[clang][deps] Remove dependency on llvm targets from lib DependencyScanning (llvm#129774)

benlangmuir · benlangmuir · commit c92dae6671cc · 2025-03-05T11:10:48.000-08:00
In d64eccf we split the object file reader from the writer and removed the dependency on clangCodeGen from the dependency scanner. However, we were still initializing all the llvm targets, which was needed for writing object file pcms but not reading them. This caused us to link more llvm target code than necessary. Shrinks clangd by nearly 50% for me. rdar://144790713 (cherry picked from commit f8ba0df) (cherry picked from commit c0eb45d)
diff --git a/clang/lib/Tooling/DependencyScanning/CMakeLists.txt b/clang/lib/Tooling/DependencyScanning/CMakeLists.txt
@@ -1,5 +1,4 @@
 set(LLVM_LINK_COMPONENTS
-  ${LLVM_TARGETS_TO_BUILD}
   Core
   Option
   Support
diff --git a/clang/lib/Tooling/DependencyScanning/DependencyScanningService.cpp b/clang/lib/Tooling/DependencyScanning/DependencyScanningService.cpp
@@ -10,7 +10,6 @@
 #include "llvm/CAS/ActionCache.h"
 #include "llvm/CAS/CachingOnDiskFileSystem.h"
 #include "llvm/CAS/ObjectStore.h"
-#include "llvm/Support/TargetSelect.h"
 
 using namespace clang;
 using namespace tooling;
@@ -27,10 +26,4 @@ DependencyScanningService::DependencyScanningService(
       SharedFS(std::move(SharedFS)) {
   if (!this->SharedFS)
     SharedCache.emplace();
-
-  // Initialize targets for object file support.
-  llvm::InitializeAllTargets();
-  llvm::InitializeAllTargetMCs();
-  llvm::InitializeAllAsmPrinters();
-  llvm::InitializeAllAsmParsers();
 }

Original file line number	Diff line number	Diff line change
`@@ -1,5 +1,4 @@`
`1`	`1`	`set(LLVM_LINK_COMPONENTS`
`2`		`- ${LLVM_TARGETS_TO_BUILD}`
`3`	`2`	`Core`
`4`	`3`	`Option`
`5`	`4`	`Support`