[libc] Removed unused flags from baremetal cache files

[petrhosek]

These flags are not needed for building libc.

[llvmbot]

@llvm/pr-subscribers-libc

Author: Petr Hosek (petrhosek)

Changes

These flags are not needed for building libc.

---

Full diff: https://github.com/llvm/llvm-project/pull/168942.diff

3 Files Affected:

• (modified) libc/cmake/caches/armv6m-none-eabi.cmake (+1-1)
• (modified) libc/cmake/caches/armv7em-none-eabi.cmake (+1-1)
• (modified) libc/cmake/caches/armv7m-none-eabi.cmake (+1-1)

diff --git a/libc/cmake/caches/armv6m-none-eabi.cmake b/libc/cmake/caches/armv6m-none-eabi.cmake
index 1f463ae5c0ead..d1d614655e557 100644
--- a/libc/cmake/caches/armv6m-none-eabi.cmake
+++ b/libc/cmake/caches/armv6m-none-eabi.cmake
@@ -2,7 +2,7 @@ set(CMAKE_SYSTEM_PROCESSOR arm CACHE STRING "")
 set(RUNTIMES_TARGET_TRIPLE "armv6m-none-eabi" CACHE STRING "")
 
 foreach(lang C;CXX;ASM)
-    set(CMAKE_${lang}_FLAGS "-march=armv6m -mcpu=cortex-m0plus -mfloat-abi=soft -Wno-atomic-alignment \"-Dvfprintf(stream, format, vlist)=vprintf(format, vlist)\" \"-Dfprintf(stream, format, ...)=printf(format)\" \"-Dfputs(string, stream)=puts(string)\" -D_LIBCPP_PRINT=1" CACHE STRING "")
+    set(CMAKE_${lang}_FLAGS "-march=armv6m -mcpu=cortex-m0plus -mfloat-abi=soft -Wno-atomic-alignment" CACHE STRING "")
 endforeach()
 
 include(${CMAKE_CURRENT_LIST_DIR}/baremetal_common.cmake)
diff --git a/libc/cmake/caches/armv7em-none-eabi.cmake b/libc/cmake/caches/armv7em-none-eabi.cmake
index afbe9c87dffe1..2b6df8fdf40ab 100644
--- a/libc/cmake/caches/armv7em-none-eabi.cmake
+++ b/libc/cmake/caches/armv7em-none-eabi.cmake
@@ -2,7 +2,7 @@ set(CMAKE_SYSTEM_PROCESSOR arm CACHE STRING "")
 set(RUNTIMES_TARGET_TRIPLE "armv7em-none-eabi" CACHE STRING "")
 
 foreach(lang C;CXX;ASM)
-    set(CMAKE_${lang}_FLAGS "-march=armv7em -mcpu=cortex-m4 -mfloat-abi=soft -Wno-atomic-alignment \"-Dvfprintf(stream, format, vlist)=vprintf(format, vlist)\" \"-Dfprintf(stream, format, ...)=printf(format)\" \"-Dfputs(string, stream)=puts(string)\" -D_LIBCPP_PRINT=1" CACHE STRING "")
+    set(CMAKE_${lang}_FLAGS "-march=armv7em -mcpu=cortex-m4 -mfloat-abi=soft -Wno-atomic-alignment" CACHE STRING "")
 endforeach()
 
 include(${CMAKE_CURRENT_LIST_DIR}/baremetal_common.cmake)
diff --git a/libc/cmake/caches/armv7m-none-eabi.cmake b/libc/cmake/caches/armv7m-none-eabi.cmake
index 796adb2f31148..fe76828fa529f 100644
--- a/libc/cmake/caches/armv7m-none-eabi.cmake
+++ b/libc/cmake/caches/armv7m-none-eabi.cmake
@@ -2,7 +2,7 @@ set(CMAKE_SYSTEM_PROCESSOR arm CACHE STRING "")
 set(RUNTIMES_TARGET_TRIPLE "armv7m-none-eabi" CACHE STRING "")
 
 foreach(lang C;CXX;ASM)
-    set(CMAKE_${lang}_FLAGS "-march=armv7m -mcpu=cortex-m4 -mfloat-abi=soft -Wno-atomic-alignment \"-Dvfprintf(stream, format, vlist)=vprintf(format, vlist)\" \"-Dfprintf(stream, format, ...)=printf(format)\" \"-Dfputs(string, stream)=puts(string)\" -D_LIBCPP_PRINT=1" CACHE STRING "")
+    set(CMAKE_${lang}_FLAGS "-march=armv7m -mcpu=cortex-m4 -mfloat-abi=soft -Wno-atomic-alignment" CACHE STRING "")
 endforeach()
 
 include(${CMAKE_CURRENT_LIST_DIR}/baremetal_common.cmake)

[github-actions]

🐧 Linux x64 Test Results

The build succeeded and no tests ran. This is expected in some build configurations.

[boomanaiden154]

Bikeshedding a bit, but why do we need -Wno-atomic-alignment?

[petrhosek]

That's because we use atomics for some internal API and there's no support unaligned accesses on Cortex-M0, but it's not a problem in practice because we don't do any unaligned accesses. We expect this will eventually get resolved by switching to TLS but we haven't had time to implement it yet.

[boomanaiden154]

It seems like clang shouldn't emit this warning for targets that don't support unaligned atomic accesses?

Not sure about the implementation (ie whether warnings can be target specific, how we would plumb information about the target, etc).