Add LLVM 14 build to GitHub Actions CI

Now that we are API-compatible with LLVM 14, update the CI workflow and the
documentation accordingly.

Author: Artem Gindinson

.github/workflows/build-IGC.yml

@@ -58,6 +58,9 @@ jobs:
           - ubuntu_version: '22.04'
             llvm_ver: 13
             experimental: true
+          - ubuntu_version: '22.04'
+            llvm_ver: 14
+            experimental: true
     steps:
       - uses: actions/checkout@v2
       - name: cloning SPIRV-LLVM-Translator repository
@@ -123,6 +126,10 @@ jobs:
             llvm_ver: 13
             compiler: gcc
             experimental: true
+          - ubuntu_version: '22.04'
+            llvm_ver: 14
+            compiler: gcc
+            experimental: true
     steps:
       - uses: actions/checkout@v2
 

documentation/build_ubuntu.md

@@ -50,7 +50,7 @@ Installing LLVM, Clang, and OpenCL Clang components means you no longer have to
       |- SPIRV-Tools                  https://github.com/KhronosGroup/SPIRV-Tools
       |- SPIRV-Headers                https://github.com/KhronosGroup/SPIRV-Headers
 ```
-Additionaly, you can use **SPIRV-Tools** prebuild pacakge. In order to do that be sure to pass to cmake command `IGC_OPTION__SPIRV_TOOLS_MODE=Prebuilds`. Until the issue 
+Additionaly, you can use **SPIRV-Tools** prebuild pacakge. In order to do that be sure to pass to cmake command `IGC_OPTION__SPIRV_TOOLS_MODE=Prebuilds`. Until the issue
 https://github.com/KhronosGroup/SPIRV-Tools/issues/3909 will not be resolved, we support only SPIRV_Tools as a shared lib, and we encourage to build SPIRV-Tools prebuild with SPIRV_TOOLS_BUILD_STATIC=OFF flag.
 
 Additionaly, OpenCL Clang and Vector Compiler share the library Spirv Translator. Cannot build llvm-spirv translator if OpenCL-Clang is taken as prebuilt from system. This can lead to problems with linking.
@@ -154,7 +154,7 @@ $ sudo make install
 
 | Version          | Product quality |
 |:----------------:|-----------------|
-| LLVM 12          | Experimental    |
+| LLVM 12-14       | Experimental    |
 | LLVM 11          | **Production**  |
 | LLVM 10 and older | Experimental    |
 
@@ -209,7 +209,7 @@ No additional steps are needed.
 
 No additional steps are needed.
 
-#### LLVM12/Clang12
+#### LLVM12/Clang12 to LLVM14/Clang14
 
 **Experimental**
-Currently there are none LLVM12/Clang12 conformance/performance guarantees.
+Currently there are none LLVM12+/Clang12+ conformance/performance guarantees.