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e0409098ae
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
22 lines
422 B
LLVM
22 lines
422 B
LLVM
; RUN: opt < %s -deadargelim -S | FileCheck %s
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; rdar://11546243
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%struct.A = type { i8 }
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define available_externally void @_Z17externallyDefinedP1A(%struct.A* %a) {
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entry:
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call void @_Z3foov()
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ret void
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}
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declare void @_Z3foov()
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define void @_Z4testP1A(%struct.A* %a) {
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; CHECK: @_Z4testP1A
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; CHECK: @_Z17externallyDefinedP1A(%struct.A* %a)
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entry:
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call void @_Z17externallyDefinedP1A(%struct.A* %a)
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ret void
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}
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