[libc] Add osutils and make libc and its tests build on Windows target

This PR first adds osutils for Windows, and changes some libc code to make
libc and its tests build on the Windows target. It then temporarily disables
some libc tests that are currently problematic on Windows.

Author: Lancern

libc/include/llvm-libc-macros/float16-macros.h

@@ -13,7 +13,8 @@
 
 #if defined(__FLT16_MANT_DIG__) &&                                             \
     (!defined(__GNUC__) || __GNUC__ >= 13 || defined(__clang__)) &&            \
-    !defined(__arm__) && !defined(_M_ARM) && !defined(__riscv)
+    !defined(__arm__) && !defined(_M_ARM) && !defined(__riscv) &&              \
+    !defined(_WIN32)
 #define LIBC_TYPES_HAS_FLOAT16
 
 // TODO: This would no longer be required if HdrGen let us guard function

libc/include/llvm-libc-macros/stdckdint-macros.h

@@ -10,8 +10,10 @@
 #define LLVM_LIBC_MACROS_STDCKDINT_MACROS_H
 
 // We need to use __builtin_*_overflow from GCC/Clang to implement the overflow
-// macros. Check __GNUC__ for availability of such builtins.
-#ifdef __GNUC__
+// macros. Check __GNUC__ or __clang__ for availability of such builtins.
+// Note that clang-cl defines __clang__ only and does not define __GNUC__ so we
+// have to check for both.
+#if defined(__GNUC__) || defined(__clang__)
 // clang/gcc overlay may provides similar macros, we need to avoid redefining
 // them.
 #ifndef __STDC_VERSION_STDCKDINT_H__

libc/src/__support/CPP/new.cpp

@@ -16,15 +16,29 @@ void operator delete(void *mem, std::align_val_t) noexcept { ::free(mem); }
 void operator delete(void *mem, size_t) noexcept { ::free(mem); }
 
 void operator delete(void *mem, size_t, std::align_val_t) noexcept {
+#ifdef LIBC_TARGET_OS_IS_WINDOWS
+  ::_aligned_free(mem);
+#else
   ::free(mem);
+#endif
 }
 
 void operator delete[](void *mem) noexcept { ::free(mem); }
 
-void operator delete[](void *mem, std::align_val_t) noexcept { ::free(mem); }
+void operator delete[](void *mem, std::align_val_t) noexcept {
+#ifdef LIBC_TARGET_OS_IS_WINDOWS
+  ::_aligned_free(mem);
+#else
+  ::free(mem);
+#endif
+}
 
 void operator delete[](void *mem, size_t) noexcept { ::free(mem); }
 
 void operator delete[](void *mem, size_t, std::align_val_t) noexcept {
+#ifdef LIBC_TARGET_OS_IS_WINDOWS
+  ::_aligned_free(mem);
+#else
   ::free(mem);
+#endif
 }

libc/src/__support/CPP/new.h

@@ -11,6 +11,7 @@
 
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
+#include "src/__support/macros/properties/os.h"
 
 #include <stddef.h> // For size_t
 #include <stdlib.h> // For malloc, free etc.
@@ -47,7 +48,15 @@ class AllocChecker {
 
   LIBC_INLINE static void *aligned_alloc(size_t s, std::align_val_t align,
                                          AllocChecker &ac) {
+#ifdef LIBC_TARGET_OS_IS_WINDOWS
+    // std::aligned_alloc is not available on Windows because std::free on
+    // Windows cannot deallocate any over-aligned memory. Microsoft provides an
+    // alternative for std::aligned_alloc named _aligned_malloc, but it must be
+    // paired with _aligned_free instead of std::free.
+    void *mem = ::_aligned_malloc(static_cast<size_t>(align), s);
+#else
     void *mem = ::aligned_alloc(static_cast<size_t>(align), s);
+#endif
     ac = (mem != nullptr);
     return mem;
   }

libc/src/__support/OSUtil/io.h

@@ -19,6 +19,8 @@
 #include "linux/io.h"
 #elif defined(__Fuchsia__)
 #include "fuchsia/io.h"
+#elif defined(_WIN32)
+#include "windows/io.h"
 #elif defined(__ELF__)
 // TODO: Ideally we would have LIBC_TARGET_OS_IS_BAREMETAL.
 #include "baremetal/io.h"

