Add support for SPV_KHR_non_semantic_info (#3110)

Add support for SPV_KHR_non_semantic_info

This entails a couple of changes:

- Allowing unknown OpExtInstImport that begin with the prefix `NonSemantic.`
- Allowing OpExtInst that reference any of those sets to contain unknown
  ext inst instruction numbers, and assume the format is always a series of IDs
  as guaranteed by the extension.
- Allowing those OpExtInst to appear in the types/variables/constants section.
- Not stripping OpString in the --strip-debug pass, since it may be referenced
  by these non-semantic OpExtInsts.
- Stripping them instead in the --strip-reflect pass.

* Add adjacency validation of non-semantic OpExtInst

- We validate and test that OpExtInst cannot appear before or between
  OpPhi instructions, or before/between OpFunctionParameter
  instructions.

* Change non-semantic extinst type to single value

* Add helper function spvExtInstIsNonSemantic() which will check if the extinst
  set is non-semantic or not, either the unknown generic value or any future
  recognised non-semantic set.

* Add test of a complex non-semantic extinst

* Use DefUseManager in StripDebugInfoPass to strip some OpStrings

* Any OpString used by a non-semantic instruction cannot be stripped, all others
  can so we search for uses to see if each string can be removed.
* We only do this if the non-semantic debug info extension is enabled, otherwise
  all strings can be trivially removed.

* Silence -Winconsistent-missing-override in protobufs

1 files changed, 3 insertions, 0 deletions

diff --git a/external/CMakeLists.txt b/external/CMakeLists.txt
index 3190f4b08..8bde13ca1 100644
--- a/external/CMakeLists.txt
+++ b/external/CMakeLists.txt
@@ -108,6 +108,9 @@ if(SPIRV_BUILD_FUZZER)
   set(protobuf_BUILD_TESTS OFF CACHE BOOL "Disable protobuf tests")
   set(protobuf_MSVC_STATIC_RUNTIME OFF CACHE BOOL "Do not build protobuf static runtime")
   if (IS_DIRECTORY ${PROTOBUF_DIR})
+    if (${CMAKE_CXX_COMPILER_ID} MATCHES Clang)
+      add_definitions(-Wno-inconsistent-missing-override)
+    endif()
     add_subdirectory(${PROTOBUF_DIR} EXCLUDE_FROM_ALL)
   else()
     message(FATAL_ERROR