[InstCombine] clean up foldICmpBinOpEqualityWithConstant / foldICmpIntrinsicWithConst...

1. Rename variables to be consistent with related/preceding code (may want to reorganize).
2. Fix comments/formatting.

llvm-svn: 281140

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index f484445..42507e4 100644 (file)
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -2230,27 +2230,29 @@ Instruction *InstCombiner::foldICmpInstWithConstant(ICmpInst &Cmp) {
   return nullptr;
 }
 
-/// Simplify icmp_eq and icmp_ne instructions with binary operator LHS and
-/// integer scalar or splat vector constant RHS.
-Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(
-    ICmpInst &ICI, BinaryOperator *BO, const APInt *RHSV) {
-  // FIXME: Some of these folds could work with arbitrary constants, but this
-  // match is limited to scalars and vector splat constants.
-  if (!ICI.isEquality())
+/// Fold an icmp equality instruction with binary operator LHS and constant RHS:
+/// icmp eq/ne BO, C.
+Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(ICmpInst &Cmp,
+                                                             BinaryOperator *BO,
+                                                             const APInt *C) {
+  // TODO: Some of these folds could work with arbitrary constants, but this
+  // function is limited to scalar and vector splat constants.
+  if (!Cmp.isEquality())
     return nullptr;
 
-  Constant *RHS = cast<Constant>(ICI.getOperand(1));
-  bool isICMP_NE = ICI.getPredicate() == ICmpInst::ICMP_NE;
+  ICmpInst::Predicate Pred = Cmp.getPredicate();
+  bool isICMP_NE = Pred == ICmpInst::ICMP_NE;
+  Constant *RHS = cast<Constant>(Cmp.getOperand(1));
   Value *BOp0 = BO->getOperand(0), *BOp1 = BO->getOperand(1);
 
