Add grammars, C header, and header generator for vendor and KHR extended instruction sets (#143)

* Add JSON grammars for extened instruction sets

Add AMD extended instruction sets
Add DebugInfo
Add OpenCL.DebugInfo.100

* Add script to generate C headers from extinst grammar

This is cloned then adapted from the same-named script in SPIRV-Tools
(contributed under same authorship but different copyright).

Invoke the script as part of the overall header generation script.

* Add generated C header for extended instruction sets

Add for DebugInfo and OpenCLDebugInfo
Add for AMD vendor extended instruction sets

* Update the README for extinst header generation

* Fix header include guard to match directory structure

* Ensure generated header ends in newline

* Fix typo in file reference

* Fix name of AMD_shader_explicit_vertex_parameter.h

* Avoid duplicate generation

* Split Revision and Version enum values by newlines

Per code review request

* Convert C header generator driver to Python3

* Fix README for Python3 for extinst header generation

* Use 4-space in generated headers, consistently

1 files changed, 53 insertions, 0 deletions

diff --git a/include/spirv/unified1/AMD_shader_ballot.h b/include/spirv/unified1/AMD_shader_ballot.h
new file mode 100644
index 0000000..59b2aaf
--- /dev/null
+++ b/include/spirv/unified1/AMD_shader_ballot.h
@@ -0,0 +1,53 @@
+// Copyright (c) 2020 The Khronos Group Inc.
+// 
+// Permission is hereby granted, free of charge, to any person obtaining a
+// copy of this software and/or associated documentation files (the
+// "Materials"), to deal in the Materials without restriction, including
+// without limitation the rights to use, copy, modify, merge, publish,
+// distribute, sublicense, and/or sell copies of the Materials, and to
+// permit persons to whom the Materials are furnished to do so, subject to
+// the following conditions:
+// 
+// The above copyright notice and this permission notice shall be included
+// in all copies or substantial portions of the Materials.
+// 
+// MODIFICATIONS TO THIS FILE MAY MEAN IT NO LONGER ACCURATELY REFLECTS
+// KHRONOS STANDARDS. THE UNMODIFIED, NORMATIVE VERSIONS OF KHRONOS
+// SPECIFICATIONS AND HEADER INFORMATION ARE LOCATED AT
+//    https://www.khronos.org/registry/
+// 
+// THE MATERIALS ARE PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
+// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+// MATERIALS OR THE USE OR OTHER DEALINGS IN THE MATERIALS.
+// 
+
+#ifndef SPIRV_UNIFIED1_AMD_shader_ballot_H_
+#define SPIRV_UNIFIED1_AMD_shader_ballot_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+enum {
+    AMD_shader_ballotRevision = 5,
+    AMD_shader_ballotRevision_BitWidthPadding = 0x7fffffff
+};
+
+enum AMD_shader_ballotInstructions {
+    AMD_shader_ballotSwizzleInvocationsAMD = 1,
+    AMD_shader_ballotSwizzleInvocationsMaskedAMD = 2,
+    AMD_shader_ballotWriteInvocationAMD = 3,
+    AMD_shader_ballotMbcntAMD = 4,
+    AMD_shader_ballotInstructionsMax = 0x7ffffff
+};
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif // SPIRV_UNIFIED1_AMD_shader_ballot_H_