[flang-commits] [clang] [flang] [CMake][Release] Statically link clang with stage1 runtimes (PR #127268)

[Tom Stellard via flang-commits]

https://github.com/tstellar updated https://github.com/llvm/llvm-project/pull/127268

>From a705acfd439e6310648b0ed1ad612eaffc408ad5 Mon Sep 17 00:00:00 2001
From: Tom Stellard <tstellar at redhat.com>
Date: Fri, 14 Feb 2025 17:46:25 +0000
Subject: [PATCH 1/3] [CMake][Release] Statically link clang with stage1
 runtimes

This change will cause clang and the other tools to statically link
against the runtimes built in stage1.  This will make the built binaries
more portable by eliminating dependencies on system libraries like
libgcc and libstdc++.
---
 clang/cmake/caches/Release.cmake | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/clang/cmake/caches/Release.cmake b/clang/cmake/caches/Release.cmake
index 23e99493087ff..290e186baf6fe 100644
--- a/clang/cmake/caches/Release.cmake
+++ b/clang/cmake/caches/Release.cmake
@@ -48,10 +48,8 @@ set(CLANG_ENABLE_BOOTSTRAP ON CACHE BOOL "")
 
 set(STAGE1_PROJECTS "clang")
 
-# Building Flang on Windows requires compiler-rt, so we need to build it in
-# stage1.  compiler-rt is also required for building the Flang tests on
-# macOS.
-set(STAGE1_RUNTIMES "compiler-rt")
+# Build all runtimes so we can statically link them into the stage2 compiler.
+set(STAGE1_RUNTIMES "compiler-rt;libcxx;libcxxabi;libunwind")
 
 if (LLVM_RELEASE_ENABLE_PGO)
   list(APPEND STAGE1_PROJECTS "lld")
@@ -90,9 +88,18 @@ else()
   set(CLANG_BOOTSTRAP_TARGETS ${LLVM_RELEASE_FINAL_STAGE_TARGETS} CACHE STRING "")
 endif()
 
+if (LLVM_RELEASE_ENABLE_LTO)
+  # Enable LTO for the runtimes.  We need to configure stage1 clang to default
+  # to using lld as the linker because the stage1 toolchain will be used to
+  # build and link the runtimes.
+  set(RUNTIMES_CMAKE_ARGS "-DCMAKE_INTERPROCEDURAL_OPTIMIZATION=ON" CACHE STRING "")
+  set(LLVM_ENABLE_LLD ON CACHE STRING "")
+endif()
+
 # Stage 1 Common Config
 set(LLVM_ENABLE_RUNTIMES ${STAGE1_RUNTIMES} CACHE STRING "")
 set(LLVM_ENABLE_PROJECTS ${STAGE1_PROJECTS} CACHE STRING "")
+set(LIBCXX_STATICALLY_LINK_ABI_IN_STATIC_LIBRARY ON CACHE STRING "")
 
 # stage2-instrumented and Final Stage Config:
 # Options that need to be set in both the instrumented stage (if we are doing
@@ -102,6 +109,11 @@ set_instrument_and_final_stage_var(LLVM_ENABLE_LTO "${LLVM_RELEASE_ENABLE_LTO}"
 if (LLVM_RELEASE_ENABLE_LTO)
   set_instrument_and_final_stage_var(LLVM_ENABLE_LLD "ON" BOOL)
 endif()
+set_instrument_and_final_stage_var(LLVM_ENABLE_LIBCXX "ON" BOOL)
+set_instrument_and_final_stage_var(LLVM_STATIC_LINK_CXX_STDLIB "ON" BOOL)
+set_instrument_and_final_stage_var(CMAKE_EXE_LINKER_FLAGS "-rtlib=compiler-rt --unwindlib=libunwind -static-libgcc" STRING)
+set_instrument_and_final_stage_var(CMAKE_SHARED_LINKER_FLAGS "-rtlib=compiler-rt --unwindlib=libunwind -static-libgcc" STRING)
+set_instrument_and_final_stage_var(CMAKE_MODULE_LINKER_FLAGS "-rtlib=compiler-rt --unwindlib=libunwind -static-libgcc" STRING)
 
