-/// Convert the llvm.part.select.iX.iY intrinsic. This intrinsic takes
-/// three integer arguments. The first argument is the Value from which the
-/// bits will be selected. It may be of any bit width. The second and third
-/// arguments specify a range of bits to select with the second argument
-/// specifying the low bit and the third argument specifying the high bit. Both
-/// must be type i32. The result is the corresponding selected bits from the
-/// Value in the same width as the Value (first argument). If the low bit index
-/// is higher than the high bit index then the inverse selection is done and
-/// the bits are returned in inverse order.
-/// @brief Lowering of llvm.part.select intrinsic.
-static Instruction *LowerPartSelect(CallInst *CI) {
- // Make sure we're dealing with a part select intrinsic here
- Function *F = CI->getCalledFunction();
- const FunctionType *FT = F->getFunctionType();
- if (!F->isDeclaration() || !FT->getReturnType()->isInteger() ||
- FT->getNumParams() != 3 || !FT->getParamType(0)->isInteger() ||
- !FT->getParamType(1)->isInteger() || !FT->getParamType(2)->isInteger())
- return CI;
-
- // Get the intrinsic implementation function by converting all the . to _
- // in the intrinsic's function name and then reconstructing the function
- // declaration.
- std::string Name(F->getName());
- for (unsigned i = 4; i < Name.length(); ++i)
- if (Name[i] == '.')
- Name[i] = '_';
- Module* M = F->getParent();
- F = cast<Function>(M->getOrInsertFunction(Name, FT));
- F->setLinkage(GlobalValue::InternalLinkage);
-
- // If we haven't defined the impl function yet, do so now
- if (F->isDeclaration()) {
-
- // Get the arguments to the function
- Value* Val = F->getOperand(0);
- Value* Right = F->getOperand(1);
- Value* Left = F->getOperand(2);
-
- // We want to select a range of bits here such that [Left, Right] is shifted
- // down to the low bits. However, it is quite possible that Left is smaller
- // than Right in which case the bits have to be reversed.
-
- // Create the blocks we will need for the two cases (forward, reverse)
- BasicBlock* CurBB = new BasicBlock("entry", F);
- BasicBlock *RevSize = new BasicBlock("revsize", CurBB->getParent());
- BasicBlock *FwdSize = new BasicBlock("fwdsize", CurBB->getParent());
- BasicBlock *Compute = new BasicBlock("compute", CurBB->getParent());
- BasicBlock *Reverse = new BasicBlock("reverse", CurBB->getParent());
- BasicBlock *RsltBlk = new BasicBlock("result", CurBB->getParent());
-
- // Cast Left and Right to the size of Val so the widths are all the same
- if (Left->getType() != Val->getType())
- Left = CastInst::createIntegerCast(Left, Val->getType(), false,
- "tmp", CurBB);
- if (Right->getType() != Val->getType())
- Right = CastInst::createIntegerCast(Right, Val->getType(), false,
- "tmp", CurBB);
-
- // Compute a few things that both cases will need, up front.
- Constant* Zero = ConstantInt::get(Val->getType(), 0);
- Constant* One = ConstantInt::get(Val->getType(), 1);
- Constant* AllOnes = ConstantInt::getAllOnesValue(Val->getType());
-
- // Compare the Left and Right bit positions. This is used to determine
- // which case we have (forward or reverse)
- ICmpInst *Cmp = new ICmpInst(ICmpInst::ICMP_ULT, Left, Right, "less",CurBB);
- new BranchInst(RevSize, FwdSize, Cmp, CurBB);
-
- // First, copmute the number of bits in the forward case.
- Instruction* FBitSize =
- BinaryOperator::createSub(Left, Right,"fbits", FwdSize);
- new BranchInst(Compute, FwdSize);
-
- // Second, compute the number of bits in the reverse case.
- Instruction* RBitSize =
- BinaryOperator::createSub(Right, Left, "rbits", RevSize);
- new BranchInst(Compute, RevSize);
-
- // Now, compute the bit range. Start by getting the bitsize and the shift
- // amount (either Left or Right) from PHI nodes. Then we compute a mask for
- // the number of bits we want in the range. We shift the bits down to the
- // least significant bits, apply the mask to zero out unwanted high bits,
- // and we have computed the "forward" result. It may still need to be
- // reversed.