   switch (BO->getOpcode()) {
   case Instruction::SRem:
     // If we have a signed (X % (2^c)) == 0, turn it into an unsigned one.
-    if (*RHSV == 0 && BO->hasOneUse()) {
+    if (*C == 0 && BO->hasOneUse()) {
       const APInt *BOC;
       if (match(BOp1, m_APInt(BOC)) && BOC->sgt(1) && BOC->isPowerOf2()) {
         Value *NewRem = Builder->CreateURem(BOp0, BOp1, BO->getName());
-        return new ICmpInst(ICI.getPredicate(), NewRem,
+        return new ICmpInst(Pred, NewRem,
                             Constant::getNullValue(BO->getType()));
       }
     }
@@ -2261,19 +2263,19 @@ Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(
     if (match(BOp1, m_APInt(BOC))) {
       if (BO->hasOneUse()) {
         Constant *SubC = ConstantExpr::getSub(RHS, cast<Constant>(BOp1));
-        return new ICmpInst(ICI.getPredicate(), BOp0, SubC);
+        return new ICmpInst(Pred, BOp0, SubC);
       }
-    } else if (*RHSV == 0) {
+    } else if (*C == 0) {
       // Replace ((add A, B) != 0) with (A != -B) if A or B is
       // efficiently invertible, or if the add has just this one use.
       if (Value *NegVal = dyn_castNegVal(BOp1))
-        return new ICmpInst(ICI.getPredicate(), BOp0, NegVal);
+        return new ICmpInst(Pred, BOp0, NegVal);
       if (Value *NegVal = dyn_castNegVal(BOp0))
-        return new ICmpInst(ICI.getPredicate(), NegVal, BOp1);
+        return new ICmpInst(Pred, NegVal, BOp1);
       if (BO->hasOneUse()) {
         Value *Neg = Builder->CreateNeg(BOp1);
         Neg->takeName(BO);
-        return new ICmpInst(ICI.getPredicate(), BOp0, Neg);
+        return new ICmpInst(Pred, BOp0, Neg);
       }
     }
     break;
@@ -2283,11 +2285,10 @@ Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(
       if (Constant *BOC = dyn_cast<Constant>(BOp1)) {
         // For the xor case, we can xor two constants together, eliminating
         // the explicit xor.
-        return new ICmpInst(ICI.getPredicate(), BOp0,
-                            ConstantExpr::getXor(RHS, BOC));
-      } else if (*RHSV == 0) {
+        return new ICmpInst(Pred, BOp0, ConstantExpr::getXor(RHS, BOC));
+      } else if (*C == 0) {
         // Replace ((xor A, B) != 0) with (A != B)
-        return new ICmpInst(ICI.getPredicate(), BOp0, BOp1);
+        return new ICmpInst(Pred, BOp0, BOp1);
       }
     }
     break;
@@ -2297,10 +2298,10 @@ Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(
       if (match(BOp0, m_APInt(BOC))) {
         // Replace ((sub A, B) != C) with (B != A-C) if A & C are constants.
         Constant *SubC = ConstantExpr::getSub(cast<Constant>(BOp0), RHS);
-        return new ICmpInst(ICI.getPredicate(), BOp1, SubC);
-      } else if (*RHSV == 0) {
+        return new ICmpInst(Pred, BOp1, SubC);
+      } else if (*C == 0) {
         // Replace ((sub A, B) != 0) with (A != B)
-        return new ICmpInst(ICI.getPredicate(), BOp0, BOp1);
+        return new ICmpInst(Pred, BOp0, BOp1);
       }
     }
     break;
@@ -2312,7 +2313,7 @@ Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(
       // This removes the -1 constant.
       Constant *NotBOC = ConstantExpr::getNot(cast<Constant>(BOp1));
       Value *And = Builder->CreateAnd(BOp0, NotBOC);
-      return new ICmpInst(ICI.getPredicate(), And, NotBOC);
+      return new ICmpInst(Pred, And, NotBOC);
     }
     break;
   }
@@ -2320,7 +2321,7 @@ Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(
     const APInt *BOC;
     if (match(BOp1, m_APInt(BOC))) {
       // If we have ((X & C) == C), turn it into ((X & C) != 0).
-      if (RHSV == BOC && RHSV->isPowerOf2())
+      if (C == BOC && C->isPowerOf2())
         return new ICmpInst(isICMP_NE ? ICmpInst::ICMP_EQ : ICmpInst::ICMP_NE,
                             BO, Constant::getNullValue(RHS->getType()));
 
@@ -2331,39 +2332,35 @@ Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(
       // Replace (and X, (1 << size(X)-1) != 0) with x s< 0
       if (BOC->isSignBit()) {
         Constant *Zero = Constant::getNullValue(BOp0->getType());
-        ICmpInst::Predicate Pred =
-            isICMP_NE ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
-        return new ICmpInst(Pred, BOp0, Zero);
+        auto NewPred = isICMP_NE ? ICmpInst::ICMP_SLT : ICmpInst::ICMP_SGE;
+        return new ICmpInst(NewPred, BOp0, Zero);
       }
 
       // ((X & ~7) == 0) --> X < 8
-      if (*RHSV == 0 && (~(*BOC) + 1).isPowerOf2()) {
+      if (*C == 0 && (~(*BOC) + 1).isPowerOf2()) {
         Constant *NegBOC = ConstantExpr::getNeg(cast<Constant>(BOp1));
-        ICmpInst::Predicate Pred =
-            isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
-        return new ICmpInst(Pred, BOp0, NegBOC);
+        auto NewPred = isICMP_NE ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_ULT;
+        return new ICmpInst(NewPred, BOp0, NegBOC);
       }
     }
     break;
   }
   case Instruction::Mul:
-    if (*RHSV == 0 && BO->hasNoSignedWrap()) {
+    if (*C == 0 && BO->hasNoSignedWrap()) {
       const APInt *BOC;
       if (match(BOp1, m_APInt(BOC)) && *BOC != 0) {
         // The trivial case (mul X, 0) is handled by InstSimplify.
         // General case : (mul X, C) != 0 iff X != 0
         //                (mul X, C) == 0 iff X == 0
-        return new ICmpInst(ICI.getPredicate(), BOp0,
-                            Constant::getNullValue(RHS->getType()));
+        return new ICmpInst(Pred, BOp0, Constant::getNullValue(RHS->getType()));
       }
     }
     break;
   case Instruction::UDiv:
-    if (*RHSV == 0) {
+    if (*C == 0) {
       // (icmp eq/ne (udiv A, B), 0) -> (icmp ugt/ule i32 B, A)
-      ICmpInst::Predicate Pred =
-          isICMP_NE ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_UGT;
-      return new ICmpInst(Pred, BOp1, BOp0);
+      auto NewPred = isICMP_NE ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_UGT;
+      return new ICmpInst(NewPred, BOp1, BOp0);
     }
     break;
   default:
@@ -2372,44 +2369,44 @@ Instruction *InstCombiner::foldICmpBinOpEqualityWithConstant(
   return nullptr;
 }
 
