Break false dependencies on target libraries

[dsanders]

Summary

For the most part this consists of replacing ${LLVM_TARGETS_TO_BUILD} with
some combination of AllTargets* so that they depend on specific components
of a target backend rather than all of it. The overall effect of this is
that, for example, tools like opt no longer falsely depend on the
disassembler, while tools like llvm-ar no longer depend on the code
generator.

There's a couple quirks to point out here:

• AllTargetsCodeGens is a bit more prevalent than expected. Tools like dsymutil seem to need it which I was surprised by.
• llvm-xray linked to all the backends but doesn't seem to need any of them. It builds and passes the tests so that seems to be correct.
• I left gold out as it's not built when binutils is not available so I'm unable to test it

[bogner]

This looks great. Looking forward to faster incremental builds!

cmake/modules/LLVM-Config.cmake

elseif( c STREQUAL "nativecodegen" )
         list(APPEND expanded_components "LLVM${LLVM_NATIVE_ARCH}Info")
       endif()
     elseif( c STREQUAL "backend" )
       # same case as in `native'.
     elseif( c STREQUAL "engine" )
       # already processed
     elseif( c STREQUAL "all" )
       list(APPEND expanded_components ${LLVM_AVAILABLE_LIBS})
+    elseif( c STREQUAL "AllTargetsCodeGens" )
+      # Link all the asm printers from all the targets
+      foreach(t ${LLVM_TARGETS_TO_BUILD})
+        if( TARGET LLVM${t}CodeGen)
+          list(APPEND expanded_components "LLVM${t}CodeGen")
+        endif()
+      endforeach(t)
     elseif( c STREQUAL "AllTargetsAsmPrinters" )
       # Link all the asm printers from all the targets
       foreach(t ${LLVM_TARGETS_TO_BUILD})
         if( TARGET LLVM${t}AsmPrinter )
           list(APPEND expanded_components "LLVM${t}AsmPrinter")
         endif()
       endforeach(t)
     elseif( c STREQUAL "AllTargetsAsmParsers" )

tools/bugpoint/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsAsmParsers
+  AllTargetsCodeGens
   Analysis
   BitWriter
   CodeGen
   Core
   IPO
   IRReader
   AggressiveInstCombine
   InstCombine

tools/dsymutil/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsAsmPrinters
+  AllTargetsCodeGens
+  AllTargetsDescs
+  AllTargetsInfos
   AsmPrinter
   DebugInfoDWARF
   MC
   Object
   Support
   Target
   )
 

tools/llc/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsAsmParsers
+  AllTargetsCodeGens
   Analysis
   AsmPrinter
   CodeGen
   Core
   IRReader
   MC
   MIRParser
   ScalarOpts

tools/llvm-ar/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsAsmParsers
+  AllTargetsDescs
+  AllTargetsInfos
   BinaryFormat
   Core
   DlltoolDriver
   LibDriver
   Object
   Support
   )
 

tools/llvm-c-test/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsAsmParsers
+  AllTargetsCodeGens
+  AllTargetsDisassemblers
   BitReader
   Core
   MCDisassembler
   Object
   Support
   Target
   )
 

tools/llvm-cxxdump/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsInfos
   Object
   Support
   )
 
 add_llvm_tool(llvm-cxxdump
   llvm-cxxdump.cpp
   Error.cpp
   )

tools/llvm-dwp/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsAsmParsers
+  AllTargetsCodeGens
   AsmPrinter
   DebugInfoDWARF
   MC
   Object
   Support
   Target
   )
 

tools/llvm-lto/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsAsmParsers
+  AllTargetsCodeGens
   BitReader
   BitWriter
   Core
   IRReader
   LTO
   MC
   Object
   Support

tools/llvm-lto2/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsAsmParsers
+  AllTargetsCodeGens
+  AllTargetsDescs
   BitReader
   Core
   Linker
   LTO
   MC
   Object
   Support
   Target
   )
 
 add_llvm_tool(llvm-lto2
   llvm-lto2.cpp
 
   DEPENDS
   intrinsics_gen
   )

tools/llvm-rtdyld/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsDisassemblers
+  AllTargetsDescs
+  AllTargetsInfos
   DebugInfoDWARF
   ExecutionEngine
   MC
   Object
   RuntimeDyld
   Support
   )
 
 add_llvm_tool(llvm-rtdyld
   llvm-rtdyld.cpp
   )

tools/llvm-xray/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
   DebugInfoDWARF
   Object
   Support
   Symbolize
   XRay
   )
 
 add_llvm_tool(llvm-xray

tools/lto/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsAsmParsers
+  AllTargetsCodeGens
+  AllTargetsDescs
+  AllTargetsDisassemblers
+  AllTargetsInfos
   BitReader
   Core
   LTO
   MC
   MCDisassembler
   Support
   Target
   )

tools/opt/CMakeLists.txt

 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
+  AllTargetsAsmParsers
+  AllTargetsCodeGens
+  AllTargetsInfos
   AggressiveInstCombine
   Analysis
   BitWriter
   CodeGen
   Core
   Coroutines
   IPO
   IRReader