libc/src/__support/OSUtil/windows/CMakeLists.txt

@@ -0,0 +1,9 @@
+add_object_library(
+  windows_util
+  SRCS
+    exit.cpp
+    io.cpp
+  HDRS
+    io.h
+  DEPENDS
+)

libc/src/__support/OSUtil/windows/exit.cpp

@@ -0,0 +1,19 @@
+//===----------- Windows implementation of an exit function -----*- C++ -*-===//
+//
+// 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/__support/macros/config.h"
+
+#include <Windows.h>
+
+namespace LIBC_NAMESPACE_DECL {
+namespace internal {
+
+[[noreturn]] void exit(int status) { ExitProcess(status); }
+
+} // namespace internal
+} // namespace LIBC_NAMESPACE_DECL

libc/src/__support/OSUtil/windows/io.cpp

@@ -0,0 +1,21 @@
+//===------------- Windows implementation of IO utils -----------*- C++ -*-===//
+//
+// 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 "io.h"
+#include "src/__support/macros/config.h"
+
+#include <Windows.h>
+
+namespace LIBC_NAMESPACE_DECL {
+
+void write_to_stderr(cpp::string_view msg) {
+  HANDLE stream = GetStdHandle(STD_ERROR_HANDLE);
+  WriteFile(stream, msg.data(), msg.size(), nullptr, nullptr);
+}
+
+} // namespace LIBC_NAMESPACE_DECL

libc/src/__support/OSUtil/windows/io.h

@@ -0,0 +1,21 @@
+//===------------- Windows implementation of IO utils -----------*- C++ -*-===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC___SUPPORT_OSUTIL_WINDOWS_IO_H
+#define LLVM_LIBC_SRC___SUPPORT_OSUTIL_WINDOWS_IO_H
+
+#include "src/__support/CPP/string_view.h"
+#include "src/__support/macros/config.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+void write_to_stderr(cpp::string_view msg);
+
+} // namespace LIBC_NAMESPACE_DECL
+
+#endif // LLVM_LIBC_SRC___SUPPORT_OSUTIL_WINDOWS_IO_H

libc/src/__support/macros/properties/types.h

@@ -35,7 +35,7 @@
 #endif // UINT64_MAX
 
 // int128 / uint128 support
-#if defined(__SIZEOF_INT128__)
+#if defined(__SIZEOF_INT128__) && !defined(LIBC_TARGET_OS_IS_WINDOWS)
 #define LIBC_TYPES_HAS_INT128
 #endif // defined(__SIZEOF_INT128__)
 

libc/test/src/__support/CMakeLists.txt

@@ -142,7 +142,7 @@ add_libc_test(
     libc.src.__support.arg_list
 )
 
-if(NOT LIBC_TARGET_ARCHITECTURE_IS_NVPTX)
+if(NOT LIBC_TARGET_ARCHITECTURE_IS_NVPTX AND NOT LIBC_TARGET_OS_IS_WINDOWS)
   add_libc_test(
     big_int_test
     SUITE

libc/test/src/__support/FPUtil/fpbits_test.cpp

@@ -427,11 +427,9 @@ TEST(LlvmLibcFPBitsTest, DoubleType) {
 
 #ifdef LIBC_TARGET_ARCH_IS_X86
 TEST(LlvmLibcFPBitsTest, X86LongDoubleType) {
+#ifndef LIBC_TYPES_LONG_DOUBLE_IS_FLOAT64
   using LongDoubleBits = FPBits<long double>;
 
-  if constexpr (sizeof(long double) == sizeof(double))
-    return; // The tests for the "double" type cover for this case.
-
   EXPECT_STREQ(LIBC_NAMESPACE::str(LongDoubleBits::inf(Sign::POS)).c_str(),
                "(+Infinity)");
   EXPECT_STREQ(LIBC_NAMESPACE::str(LongDoubleBits::inf(Sign::NEG)).c_str(),
@@ -501,6 +499,7 @@ TEST(LlvmLibcFPBitsTest, X86LongDoubleType) {
 
