diff options
Diffstat (limited to 'lib/VMCore/Constants.cpp')
| -rw-r--r-- | lib/VMCore/Constants.cpp | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/lib/VMCore/Constants.cpp b/lib/VMCore/Constants.cpp index e3c6144..64fb0aa 100644 --- a/lib/VMCore/Constants.cpp +++ b/lib/VMCore/Constants.cpp @@ -197,6 +197,24 @@ Constant::PossibleRelocationsTy Constant::getRelocationInfo() const { if (const BlockAddress *BA = dyn_cast<BlockAddress>(this)) return BA->getFunction()->getRelocationInfo(); + // While raw uses of blockaddress need to be relocated, differences between + // two of them don't when they are for labels in the same function. This is a + // common idiom when creating a table for the indirect goto extension, so we + // handle it efficiently here. + if (const ConstantExpr *CE = dyn_cast<ConstantExpr>(this)) + if (CE->getOpcode() == Instruction::Sub) { + ConstantExpr *LHS = dyn_cast<ConstantExpr>(CE->getOperand(0)); + ConstantExpr *RHS = dyn_cast<ConstantExpr>(CE->getOperand(1)); + if (LHS && RHS && + LHS->getOpcode() == Instruction::PtrToInt && + RHS->getOpcode() == Instruction::PtrToInt && + isa<BlockAddress>(LHS->getOperand(0)) && + isa<BlockAddress>(RHS->getOperand(0)) && + cast<BlockAddress>(LHS->getOperand(0))->getFunction() == + cast<BlockAddress>(RHS->getOperand(0))->getFunction()) + return NoRelocation; + } + PossibleRelocationsTy Result = NoRelocation; for (unsigned i = 0, e = getNumOperands(); i != e; ++i) Result = std::max(Result, |