[libc-commits] [libc] [libc] Remove atomic alignment diagnostics globally (PR #96803)

[Joseph Huber via libc-commits]

https://github.com/jhuber6 created https://github.com/llvm/llvm-project/pull/96803

Summary:
These warnings mean that it will lower to a libcall. Previously we just
disabled it locally, which didn't work with GCC. This patch does it
globally in the compiler options if the compiler is clang.


>From 6ec16ebe46c52bb193075c5fabec847f8a77986f Mon Sep 17 00:00:00 2001
From: Joseph Huber <huberjn at outlook.com>
Date: Wed, 26 Jun 2024 12:58:22 -0500
Subject: [PATCH] [libc] Remove atomic alignment diagnostics globally

Summary:
These warnings mean that it will lower to a libcall. Previously we just
disabled it locally, which didn't work with GCC. This patch does it
globally in the compiler options if the compiler is clang.
---
 libc/cmake/modules/LLVMLibCCompileOptionRules.cmake | 1 +
 libc/src/stdlib/rand.cpp                            | 6 ------
 libc/src/stdlib/srand.cpp                           | 6 ------
 3 files changed, 1 insertion(+), 12 deletions(-)

diff --git a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
index 3bf429381d4af..b49df8b4df6c0 100644
--- a/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
+++ b/libc/cmake/modules/LLVMLibCCompileOptionRules.cmake
@@ -87,6 +87,7 @@ function(_get_common_compile_options output_var flags)
       list(APPEND compile_options "-Wstrict-prototypes")
       list(APPEND compile_options "-Wthread-safety")
       list(APPEND compile_options "-Wglobal-constructors")
+      list(APPEND compile_options "-Wno-atomic-alignment")
     endif()
   elseif(MSVC)
     list(APPEND compile_options "/EHs-c-")
diff --git a/libc/src/stdlib/rand.cpp b/libc/src/stdlib/rand.cpp
index 8f2ae90336d51..ff3875c2f6959 100644
--- a/libc/src/stdlib/rand.cpp
+++ b/libc/src/stdlib/rand.cpp
@@ -13,10 +13,6 @@
 
 namespace LIBC_NAMESPACE {
 
-// Silence warnings on targets with slow atomics.
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Watomic-alignment"
-
 // An implementation of the xorshift64star pseudo random number generator. This
 // is a good general purpose generator for most non-cryptographics applications.
 LLVM_LIBC_FUNCTION(int, rand, (void)) {
@@ -33,6 +29,4 @@ LLVM_LIBC_FUNCTION(int, rand, (void)) {
   }
 }
 
-#pragma GCC diagnostic pop
-
 } // namespace LIBC_NAMESPACE
diff --git a/libc/src/stdlib/srand.cpp b/libc/src/stdlib/srand.cpp
index 681aad8fac4e8..21166c7a6754e 100644
--- a/libc/src/stdlib/srand.cpp
+++ b/libc/src/stdlib/srand.cpp
@@ -12,14 +12,8 @@
 
 namespace LIBC_NAMESPACE {
 
-// Silence warnings on targets with slow atomics.
-#pragma GCC diagnostic push
-#pragma GCC diagnostic ignored "-Watomic-alignment"
-
 LLVM_LIBC_FUNCTION(void, srand, (unsigned int seed)) {
   rand_next.store(seed, cpp::MemoryOrder::RELAXED);
 }
 
-#pragma GCC diagnostic pop
-
 } // namespace LIBC_NAMESPACE