-
- // Get the BitSize from one of the two subtractions
- PHINode *BitSize = new PHINode(Val->getType(), "bits", Compute);
- BitSize->reserveOperandSpace(2);
- BitSize->addIncoming(FBitSize, FwdSize);
- BitSize->addIncoming(RBitSize, RevSize);
-
- // Get the ShiftAmount as the smaller of Left/Right
- PHINode *ShiftAmt = new PHINode(Val->getType(), "shiftamt", Compute);
- ShiftAmt->reserveOperandSpace(2);
- ShiftAmt->addIncoming(Right, FwdSize);
- ShiftAmt->addIncoming(Left, RevSize);
-
- // Increment the bit size
- Instruction *BitSizePlusOne =
- BinaryOperator::createAdd(BitSize, One, "bits", Compute);
-
- // Create a Mask to zero out the high order bits.
- Instruction* Mask =
- BinaryOperator::createShl(AllOnes, BitSizePlusOne, "mask", Compute);
- Mask = BinaryOperator::createNot(Mask, "mask", Compute);
-
- // Shift the bits down and apply the mask
- Instruction* FRes =
- BinaryOperator::createLShr(Val, ShiftAmt, "fres", Compute);
- FRes = BinaryOperator::createAnd(FRes, Mask, "fres", Compute);
- new BranchInst(Reverse, RsltBlk, Cmp, Compute);
-
- // In the Reverse block we have the mask already in FRes but we must reverse
- // it by shifting FRes bits right and putting them in RRes by shifting them
- // in from left.
-
- // First set up our loop counters
- PHINode *Count = new PHINode(Val->getType(), "count", Reverse);
- Count->reserveOperandSpace(2);
- Count->addIncoming(BitSizePlusOne, Compute);
-
- // Next, get the value that we are shifting.
- PHINode *BitsToShift = new PHINode(Val->getType(), "val", Reverse);
- BitsToShift->reserveOperandSpace(2);
- BitsToShift->addIncoming(FRes, Compute);
-
- // Finally, get the result of the last computation
- PHINode *RRes = new PHINode(Val->getType(), "rres", Reverse);
- RRes->reserveOperandSpace(2);
- RRes->addIncoming(Zero, Compute);
-
- // Decrement the counter
- Instruction *Decr = BinaryOperator::createSub(Count, One, "decr", Reverse);
- Count->addIncoming(Decr, Reverse);
-
- // Compute the Bit that we want to move
- Instruction *Bit =
- BinaryOperator::createAnd(BitsToShift, One, "bit", Reverse);
-
- // Compute the new value for next iteration.
- Instruction *NewVal =
- BinaryOperator::createLShr(BitsToShift, One, "rshift", Reverse);
- BitsToShift->addIncoming(NewVal, Reverse);
-
- // Shift the bit into the low bits of the result.
- Instruction *NewRes =
- BinaryOperator::createShl(RRes, One, "lshift", Reverse);
- NewRes = BinaryOperator::createOr(NewRes, Bit, "addbit", Reverse);
- RRes->addIncoming(NewRes, Reverse);
-
- // Terminate loop if we've moved all the bits.
- ICmpInst *Cond =
- new ICmpInst(ICmpInst::ICMP_EQ, Decr, Zero, "cond", Reverse);
- new BranchInst(RsltBlk, Reverse, Cond, Reverse);
-
- // Finally, in the result block, select one of the two results with a PHI
- // node and return the result;
- CurBB = RsltBlk;
- PHINode *BitSelect = new PHINode(Val->getType(), "part_select", CurBB);
- BitSelect->reserveOperandSpace(2);
- BitSelect->addIncoming(FRes, Compute);
- BitSelect->addIncoming(NewRes, Reverse);
- new ReturnInst(BitSelect, CurBB);
- }
-
- // Return a call to the implementation function
- Value *Args[3];
- Args[0] = CI->getOperand(0);
- Args[1] = CI->getOperand(1);
- Args[2] = CI->getOperand(2);
- return new CallInst(F, Args, 3, CI->getName(), CI);
-}
-
-/// Convert the llvm.part.set.iX.iY.iZ intrinsic. This intrinsic takes
-/// four integer arguments (iAny %Value, iAny %Replacement, i32 %Low, i32 %High)
-/// The first two arguments can be any bit width. The result is the same width
-/// as %Value. The operation replaces bits between %Low and %High with the value
-/// in %Replacement. If %Replacement is not the same width, it is truncated or
-/// zero extended as appropriate to fit the bits being replaced. If %Low is
-/// greater than %High then the inverse set of bits are replaced.
-/// @brief Lowering of llvm.bit.part.set intrinsic.
