* [PATCH] python: fix gcc 8 alignement error.
@ 2018-06-21 6:59 Nicolas Cornu
2018-06-21 7:11 ` Nicolas Cornu
0 siblings, 1 reply; 3+ messages in thread
From: Nicolas Cornu @ 2018-06-21 6:59 UTC (permalink / raw)
To: bitbake-devel; +Cc: Vivien Henriet
From: Vivien Henriet <v.henriet@overkiz.com>
https://bugs.python.org/issue33374
Change-Id: I2c573447bbe79098317409a8168393f9eb58644c
---
This patch is not here to be merged, but to have review on it.
The problem that this patch try to fix is that if your google-repo got 150 projects, and you want to build each with
a specific recipe, sources vill be copied each time.
.../fix-generate-posix-vars-crash.patch | 62 +++++++++++++++++++
.../python/python-native_2.7.12.bb | 1 +
2 files changed, 63 insertions(+)
create mode 100644 meta/recipes-devtools/python/python-native/fix-generate-posix-vars-crash.patch
diff --git a/meta/recipes-devtools/python/python-native/fix-generate-posix-vars-crash.patch b/meta/recipes-devtools/python/python-native/fix-generate-posix-vars-crash.patch
new file mode 100644
index 0000000000..277d822744
--- /dev/null
+++ b/meta/recipes-devtools/python/python-native/fix-generate-posix-vars-crash.patch
@@ -0,0 +1,62 @@
+From 0b91f8a668201fc58fa732b8acc496caedfdbae0 Mon Sep 17 00:00:00 2001
+From: Florian Weimer <fw@deneb.enyo.de>
+Date: Sun, 29 Apr 2018 12:18:33 -0700
+Subject: [PATCH] Indicate that _PyGC_Head is only 8-byte aligned. (closes
+ bpo-33374)
+
+By spec, the "long double" in _PyGC_Head requires the union to always be 16-byte
+aligned. However, obmalloc only yields 8-byte alignment. Compilers including GCC
+8 are starting to use alignment information to do store-merging. So, the "long
+double" needs to be changed to a simple "double" as was long ago done in Python
+3 by e348c8d154cf6342c79d627ebfe89dfe9de23817. For 2.7, we need to add some
+dummy padding to make sure _PyGC_Head stays the same size.
+---
+ Include/objimpl.h | 17 ++++++++++++++++-
+ .../2018-04-29-12-07-00.bpo-33374.-xegL6.rst | 3 +++
+ 2 files changed, 19 insertions(+), 1 deletion(-)
+ create mode 100644 Misc/NEWS.d/next/Core and Builtins/2018-04-29-12-07-00.bpo-33374.-xegL6.rst
+
+diff --git a/Include/objimpl.h b/Include/objimpl.h
+index 5f2868332955..cbf6bc3f8763 100644
+--- a/Include/objimpl.h
++++ b/Include/objimpl.h
+@@ -248,6 +248,20 @@ PyAPI_FUNC(PyVarObject *) _PyObject_GC_Resize(PyVarObject *, Py_ssize_t);
+ /* for source compatibility with 2.2 */
+ #define _PyObject_GC_Del PyObject_GC_Del
+
++/*
++ * Former over-aligned definition of PyGC_Head, used to compute the size of the
++ * padding for the new version below.
++ */
++union _gc_head;
++union _gc_head_old {
++ struct {
++ union _gc_head_old *gc_next;
++ union _gc_head_old *gc_prev;
++ Py_ssize_t gc_refs;
++ } gc;
++ long double dummy;
++};
++
+ /* GC information is stored BEFORE the object structure. */
+ typedef union _gc_head {
+ struct {
+@@ -255,7 +269,8 @@ typedef union _gc_head {
+ union _gc_head *gc_prev;
+ Py_ssize_t gc_refs;
+ } gc;
+- long double dummy; /* force worst-case alignment */
++ double dummy; /* Force at least 8-byte alignment. */
++ char dummy_padding[sizeof(union _gc_head_old)];
+ } PyGC_Head;
+
+ extern PyGC_Head *_PyGC_generation0;
+diff --git a/Misc/NEWS.d/next/Core and Builtins/2018-04-29-12-07-00.bpo-33374.-xegL6.rst b/Misc/NEWS.d/next/Core and Builtins/2018-04-29-12-07-00.bpo-33374.-xegL6.rst
+new file mode 100644
+index 000000000000..9ec1a605c8f2
+--- /dev/null
++++ b/Misc/NEWS.d/next/Core and Builtins/2018-04-29-12-07-00.bpo-33374.-xegL6.rst
+@@ -0,0 +1,3 @@
++Tweak the definition of PyGC_Head, so compilers do not believe it is always
++16-byte aligned on x86. This prevents crashes with more aggressive
++optimizations present in GCC 8.
diff --git a/meta/recipes-devtools/python/python-native_2.7.12.bb b/meta/recipes-devtools/python/python-native_2.7.12.bb
index de83cbd76a..adb23637ae 100644
--- a/meta/recipes-devtools/python/python-native_2.7.12.bb
+++ b/meta/recipes-devtools/python/python-native_2.7.12.bb
@@ -17,6 +17,7 @@ SRC_URI += "\
file://builddir.patch \
file://parallel-makeinst-create-bindir.patch \
file://revert_use_of_sysconfigdata.patch \
+ file://fix-generate-posix-vars-crash.patch \
"
S = "${WORKDIR}/Python-${PV}"
--
2.17.1
^ permalink raw reply related [flat|nested] 3+ messages in thread
* Re: [PATCH] python: fix gcc 8 alignement error.
2018-06-21 6:59 [PATCH] python: fix gcc 8 alignement error Nicolas Cornu
@ 2018-06-21 7:11 ` Nicolas Cornu
2018-06-22 11:07 ` Furkan Tokac
0 siblings, 1 reply; 3+ messages in thread
From: Nicolas Cornu @ 2018-06-21 7:11 UTC (permalink / raw)
To: Nicolas Cornu; +Cc: Vivien Henriet, bitbake-devel
Ignore this thread please. It's a terrible mistake from me.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH] python: fix gcc 8 alignement error.
2018-06-21 7:11 ` Nicolas Cornu
@ 2018-06-22 11:07 ` Furkan Tokac
0 siblings, 0 replies; 3+ messages in thread
From: Furkan Tokac @ 2018-06-22 11:07 UTC (permalink / raw)
To: bitbake-devel
We're human beings, we do mistakes :)
On 6/21/18 10:11 AM, Nicolas Cornu via bitbake-devel wrote:
> Ignore this thread please. It's a terrible mistake from me.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2018-06-21 6:59 [PATCH] python: fix gcc 8 alignement error Nicolas Cornu
2018-06-21 7:11 ` Nicolas Cornu
2018-06-22 11:07 ` Furkan Tokac
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