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__attibute__((__aligned__)) for RSTRING_PTR()

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For instance array.c:rb_ary_product() uses RSTRING_PTR() as an
array of int. So to avoid misaligned memory access RSTRING_PTR()
must at least be sizeof(int)-aligned.  However the type of
RSTRING_PTR() is char*, which of course can expect alignment as
much as 1.  This is a problem.

The reality is, there is no misaligned memory access because the
memory region behind RSTRING_PTR() is allocated using malloc().
Memory regions returned from malloc() are always aligned
appropriately.  So let's tell the compiler about this information.
It seems GCC, clang, and MSVC have such feature.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@61827 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
This commit is contained in:
shyouhei 2018-01-15 02:35:16 +00:00
parent 630ab3b925
commit f089a52865
5 changed files with 39 additions and 11 deletions
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1
win32/Makefile.sub
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@ -636,6 +636,7 @@ $(CONFIG_H): $(MKFILES) $(srcdir)/win32/Makefile.sub $(win_srcdir)/Makefile.sub
#define PACKED_STRUCT_UNALIGNED(x) x
!endif
#define RUBY_EXTERN extern __declspec(dllimport)
#define RUBY_ALIGNAS(n) __declspec(align(n))
#define HAVE_DECL_SYS_NERR 1
#define HAVE_LIMITS_H 1
#define HAVE_FCNTL_H 1