[libc-commits] [libc] Revert "Revert "[libc] make integration test malloc work properly when threaded"" (PR #152236)

[Schrodinger ZHU Yifan via libc-commits]

https://github.com/SchrodingerZhu updated https://github.com/llvm/llvm-project/pull/152236

>From 021d954acee76dede0815722ae2b85de18e9b712 Mon Sep 17 00:00:00 2001
From: Schrodinger ZHU Yifan <i at zhuyi.fan>
Date: Tue, 5 Aug 2025 21:22:23 -0400
Subject: [PATCH 1/3] =?UTF-8?q?Revert=20"Revert=20"[libc]=20make=20integra?=
 =?UTF-8?q?tion=20test=20malloc=20work=20properly=20when=20thread=E2=80=A6?=
 =?UTF-8?q?"?=
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This reverts commit 6393a9edde6da41d0e927b34a6c9ba965289c6da.
---
 libc/test/IntegrationTest/CMakeLists.txt |  1 +
 libc/test/IntegrationTest/test.cpp       | 15 ++++++++++-----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/libc/test/IntegrationTest/CMakeLists.txt b/libc/test/IntegrationTest/CMakeLists.txt
index 3afe354eca986..235e9fe2f55ee 100644
--- a/libc/test/IntegrationTest/CMakeLists.txt
+++ b/libc/test/IntegrationTest/CMakeLists.txt
@@ -13,5 +13,6 @@ add_object_library(
   DEPENDS
     libc.hdr.stdint_proxy
     libc.src.__support.OSUtil.osutil
+    libc.src.__support.CPP.atomic
     ${arch_specific_deps}
 )
diff --git a/libc/test/IntegrationTest/test.cpp b/libc/test/IntegrationTest/test.cpp
index 8baf74637b309..ec45e28a4e7a6 100644
--- a/libc/test/IntegrationTest/test.cpp
+++ b/libc/test/IntegrationTest/test.cpp
@@ -5,8 +5,8 @@
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
-
 #include "hdr/stdint_proxy.h"
+#include "src/__support/CPP/atomic.h"
 #include "src/__support/common.h"
 #include "src/__support/macros/config.h"
 #include <stddef.h>
@@ -65,14 +65,19 @@ int atexit(void (*func)(void)) { return LIBC_NAMESPACE::atexit(func); }
 
 static constexpr uint64_t MEMORY_SIZE = 16384;
 static uint8_t memory[MEMORY_SIZE];
-static uint8_t *ptr = memory;
+static LIBC_NAMESPACE::cpp::Atomic<size_t> used = 0;
 
 extern "C" {
 
+// For simple test purposes.
 void *malloc(size_t s) {
-  void *mem = ptr;
-  ptr += s;
-  return static_cast<uint64_t>(ptr - memory) >= MEMORY_SIZE ? nullptr : mem;
+  // Emulate the alignment of std::max_align_t.
+  constexpr size_t DEFAULT_ALIGNMENT = alignof(long double);
+  s += (-s) & (DEFAULT_ALIGNMENT - 1); // Align to default alignment.
+  auto res = used.fetch_add(s, LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED);
+  if (res + s > MEMORY_SIZE)
+    return nullptr; // Out of memory.
+  return &memory[res];
 }
 
 void free(void *) {}

>From 898849c51b92d407d743c480cc7bb63aa145d4e2 Mon Sep 17 00:00:00 2001
From: Schrodinger ZHU Yifan <i at zhuyi.fan>
Date: Tue, 5 Aug 2025 21:25:44 -0400
Subject: [PATCH 2/3] skip gpu

