[Pass] fix sqrt add to or bug and getFirst/LastInst refactor

Author: chen.qian

llvm/lib/Target/RISCV/RISCVLoopUnrollAndRemainder.cpp

@@ -85,6 +85,7 @@
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/IPO.h"
+#include "llvm/Transforms/InstCombine/InstCombine.h"
 #include "llvm/Transforms/Scalar.h"
 #include "llvm/Transforms/Scalar/DCE.h"
 #include "llvm/Transforms/Scalar/DeadStoreElimination.h"
@@ -171,21 +172,19 @@ static ICmpInst *getLastICmpInstWithPredicate(BasicBlock *BB,
   return lastICmp;
 }
 
-// Helper function to get the first ICmp instruction in a basic block
-static ICmpInst *getFirstICmpInst(BasicBlock *BB) {
+template <typename T> static T *getFirstInst(BasicBlock *BB) {
   for (Instruction &I : *BB) {
-    if (auto *CI = dyn_cast<ICmpInst>(&I)) {
-      return CI;
+    if (T *Inst = dyn_cast<T>(&I)) {
+      return Inst;
     }
   }
   return nullptr;
 }
 
-// Helper function to get the last ICmp instruction in a basic block
-static ICmpInst *getLastICmpInst(BasicBlock *BB) {
-  for (auto it = BB->rbegin(); it != BB->rend(); ++it) {
-    if (auto *icmp = dyn_cast<ICmpInst>(&*it)) {
-      return icmp;
+template <typename T> static T *getLastInst(BasicBlock *BB) {
+  for (Instruction &I : reverse(*BB)) {
+    if (T *Inst = dyn_cast<T>(&I)) {
+      return Inst;
     }
   }
   return nullptr;
@@ -239,16 +238,6 @@ static PHINode *getLastI32Phi(BasicBlock *BB) {
   return nullptr;
 }
 
-// Helper function to get the last PHI node in a basic block
-static PHINode *getLastPhi(BasicBlock *BB) {
-  for (auto it = BB->rbegin(); it != BB->rend(); ++it) {
-    if (auto *Phi = dyn_cast<PHINode>(&*it)) {
-      return Phi;
-    }
-  }
-  return nullptr;
-}
-
 // Helper function to get the first CallInst with a specific name in a basic
 // block
 static CallInst *getFirstCallInstWithName(BasicBlock *BB, StringRef Name) {
@@ -406,6 +395,38 @@ static void movePHINodesToTop(BasicBlock &BB,
   }
 }
 
+static void modifyFirdAddToOr(BasicBlock *ClonedForBody) {
+  SmallVector<BinaryOperator *> addInsts;
+
+  // Collect all add instructions that meet the criteria
+  for (auto &I : *ClonedForBody) {
+    if (auto *binOp = dyn_cast<BinaryOperator>(&I)) {
+      if (binOp->getOpcode() == Instruction::Add && binOp->hasNoSignedWrap() &&
+          binOp->hasNoUnsignedWrap()) {
+        addInsts.push_back(binOp);
+      }
+    }
+  }
+  if (addInsts.empty()) {
+    return;
+  }
+  // Replace each add instruction with an or disjoint instruction
+  for (auto it = addInsts.begin(); it != std::prev(addInsts.end()); ++it) {
+    auto *addInst = *it;
+    // Create a new or disjoint instruction
+    Instruction *orInst =
+        BinaryOperator::CreateDisjoint(Instruction::Or, addInst->getOperand(0),
+                                       addInst->getOperand(1), "add", addInst);
+
+    // Replace all uses of the add instruction
+    addInst->replaceAllUsesWith(orInst);
+
+    // Delete the original add instruction
+    addInst->eraseFromParent();
+    orInst->setName("add");
+  }
+}
+
 // Helper function to update predecessors to point to a new preheader
 static void updatePredecessorsToPreheader(BasicBlock *ForBody,
                                           BasicBlock *ForBodyPreheader) {
@@ -1151,7 +1172,7 @@ static Value *expandForCondPreheader(
   }
 
   // Get the icmp instruction in ForCondPreheader
-  ICmpInst *icmpInst = getFirstICmpInst(ForCondPreheader);
+  ICmpInst *icmpInst = getFirstInst<ICmpInst>(ForCondPreheader);
 
