forked from OSchip/llvm-project
1cab418ce2
If a function seen at compile time is not necessarily the one linked to
the binary being built, it is illegal to change the actual arguments
passing to it.
e.g.
--------------------------
void foo(int lol) {
// foo() has linkage satisifying isWeakForLinker()
// "lol" is not used at all.
}
void bar(int lo2) {
// xform to foo(undef) is illegal, as compiler dose not know which
// instance of foo() will be linked to the the binary being built.
foo(lol2);
}
-----------------------------
Such functions can be captured by isWeakForLinker(). NOTE that
mayBeOverridden() is insufficient for this purpose as it dosen't include
linkage types like AvailableExternallyLinkage and LinkOnceODRLinkage.
Take link_odr* as an example, it indicates a set of *EQUIVALENT* globals
that can be merged at link-time. However, the semantic of
*EQUIVALENT*-functions includes parameters. Changing parameters breaks
the assumption.
Thank John McCall for help, especially for the explanation of subtle
difference between linkage types.
rdar://11546243
llvm-svn: 192302
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|---|---|---|
| .. | ||
| 2006-06-27-struct-ret.ll | ||
| 2007-02-07-FuncRename.ll | ||
| 2007-10-18-VarargsReturn.ll | ||
| 2007-12-20-ParamAttrs.ll | ||
| 2008-01-16-VarargsParamAttrs.ll | ||
| 2008-06-23-DeadAfterLive.ll | ||
| 2009-03-17-MRE-Invoke.ll | ||
| 2010-04-30-DbgInfo.ll | ||
| 2013-05-17-VarargsAndBlockAddress.ll | ||
| basictest.ll | ||
| canon.ll | ||
| dbginfo.ll | ||
| dead_vaargs.ll | ||
| deadexternal.ll | ||
| deadretval.ll | ||
| deadretval2.ll | ||
| keepalive.ll | ||
| linkage.ll | ||
| multdeadretval.ll | ||
| returned.ll | ||
| variadic_safety.ll | ||