bpo-27987 for v3.5.10 and v3.6.15: align by 16bytes on 64bit platforms

This commit is contained in:
Chaim Halbert 2023-02-24 12:19:13 -07:00
parent 68918e69b7
commit 28be65992d
4 changed files with 166 additions and 0 deletions

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@ -0,0 +1,43 @@
From 112cceb514e79b4c9805f9e5ea037a205be428da Mon Sep 17 00:00:00 2001
From: Inada Naoki <songofacandy@gmail.com>
Date: Tue, 14 May 2019 18:51:15 +0900
Subject: [PATCH 1/2] bpo-27987: pymalloc: align by 16bytes on 64bit platform
(GH-12850)
---
.../2019-04-16-11-52-21.bpo-27987.n2_DcQ.rst | 3 +++
Objects/obmalloc.c | 6 ++++++
2 files changed, 9 insertions(+)
create mode 100644 Misc/NEWS.d/next/Core and Builtins/2019-04-16-11-52-21.bpo-27987.n2_DcQ.rst
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-04-16-11-52-21.bpo-27987.n2_DcQ.rst b/Misc/NEWS.d/next/Core and Builtins/2019-04-16-11-52-21.bpo-27987.n2_DcQ.rst
new file mode 100644
index 0000000000..b0f32a5c6c
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-04-16-11-52-21.bpo-27987.n2_DcQ.rst
@@ -0,0 +1,3 @@
+pymalloc returns memory blocks aligned by 16 bytes, instead of 8 bytes, on
+64-bit platforms to conform x86-64 ABI. Recent compilers assume this alignment
+more often. Patch by Inada Naoki.
diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c
index 9dd8421a33..da9029c4a6 100644
--- a/Objects/obmalloc.c
+++ b/Objects/obmalloc.c
@@ -540,8 +540,14 @@ static int running_on_valgrind = -1;
*
* You shouldn't change this unless you know what you are doing.
*/
+
+#if SIZEOF_VOID_P > 4
+#define ALIGNMENT 16 /* must be 2^N */
+#define ALIGNMENT_SHIFT 4
+#else
#define ALIGNMENT 8 /* must be 2^N */
#define ALIGNMENT_SHIFT 3
+#endif
/* Return the number of bytes in size class I, as a uint. */
#define INDEX2SIZE(I) (((uint)(I) + 1) << ALIGNMENT_SHIFT)
--
2.38.4

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@ -0,0 +1,40 @@
From 618ef35426ecc57da1bee50f8dc5896f5fb178a9 Mon Sep 17 00:00:00 2001
From: Inada Naoki <songofacandy@gmail.com>
Date: Sat, 25 May 2019 21:13:33 +0900
Subject: [PATCH 2/2] bpo-27987: align PyGC_Head to alignof(long double)
(GH-13335)
---
Include/objimpl.h | 6 +++++-
.../2019-05-15-18-28-43.bpo-27987.FaxuLy.rst | 2 ++
2 files changed, 7 insertions(+), 1 deletion(-)
create mode 100644 Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst
diff --git a/Include/objimpl.h b/Include/objimpl.h
index 65b6d91c36..eaf57975c8 100644
--- a/Include/objimpl.h
+++ b/Include/objimpl.h
@@ -250,7 +250,11 @@ typedef union _gc_head {
union _gc_head *gc_prev;
Py_ssize_t gc_refs;
} gc;
- double dummy; /* force worst-case alignment */
+ long double dummy; /* force worst-case alignment */
+ // malloc returns memory block aligned for any built-in types and
+ // long double is the largest standard C type.
+ // On amd64 linux, long double requires 16 byte alignment.
+ // See bpo-27987 for more discussion.
} PyGC_Head;
extern PyGC_Head *_PyGC_generation0;
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst b/Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst
new file mode 100644
index 0000000000..97ca37b262
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst
@@ -0,0 +1,2 @@
+``PyGC_Head`` structure is aligned to ``long double``. This is needed to
+GC-ed objects are aligned properly. Patch by Inada Naoki.
--
2.38.4