   // Ensure we found the icmp instruction
   assert(icmpInst && "Failed to find icmp instruction in ForCondPreheader");
@@ -1278,7 +1299,7 @@ static void insertUnusedInstructionsBeforeIcmp(PHINode *phiI32InClonedForBody,
 
 static void modifyClonedForBody(BasicBlock *ClonedForBody) {
 
-  ICmpInst *lastIcmpEq = getLastICmpInst(ClonedForBody);
+  ICmpInst *lastIcmpEq = getLastInst<ICmpInst>(ClonedForBody);
   assert(lastIcmpEq &&
          "Failed to find last icmp eq instruction in ClonedForBody");
 
@@ -1472,7 +1493,7 @@ static void modifyForCondPreheader2(BasicBlock *ClonedForBody,
   }
 
   // Find operand 1 of the icmp instruction from ClonedForBody
-  ICmpInst *firstIcmp = getFirstICmpInst(ClonedForBody);
+  ICmpInst *firstIcmp = getFirstInst<ICmpInst>(ClonedForBody);
   assert(firstIcmp && "Unable to find icmp instruction in ClonedForBody");
   Value *IcmpOperand1 = firstIcmp->getOperand(1);
 
@@ -1549,7 +1570,7 @@ static void modifyForCondPreheader2(BasicBlock *ClonedForBody,
 
 static Value *modifyClonedForBodyPreheader(BasicBlock *ClonedForBodyPreheader,
                                            BasicBlock *ForBody) {
-  ICmpInst *firstIcmp = getFirstICmpInst(ForBody);
+  ICmpInst *firstIcmp = getFirstInst<ICmpInst>(ForBody);
   assert(firstIcmp && "Unable to find icmp instruction in ForBody");
 
   Value *IcmpOperand1 = firstIcmp->getOperand(1);
@@ -2011,35 +2032,27 @@ static Instruction *modifyAddToOrInClonedForBody(BasicBlock *ClonedForBody) {
   return orInst;
 }
 
-static void modifyAddToOr(BasicBlock *ClonedForBody) {
-  SmallVector<BinaryOperator *> addInsts;
+static void runInstCombinePass(Function &F) {
+  // Create necessary analysis managers
+  LoopAnalysisManager LAM;
+  FunctionAnalysisManager FAM;
+  CGSCCAnalysisManager CGAM;
+  ModuleAnalysisManager MAM;
 
-  // Collect all add instructions that meet the criteria
-  for (auto &I : *ClonedForBody) {
-    if (auto *binOp = dyn_cast<BinaryOperator>(&I)) {
-      if (binOp->getOpcode() == Instruction::Add) {
-        addInsts.push_back(binOp);
-      }
-    }
-  }
-  if (addInsts.empty()) {
-    return;
-  }
-  // Replace each add instruction with an or disjoint instruction
-  for (auto it = addInsts.begin(); it != std::prev(addInsts.end()); ++it) {
-    auto *addInst = *it;
-    // Create a new or disjoint instruction
-    Instruction *orInst =
-        BinaryOperator::CreateDisjoint(Instruction::Or, addInst->getOperand(0),
-                                       addInst->getOperand(1), "add", addInst);
+  // Create pass builder
+  PassBuilder PB;
 
-    // Replace all uses of the add instruction
-    addInst->replaceAllUsesWith(orInst);
+  // Register analyses
+  PB.registerModuleAnalyses(MAM);
+  PB.registerCGSCCAnalyses(CGAM);
+  PB.registerFunctionAnalyses(FAM);
+  PB.registerLoopAnalyses(LAM);
+  PB.crossRegisterProxies(LAM, FAM, CGAM, MAM);
 
-    // Delete the original add instruction
-    addInst->eraseFromParent();
-    orInst->setName("add");
-  }
+  // Create function-level optimization pipeline
+  FunctionPassManager FPM;
+  FPM.addPass(InstCombinePass());
+  FPM.run(F, FAM);
 }
 
 static Value *unrolladdcClonedForBody(BasicBlock *ClonedForBody,
@@ -2058,7 +2071,7 @@ static Value *unrolladdcClonedForBody(BasicBlock *ClonedForBody,
   assert(firstNonPHI && orInst && "Start or end instruction not found");
 
   // Find the icmp instruction
-  Instruction *icmpInst = getFirstICmpInst(ClonedForBody);
+  Instruction *icmpInst = getFirstInst<ICmpInst>(ClonedForBody);
 
