diff options
Diffstat (limited to 'llvm/lib/Transforms/Utils/Local.cpp')
| -rw-r--r-- | llvm/lib/Transforms/Utils/Local.cpp | 28 |
1 files changed, 28 insertions, 0 deletions
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp index a5e443f..d891fc0 100644 --- a/llvm/lib/Transforms/Utils/Local.cpp +++ b/llvm/lib/Transforms/Utils/Local.cpp @@ -301,6 +301,14 @@ bool llvm::isInstructionTriviallyDead(Instruction *I, if (II->getIntrinsicID() == Intrinsic::lifetime_start || II->getIntrinsicID() == Intrinsic::lifetime_end) return isa<UndefValue>(II->getArgOperand(1)); + + // Assumptions are dead if their condition is trivially true. + if (II->getIntrinsicID() == Intrinsic::assume) { + if (ConstantInt *Cond = dyn_cast<ConstantInt>(II->getArgOperand(0))) + return !Cond->isZero(); + + return false; + } } if (isAllocLikeFn(I, TLI)) return true; @@ -1183,6 +1191,26 @@ static bool markAliveBlocks(BasicBlock *BB, // instructions into LLVM unreachable insts. The instruction combining pass // canonicalizes unreachable insts into stores to null or undef. for (BasicBlock::iterator BBI = BB->begin(), E = BB->end(); BBI != E;++BBI){ + // Assumptions that are known to be false are equivalent to unreachable. + // Also, if the condition is undefined, then we make the choice most + // beneficial to the optimizer, and choose that to also be unreachable. + if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(BBI)) + if (II->getIntrinsicID() == Intrinsic::assume) { + bool MakeUnreachable = false; + if (isa<UndefValue>(II->getArgOperand(0))) + MakeUnreachable = true; + else if (ConstantInt *Cond = + dyn_cast<ConstantInt>(II->getArgOperand(0))) + MakeUnreachable = Cond->isZero(); + + if (MakeUnreachable) { + // Don't insert a call to llvm.trap right before the unreachable. + changeToUnreachable(BBI, false); + Changed = true; + break; + } + } + if (CallInst *CI = dyn_cast<CallInst>(BBI)) { if (CI->doesNotReturn()) { // If we found a call to a no-return function, insert an unreachable |