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| author | Dan Gohman <gohman@apple.com> | 2009-08-16 21:26:11 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2009-08-16 21:26:11 +0000 |
| commit | 3778f21b17e675c2fd1600901361fa4a73888eba (patch) | |
| tree | e975284da0629a07af5221e21342860c2678c4c4 /lib | |
| parent | face41a4de759e881bea1769d86c4cfda2cd1545 (diff) | |
| download | external_llvm-3778f21b17e675c2fd1600901361fa4a73888eba.zip external_llvm-3778f21b17e675c2fd1600901361fa4a73888eba.tar.gz external_llvm-3778f21b17e675c2fd1600901361fa4a73888eba.tar.bz2 | |
Add a getOffsetOf, for building a target-independent expression for
offsetof, similar to getSizeOf for sizeof.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79208 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/VMCore/Constants.cpp | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/lib/VMCore/Constants.cpp b/lib/VMCore/Constants.cpp index 647bc12..f820033 100644 --- a/lib/VMCore/Constants.cpp +++ b/lib/VMCore/Constants.cpp @@ -1391,6 +1391,18 @@ Constant* ConstantExpr::getAlignOf(const Type* Ty) { Type::getInt32Ty(Ty->getContext())); } +Constant* ConstantExpr::getOffsetOf(const StructType* STy, unsigned FieldNo) { + // offsetof is implemented as: (i64) gep (Ty*)null, 0, FieldNo + // Note that a non-inbounds gep is used, as null isn't within any object. + Constant *GEPIdx[] = { + ConstantInt::get(Type::getInt64Ty(STy->getContext()), 0), + ConstantInt::get(Type::getInt32Ty(STy->getContext()), FieldNo) + }; + Constant *GEP = getGetElementPtr( + Constant::getNullValue(PointerType::getUnqual(STy)), GEPIdx, 2); + return getCast(Instruction::PtrToInt, GEP, + Type::getInt64Ty(STy->getContext())); +} Constant *ConstantExpr::getCompare(unsigned short pred, Constant *C1, Constant *C2) { |