   // Ensure that the icmp instruction is found
   assert(icmpInst && "icmp instruction not found");
@@ -2298,7 +2311,7 @@ static void unrollAddc(Function &F, ScalarEvolution &SE, Loop *L,
   assert(ForCondPreheader && "Expected to find for.cond.preheader!");
   expandForCondPreheaderaddc(F, ForCondPreheader, ClonedForBody, ForBody, sub,
                              unroll_factor);
-  modifyAddToOr(ClonedForBody);
+  runInstCombinePass(F);
   groupAndReorderInstructions(ClonedForBody);
 
   // Verify the function
@@ -2816,11 +2829,11 @@ static void postUnrollLoopWithCount(Function &F, Loop *L, int unroll_count) {
   insertPhiNodesForFMulAdd(LoopHeader, LoopPreheader, FMulAddCalls);
 
   movePHINodesToTop(*LoopHeader);
-  modifyAddToOr(LoopHeader);
+  runInstCombinePass(F);
   groupAndReorderInstructions(LoopHeader);
 
   // Create for.end basic block after LoopHeader
-  ICmpInst *LastICmp = getLastICmpInst(LoopHeader);
+  ICmpInst *LastICmp = getLastInst<ICmpInst>(LoopHeader);
   LastICmp->setPredicate(ICmpInst::ICMP_ULT);
   // Get the first operand of LastICmp
   Value *Operand1 = LastICmp->getOperand(1);
@@ -3023,7 +3036,7 @@ static bool shouldUnrollDotprodType(Function &F, LoopInfo *LI) {
 }
 
 static std::pair<Value *, Value *> modifyEntryBB(BasicBlock &entryBB) {
-  ICmpInst *icmp = getLastICmpInst(&entryBB);
+  ICmpInst *icmp = getLastInst<ICmpInst>(&entryBB);
   assert(icmp && "icmp not found");
   Value *start_index = icmp->getOperand(0);
   Value *end_index = icmp->getOperand(1);
@@ -3115,7 +3128,7 @@ static void postUnrollLoopWithVariable(Function &F, Loop *L, int unroll_count) {
     temp->insertBefore(LoopPreheader->getTerminator());
   }
 
-  ICmpInst *lastICmp = getLastICmpInst(ForBody7);
+  ICmpInst *lastICmp = getLastInst<ICmpInst>(ForBody7);
   assert(lastICmp && "icmp not found");
   lastICmp->setOperand(1, Sub);
   lastICmp->setPredicate(ICmpInst::ICMP_SLT);
@@ -3552,7 +3565,7 @@ static std::tuple<Value *, GetElementPtrInst *, Value *>
 modifyOuterLoop4(Loop *L, BasicBlock *ForBodyMerged,
                  BasicBlock *CloneForBodyPreheader) {
   BasicBlock *BB = L->getHeader();
-  PHINode *phi = getLastPhi(BB);
+  PHINode *phi = getLastInst<PHINode>(BB);
   // Add new instructions
   IRBuilder<> Builder(BB);
   Builder.SetInsertPoint(phi->getNextNode());
@@ -3596,7 +3609,7 @@ static void modifyInnerLoop4(Loop *L, BasicBlock *ForBodyMerged, Value *Sub,
   movePHINodesToTop(*ForBodyMerged);
 
   groupAndReorderInstructions(ForBodyMerged);
-  ICmpInst *LastICmp = getLastICmpInst(ForBodyMerged);
+  ICmpInst *LastICmp = getLastInst<ICmpInst>(ForBodyMerged);
   LastICmp->setPredicate(ICmpInst::ICMP_ULT);
   LastICmp->setOperand(1, Sub);
   swapTerminatorSuccessors(ForBodyMerged);
@@ -3653,7 +3666,8 @@ static void modifyInnerLoop4(Loop *L, BasicBlock *ForBodyMerged, Value *Sub,
   AddPHI->addIncoming(Add2, NewForEnd);
   Value *phifloatincomingvalue0 =
       getFirstCallInstWithName(CloneForBody, "llvm.fmuladd.f32");
-  Value *phii32incomingvalue0 = getLastICmpInst(CloneForBody)->getOperand(0);
+  Value *phii32incomingvalue0 =
+      getLastInst<ICmpInst>(CloneForBody)->getOperand(0);
   for (PHINode &Phi : CloneForBody->phis()) {
     if (Phi.getType()->isIntegerTy(32)) {
       Phi.setIncomingValue(0, AddPHI);
@@ -3676,7 +3690,7 @@ static void modifyInnerLoop4(Loop *L, BasicBlock *ForBodyMerged, Value *Sub,
 static std::tuple<Value *, Value *, GetElementPtrInst *>
 modifyOuterLoop8(Loop *L) {
   BasicBlock *BB = L->getHeader();
-  ICmpInst *LastICmp = getLastICmpInst(BB);
+  ICmpInst *LastICmp = getLastInst<ICmpInst>(BB);
   LastICmp->setPredicate(ICmpInst::ICMP_ULT);
   swapTerminatorSuccessors(BB);
 
