Revert "Fetch slang-llvm.so from correct release (#4847)" (#4893)

This reverts commit 579d59c.

CMakeLists.txt

@@ -46,7 +46,6 @@ include(Glob)
 include(LLVM)
 include(SlangTarget)
 include(AutoOption)
-include(GitHubRelease)
 
 #
 # Options
@@ -126,26 +125,25 @@ enum_option(
     "How to get or build slang-llvm:"
     # Options
     FETCH_BINARY
-    "Use a binary distribution of the slang-llvm library instead of building or using LLVM (default)"
+    "Use a binary distribution of the slang-llvm library instead of building or using LLVM (default for Windows)"
     USE_SYSTEM_LLVM
-    "Build slang-llvm using system-provided LLVM and Clang binaries"
+    "Build slang-llvm using system-provided LLVM and Clang binaries (default for non-Windows hosts)"
     DISABLE
     "Do not build llvm or fetch slang-llvm"
 )
-
-if(SLANG_SLANG_LLVM_FLAVOR MATCHES FETCH_BINARY)
-    # If the user didn't specify a URL, find the best one now
-    if(NOT SLANG_SLANG_LLVM_BINARY_URL)
-        get_best_slang_binary_release_url(url)
-        if(NOT url)
-            message(FATAL_ERROR "Unable to find binary release for slang-llvm, please set a different SLANG_SLANG_LLVM_FLAVOR or set SLANG_SLANG_LLVM_BINARY_URL manually")
-        endif()
-    endif()
+macro(slang_llvm_binary_url_option version filename)
     set(SLANG_SLANG_LLVM_BINARY_URL
-        ${url}
+        "https://github.com/shader-slang/slang-llvm/releases/download/${version}/${filename}"
         CACHE STRING
         "URL specifying the location of the slang-llvm prebuilt library"
     )
+endmacro()
+if(CMAKE_SYSTEM_NAME MATCHES "Windows")
+    slang_llvm_binary_url_option("v13.x-43" "slang-llvm-13.x-43-win64.zip")
+elseif(CMAKE_SYSTEM_NAME MATCHES "Darwin")
+    slang_llvm_binary_url_option("v13.x-43" "slang-llvm-v13.x-43-macosx-x86_64-release.zip")
+else()
+    slang_llvm_binary_url_option("v13.x-43" "slang-llvm-v13.x-43-linux-x86_64-release.zip")
 endif()
 
 #
@@ -394,7 +392,7 @@ if(SLANG_SLANG_LLVM_FLAVOR STREQUAL "FETCH_BINARY")
     endif()
 
     set(slang_llvm_dest_object
-        ${CMAKE_BINARY_DIR}/$<CONFIG>/${module_subdir}/${slang_llvm_filename}
+        ${CMAKE_BINARY_DIR}/$<CONFIG>/${runtime_subdir}/${slang_llvm_filename}
     )
     add_custom_command(
         OUTPUT ${slang_llvm_dest_object}

docs/building.md

@@ -101,10 +101,6 @@ There are several options for getting llvm-support:
     - You can set `SLANG_SLANG_LLVM_BINARY_URL` to point to a local
       `libslang-llvm.so/slang-llvm.dll` or set it to a URL of an zip/archive
       containing such a file
-    - If this isn't set then the build system tries to download it from the
-      release on github matching the current tag. If such a tag doesn't exist
-      or doesn't have the correct os*arch combination then the latest release
-      will be tried.
 - Use a system supplied LLVM: `-DSLANG_SLANG_LLVM_FLAVOR=USE_SYSTEM_LLVM`, you
   must have llvm-13.0 and a matching libclang installed. It's important that
   either: