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+//===-- SystemZTDC.cpp - Utilize Test Data Class instruction --------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This pass looks for instructions that can be replaced by a Test Data Class
+// instruction, and replaces them when profitable.
+//
+// Roughly, the following rules are recognized:
+//
+// 1: fcmp pred X, 0 -> tdc X, mask
+// 2: fcmp pred X, +-inf -> tdc X, mask
+// 3: fcmp pred X, +-minnorm -> tdc X, mask
+// 4: tdc (fabs X), mask -> tdc X, newmask
+// 5: icmp slt (bitcast float X to int), 0 -> tdc X, mask [ie. signbit]
+// 6: icmp sgt (bitcast float X to int), -1 -> tdc X, mask
+// 7: icmp ne/eq (call @llvm.s390.tdc.*(X, mask)) -> tdc X, mask/~mask
+// 8: and i1 (tdc X, M1), (tdc X, M2) -> tdc X, (M1 & M2)
+// 9: or i1 (tdc X, M1), (tdc X, M2) -> tdc X, (M1 | M2)
+// 10: xor i1 (tdc X, M1), (tdc X, M2) -> tdc X, (M1 ^ M2)
+//
+// The pass works in 4 steps:
+//
+// 1. All fcmp and icmp instructions in a function are checked for a match
+// with rules 1-3 and 5-7. Their TDC equivalents are stored in
+// the ConvertedInsts mapping. If the operand of a fcmp instruction is
+// a fabs, it's also folded according to rule 4.
+// 2. All and/or/xor i1 instructions whose both operands have been already
+// mapped are mapped according to rules 8-10. LogicOpsWorklist is used
+// as a queue of instructions to check.
+// 3. All mapped instructions that are considered worthy of conversion (ie.
+// replacing them will actually simplify the final code) are replaced
+// with a call to the s390.tdc intrinsic.
+// 4. All intermediate results of replaced instructions are removed if unused.
+//
+// Instructions that match rules 1-3 are considered unworthy of conversion
+// on their own (since a comparison instruction is superior), but are mapped
+// in the hopes of folding the result using rules 4 and 8-10 (likely removing
+// the original comparison in the process).
+//
+//===----------------------------------------------------------------------===//
+
+#include "SystemZ.h"
+#include "llvm/ADT/MapVector.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/InstIterator.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/LegacyPassManager.h"
+#include "llvm/IR/Module.h"
+#include <deque>
+#include <set>
+
+using namespace llvm;
+
+namespace llvm {
+ void initializeSystemZTDCPassPass(PassRegistry&);
+}
+
+namespace {
+
+class SystemZTDCPass : public FunctionPass {
+public:
+ static char ID;
+ SystemZTDCPass() : FunctionPass(ID) {
+ initializeSystemZTDCPassPass(*PassRegistry::getPassRegistry());
+ }
+
+ bool runOnFunction(Function &F) override;
+private:
+ // Maps seen instructions that can be mapped to a TDC, values are
+ // (TDC operand, TDC mask, worthy flag) triples.
+ MapVector<Instruction *, std::tuple<Value *, int, bool>> ConvertedInsts;
+ // The queue of and/or/xor i1 instructions to be potentially folded.
+ std::vector<BinaryOperator *> LogicOpsWorklist;
+ // Instructions matched while folding, to be removed at the end if unused.
+ std::set<Instruction *> PossibleJunk;
+
+ // Tries to convert a fcmp instruction.
+ void convertFCmp(CmpInst &I);
+
+ // Tries to convert an icmp instruction.
+ void convertICmp(CmpInst &I);
+
+ // Tries to convert an i1 and/or/xor instruction, whose both operands
+ // have been already converted.
+ void convertLogicOp(BinaryOperator &I);
+
+ // Marks an instruction as converted - adds it to ConvertedInsts and adds
+ // any and/or/xor i1 users to the queue.
