Use ninja pools to limit the number of concurrent compile/link jobs.

This change makes use of the new "job pool" capability in cmake 3.0
with ninja generator to allow limiting the number of concurrent jobs
of a certain type.

llvm-svn: 222341

2 files changed, 21 insertions, 0 deletions

diff --git a/llvm/CMakeLists.txt b/llvm/CMakeLists.txt
index e3ddb267966..6691189b724 100644
--- a/llvm/CMakeLists.txt
+++ b/llvm/CMakeLists.txt
@@ -24,6 +24,21 @@ endif()
 
 project(LLVM)
 
+# The following only works with the Ninja generator in CMake >= 3.0.
+set(LLVM_PARALLEL_COMPILE_JOBS "" CACHE STRING
+  "Define the maximum number of concurrent compilation jobs.")
+if(LLVM_PARALLEL_COMPILE_JOBS)
+  set_property(GLOBAL APPEND PROPERTY JOB_POOLS compile_job_pool=${LLVM_PARALLEL_COMPILE_JOBS})
+  set(CMAKE_JOB_POOL_COMPILE compile_job_pool)
+endif()
+
+set(LLVM_PARALLEL_LINK_JOBS "" CACHE STRING
+  "Define the maximum number of concurrent link jobs.")
+if(LLVM_PARALLEL_LINK_JOBS)
+  set_property(GLOBAL APPEND PROPERTY JOB_POOLS link_job_pool=${LLVM_PARALLEL_LINK_JOBS})
+  set(CMAKE_JOB_POOL_LINK link_job_pool)
+endif()
+
 # Add path for custom modules
 set(CMAKE_MODULE_PATH
   ${CMAKE_MODULE_PATH}
diff --git a/llvm/docs/CMake.rst b/llvm/docs/CMake.rst
index 4a5165b7a13..653fa16a675 100644
--- a/llvm/docs/CMake.rst
+++ b/llvm/docs/CMake.rst
@@ -291,6 +291,12 @@ LLVM-specific variables
   are ``Address``, ``Memory``, ``MemoryWithOrigins`` and ``Undefined``.
   Defaults to empty string.
 
+**LLVM_PARALLEL_COMPILE_JOBS**:STRING
+  Define the maximum number of concurrent compilation jobs.
+
+**LLVM_PARALLEL_LINK_JOBS**:STRING
+  Define the maximum number of concurrent link jobs.
+
 **LLVM_BUILD_DOCS**:BOOL
   Enables all enabled documentation targets (i.e. Doxgyen and Sphinx targets) to
   be built as part of the normal build. If the ``install`` target is run then