diff options
| -rw-r--r-- | lib/Module/IntrinsicCleaner.cpp | 69 |
1 files changed, 69 insertions, 0 deletions
diff --git a/lib/Module/IntrinsicCleaner.cpp b/lib/Module/IntrinsicCleaner.cpp index 92107f4f..921e6766 100644 --- a/lib/Module/IntrinsicCleaner.cpp +++ b/lib/Module/IntrinsicCleaner.cpp @@ -191,6 +191,75 @@ bool IntrinsicCleanerPass::runOnBasicBlock(BasicBlock &b, Module &M) { dirty = true; break; } +#if LLVM_VERSION_CODE >= LLVM_VERSION(8, 0) + case Intrinsic::sadd_sat: + case Intrinsic::ssub_sat: + case Intrinsic::uadd_sat: + case Intrinsic::usub_sat: { + IRBuilder<> builder(ii); + + Value *op1 = ii->getArgOperand(0); + Value *op2 = ii->getArgOperand(1); + + unsigned int bw = op1->getType()->getPrimitiveSizeInBits(); + assert(bw == op2->getType()->getPrimitiveSizeInBits()); + + Value *overflow = nullptr; + Value *result = nullptr; + Value *saturated = nullptr; + switch(ii->getIntrinsicID()) { + case Intrinsic::usub_sat: + result = builder.CreateSub(op1, op2); + overflow = builder.CreateICmpULT(op1, op2); // a < b => a - b < 0 + saturated = ConstantInt::get(ctx, APInt(bw, 0)); + break; + case Intrinsic::uadd_sat: + result = builder.CreateAdd(op1, op2); + overflow = builder.CreateICmpULT(result, op1); // a + b < a + saturated = ConstantInt::get(ctx, APInt::getMaxValue(bw)); + break; + case Intrinsic::ssub_sat: + case Intrinsic::sadd_sat: { + if (ii->getIntrinsicID() == Intrinsic::ssub_sat) { + result = builder.CreateSub(op1, op2); + } else { + result = builder.CreateAdd(op1, op2); + } + ConstantInt *zero = ConstantInt::get(ctx, APInt(bw, 0)); + ConstantInt *smin = ConstantInt::get(ctx, APInt::getSignedMinValue(bw)); + ConstantInt *smax = ConstantInt::get(ctx, APInt::getSignedMaxValue(bw)); + + Value *sign1 = builder.CreateICmpSLT(op1, zero); + Value *sign2 = builder.CreateICmpSLT(op2, zero); + Value *signR = builder.CreateICmpSLT(result, zero); + + if (ii->getIntrinsicID() == Intrinsic::ssub_sat) { + saturated = builder.CreateSelect(sign2, smax, smin); + } else { + saturated = builder.CreateSelect(sign2, smin, smax); + } + + // The sign of the result differs from the sign of the first operand + overflow = builder.CreateXor(sign1, signR); + if (ii->getIntrinsicID() == Intrinsic::ssub_sat) { + // AND the signs of the operands differ + overflow = builder.CreateAnd(overflow, builder.CreateXor(sign1, sign2)); + } else { + // AND the signs of the operands are the same + overflow = builder.CreateAnd(overflow, builder.CreateNot(builder.CreateXor(sign1, sign2))); + } + break; + } + default: ; + } + + result = builder.CreateSelect(overflow, saturated, result); + ii->replaceAllUsesWith(result); + ii->eraseFromParent(); + dirty = true; + break; + } +#endif case Intrinsic::trap: { // Intrinsic instruction "llvm.trap" found. Directly lower it to |