+ void converted(Instruction *I, Value *V, int Mask, bool Worthy) {
+ ConvertedInsts[I] = std::make_tuple(V, Mask, Worthy);
+ auto &M = *I->getFunction()->getParent();
+ auto &Ctx = M.getContext();
+ for (auto *U : I->users()) {
+ auto *LI = dyn_cast<BinaryOperator>(U);
+ if (LI && LI->getType() == Type::getInt1Ty(Ctx) &&
+ (LI->getOpcode() == Instruction::And ||
+ LI->getOpcode() == Instruction::Or ||
+ LI->getOpcode() == Instruction::Xor)) {
+ LogicOpsWorklist.push_back(LI);
+ }
+ }
+ }
+};
+
+} // end anonymous namespace
+
+char SystemZTDCPass::ID = 0;
+INITIALIZE_PASS(SystemZTDCPass, "systemz-tdc",
+ "SystemZ Test Data Class optimization", false, false)
+
+FunctionPass *llvm::createSystemZTDCPass() {
+ return new SystemZTDCPass();
+}
+
+void SystemZTDCPass::convertFCmp(CmpInst &I) {
+ Value *Op0 = I.getOperand(0);
+ auto *Const = dyn_cast<ConstantFP>(I.getOperand(1));
+ auto Pred = I.getPredicate();
+ // Only comparisons with consts are interesting.
+ if (!Const)
+ return;
+ // Compute the smallest normal number (and its negation).
+ auto &Sem = Op0->getType()->getFltSemantics();
+ APFloat Smallest = APFloat::getSmallestNormalized(Sem);
+ APFloat NegSmallest = Smallest;
+ NegSmallest.changeSign();
+ // Check if Const is one of our recognized consts.
+ int WhichConst;
+ if (Const->isZero()) {
+ // All comparisons with 0 can be converted.
+ WhichConst = 0;
+ } else if (Const->isInfinity()) {
+ // Likewise for infinities.
+ WhichConst = Const->isNegative() ? 2 : 1;
+ } else if (Const->isExactlyValue(Smallest)) {
+ // For Smallest, we cannot do EQ separately from GT.
+ if ((Pred & CmpInst::FCMP_OGE) != CmpInst::FCMP_OGE &&
+ (Pred & CmpInst::FCMP_OGE) != 0)
+ return;
+ WhichConst = 3;
+ } else if (Const->isExactlyValue(NegSmallest)) {
+ // Likewise for NegSmallest, we cannot do EQ separately from LT.
+ if ((Pred & CmpInst::FCMP_OLE) != CmpInst::FCMP_OLE &&
+ (Pred & CmpInst::FCMP_OLE) != 0)
+ return;
+ WhichConst = 4;
+ } else {
+ // Not one of our special constants.
+ return;
+ }
+ // Partial masks to use for EQ, GT, LT, UN comparisons, respectively.
+ static const int Masks[][4] = {
+ { // 0
+ SystemZ::TDCMASK_ZERO, // eq
+ SystemZ::TDCMASK_POSITIVE, // gt
+ SystemZ::TDCMASK_NEGATIVE, // lt
+ SystemZ::TDCMASK_NAN, // un
+ },
+ { // inf
+ SystemZ::TDCMASK_INFINITY_PLUS, // eq
+ 0, // gt
+ (SystemZ::TDCMASK_ZERO |
+ SystemZ::TDCMASK_NEGATIVE |
+ SystemZ::TDCMASK_NORMAL_PLUS |
+ SystemZ::TDCMASK_SUBNORMAL_PLUS), // lt
+ SystemZ::TDCMASK_NAN, // un
+ },
+ { // -inf
+ SystemZ::TDCMASK_INFINITY_MINUS, // eq
+ (SystemZ::TDCMASK_ZERO |
+ SystemZ::TDCMASK_POSITIVE |
+ SystemZ::TDCMASK_NORMAL_MINUS |
+ SystemZ::TDCMASK_SUBNORMAL_MINUS), // gt
+ 0, // lt
+ SystemZ::TDCMASK_NAN, // un
+ },
+ { // minnorm
+ 0, // eq (unsupported)
+ (SystemZ::TDCMASK_NORMAL_PLUS |
+ SystemZ::TDCMASK_INFINITY_PLUS), // gt (actually ge)
+ (SystemZ::TDCMASK_ZERO |
+ SystemZ::TDCMASK_NEGATIVE |
+ SystemZ::TDCMASK_SUBNORMAL_PLUS), // lt
+ SystemZ::TDCMASK_NAN, // un
+ },
+ { // -minnorm
+ 0, // eq (unsupported)
+ (SystemZ::TDCMASK_ZERO |
+ SystemZ::TDCMASK_POSITIVE |
+ SystemZ::TDCMASK_SUBNORMAL_MINUS), // gt
+ (SystemZ::TDCMASK_NORMAL_MINUS |
+ SystemZ::TDCMASK_INFINITY_MINUS), // lt (actually le)
+ SystemZ::TDCMASK_NAN, // un
+ }
+ };
+ // Construct the mask as a combination of the partial masks.