 # Final Stage Config (stage2)
 set_final_stage_var(LLVM_ENABLE_RUNTIMES "${LLVM_RELEASE_ENABLE_RUNTIMES}" STRING)

>From c5680225d3fa6ef229b9d7bf8624fb9c81dddb2b Mon Sep 17 00:00:00 2001
From: Tom Stellard <tstellar at redhat.com>
Date: Sat, 15 Feb 2025 03:02:07 +0000
Subject: [PATCH 2/3] Fix linker usage

---
 clang/cmake/caches/Release.cmake | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/clang/cmake/caches/Release.cmake b/clang/cmake/caches/Release.cmake
index 290e186baf6fe..310717ab47889 100644
--- a/clang/cmake/caches/Release.cmake
+++ b/clang/cmake/caches/Release.cmake
@@ -92,8 +92,7 @@ if (LLVM_RELEASE_ENABLE_LTO)
   # Enable LTO for the runtimes.  We need to configure stage1 clang to default
   # to using lld as the linker because the stage1 toolchain will be used to
   # build and link the runtimes.
-  set(RUNTIMES_CMAKE_ARGS "-DCMAKE_INTERPROCEDURAL_OPTIMIZATION=ON" CACHE STRING "")
-  set(LLVM_ENABLE_LLD ON CACHE STRING "")
+  set(RUNTIMES_CMAKE_ARGS "-DCMAKE_INTERPROCEDURAL_OPTIMIZATION=ON -DLLVM_ENABLE_LLD=ON" CACHE STRING "")
 endif()
 
 # Stage 1 Common Config

>From 88e8ad406c26c6c65a2a6ed51d8b4696a0acf36e Mon Sep 17 00:00:00 2001
From: Tom Stellard <tstellar at redhat.com>
Date: Sat, 15 Feb 2025 14:46:20 +0000
Subject: [PATCH 3/3] flang: Fix build with latest libc++

I think this first stopped working with
954836634abb446f18719b14120c386a929a42d1.  This patch fixes the
following error:

/home/runner/work/llvm-project/llvm-project/flang/runtime/io-api-minimal.cpp:153:11: error: '__libcpp_verbose_abort' is missing exception specification 'noexcept'
   153 | void std::__libcpp_verbose_abort(char const *format, ...) {
       |           ^
       |                                                           noexcept
/mnt/build/bin/../include/c++/v1/__verbose_abort:30:28: note: previous declaration is here
    30 |     __printf__, 1, 2) void __libcpp_verbose_abort(const char* __format, ...) _LIBCPP_VERBOSE_ABORT_NOEXCEPT;
       |                            ^
1 error generated.
---
 flang/runtime/io-api-minimal.cpp | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/flang/runtime/io-api-minimal.cpp b/flang/runtime/io-api-minimal.cpp
index 68768427be0c2..6aefef824a9e9 100644
--- a/flang/runtime/io-api-minimal.cpp
+++ b/flang/runtime/io-api-minimal.cpp
@@ -150,7 +150,12 @@ bool IODEF(OutputLogical)(Cookie cookie, bool truth) {
 // Provide own definition for `std::__libcpp_verbose_abort` to avoid dependency
 // on the version provided by libc++.
 
-void std::__libcpp_verbose_abort(char const *format, ...) {
+#if !defined(_LIBCPP_VERBOSE_ABORT_NOT_NOEXCEPT)
+  #define _LIBCPP_VERBOSE_ABORT_NOT_NOEXCEPT
+#endif
+
+
+void std::__libcpp_verbose_abort(char const *format, ...) _LIBCPP_VERBOSE_ABORT_NOT_NOEXCEP {
   va_list list;
   va_start(list, format);
   std::vfprintf(stderr, format, list);