llvmbuildectomy - replace llvm-build by plain cmake

No longer rely on an external tool to build the llvm component layout.

Instead, leverage the existing `add_llvm_componentlibrary` cmake function and
introduce `add_llvm_component_group` to accurately describe component behavior.

These function store extra properties in the created targets. These properties
are processed once all components are defined to resolve library dependencies
and produce the header expected by llvm-config.

Differential Revision: https://reviews.llvm.org/D90848

llvm/lib/Bitcode/LLVMBuild.txt

@@ -1,23 +0,0 @@
-;===- ./lib/Bitcode/LLVMBuild.txt ------------------------------*- Conf -*--===;
-;
-; Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-; See https://llvm.org/LICENSE.txt for license information.
-; SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-;
-;===------------------------------------------------------------------------===;
-;
-; This is an LLVMBuild description file for the components in this subdirectory.
-;
-; For more information on the LLVMBuild system, please see:
-;
-;   http://llvm.org/docs/LLVMBuild.html
-;
-;===------------------------------------------------------------------------===;
-
-[common]
-subdirectories = Reader Writer
-
-[component_0]
-type = Group
-name = Bitcode
-parent = Libraries

llvm/lib/Bitcode/Reader/CMakeLists.txt

@@ -10,4 +10,9 @@ add_llvm_component_library(LLVMBitReader
 
   DEPENDS
   intrinsics_gen
+
+  LINK_COMPONENTS
+  BitstreamReader
+  Core
+  Support
   )

llvm/lib/Bitcode/Reader/LLVMBuild.txt

@@ -1,21 +0,0 @@
-;===- ./lib/Bitcode/Reader/LLVMBuild.txt -----------------------*- Conf -*--===;
-;
-; Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-; See https://llvm.org/LICENSE.txt for license information.
-; SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-;
-;===------------------------------------------------------------------------===;
-;
-; This is an LLVMBuild description file for the components in this subdirectory.
-;
-; For more information on the LLVMBuild system, please see:
-;
-;   http://llvm.org/docs/LLVMBuild.html
-;
-;===------------------------------------------------------------------------===;
-
-[component_0]
-type = Library
-name = BitReader
-parent = Bitcode
-required_libraries = BitstreamReader Core Support

llvm/lib/Bitcode/Writer/CMakeLists.txt

@@ -6,4 +6,11 @@ add_llvm_component_library(LLVMBitWriter
 
   DEPENDS
   intrinsics_gen
+
+  LINK_COMPONENTS
+  Analysis
+  Core
+  MC
+  Object
+  Support
   )

llvm/lib/Bitcode/Writer/LLVMBuild.txt

@@ -1,21 +0,0 @@
-;===- ./lib/Bitcode/Writer/LLVMBuild.txt -----------------------*- Conf -*--===;
-;
-; Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
-; See https://llvm.org/LICENSE.txt for license information.
-; SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
-;
-;===------------------------------------------------------------------------===;
-;
-; This is an LLVMBuild description file for the components in this subdirectory.
-;
-; For more information on the LLVMBuild system, please see:
-;
-;   http://llvm.org/docs/LLVMBuild.html
-;
-;===------------------------------------------------------------------------===;
-
-[component_0]
-type = Library
-name = BitWriter
-parent = Bitcode
-required_libraries = Analysis Core MC Object Support