llvm-6502/test/Transforms/DeadArgElim
Shuxin Yang e0409098ae Fix a bug in Dead Argument Elimination.
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


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192302 91177308-0d34-0410-b5e6-96231b3b80d8
2013-10-09 17:21:44 +00:00
..
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
deadretval2.ll
deadretval.ll
keepalive.ll
linkage.ll
multdeadretval.ll
returned.ll
variadic_safety.ll