-static Instruction *LowerPartSet(CallInst *CI) {
- // Make sure we're dealing with a part select intrinsic here
- Function *F = CI->getCalledFunction();
- const FunctionType *FT = F->getFunctionType();
- if (!F->isDeclaration() || !FT->getReturnType()->isInteger() ||
- FT->getNumParams() != 4 || !FT->getParamType(0)->isInteger() ||
- !FT->getParamType(1)->isInteger() || !FT->getParamType(2)->isInteger() ||
- !FT->getParamType(3)->isInteger())
- return CI;
-
- // Get the intrinsic implementation function by converting all the . to _
- // in the intrinsic's function name and then reconstructing the function
- // declaration.
- std::string Name(F->getName());
- for (unsigned i = 4; i < Name.length(); ++i)
- if (Name[i] == '.')
- Name[i] = '_';
- Module* M = F->getParent();
- F = cast<Function>(M->getOrInsertFunction(Name, FT));
- F->setLinkage(GlobalValue::InternalLinkage);
-
- // If we haven't defined the impl function yet, do so now
- if (F->isDeclaration()) {
- // Note: the following code is based on code generated by llvm2cpp with
- // the following input. This is just *one* example of a generated function.
- // The functions vary by bit width of result and first two arguments.
- // The generated code has been changed to deal with any bit width not just
- // the 32/64 bitwidths used in the above sample.
- //
- // define i64 @part_set(i64 %Val, i32 %Rep, i32 %Lo, i32 %Hi) {
- // entry:
- // %is_forward = icmp ult i32 %Lo, %Hi
- // %Lo.pn = select i1 %is_forward, i32 %Hi, i32 %Lo
- // %Hi.pn = select i1 %is_forward, i32 %Lo, i32 %Hi
- // %iftmp.16.0 = sub i32 %Lo.pn, %Hi.pn
- // icmp ult i32 %iftmp.16.0, 32
- // br i1 %1, label %cond_true11, label %cond_next19
- // cond_true11:
- // %tmp13 = sub i32 32, %iftmp.16.0
- // %tmp14 = lshr i32 -1, %tmp13
- // %tmp16 = and i32 %tmp14, %Rep
- // br label %cond_next19
- // cond_next19:
- // %iftmp.17.0 = phi i32 [ %tmp16, %cond_true11 ], [ %Rep, %entry ]
- // %tmp2021 = zext i32 %iftmp.17.0 to i64
- // icmp ugt i32 %Lo, %Hi
- // br i1 %2, label %cond_next60, label %cond_true24
- // cond_true24:
- // %tmp25.cast = zext i32 %Hi to i64
- // %tmp26 = lshr i64 -1, %tmp25.cast
- // %tmp27.cast = zext i32 %Lo to i64
- // %tmp28 = shl i64 %tmp26, %tmp27.cast
- // %tmp28not = xor i64 %tmp28, -1
- // %tmp31 = shl i64 %tmp2021, %tmp27.cast
- // %tmp34 = and i64 %tmp28not, %Val
- // %Val_addr.064 = or i64 %tmp31, %tmp34
- // ret i64 %Val_addr.064
- // cond_next60:
- // %tmp39.cast = zext i32 %Lo to i64
- // %tmp40 = shl i64 -1, %tmp39.cast
- // %tmp41.cast = zext i32 %Hi to i64
- // %tmp42 = shl i64 -1, %tmp41.cast
- // %tmp45.demorgan = or i64 %tmp42, %tmp40
- // %tmp45 = xor i64 %tmp45.demorgan, -1
- // %tmp47 = and i64 %tmp45, %Val
- // %tmp50 = shl i64 %tmp2021, %tmp39.cast
- // %tmp52 = sub i32 32, %Hi
- // %tmp52.cast = zext i32 %tmp52 to i64
- // %tmp54 = lshr i64 %tmp2021, %tmp52.cast
- // %tmp57 = or i64 %tmp50, %tmp47
- // %Val_addr.0 = or i64 %tmp57, %tmp54
- // ret i64 %Val_addr.0
- // }
-
- // Get the arguments for the function.