   LongDoubleBits quiet_nan = LongDoubleBits::quiet_nan();
   EXPECT_EQ(quiet_nan.is_quiet_nan(), true);
+#endif
 }
 #else
 TEST(LlvmLibcFPBitsTest, LongDoubleType) {

libc/test/src/__support/arg_list_test.cpp

@@ -120,7 +120,7 @@ TEST(LlvmLibcArgListTest, TestStructTypes) {
 }
 
 // Test vector extensions from clang.
-#if __has_attribute(ext_vector_type)
+#if !defined(LIBC_TARGET_OS_IS_WINDOWS) && __has_attribute(ext_vector_type)
 
 using int1 = int __attribute__((ext_vector_type(1)));
 using int2 = int __attribute__((ext_vector_type(2)));

libc/test/src/fenv/getenv_and_setenv_test.cpp

@@ -20,6 +20,7 @@
 
 using LlvmLibcFEnvTest = LIBC_NAMESPACE::testing::FEnvSafeTest;
 
+#ifndef LIBC_TARGET_OS_IS_WINDOWS
 TEST_F(LlvmLibcFEnvTest, GetEnvAndSetEnv) {
   // We will disable all exceptions to prevent invocation of the exception
   // handler.
@@ -71,8 +72,9 @@ TEST_F(LlvmLibcFEnvTest, Set_FE_DFL_ENV) {
   int rm = LIBC_NAMESPACE::fegetround();
   EXPECT_EQ(rm, FE_TONEAREST);
 }
+#endif
 
-#ifdef _WIN32
+#ifdef LIBC_TARGET_OS_IS_WINDOWS
 TEST_F(LlvmLibcFEnvTest, Windows_Set_Get_Test) {
   // If a valid fenv_t is written, then reading it back out should be identical.
   fenv_t setEnv = {0x7e00053e, 0x0f00000f};

libc/test/src/math/smoke/AddTest.h

@@ -53,6 +53,7 @@ class AddTest : public LIBC_NAMESPACE::testing::FEnvSafeTest {
   }
 
   void test_range_errors(AddFunc func) {
+#ifndef LIBC_TARGET_OS_IS_WINDOWS
     using namespace LIBC_NAMESPACE::fputil::testing;
 
     if (ForceRoundingMode r(RoundingMode::Nearest); r.success) {
@@ -121,6 +122,7 @@ class AddTest : public LIBC_NAMESPACE::testing::FEnvSafeTest {
           FE_UNDERFLOW | FE_INEXACT);
       EXPECT_MATH_ERRNO(ERANGE);
     }
+#endif
   }
 
   void test_inexact_results(AddFunc func) {

libc/test/src/math/smoke/SubTest.h

@@ -52,6 +52,7 @@ class SubTest : public LIBC_NAMESPACE::testing::FEnvSafeTest {
   }
 
   void test_range_errors(SubFunc func) {
+#ifndef LIBC_TARGET_OS_IS_WINDOWS
     using namespace LIBC_NAMESPACE::fputil::testing;
 
     if (ForceRoundingMode r(RoundingMode::Nearest); r.success) {
@@ -123,6 +124,7 @@ class SubTest : public LIBC_NAMESPACE::testing::FEnvSafeTest {
                                   FE_UNDERFLOW | FE_INEXACT);
       EXPECT_MATH_ERRNO(ERANGE);
     }
+#endif
   }
 
   void test_inexact_results(SubFunc func) {

libc/test/src/string/memory_utils/op_tests.cpp

@@ -294,7 +294,7 @@ TYPED_TEST(LlvmLibcOpTest, Bcmp, BcmpImplementations) {
 #endif // LIBC_TARGET_ARCH_IS_X86_64
 
 using MemcmpImplementations = testing::TypeList<
-#ifdef LIBC_TARGET_ARCH_IS_X86_64
+#if defined(LIBC_TARGET_ARCH_IS_X86_64) && !defined(LIBC_TARGET_OS_IS_WINDOWS)
 #ifdef __SSE2__
     generic::Memcmp<__m128i>, //
 #endif