[compiler-rt] [compiler-rt][CMake] Pass all flags to _Float16 try-compile (PR #133952)

[Evan Wilde via llvm-commits]

https://github.com/etcwilde updated https://github.com/llvm/llvm-project/pull/133952

>From c6023ce5b8da67fc3d2191aeeccc01c3e901ba0a Mon Sep 17 00:00:00 2001
From: Evan Wilde <ewilde at apple.com>
Date: Tue, 1 Apr 2025 10:50:16 -0700
Subject: [PATCH 1/2] [compiler-rt][CMake] Pass all flags to try-compile

The try-compile mechanism requires that `CMAKE_REQUIRED_FLAGS` is a
space-separated string instead of a list of flags. The original code
expanded BUILTIN_FLAGS into CMAKE_REQUIRED_FLAGS as a space-separated
string and then would overwrite CMAKE_REQUIRED_FLAGS with
TARGET_${arch}_CFLAGS prepended to the unexpanded
BUILTIN_CFLAGS_${arch}. This resulted in the first two arguments being
passed into the try-compile invocation, but dropping the other arguments
listed in BUILTIN_CFLAGS_${arch}.

This patch takes the contents of both TARGET_${arch}_CLFAGS and
BUILTIN_FLAGS_${arch}, combines them into a single list, and then
joins that list as a space-separated string in `CMAKE_REQUIRED_FLAGS`.
---
 compiler-rt/lib/builtins/CMakeLists.txt | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
index 626b21e30ed6b..b13d8cd35558e 100644
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -854,10 +854,11 @@ else ()
       cmake_push_check_state()
       # TODO: we should probably make most of the checks in builtin-config depend on the target flags.
       set(BUILTIN_CFLAGS_${arch} ${BUILTIN_CFLAGS})
-      # CMAKE_REQUIRED_FLAGS must be a space separated string but unlike TARGET_${arch}_CFLAGS,
-      # BUILTIN_CFLAGS_${arch} is a CMake list, so we have to join it to create a valid command line.
-      list(JOIN BUILTIN_CFLAGS " " CMAKE_REQUIRED_FLAGS)
-      set(CMAKE_REQUIRED_FLAGS "${TARGET_${arch}_CFLAGS} ${BUILTIN_CFLAGS_${arch}}")
+      # CMAKE_REQUIRED_FLAGS must be a space separated string
+      # Join BUILTIN_CFLAGS_${arch} and TARGET_${arch}_CFLAGS as a
+      # space-separated string.
+      set(CMAKE_REQUIRED_FLAGS ${BUILTIN_CFLAGS_${arch}} ${TARGET_${arch}_CFLAGS})
+      list(JOIN CMAKE_REQUIRED_FLAGS " " CMAKE_REQUIRED_FLAGS)
       message(STATUS "Performing additional configure checks with target flags: ${CMAKE_REQUIRED_FLAGS}")
       # For ARM archs, exclude any VFP builtins if VFP is not supported
       if (${arch} MATCHES "^(arm|armhf|armv7|armv7s|armv7k|armv7m|armv7em|armv8m.main|armv8.1m.main)$")

>From 4e29148a666a0b3e92092028a12d2818101ebe16 Mon Sep 17 00:00:00 2001
From: Evan Wilde <ewilde at apple.com>
Date: Wed, 2 Apr 2025 16:23:19 -0700
Subject: [PATCH 2/2] [compiler-rt][CMake] Simplify ARM VFP check

`TARGET_${arch}_CFLAGS` is expanded into `CMAKE_REQUIRED_FLAGS`, which
is implicitly added to the flags by `check_compile_definition`. We don't
need to re-expand the `TARGET_${arch}_CFLAGS` variable again.
---
 compiler-rt/lib/builtins/CMakeLists.txt | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/compiler-rt/lib/builtins/CMakeLists.txt b/compiler-rt/lib/builtins/CMakeLists.txt
index b13d8cd35558e..8b7a0c20d8f9c 100644
--- a/compiler-rt/lib/builtins/CMakeLists.txt
+++ b/compiler-rt/lib/builtins/CMakeLists.txt
@@ -862,8 +862,7 @@ else ()
       message(STATUS "Performing additional configure checks with target flags: ${CMAKE_REQUIRED_FLAGS}")
       # For ARM archs, exclude any VFP builtins if VFP is not supported
       if (${arch} MATCHES "^(arm|armhf|armv7|armv7s|armv7k|armv7m|armv7em|armv8m.main|armv8.1m.main)$")
-        string(REPLACE ";" " " _TARGET_${arch}_CFLAGS "${TARGET_${arch}_CFLAGS}")
-        check_compile_definition(__ARM_FP "${CMAKE_C_FLAGS} ${_TARGET_${arch}_CFLAGS}" COMPILER_RT_HAS_${arch}_VFP)
+        check_compile_definition(__ARM_FP "${CMAKE_C_FLAGS}" COMPILER_RT_HAS_${arch}_VFP)
         if(NOT COMPILER_RT_HAS_${arch}_VFP)
           list(REMOVE_ITEM ${arch}_SOURCES ${arm_Thumb1_VFPv2_DP_SOURCES} ${arm_Thumb1_VFPv2_SP_SOURCES} ${arm_Thumb1_SjLj_EH_SOURCES})
         else()