[libc] Implement placeholder memory functions on the GPU (#101082)

Summary:
These functions are needed for `libc++` to link successfully. We can't
implement them well currently, so simply provide some stand-in
implementations. `realloc` will currently copy garbage and potentially
fault and `aligned_alloc` will work unless your alignment is more than
4K alignment. However, these should work in practice to get tests
running. I will write a real allocator soon™.

1 files changed, 29 insertions, 0 deletions

diff --git a/libc/src/stdlib/gpu/aligned_alloc.cpp b/libc/src/stdlib/gpu/aligned_alloc.cpp
new file mode 100644
index 000000000000..cd2c7e55128f
--- /dev/null
+++ b/libc/src/stdlib/gpu/aligned_alloc.cpp
@@ -0,0 +1,29 @@
+//===-- GPU Implementation of aligned_alloc -------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdlib/aligned_alloc.h"
+
+#include "src/__support/GPU/allocator.h"
+#include "src/__support/common.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+LLVM_LIBC_FUNCTION(void *, aligned_alloc, (size_t alignment, size_t size)) {
+  if ((alignment & -alignment) != alignment)
+    return nullptr;
+
+  void *ptr = gpu::allocate(size);
+  if ((reinterpret_cast<uintptr_t>(ptr) & (alignment - 1)) != 0) {
+    gpu::deallocate(ptr);
+    return nullptr;
+  }
+  return ptr;
+}
+
+} // namespace LIBC_NAMESPACE_DECL