From a1b7f5e64d392a802adb586b97deea0a6f4f500e Mon Sep 17 00:00:00 2001 From: Stefan Becker Date: Wed, 2 May 2018 14:14:48 +0300 Subject: [PATCH] package/python: add upstream GCC8 build fix Fedora 28 switched to GCC8. Signed-off-by: Stefan Becker [Thomas: fixup location of SoB in the patch.] Signed-off-by: Thomas Petazzoni --- package/python/0035-GCC8-alignment-fix.patch | 65 ++++++++++++++++++++ 1 file changed, 65 insertions(+) create mode 100644 package/python/0035-GCC8-alignment-fix.patch diff --git a/package/python/0035-GCC8-alignment-fix.patch b/package/python/0035-GCC8-alignment-fix.patch new file mode 100644 index 0000000000..b742aa09de --- /dev/null +++ b/package/python/0035-GCC8-alignment-fix.patch @@ -0,0 +1,65 @@ +From 0b91f8a668201fc58fa732b8acc496caedfdbae0 Mon Sep 17 00:00:00 2001 +From: Florian Weimer +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. + +Upstream: https://bugs.python.org/issue33374 +Signed-off-by: Stefan Becker +--- + 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. -- 2.30.2