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[Bug c++/17736] New: Optimization for global initialization with trivial constructors
- From: "austern at apple dot com" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 29 Sep 2004 19:35:21 -0000
- Subject: [Bug c++/17736] New: Optimization for global initialization with trivial constructors
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
Consider the following file:
struct X { X() { } };
struct Y { Y() { } };
X x1, x2, x3;
Y y1, y2, y3;
Compiling this to assembly code with -Os, we can see that the compiler is correctly optimizing away
the do-nothing constructors: nothing is being done for any of these six global objects. However, the
compiler still generates a do-nothing mod_init function. The relevant part of the assembly file is:
.mod_init_func
.align 2
.long __GLOBAL__I_x1
...
__GLOBAL__I_x1:
LFB9:
blr
LFE9:
At least we're only getting one do-nothing function per translation unit, instead of one per class or one
per global. But it would be nice if we didn't get it at all.
--
Summary: Optimization for global initialization with trivial
constructors
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P2
Component: c++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: austern at apple dot com
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: powerpc-apple-darwin
GCC host triplet: powerpc-apple-darwin
GCC target triplet: powerpc-apple-darwin
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17736