[clang] [compiler-rt] [llvm] [CMake] Use Clang to infer the target triple (PR #89425)

[Petr Hosek via cfe-commits]

https://github.com/petrhosek created https://github.com/llvm/llvm-project/pull/89425

When using Clang as a compiler, use Clang to normalize the triple that's used to construct path for runtime library build and install paths. This ensures that paths are consistent and avoids the issue where the build uses a different triple spelling.

Differential Revision: https://reviews.llvm.org/D140925

>From eb2459876526b78c97b04801dd07bd53540b2892 Mon Sep 17 00:00:00 2001
From: Petr Hosek <phosek at google.com>
Date: Tue, 15 Feb 2022 22:59:58 -0800
Subject: [PATCH] [CMake] Use Clang to infer the target triple

When using Clang as a compiler, use Clang to normalize the triple that's
used to construct path for runtime library build and install paths. This
ensures that paths are consistent and avoids the issue where the build
uses a different triple spelling.

Differential Revision: https://reviews.llvm.org/D140925
---
 clang/cmake/caches/Fuchsia-stage2.cmake |  2 +-
 compiler-rt/lib/builtins/CMakeLists.txt | 13 +++++++++++++
 runtimes/CMakeLists.txt                 | 14 ++++++++++++++
 3 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/clang/cmake/caches/Fuchsia-stage2.cmake b/clang/cmake/caches/Fuchsia-stage2.cmake
index d5546e20873b3c..029c069997396d 100644
--- a/clang/cmake/caches/Fuchsia-stage2.cmake
+++ b/clang/cmake/caches/Fuchsia-stage2.cmake
@@ -142,7 +142,7 @@ if(WIN32 OR LLVM_WINSYSROOT)
   set(RUNTIMES_${target}_CMAKE_MODULE_LINKER_FLAGS ${WINDOWS_LINK_FLAGS} CACHE STRING "")
 endif()
 
-foreach(target aarch64-unknown-linux-gnu;armv7-unknown-linux-gnueabihf;i386-unknown-linux-gnu;riscv64-unknown-linux-gnu;x86_64-unknown-linux-gnu)
+foreach(target aarch64-linux-gnu;armv7-linux-gnueabihf;i386-linux-gnu;riscv64-linux-gnu;x86_64-linux-gnu)
   if(LINUX_${target}_SYSROOT)
     # Set the per-target builtins options.
     list(APPEND BUILTIN_TARGETS "${target}")
diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
index f9611574a562b4..4c6de992204c16 100644
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -28,6 +28,19 @@ if (CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
   if (NOT LLVM_RUNTIMES_BUILD)
     load_llvm_config()
   endif()
+  if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
+    set(print_target_triple ${CMAKE_CXX_COMPILER} --target=${LLVM_RUNTIME_TRIPLE} -print-target-triple)
+    execute_process(COMMAND ${print_target_triple}
+      RESULT_VARIABLE result
+      OUTPUT_VARIABLE output
+      OUTPUT_STRIP_TRAILING_WHITESPACE)
+    if(result EQUAL 0)
+      set(LLVM_RUNTIME_TRIPLE ${output})
+    else()
+      string(REPLACE ";" " " print_target_triple "${print_target_triple}")
+      message(WARNING "Failed to execute `${print_target_triple}` to normalize target triple.")
+    endif()
+  endif()
   construct_compiler_rt_default_triple()
 
   include(SetPlatformToolchainTools)
diff --git a/runtimes/CMakeLists.txt b/runtimes/CMakeLists.txt
index 6f24fbcccec955..bb1f544706f2bf 100644
--- a/runtimes/CMakeLists.txt
+++ b/runtimes/CMakeLists.txt
@@ -181,6 +181,20 @@ message(STATUS "LLVM default target triple: ${LLVM_DEFAULT_TARGET_TRIPLE}")
 
 set(LLVM_TARGET_TRIPLE "${LLVM_DEFAULT_TARGET_TRIPLE}")
 
+if(LLVM_ENABLE_PER_TARGET_RUNTIME_DIR AND NOT APPLE)
+  set(print_target_triple ${CMAKE_CXX_COMPILER} --target=${LLVM_RUNTIME_TRIPLE} -print-target-triple)
+  execute_process(COMMAND ${print_target_triple}
+    RESULT_VARIABLE result
+    OUTPUT_VARIABLE output
+    OUTPUT_STRIP_TRAILING_WHITESPACE)
+  if(result EQUAL 0)
+    set(LLVM_RUNTIME_TRIPLE ${output})
+  else()
+    string(REPLACE ";" " " print_target_triple "${print_target_triple}")
+    message(WARNING "Failed to execute `${print_target_triple}` to normalize target triple.")
+  endif()
+endif()
+
 option(LLVM_INCLUDE_TESTS "Generate build targets for the runtimes unit tests." ON)
 option(LLVM_INCLUDE_DOCS "Generate build targets for the runtimes documentation." ON)
 option(LLVM_ENABLE_SPHINX "Use Sphinx to generate the runtimes documentation." OFF)