Factor out common parts of LVI and Float2Int into ConstantRange [NFCI]

This just extracts out the transfer rules for constant ranges into a single shared point. As it happens, neither bit of code actually overlaps in terms of the handled operators, but with this change that could easily be tweaked in the future.

I also want to have this separated out to make experimenting with a eager value info implementation and possibly a ValueTracking-like fixed depth recursion peephole version. There's no reason all four of these can't share a common implementation which reduces the chances of bugs.

Differential Revision: https://reviews.llvm.org/D27294




git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@288413 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/IR/ConstantRange.h

@@ -233,6 +233,15 @@ public:
   ///
   ConstantRange unionWith(const ConstantRange &CR) const;
 
+  /// Return a new range representing the possible values resulting
+  /// from an application of the specified cast operator to this range. \p
+  /// BitWidth is the target bitwidth of the cast.  For casts which don't
+  /// change bitwidth, it must be the same as the source bitwidth.  For casts
+  /// which do change bitwidth, the bitwidth must be consistent with the
+  /// requested cast and source bitwidth.
+  ConstantRange castOp(Instruction::CastOps CastOp,
+                       uint32_t BitWidth) const;
+
   /// Return a new range in the specified integer type, which must
   /// be strictly larger than the current type.  The returned range will
   /// correspond to the possible range of values if the source range had been
@@ -259,6 +268,12 @@ public:
   /// value is sign extended, truncated, or left alone to make it that width.
   ConstantRange sextOrTrunc(uint32_t BitWidth) const;
 
+  /// Return a new range representing the possible values resulting
+  /// from an application of the specified binary operator to an left hand side
+  /// of this range and a right hand side of \p Other.
+  ConstantRange binaryOp(Instruction::BinaryOps BinOp,
+                         const ConstantRange &Other) const;
+
   /// Return a new range representing the possible values resulting
   /// from an addition of a value in this range and a value in \p Other.
   ConstantRange add(const ConstantRange &Other) const;

lib/Analysis/LazyValueInfo.cpp

@@ -1160,25 +1160,8 @@ bool LazyValueInfoImpl::solveBlockValueCast(LVILatticeVal &BBLV,
   // can evaluate symbolically.  Enhancing that set will allows us to analyze
   // more definitions.
   LVILatticeVal Result;
-  switch (BBI->getOpcode()) {
+  auto CastOp = (Instruction::CastOps) BBI->getOpcode();
-  case Instruction::Trunc:
+  Result.markConstantRange(LHSRange.castOp(CastOp, ResultBitWidth));
-    Result.markConstantRange(LHSRange.truncate(ResultBitWidth));
-    break;
-  case Instruction::SExt:
-    Result.markConstantRange(LHSRange.signExtend(ResultBitWidth));
-    break;
-  case Instruction::ZExt:
-    Result.markConstantRange(LHSRange.zeroExtend(ResultBitWidth));
-    break;
-  case Instruction::BitCast:
-    Result.markConstantRange(LHSRange);
-    break;
-  default:
-    // Should be dead if the code above is correct
-    llvm_unreachable("inconsistent with above");
-    break;
-  }
-
   BBLV = Result;
   return true;
 }
@@ -1238,37 +1221,8 @@ bool LazyValueInfoImpl::solveBlockValueBinaryOp(LVILatticeVal &BBLV,
   // can evaluate symbolically.  Enhancing that set will allows us to analyze
   // more definitions.
   LVILatticeVal Result;
-  switch (BBI->getOpcode()) {
+  auto BinOp = (Instruction::BinaryOps) BBI->getOpcode();
-  case Instruction::Add:
+  Result.markConstantRange(LHSRange.binaryOp(BinOp, RHSRange));
-    Result.markConstantRange(LHSRange.add(RHSRange));
-    break;
-  case Instruction::Sub:
-    Result.markConstantRange(LHSRange.sub(RHSRange));
-    break;
-  case Instruction::Mul:
-    Result.markConstantRange(LHSRange.multiply(RHSRange));
-    break;
-  case Instruction::UDiv:
-    Result.markConstantRange(LHSRange.udiv(RHSRange));
-    break;
-  case Instruction::Shl:
-    Result.markConstantRange(LHSRange.shl(RHSRange));
-    break;
-  case Instruction::LShr:
-    Result.markConstantRange(LHSRange.lshr(RHSRange));
-    break;
-  case Instruction::And:
-    Result.markConstantRange(LHSRange.binaryAnd(RHSRange));
-    break;
-  case Instruction::Or:
-    Result.markConstantRange(LHSRange.binaryOr(RHSRange));
-    break;
-  default:
-    // Should be dead if the code above is correct
-    llvm_unreachable("inconsistent with above");
-    break;
-  }
-
   BBLV = Result;
   return true;
 }

lib/IR/ConstantRange.cpp

@@ -534,6 +534,49 @@ ConstantRange ConstantRange::unionWith(const ConstantRange &CR) const {
   return ConstantRange(L, U);
 }
 
+ConstantRange ConstantRange::castOp(Instruction::CastOps CastOp,
+                                    uint32_t ResultBitWidth) const {
+  switch (CastOp) {
+  default:
+    llvm_unreachable("unsupported cast type");
+  case Instruction::Trunc:
+    return truncate(ResultBitWidth);
+  case Instruction::SExt:
+    return signExtend(ResultBitWidth);
+  case Instruction::ZExt:
+    return zeroExtend(ResultBitWidth);
+  case Instruction::BitCast:
+    return *this;
+  case Instruction::FPToUI:
+  case Instruction::FPToSI:
+    if (getBitWidth() == ResultBitWidth)
+      return *this;
+    else
+      return ConstantRange(getBitWidth(), /*isFullSet=*/true);
+  case Instruction::UIToFP: {
+    // TODO: use input range if available
+    auto BW = getBitWidth();
+    APInt Min = APInt::getMinValue(BW).zextOrSelf(ResultBitWidth);
+    APInt Max = APInt::getMaxValue(BW).zextOrSelf(ResultBitWidth);
+    return ConstantRange(Min, Max);
+  }
+  case Instruction::SIToFP: {
+    // TODO: use input range if available
+    auto BW = getBitWidth();
+    APInt SMin = APInt::getSignedMinValue(BW).sextOrSelf(ResultBitWidth);
+    APInt SMax = APInt::getSignedMaxValue(BW).sextOrSelf(ResultBitWidth);
+    return ConstantRange(SMin, SMax);
+  }
+  case Instruction::FPTrunc:
+  case Instruction::FPExt:
+  case Instruction::IntToPtr:
+  case Instruction::PtrToInt:
+  case Instruction::AddrSpaceCast:
+    // Conservatively return full set.
+    return ConstantRange(getBitWidth(), /*isFullSet=*/true);
+  };
+}
+
 /// zeroExtend - Return a new range in the specified integer type, which must
 /// be strictly larger than the current type.  The returned range will
 /// correspond to the possible range of values as if the source range had been
@@ -653,6 +696,42 @@ ConstantRange ConstantRange::sextOrTrunc(uint32_t DstTySize) const {
   return *this;
 }
 
+ConstantRange ConstantRange::binaryOp(Instruction::BinaryOps BinOp,
+                                      const ConstantRange &Other) const {
+  assert(BinOp >= Instruction::BinaryOpsBegin &&
+         BinOp < Instruction::BinaryOpsEnd && "Binary operators only!");
+
+  switch (BinOp) {
+  case Instruction::Add:
+    return add(Other);
+  case Instruction::Sub:
+    return sub(Other);
+  case Instruction::Mul:
+    return multiply(Other);
+  case Instruction::UDiv:
+    return udiv(Other);
+  case Instruction::Shl:
+    return shl(Other);
+  case Instruction::LShr:
+    return lshr(Other);
+  case Instruction::And:
+    return binaryAnd(Other);
+  case Instruction::Or:
+    return binaryOr(Other);
+  // Note: floating point operations applied to abstract ranges are just
+  // ideal integer operations with a lossy representation
+  case Instruction::FAdd:
+    return add(Other);
+  case Instruction::FSub:
+    return sub(Other);
+  case Instruction::FMul:
+    return multiply(Other);
+  default:
+    // Conservatively return full set.
+    return ConstantRange(getBitWidth(), /*isFullSet=*/true);
+  }
+}
+
 ConstantRange
 ConstantRange::add(const ConstantRange &Other) const {
   if (isEmptySet() || Other.isEmptySet())

