swscale/vulkan: compile SPIR-V backed only if SPIR-V headers are found

Instead of making Vulkan depend on the headers, make the compilation of
the SPIR-V backend depend on the headers.

Sponsored-by: Sovereign Tech Fund

configure

@@ -2496,6 +2496,8 @@ HEADERS_LIST="
     valgrind_valgrind_h
     windows_h
     winsock2_h
+    spirv_headers_spirv_h
+    spirv_unified1_spirv_h
 "
 
 INTRINSICS_LIST="
@@ -7796,9 +7798,6 @@ enabled vdpau &&
     check_lib vdpau_x11 "vdpau/vdpau.h vdpau/vdpau_x11.h" vdp_device_create_x11 -lvdpau -lX11
 
 # Check for the Vulkan headers
-if enabled vulkan; then
-    check_cpp_condition vulkan "spirv/unified1/spirv.h" "defined(SPV_VERSION)"
-fi
 if enabled_all vulkan vulkan_static; then
     check_pkg_config vulkan "vulkan >= 1.3.277" "vulkan/vulkan.h" "defined VK_VERSION_1_3" ||
         check_lib vulkan "vulkan/vulkan.h" vkGetInstanceProcAddr -lvulkan
@@ -7856,6 +7855,12 @@ else
     disable libglslang libshaderc spirv_library spirv_compiler
 fi
 
+if enabled vulkan; then
+    check_headers spirv-headers/spirv.h ||
+    check_headers spirv/unified1/spirv.h ||
+    warn "spirv-headers not found, swscale SPIR-V backend unavailable"
+fi
+
 if enabled x86; then
     case $target_os in
         freebsd|mingw32*|mingw64*|win32|win64|linux|cygwin*)

libswscale/ops.c

@@ -34,7 +34,9 @@ extern const SwsOpBackend backend_c;
 extern const SwsOpBackend backend_murder;
 extern const SwsOpBackend backend_aarch64;
 extern const SwsOpBackend backend_x86;
+#if HAVE_SPIRV_HEADERS_SPIRV_H || HAVE_SPIRV_UNIFIED1_SPIRV_H
 extern const SwsOpBackend backend_spirv;
+#endif
 #if CONFIG_LIBSHADERC || CONFIG_LIBGLSLANG
 extern const SwsOpBackend backend_glsl;
 #endif
@@ -47,11 +49,11 @@ const SwsOpBackend * const ff_sws_op_backends[] = {
     &backend_x86,
 #endif
     &backend_c,
-#if CONFIG_VULKAN
+#if HAVE_SPIRV_HEADERS_SPIRV_H || HAVE_SPIRV_UNIFIED1_SPIRV_H
     &backend_spirv,
+#endif
 #if CONFIG_LIBSHADERC || CONFIG_LIBGLSLANG
     &backend_glsl,
-#endif
 #endif
     NULL
 };

libswscale/vulkan/ops.c

@@ -25,7 +25,10 @@
 #include "../swscale_internal.h"
 
 #include "ops.h"
+
+#if HAVE_SPIRV_HEADERS_SPIRV_H || HAVE_SPIRV_UNIFIED1_SPIRV_H
 #include "spvasm.h"
+#endif
 
 static void ff_sws_vk_uninit(AVRefStructOpaque opaque, void *obj)
 {
@@ -204,6 +207,7 @@ fail:
     return err;
 }
 
+#if HAVE_SPIRV_HEADERS_SPIRV_H || HAVE_SPIRV_UNIFIED1_SPIRV_H
 struct DitherData {
         int size;
         int arr_1d_id;
@@ -883,6 +887,7 @@ static int add_ops_spirv(VulkanPriv *p, FFVulkanOpsCtx *s,
 
     return ff_vk_shader_link(&s->vkctx, shd, spvbuf, len, "main");
 }
+#endif
 
 #if CONFIG_LIBSHADERC || CONFIG_LIBGLSLANG
 static void add_desc_read_write(FFVulkanDescriptorSetBinding *out_desc,
@@ -1159,19 +1164,18 @@ static int compile(SwsContext *sws, SwsOpList *ops, SwsCompiledOp *out, int glsl
     }
 
     if (glsl) {
+        err = AVERROR(ENOTSUP);
 #if CONFIG_LIBSHADERC || CONFIG_LIBGLSLANG
         err = add_ops_glsl(p, s, ops, &p->shd);
-        if (err < 0)
-            goto fail;
-#else
-        err = AVERROR(ENOTSUP);
-        goto fail;
 #endif
     } else {
+        err = AVERROR(ENOTSUP);
+#if HAVE_SPIRV_HEADERS_SPIRV_H || HAVE_SPIRV_UNIFIED1_SPIRV_H
         err = add_ops_spirv(p, s, ops, &p->shd);
-        if (err < 0)
-            goto fail;
+#endif
     }
+    if (err < 0)
+        goto fail;
 
     err = ff_vk_shader_register_exec(&s->vkctx, &p->e, &p->shd);
     if (err < 0)
@@ -1196,6 +1200,7 @@ fail:
     return err;
 }
 
+#if HAVE_SPIRV_HEADERS_SPIRV_H || HAVE_SPIRV_UNIFIED1_SPIRV_H
 static int compile_spirv(SwsContext *sws, SwsOpList *ops, SwsCompiledOp *out)
 {
     return compile(sws, ops, out, 0);
@@ -1206,6 +1211,7 @@ const SwsOpBackend backend_spirv = {
     .compile   = compile_spirv,
     .hw_format = AV_PIX_FMT_VULKAN,
 };
+#endif
 
 #if CONFIG_LIBSHADERC || CONFIG_LIBGLSLANG
 static int compile_glsl(SwsContext *sws, SwsOpList *ops, SwsCompiledOp *out)

libswscale/vulkan/spvasm.h

@@ -23,11 +23,20 @@
 
 #include <stdint.h>
 #include <string.h>
+#include "config.h"
 
 #include "libavutil/intreadwrite.h"
 #include "libavutil/avassert.h"
+
+#if HAVE_SPIRV_HEADERS_SPIRV_H
+#include <spirv-headers/spirv.h>
+#include <spirv-headers/GLSL.std.450.h>
+#endif
+
+#if HAVE_SPIRV_UNIFIED1_SPIRV_H
 #include <spirv/unified1/spirv.h>
 #include <spirv/unified1/GLSL.std.450.h>
+#endif
 
 /* COUNT_ARGS: counts variadic macro arguments, including zero.
  * The sentinel 0 is prepended so the compound literal is never empty,