-Instruction *InstCombiner::foldICmpIntrinsicWithConstant(ICmpInst &ICI,
-                                                         const APInt *Op1C) {
-  IntrinsicInst *II = dyn_cast<IntrinsicInst>(ICI.getOperand(0));
-  if (!II || !ICI.isEquality())
+/// Fold an icmp with LLVM intrinsic and constant operand: icmp Pred II, C.
+Instruction *InstCombiner::foldICmpIntrinsicWithConstant(ICmpInst &Cmp,
+                                                         const APInt *C) {
+  IntrinsicInst *II = dyn_cast<IntrinsicInst>(Cmp.getOperand(0));
+  if (!II || !Cmp.isEquality())
     return nullptr;
 
   // Handle icmp {eq|ne} <intrinsic>, intcst.
   switch (II->getIntrinsicID()) {
   case Intrinsic::bswap:
     Worklist.Add(II);
-    ICI.setOperand(0, II->getArgOperand(0));
-    ICI.setOperand(1, Builder->getInt(Op1C->byteSwap()));
-    return &ICI;
+    Cmp.setOperand(0, II->getArgOperand(0));
+    Cmp.setOperand(1, Builder->getInt(C->byteSwap()));
+    return &Cmp;
   case Intrinsic::ctlz:
   case Intrinsic::cttz:
     // ctz(A) == bitwidth(A)  ->  A == 0 and likewise for !=
-    if (*Op1C == Op1C->getBitWidth()) {
+    if (*C == C->getBitWidth()) {
       Worklist.Add(II);
-      ICI.setOperand(0, II->getArgOperand(0));
-      ICI.setOperand(1, ConstantInt::getNullValue(II->getType()));
-      return &ICI;
+      Cmp.setOperand(0, II->getArgOperand(0));
+      Cmp.setOperand(1, ConstantInt::getNullValue(II->getType()));
+      return &Cmp;
     }
     break;
   case Intrinsic::ctpop: {
     // popcount(A) == 0  ->  A == 0 and likewise for !=
     // popcount(A) == bitwidth(A)  ->  A == -1 and likewise for !=
-    bool IsZero = *Op1C == 0;
-    if (IsZero || *Op1C == Op1C->getBitWidth()) {
+    bool IsZero = *C == 0;
+    if (IsZero || *C == C->getBitWidth()) {
       Worklist.Add(II);
-      ICI.setOperand(0, II->getArgOperand(0));
-      auto *NewOp = IsZero
-        ? ConstantInt::getNullValue(II->getType())
-        : ConstantInt::getAllOnesValue(II->getType());
-      ICI.setOperand(1, NewOp);
-      return &ICI;
-    }
+      Cmp.setOperand(0, II->getArgOperand(0));
+      auto *NewOp = IsZero ? Constant::getNullValue(II->getType())
+                           : Constant::getAllOnesValue(II->getType());
+      Cmp.setOperand(1, NewOp);
+      return &Cmp;
     }
     break;
+  }
   default:
     break;
   }