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@ -0,0 +1,43 @@
From 54dc627769bf112b0181972a52c4b45e4a02da57 Mon Sep 17 00:00:00 2001
From: Inada Naoki <songofacandy@gmail.com>
Date: Tue, 14 May 2019 18:51:15 +0900
Subject: [PATCH 09/10] bpo-27987: pymalloc: align by 16bytes on 64bit platform
(GH-12850)
---
.../2019-04-16-11-52-21.bpo-27987.n2_DcQ.rst | 3 +++
Objects/obmalloc.c | 6 ++++++
2 files changed, 9 insertions(+)
create mode 100644 Misc/NEWS.d/next/Core and Builtins/2019-04-16-11-52-21.bpo-27987.n2_DcQ.rst
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-04-16-11-52-21.bpo-27987.n2_DcQ.rst b/Misc/NEWS.d/next/Core and Builtins/2019-04-16-11-52-21.bpo-27987.n2_DcQ.rst
new file mode 100644
index 0000000000..b0f32a5c6c
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-04-16-11-52-21.bpo-27987.n2_DcQ.rst
@@ -0,0 +1,3 @@
+pymalloc returns memory blocks aligned by 16 bytes, instead of 8 bytes, on
+64-bit platforms to conform x86-64 ABI. Recent compilers assume this alignment
+more often. Patch by Inada Naoki.
diff --git a/Objects/obmalloc.c b/Objects/obmalloc.c
index d46d149311..47283354f4 100644
--- a/Objects/obmalloc.c
+++ b/Objects/obmalloc.c
@@ -650,8 +650,14 @@ static int running_on_valgrind = -1;
*
* You shouldn't change this unless you know what you are doing.
*/
+
+#if SIZEOF_VOID_P > 4
+#define ALIGNMENT 16 /* must be 2^N */
+#define ALIGNMENT_SHIFT 4
+#else
#define ALIGNMENT 8 /* must be 2^N */
#define ALIGNMENT_SHIFT 3
+#endif
/* Return the number of bytes in size class I, as a uint. */
#define INDEX2SIZE(I) (((uint)(I) + 1) << ALIGNMENT_SHIFT)
--
2.38.4

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@ -0,0 +1,40 @@
From e68ff170dc6764b22886e703f583fb53e90367ef Mon Sep 17 00:00:00 2001
From: Inada Naoki <songofacandy@gmail.com>
Date: Sat, 25 May 2019 21:13:33 +0900
Subject: [PATCH 10/10] bpo-27987: align PyGC_Head to alignof(long double)
(GH-13335)
---
Include/objimpl.h | 6 +++++-
.../2019-05-15-18-28-43.bpo-27987.FaxuLy.rst | 2 ++
2 files changed, 7 insertions(+), 1 deletion(-)
create mode 100644 Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst
diff --git a/Include/objimpl.h b/Include/objimpl.h
index e7a3696d7a..90d71b87ea 100644
--- a/Include/objimpl.h
+++ b/Include/objimpl.h
@@ -255,7 +255,11 @@ typedef union _gc_head {
union _gc_head *gc_prev;
Py_ssize_t gc_refs;
} gc;
- double dummy; /* force worst-case alignment */
+ long double dummy; /* force worst-case alignment */
+ // malloc returns memory block aligned for any built-in types and
+ // long double is the largest standard C type.
+ // On amd64 linux, long double requires 16 byte alignment.
+ // See bpo-27987 for more discussion.
} PyGC_Head;
extern PyGC_Head *_PyGC_generation0;
diff --git a/Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst b/Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst
new file mode 100644
index 0000000000..97ca37b262
--- /dev/null
+++ b/Misc/NEWS.d/next/Core and Builtins/2019-05-15-18-28-43.bpo-27987.FaxuLy.rst
@@ -0,0 +1,2 @@
+``PyGC_Head`` structure is aligned to ``long double``. This is needed to
+GC-ed objects are aligned properly. Patch by Inada Naoki.
--
2.38.4