+ int Mask = 0;
+ if (Pred & CmpInst::FCMP_OEQ)
+ Mask |= Masks[WhichConst][0];
+ if (Pred & CmpInst::FCMP_OGT)
+ Mask |= Masks[WhichConst][1];
+ if (Pred & CmpInst::FCMP_OLT)
+ Mask |= Masks[WhichConst][2];
+ if (Pred & CmpInst::FCMP_UNO)
+ Mask |= Masks[WhichConst][3];
+ // A lone fcmp is unworthy of tdc conversion on its own, but may become
+ // worthy if combined with fabs.
+ bool Worthy = false;
+ if (CallInst *CI = dyn_cast<CallInst>(Op0)) {
+ Function *F = CI->getCalledFunction();
+ if (F && F->getIntrinsicID() == Intrinsic::fabs) {
+ // Fold with fabs - adjust the mask appropriately.
+ Mask &= SystemZ::TDCMASK_PLUS;
+ Mask |= Mask >> 1;
+ Op0 = CI->getArgOperand(0);
+ // A combination of fcmp with fabs is a win, unless the constant
+ // involved is 0 (which is handled by later passes).
+ Worthy = WhichConst != 0;
+ PossibleJunk.insert(CI);
+ }
+ }
+ converted(&I, Op0, Mask, Worthy);
+}
+
+void SystemZTDCPass::convertICmp(CmpInst &I) {
+ Value *Op0 = I.getOperand(0);
+ auto *Const = dyn_cast<ConstantInt>(I.getOperand(1));
+ auto Pred = I.getPredicate();
+ // All our icmp rules involve comparisons with consts.
+ if (!Const)
+ return;
+ if (auto *Cast = dyn_cast<BitCastInst>(Op0)) {
+ // Check for icmp+bitcast used for signbit.
+ if (!Cast->getSrcTy()->isFloatTy() &&
+ !Cast->getSrcTy()->isDoubleTy() &&
+ !Cast->getSrcTy()->isFP128Ty())
+ return;
+ Value *V = Cast->getOperand(0);
+ int Mask;
+ if (Pred == CmpInst::ICMP_SLT && Const->isZero()) {
+ // icmp slt (bitcast X), 0 - set if sign bit true
+ Mask = SystemZ::TDCMASK_MINUS;
+ } else if (Pred == CmpInst::ICMP_SGT && Const->isMinusOne()) {
+ // icmp sgt (bitcast X), -1 - set if sign bit false
+ Mask = SystemZ::TDCMASK_PLUS;
+ } else {
+ // Not a sign bit check.
+ return;
+ }
+ PossibleJunk.insert(Cast);
+ converted(&I, V, Mask, true);
+ } else if (auto *CI = dyn_cast<CallInst>(Op0)) {
+ // Check if this is a pre-existing call of our tdc intrinsic.
+ Function *F = CI->getCalledFunction();
+ if (!F || F->getIntrinsicID() != Intrinsic::s390_tdc)
+ return;
+ if (!Const->isZero())
+ return;
+ Value *V = CI->getArgOperand(0);
+ auto *MaskC = dyn_cast<ConstantInt>(CI->getArgOperand(1));
+ // Bail if the mask is not a constant.
+ if (!MaskC)
+ return;
+ int Mask = MaskC->getZExtValue();
+ Mask &= SystemZ::TDCMASK_ALL;
+ if (Pred == CmpInst::ICMP_NE) {
+ // icmp ne (call llvm.s390.tdc(...)), 0 -> simple TDC
+ } else if (Pred == CmpInst::ICMP_EQ) {
+ // icmp eq (call llvm.s390.tdc(...)), 0 -> TDC with inverted mask
+ Mask ^= SystemZ::TDCMASK_ALL;
+ } else {
+ // An unknown comparison - ignore.
