgba_fetch)) {
       unsigned x, y, i, j;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -348,7 +392,7 @@ util_format_dxt3_rgba_unpack_float(float *dst_row, unsigned dst_stride, const ui
 void
 util_format_dxt5_rgba_unpack_float(float *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxt5_rgba_fetch) {
+   if (!is_nop(util_format_dxt5_rgba_fetch)) {
       unsigned x, y, i, j;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -379,7 +423,7 @@ util_format_dxt5_rgba_unpack_float(float *dst_row, unsigned dst_stride, const ui
 void
 util_format_dxt1_rgb_pack_8unorm(uint8_t *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxtn_pack) {
+   if (!is_nop(util_format_dxtn_pack)) {
       unsigned x, y, i, j, k;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -406,7 +450,7 @@ util_format_dxt1_rgb_pack_8unorm(uint8_t *dst_row, unsigned dst_stride, const ui
 void
 util_format_dxt1_rgba_pack_8unorm(uint8_t *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxtn_pack) {
+   if (!is_nop(util_format_dxtn_pack)) {
       unsigned x, y, i, j, k;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -433,7 +477,7 @@ util_format_dxt1_rgba_pack_8unorm(uint8_t *dst_row, unsigned dst_stride, const u
 void
 util_format_dxt3_rgba_pack_8unorm(uint8_t *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxtn_pack) {
+   if (!is_nop(util_format_dxtn_pack)) {
       unsigned x, y, i, j, k;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -460,7 +504,7 @@ util_format_dxt3_rgba_pack_8unorm(uint8_t *dst_row, unsigned dst_stride, const u
 void
 util_format_dxt5_rgba_pack_8unorm(uint8_t *dst_row, unsigned dst_stride, const uint8_t *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxtn_pack) {
+   if (!is_nop(util_format_dxtn_pack)) {
       unsigned x, y, i, j, k;
       for(y = 0; y < height; y += 4) {
          const uint8_t *src = src_row;
@@ -487,7 +531,7 @@ util_format_dxt5_rgba_pack_8unorm(uint8_t *dst_row, unsigned dst_stride, const u
 void
 util_format_dxt1_rgb_pack_float(uint8_t *dst_row, unsigned dst_stride, const float *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxtn_pack) {
+   if (!is_nop(util_format_dxtn_pack)) {
       unsigned x, y, i, j, k;
       for(y = 0; y < height; y += 4) {
          const float *src = src_row;
@@ -514,7 +558,7 @@ util_format_dxt1_rgb_pack_float(uint8_t *dst_row, unsigned dst_stride, const flo
 void
 util_format_dxt1_rgba_pack_float(uint8_t *dst_row, unsigned dst_stride, const float *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxtn_pack) {
+   if (!is_nop(util_format_dxtn_pack)) {
       unsigned x, y, i, j, k;
       for(y = 0; y < height; y += 4) {
          const float *src = src_row;
@@ -541,7 +585,7 @@ util_format_dxt1_rgba_pack_float(uint8_t *dst_row, unsigned dst_stride, const fl
 void
 util_format_dxt3_rgba_pack_float(uint8_t *dst_row, unsigned dst_stride, const float *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxtn_pack) {
+   if (!is_nop(util_format_dxtn_pack)) {
       unsigned x, y, i, j, k;
       for(y = 0; y < height; y += 4) {
          const float *src = src_row;
@@ -568,7 +612,7 @@ util_format_dxt3_rgba_pack_float(uint8_t *dst_row, unsigned dst_stride, const fl
 void
 util_format_dxt5_rgba_pack_float(uint8_t *dst_row, unsigned dst_stride, const float *src_row, unsigned src_stride, unsigned width, unsigned height)
 {
-   if (util_format_dxtn_pack) {
+   if (!is_nop(util_format_dxtn_pack)) {
       unsigned x, y, i, j, k;
       for(y = 0; y < height; y += 4) {
          const float *src = src_row;
diff --git a/src/gallium/auxiliary/util/u_format_s3tc.h b/src/gallium/auxiliary/util/u_format_s3tc.h
index 5c3a9dd22c7..5be4bbec12a 100644
--- a/src/gallium/auxiliary/util/u_format_s3tc.h
+++ b/src/gallium/auxiliary/util/u_format_s3tc.h
@@ -31,6 +31,7 @@
 
 
 #include "pipe/p_compiler.h"
+#include "util/u_inline_init.h"
 
 
 enum util_format_dxtn {
@@ -65,8 +66,7 @@ extern util_format_dxtn_fetch_t util_format_dxt5_rgba_fetch;
 extern util_format_dxtn_pack_t util_format_dxtn_pack;
 
 
-void
-util_format_s3tc_init(void);
+UTIL_INLINE_INIT(util_format_s3tc);
 
 
 void