lib/Transforms/Scalar/Float2Int.cpp

@@ -190,21 +190,14 @@ void Float2IntPass::walkBackwards(const SmallPtrSetImpl<Instruction*> &Roots) {
       seen(I, badRange());
       break;
 
-    case Instruction::UIToFP: {
+    case Instruction::UIToFP:
-      // Path terminated cleanly.
-      unsigned BW = I->getOperand(0)->getType()->getPrimitiveSizeInBits();
-      APInt Min = APInt::getMinValue(BW).zextOrSelf(MaxIntegerBW+1);
-      APInt Max = APInt::getMaxValue(BW).zextOrSelf(MaxIntegerBW+1);
-      seen(I, validateRange(ConstantRange(Min, Max)));
-      continue;
-    }
-
     case Instruction::SIToFP: {
-      // Path terminated cleanly.
+      // Path terminated cleanly - use the type of the integer input to seed
+      // the analysis.
       unsigned BW = I->getOperand(0)->getType()->getPrimitiveSizeInBits();
-      APInt SMin = APInt::getSignedMinValue(BW).sextOrSelf(MaxIntegerBW+1);
+      auto Input = ConstantRange(BW, true);
-      APInt SMax = APInt::getSignedMaxValue(BW).sextOrSelf(MaxIntegerBW+1);
+      auto CastOp = (Instruction::CastOps)I->getOpcode();
-      seen(I, validateRange(ConstantRange(SMin, SMax)));
+      seen(I, validateRange(Input.castOp(CastOp, MaxIntegerBW+1)));
       continue;
     }
 
@@ -249,23 +242,12 @@ void Float2IntPass::walkForwards() {
       llvm_unreachable("Should have been handled in walkForwards!");
 
     case Instruction::FAdd:
-      Op = [](ArrayRef<ConstantRange> Ops) {
-        assert(Ops.size() == 2 && "FAdd is a binary operator!");
-        return Ops[0].add(Ops[1]);
-      };
-      break;
-
     case Instruction::FSub:
-      Op = [](ArrayRef<ConstantRange> Ops) {
-        assert(Ops.size() == 2 && "FSub is a binary operator!");
-        return Ops[0].sub(Ops[1]);
-      };
-      break;
-
     case Instruction::FMul:
-      Op = [](ArrayRef<ConstantRange> Ops) {
+      Op = [I](ArrayRef<ConstantRange> Ops) {
-        assert(Ops.size() == 2 && "FMul is a binary operator!");
+        assert(Ops.size() == 2 && "its a binary operator!");
-        return Ops[0].multiply(Ops[1]);
+        auto BinOp = (Instruction::BinaryOps) I->getOpcode();
+        return Ops[0].binaryOp(BinOp, Ops[1]);
       };
       break;
 
@@ -275,9 +257,12 @@ void Float2IntPass::walkForwards() {
     //
     case Instruction::FPToUI:
     case Instruction::FPToSI:
-      Op = [](ArrayRef<ConstantRange> Ops) {
+      Op = [I](ArrayRef<ConstantRange> Ops) {
         assert(Ops.size() == 1 && "FPTo[US]I is a unary operator!");
-        return Ops[0];
+        // Note: We're ignoring the casts output size here as that's what the
+        // caller expects.
+        auto CastOp = (Instruction::CastOps)I->getOpcode();
+        return Ops[0].castOp(CastOp, MaxIntegerBW+1);
       };
       break;