+ return;
+ }
+ PossibleJunk.insert(CI);
+ converted(&I, V, Mask, false);
+ }
+}
+
+void SystemZTDCPass::convertLogicOp(BinaryOperator &I) {
+ Value *Op0, *Op1;
+ int Mask0, Mask1;
+ bool Worthy0, Worthy1;
+ std::tie(Op0, Mask0, Worthy0) = ConvertedInsts[cast<Instruction>(I.getOperand(0))];
+ std::tie(Op1, Mask1, Worthy1) = ConvertedInsts[cast<Instruction>(I.getOperand(1))];
+ if (Op0 != Op1)
+ return;
+ int Mask;
+ switch (I.getOpcode()) {
+ case Instruction::And:
+ Mask = Mask0 & Mask1;
+ break;
+ case Instruction::Or:
+ Mask = Mask0 | Mask1;
+ break;
+ case Instruction::Xor:
+ Mask = Mask0 ^ Mask1;
+ break;
+ default:
+ llvm_unreachable("Unknown op in convertLogicOp");
+ }
+ converted(&I, Op0, Mask, true);
+}
+
+bool SystemZTDCPass::runOnFunction(Function &F) {
+ ConvertedInsts.clear();
+ LogicOpsWorklist.clear();
+ PossibleJunk.clear();
+
+ // Look for icmp+fcmp instructions.
+ for (auto &I : instructions(F)) {
+ if (I.getOpcode() == Instruction::FCmp)
+ convertFCmp(cast<CmpInst>(I));
+ else if (I.getOpcode() == Instruction::ICmp)
+ convertICmp(cast<CmpInst>(I));
+ }
+
+ // If none found, bail already.
+ if (ConvertedInsts.empty())
+ return false;
+
+ // Process the queue of logic instructions.
+ while (!LogicOpsWorklist.empty()) {
+ BinaryOperator *Op = LogicOpsWorklist.back();
+ LogicOpsWorklist.pop_back();
+ // If both operands mapped, and the instruction itself not yet mapped,
+ // convert it.
+ if (ConvertedInsts.count(dyn_cast<Instruction>(Op->getOperand(0))) &&
+ ConvertedInsts.count(dyn_cast<Instruction>(Op->getOperand(1))) &&
+ !ConvertedInsts.count(Op))
+ convertLogicOp(*Op);
+ }
+
+ // Time to actually replace the instructions. Do it in the reverse order
+ // of finding them, since there's a good chance the earlier ones will be
+ // unused (due to being folded into later ones).
+ Module &M = *F.getParent();
+ auto &Ctx = M.getContext();
+ Value *Zero32 = ConstantInt::get(Type::getInt32Ty(Ctx), 0);
+ bool MadeChange = false;
+ for (auto &It : reverse(ConvertedInsts)) {
+ Instruction *I = It.first;
+ Value *V;
+ int Mask;
+ bool Worthy;
+ std::tie(V, Mask, Worthy) = It.second;
+ if (!I->user_empty()) {
+ // If used and unworthy of conversion, skip it.
+ if (!Worthy)
+ continue;
+ // Call the intrinsic, compare result with 0.
+ Value *TDCFunc = Intrinsic::getDeclaration(&M, Intrinsic::s390_tdc,
+ V->getType());
+ IRBuilder<> IRB(I);
+ Value *MaskVal = ConstantInt::get(Type::getInt64Ty(Ctx), Mask);
+ Instruction *TDC = IRB.CreateCall(TDCFunc, {V, MaskVal});
+ Value *ICmp = IRB.CreateICmp(CmpInst::ICMP_NE, TDC, Zero32);
+ I->replaceAllUsesWith(ICmp);
+ }
+ // If unused, or used and converted, remove it.
+ I->eraseFromParent();
+ MadeChange = true;
+ }
+
+ if (!MadeChange)
+ return false;
+
+ // We've actually done something - now clear misc accumulated junk (fabs,
+ // bitcast).
+ for (auto *I : PossibleJunk)
+ if (I->user_empty())
+ I->eraseFromParent();
+
+ return true;
+}
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