@@ -3714,7 +3728,7 @@ static std::tuple<Value *, Value *, GetElementPtrInst *>
 modifyOuterLoop16(Loop *L) {
   BasicBlock *BB = L->getHeader();
   BasicBlock *BBLoopPreHeader = L->getLoopPreheader();
-  ICmpInst *LastICmp = getLastICmpInst(BB);
+  ICmpInst *LastICmp = getLastInst<ICmpInst>(BB);
   LastICmp->setPredicate(ICmpInst::ICMP_ULT);
   swapTerminatorSuccessors(BB);
 
@@ -3763,7 +3777,7 @@ static void modifyInnerLoop(Loop *L, BasicBlock *ForBodyMerged, Value *Add60,
   movePHINodesToTop(*ForBodyMerged);
 
   groupAndReorderInstructions(ForBodyMerged);
-  ICmpInst *LastICmp = getLastICmpInst(ForBodyMerged);
+  ICmpInst *LastICmp = getLastInst<ICmpInst>(ForBodyMerged);
   LastICmp->setPredicate(ICmpInst::ICMP_ULT);
   LastICmp->setOperand(1, Add60);
   swapTerminatorSuccessors(ForBodyMerged);
@@ -3873,7 +3887,7 @@ static void modifyInnerLoop(Loop *L, BasicBlock *ForBodyMerged, Value *Add60,
 
   Value *operand1 = unroll_count == 16
                         ? getFirstI32Phi(OuterBB)
-                        : getLastICmpInst(CloneForBody)->getOperand(1);
+                        : getLastInst<ICmpInst>(CloneForBody)->getOperand(1);
   // Create a new comparison instruction
   ICmpInst *NewCmp =
       new ICmpInst(ICmpInst::ICMP_UGT, PhiSum, operand1, "cmp182.not587");
@@ -3890,7 +3904,8 @@ static void modifyInnerLoop(Loop *L, BasicBlock *ForBodyMerged, Value *Add60,
       getFirstCallInstWithName(CloneForBody, "llvm.fmuladd.f32");
   for (PHINode &Phi : CloneForBody->phis()) {
     if (Phi.getType()->isIntegerTy(32)) {
-      Phi.setIncomingValue(0, getLastICmpInst(CloneForBody)->getOperand(0));
+      Phi.setIncomingValue(0,
+                           getLastInst<ICmpInst>(CloneForBody)->getOperand(0));
       Phi.setIncomingBlock(0, CloneForBody);
       Phi.setIncomingValue(1, PhiSum);
       Phi.setIncomingBlock(1, ForEnd164);
@@ -3981,7 +3996,7 @@ static void modifyFirstCloneForBody(BasicBlock *CloneForBody,
       lastAddInst = &I;
     }
   }
-  ICmpInst *LastCmpInst = getLastICmpInst(CloneForBody);
+  ICmpInst *LastCmpInst = getLastInst<ICmpInst>(CloneForBody);
   LastCmpInst->setOperand(0, lastAddInst);
   LastCmpInst->setOperand(1, Operand1);
   FirstI32Phi->setIncomingValue(1, lastAddInst);
@@ -4045,7 +4060,7 @@ static void modifyFirdFirstLoop(Function &F, Loop *L, BasicBlock *ForBodyMerged,
       getFirstI32Phi(ForCond23Preheader)->getIncomingBlock(0);
   Instruction *FirstI32Phi = getFirstI32Phi(ForCondCleanup3);
 
-  ICmpInst *LastICmp = getLastICmpInst(ForCondCleanup3);
+  ICmpInst *LastICmp = getLastInst<ICmpInst>(ForCondCleanup3);
   // Create new add instruction
   IRBuilder<> Builder(LastICmp);
   Value *Add269 = Builder.CreateNSWAdd(
@@ -4067,7 +4082,7 @@ static void modifyFirdFirstLoop(Function &F, Loop *L, BasicBlock *ForBodyMerged,
 
   N_069->setIncomingValue(1, Add281);
 
