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Fix an obscure bug in PointerUnion that would bite PointerUnion3/4. Basically, 

when checking isNull(), we'd pick off the sentinel bit for the outer 
PointerUnion, but would not recursively convert the inner pointerunion to bool,
so if *its* sentinel bit is set, isNull() would incorrectly return false.

No testcase, because someone hit this when they were trying to refactor code
to use PointerUnion3, but they since found a better solution.

llvm-svn: 137428
This commit is contained in:
Chris Lattner 2011-08-12 04:31:38 +00:00
parent a2dee81dec
commit 1ec8114eb8
1 changed files with 5 additions and 1 deletions
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6
llvm/include/llvm/ADT/PointerUnion.h
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@ -108,7 +108,11 @@ namespace llvm {
/// isNull - Return true if the pointer held in the union is null,
/// regardless of which type it is.
bool isNull() const { return Val.getPointer() == 0; }
bool isNull() const {
// Convert from the void* to one of the pointer types, to make sure that
// we recursively strip off low bits if we have a nested PointerUnion.
return !PointerLikeTypeTraits<PT1>::getFromVoidPointer(Val.getPointer());
}
operator bool() const { return !isNull(); }
/// is<T>() return true if the Union currently holds the type matching T.