- Function::arg_iterator args = F->arg_begin();
- Value* Val = args++; Val->setName("Val");
- Value* Rep = args++; Rep->setName("Rep");
- Value* Lo = args++; Lo->setName("Lo");
- Value* Hi = args++; Hi->setName("Hi");
-
- // Get some types we need
- const IntegerType* ValTy = cast<IntegerType>(Val->getType());
- const IntegerType* RepTy = cast<IntegerType>(Rep->getType());
- uint32_t ValBits = ValTy->getBitWidth();
- uint32_t RepBits = RepTy->getBitWidth();
-
- // Constant Definitions
- ConstantInt* RepBitWidth = ConstantInt::get(Type::Int32Ty, RepBits);
- ConstantInt* RepMask = ConstantInt::getAllOnesValue(RepTy);
- ConstantInt* ValMask = ConstantInt::getAllOnesValue(ValTy);
-
- BasicBlock* entry = new BasicBlock("entry",F,0);
- BasicBlock* large = new BasicBlock("large",F,0);
- BasicBlock* small = new BasicBlock("small",F,0);
- BasicBlock* forward = new BasicBlock("cond_true24",F,0);
- BasicBlock* reverse = new BasicBlock("cond_next60",F,0);
-
- // Block entry (entry)
- // First, convert Lo and Hi to ValTy bit width
- if (ValBits > 32) {
- Hi = new ZExtInst(Hi, ValTy, "", entry);
- Lo = new ZExtInst(Lo, ValTy, "", entry);
- } else if (ValBits < 32) {
- Hi = new TruncInst(Hi, ValTy, "", entry);
- Lo = new TruncInst(Lo, ValTy, "", entry);
- }
- ICmpInst* is_forward =
- new ICmpInst(ICmpInst::ICMP_ULT, Lo, Hi, "", entry);
- SelectInst* Lo_pn = new SelectInst(is_forward, Hi, Lo, "", entry);
- SelectInst* Hi_pn = new SelectInst(is_forward, Lo, Hi, "", entry);
- BinaryOperator* NumBits = BinaryOperator::createSub(Lo_pn, Hi_pn, "",entry);
- ICmpInst* is_large =
- new ICmpInst(ICmpInst::ICMP_ULT, NumBits, RepBitWidth, "", entry);
- new BranchInst(large, small, is_large, entry);
-
- // Block "large"
- BinaryOperator* MaskBits =
- BinaryOperator::createSub(RepBitWidth, NumBits, "", large);
- BinaryOperator* Mask1 =
- BinaryOperator::createLShr(RepMask, MaskBits, "", large);
- BinaryOperator* Rep2 = BinaryOperator::createAnd(Mask1, Rep, "", large);
- new BranchInst(small, large);
-
- // Block "small"
- PHINode* Rep3 = new PHINode(RepTy, "", small);
- Rep3->reserveOperandSpace(2);
- Rep3->addIncoming(Rep2, small);
- Rep3->addIncoming(Rep, entry);
- CastInst* Rep4 = new ZExtInst(Rep3, ValTy, "", small);
- ICmpInst* is_reverse =
- new ICmpInst(ICmpInst::ICMP_UGT, Lo, Hi, "", small);
- new BranchInst(reverse, forward, is_reverse, small);
-
- // Block "forward"
- Value* t1 = BinaryOperator::createLShr(ValMask, Hi, "", forward);
- Value* t2 = BinaryOperator::createShl(t1, Lo, "", forward);
- Value* nott2 = BinaryOperator::createXor(t2, ValMask, "", forward);
- Value* t3 = BinaryOperator::createShl(Rep4, Lo, "", forward);
- Value* t4 = BinaryOperator::createAnd(nott2, Val, "", forward);
- Value* FRslt = BinaryOperator::createOr(t3, t4, "", forward);
- new ReturnInst(FRslt, forward);
-
- // Block "reverse"
- Value* t5 = BinaryOperator::createShl(ValMask, Lo, "", reverse);
- Value* t6 = BinaryOperator::createShl(ValMask, Hi, "", reverse);
- Value* t7 = BinaryOperator::createOr(t6, t5, "", reverse);
- Value* t8 = BinaryOperator::createXor(t7, ValMask, "", reverse);
- Value* t9 = BinaryOperator::createAnd(t8, Val, "", reverse);
- Value* t10 = BinaryOperator::createShl(Rep4, Lo, "", reverse);
- Value* t11 = BinaryOperator::createSub(RepBitWidth, Hi, "", reverse);
- Value* t12 = new ZExtInst(t11, ValTy, "", reverse);
- Value* t13 = BinaryOperator::createLShr(Rep4, t12, "",reverse);
- Value* t14 = BinaryOperator::createOr(t10, t9, "", reverse);
- Value* RRslt = BinaryOperator::createOr(t14, t13, "", reverse);
- new ReturnInst(RRslt, reverse);