---
 libc/test/IntegrationTest/test.cpp | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/libc/test/IntegrationTest/test.cpp b/libc/test/IntegrationTest/test.cpp
index ec45e28a4e7a6..627e068f9e30b 100644
--- a/libc/test/IntegrationTest/test.cpp
+++ b/libc/test/IntegrationTest/test.cpp
@@ -65,11 +65,22 @@ int atexit(void (*func)(void)) { return LIBC_NAMESPACE::atexit(func); }
 
 static constexpr uint64_t MEMORY_SIZE = 16384;
 static uint8_t memory[MEMORY_SIZE];
+
+#ifdef LIBC_TARGET_ARCH_IS_GPU
+static size_t used = 0;
+#else
 static LIBC_NAMESPACE::cpp::Atomic<size_t> used = 0;
+#endif
 
 extern "C" {
 
-// For simple test purposes.
+#ifdef LIBC_TARGET_ARCH_IS_GPU
+void *malloc(size_t s) {
+  void *mem = ptr;
+  ptr += s;
+  return static_cast<uint64_t>(ptr - memory) >= MEMORY_SIZE ? nullptr : mem;
+}
+#else
 void *malloc(size_t s) {
   // Emulate the alignment of std::max_align_t.
   constexpr size_t DEFAULT_ALIGNMENT = alignof(long double);
@@ -79,6 +90,7 @@ void *malloc(size_t s) {
     return nullptr; // Out of memory.
   return &memory[res];
 }
+#endif
 
 void free(void *) {}
 

>From 1ced5ca71a26c912e855fc6fce66ddefa099d698 Mon Sep 17 00:00:00 2001
From: Schrodinger ZHU Yifan <i at zhuyi.fan>
Date: Tue, 5 Aug 2025 21:58:53 -0400
Subject: [PATCH 3/3] use jhuber6's patch

---
 libc/test/IntegrationTest/test.cpp | 36 ++++++++++--------------------
 1 file changed, 12 insertions(+), 24 deletions(-)

diff --git a/libc/test/IntegrationTest/test.cpp b/libc/test/IntegrationTest/test.cpp
index 627e068f9e30b..0e4825202a9e2 100644
--- a/libc/test/IntegrationTest/test.cpp
+++ b/libc/test/IntegrationTest/test.cpp
@@ -63,34 +63,22 @@ int atexit(void (*func)(void)) { return LIBC_NAMESPACE::atexit(func); }
 // which just hands out continuous blocks from a statically allocated chunk of
 // memory.
 
-static constexpr uint64_t MEMORY_SIZE = 16384;
-static uint8_t memory[MEMORY_SIZE];
-
-#ifdef LIBC_TARGET_ARCH_IS_GPU
-static size_t used = 0;
-#else
-static LIBC_NAMESPACE::cpp::Atomic<size_t> used = 0;
-#endif
+static constexpr uint64_t ALIGNMENT = alignof(long double);
+static constexpr uint64_t MEMORY_SIZE = 65336;
+alignas(ALIGNMENT) static uint8_t memory[MEMORY_SIZE];
+static size_t ptr = 0;
 
 extern "C" {
 
-#ifdef LIBC_TARGET_ARCH_IS_GPU
-void *malloc(size_t s) {
-  void *mem = ptr;
-  ptr += s;
-  return static_cast<uint64_t>(ptr - memory) >= MEMORY_SIZE ? nullptr : mem;
+void *malloc(size_t size) {
+  LIBC_NAMESPACE::cpp::AtomicRef<size_t> ref(ptr);
+  size = (size + ALIGNMENT - 1) & ~(ALIGNMENT - 1);
+  size_t old_ptr =
+      ref.fetch_add(size, LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED);
+  if (static_cast<size_t>(old_ptr + size) > MEMORY_SIZE)
+    return nullptr;
+  return &memory[old_ptr];
 }
-#else
-void *malloc(size_t s) {
-  // Emulate the alignment of std::max_align_t.
-  constexpr size_t DEFAULT_ALIGNMENT = alignof(long double);
-  s += (-s) & (DEFAULT_ALIGNMENT - 1); // Align to default alignment.
-  auto res = used.fetch_add(s, LIBC_NAMESPACE::cpp::MemoryOrder::RELAXED);
-  if (res + s > MEMORY_SIZE)
-    return nullptr; // Out of memory.
-  return &memory[res];
-}
-#endif
 
 void free(void *) {}