-  ICmpInst *LastICmpInPreheader = getLastICmpInst(ForCond23Preheader);
+  ICmpInst *LastICmpInPreheader = getLastInst<ICmpInst>(ForCond23Preheader);
   // Create new phi node
   PHINode *N_0_lcssa = PHINode::Create(Type::getInt32Ty(F.getContext()), 2,
                                        "n.0.lcssa", LastICmpInPreheader);
@@ -4093,7 +4108,7 @@ static void modifyFirdFirstLoop(Function &F, Loop *L, BasicBlock *ForBodyMerged,
   Value *Add11 = Builder.CreateAdd(Operand1, CoeffPosLcssa);
 
   ForBody27LrPh->getTerminator()->setSuccessor(0, CloneForBody);
-  ICmpInst *LastICmpInForBodyMerged = getLastICmpInst(ForBodyMerged);
+  ICmpInst *LastICmpInForBodyMerged = getLastInst<ICmpInst>(ForBodyMerged);
   LastICmpInForBodyMerged->setOperand(1, Operand1);
   LastICmpInForBodyMerged->setOperand(0, Inc20_7);
 
@@ -4159,9 +4174,8 @@ static void modifyFirdFirstLoop(Function &F, Loop *L, BasicBlock *ForBodyMerged,
     CI->setOperand(2, PHI);
   }
   movePHINodesToTop(*ForBodyMerged);
-  modifyAddToOr(ForBodyMerged);
-
-  ICmpInst *LastICmpForBodyMerged = getLastICmpInst(ForBodyMerged);
+  modifyFirdAddToOr(ForBodyMerged);
+  ICmpInst *LastICmpForBodyMerged = getLastInst<ICmpInst>(ForBodyMerged);
   LastICmpForBodyMerged->setPredicate(ICmpInst::ICMP_SGT);
   cast<Instruction>(LastICmpForBodyMerged->getOperand(0))
       ->setOperand(0, getFirstI32Phi(ForBodyMerged));
@@ -4256,7 +4270,7 @@ static void modifyFirdFirstLoop(Function &F, Loop *L, BasicBlock *ForBodyMerged,
   CoeffPosLcssaPhi->addIncoming(SubResult, ForCondCleanup26LoopExit);
   // eraseAllStoreInstInBB(ForCondCleanup26);
 
-  ICmpInst *LastICmpForCondCleanup26 = getLastICmpInst(ForCondCleanup26);
+  ICmpInst *LastICmpForCondCleanup26 = getLastInst<ICmpInst>(ForCondCleanup26);
 
   LastICmpForCondCleanup26->setPredicate(ICmpInst::ICMP_SLT);
   PHINode *FirstI32ForCondCleanup3 = getFirstI32Phi(ForCondCleanup3);
@@ -4314,7 +4328,7 @@ static void modifyFirdFirstLoop(Function &F, Loop *L, BasicBlock *ForBodyMerged,
       0, ConstantInt::get(getLastI32Phi(ForCond130Preheader)->getType(), 0));
   LastI32Phi130->setIncomingValue(1, AndResult);
 
-  ICmpInst *LastICmp130 = getLastICmpInst(ForCond130Preheader);
+  ICmpInst *LastICmp130 = getLastInst<ICmpInst>(ForCond130Preheader);
   LastICmp130->setOperand(1, FirstI32ForCondCleanup3);
 
   PHINode *LastI32PhiClone = getLastFloatPhi(CloneForBody);
@@ -4434,9 +4448,8 @@ static void modifyFirdSecondLoop(Function &F, Loop *L,
   Add76310->addIncoming(Add76, ForBodyMerged);
 
   movePHINodesToTop(*ForBodyMerged);
-  modifyAddToOr(ForBodyMerged);
-
-  ICmpInst *LastICmp = getLastICmpInst(ForBodyMerged);
+  modifyFirdAddToOr(ForBodyMerged);
+  ICmpInst *LastICmp = getLastInst<ICmpInst>(ForBodyMerged);
   LastICmp->setPredicate(ICmpInst::ICMP_SGT);
   cast<Instruction>(Add76)->moveBefore(LastICmp);
   LastICmp->setOperand(0, Add76);
@@ -5043,6 +5056,7 @@ RISCVLoopUnrollAndRemainderPass::run(Function &F, FunctionAnalysisManager &AM) {
   if (currentUnrollType == UnrollType::FIRD) {
     addLegacyCommonOptimizationPasses(F);
   }
+
   // Verify function
   if (verifyFunction(F, &errs())) {
     LLVM_DEBUG(errs() << "Function verification failed\n");