[XRay] Clean up XRay build configuration

Summary:
This change spans both LLVM and compiler-rt, where we do the following:

- Add XRay to the LLVMBuild system, to allow for distributing the XRay
  trace loading library along with the LLVM distributions.

- Use `llvm-config` better in the compiler-rt XRay implementation, to
  depend on the potentially already-distributed LLVM XRay library.

While this is tested with the standalone compiler-rt build, it does
require that the LLVMXRay library (and LLVMSupport as well) are
available during the build. In case the static libraries are available,
the unit tests will build and work fine. We're still having issues with
attempting to use a shared library version of the LLVMXRay library since
the shared library might not be accessible from the standard shared
library lookup paths.

The larger change here is the inclusion of the LLVMXRay library in the
distribution, which allows for building tools around the XRay traces and
profiles that the XRay runtime already generates.

Reviewers: echristo, beanz

Subscribers: mgorny, hiraditya, mboerger, llvm-commits

Differential Revision: https://reviews.llvm.org/D52349

git-svn-id: https://llvm.org/svn/llvm-project/compiler-rt/trunk@342859 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 18 insertions, 0 deletions

diff --git a/cmake/Modules/CompilerRTUtils.cmake b/cmake/Modules/CompilerRTUtils.cmake
index e2884e23e..d2cb48677 100644
--- a/cmake/Modules/CompilerRTUtils.cmake
+++ b/cmake/Modules/CompilerRTUtils.cmake
@@ -236,6 +236,24 @@ macro(load_llvm_config)
     set(LLVM_TOOLS_BINARY_DIR ${TOOLS_BINARY_DIR} CACHE PATH "Path to llvm/bin")
     set(LLVM_INCLUDE_DIR ${INCLUDE_DIR} CACHE PATH "Paths to LLVM headers")
 
+    # Detect if we have the LLVMXRay and TestingSupport library installed and
+    # available from llvm-config.
+    execute_process(
+      COMMAND ${LLVM_CONFIG_PATH} "--ldflags" "--libs" "xray" "testingsupport"
+      RESULT_VARIABLE HAD_ERROR
+      OUTPUT_VARIABLE CONFIG_OUTPUT)
+    if (HAD_ERROR)
+      message(WARNING "llvm-config finding xray failed with status ${HAD_ERROR}")
+      set(COMPILER_RT_HAS_LLVMXRAY FALSE)
+    else()
+      string(REGEX REPLACE "[ \t]*[\r\n]+[ \t]*" ";" CONFIG_OUTPUT ${CONFIG_OUTPUT})
+      list(GET CONFIG_OUTPUT 0 LDFLAGS)
+      list(GET CONFIG_OUTPUT 1 LIBLIST)
+      set(LLVM_XRAY_LDFLAGS ${LDFLAGS} CACHE STRING "Linker flags for LLVMXRay library")
+      set(LLVM_XRAY_LIBLIST ${LIBLIST} CACHE STRING "Library list for LLVMXRay")
+      set(COMPILER_RT_HAS_LLVMXRAY TRUE)
+    endif()
+
     # Make use of LLVM CMake modules.
     # --cmakedir is supported since llvm r291218 (4.0 release)
     execute_process(