[libc] fix 32bit riscv atomic tests

[SchrodingerZhu]

This patch fix test build failures on rv32 platforms. For non-integral data, it always limits the size and align to be the same as platform pointer layout. This should avoid the emitting of call to external libatomic symbols.

[llvmbot]

@llvm/pr-subscribers-libc

Author: Schrodinger ZHU Yifan (SchrodingerZhu)

Changes

---

Full diff: https://github.com/llvm/llvm-project/pull/119087.diff

1 Files Affected:

• (modified) libc/test/src/__support/CPP/atomic_test.cpp (+13-12)

diff --git a/libc/test/src/__support/CPP/atomic_test.cpp b/libc/test/src/__support/CPP/atomic_test.cpp
index 8772ad05f49ff7..5c3f60e9a68cd3 100644
--- a/libc/test/src/__support/CPP/atomic_test.cpp
+++ b/libc/test/src/__support/CPP/atomic_test.cpp
@@ -33,19 +33,20 @@ TEST(LlvmLibcAtomicTest, CompareExchangeStrong) {
   ASSERT_EQ(aint.load(LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED), 100);
 }
 
-struct TrivialData {
-  int a;
-  int b;
+struct alignas(void *) TrivialData {
+  char a;
+  char b;
+  char padding[sizeof(void *) - 2];
 };
 
 TEST(LlvmLibcAtomicTest, TrivialCompositeData) {
-  LIBC_NAMESPACE::cpp::Atomic<TrivialData> data({1, 2});
-  ASSERT_EQ(data.load(LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED).a, 1);
-  ASSERT_EQ(data.load(LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED).b, 2);
-
-  auto old = data.exchange({3, 4});
-  ASSERT_EQ(data.load(LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED).a, 3);
-  ASSERT_EQ(data.load(LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED).b, 4);
-  ASSERT_EQ(old.a, 1);
-  ASSERT_EQ(old.b, 2);
+  LIBC_NAMESPACE::cpp::Atomic<TrivialData> data({'a', 'b', {}});
+  ASSERT_EQ(data.load(LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED).a, 'a');
+  ASSERT_EQ(data.load(LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED).b, 'b');
+
+  auto old = data.exchange({'c', 'd', {}});
+  ASSERT_EQ(data.load(LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED).a, 'c');
+  ASSERT_EQ(data.load(LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED).b, 'd');
+  ASSERT_EQ(old.a, 'a');
+  ASSERT_EQ(old.b, 'b');
 }