[ConstantRange] Add API for intrinsics (NFC)

This adds a common API for compute constant ranges of intrinsics.
The intention here is that
a) we can reuse the same code across different passes that handle
   constant ranges, i.e. this can be reused in SCCP
b) we only have to add knowledge about supported intrinsics to
   ConstantRange, not any consumers.

Differential Revision: https://reviews.llvm.org/D84587

llvm/include/llvm/IR/ConstantRange.h

@@ -150,6 +150,14 @@ class LLVM_NODISCARD ConstantRange {
                                              const APInt &Other,
                                              unsigned NoWrapKind);
 
+  /// Returns true if ConstantRange calculations are supported for intrinsic
+  /// with \p IntrinsicID.
+  static bool isIntrinsicSupported(Intrinsic::ID IntrinsicID);
+
+  /// Compute range of intrinsic result for the given operand ranges.
+  static ConstantRange intrinsic(Intrinsic::ID IntrinsicID,
+                                 ArrayRef<ConstantRange> Ops);
+
   /// Set up \p Pred and \p RHS such that
   /// ConstantRange::makeExactICmpRegion(Pred, RHS) == *this.  Return true if
   /// successful.

llvm/lib/Analysis/LazyValueInfo.cpp

@@ -400,8 +400,6 @@ class LazyValueInfoImpl {
                                                     BasicBlock *BB);
   Optional<ValueLatticeElement> solveBlockValueOverflowIntrinsic(
       WithOverflowInst *WO, BasicBlock *BB);
-  Optional<ValueLatticeElement> solveBlockValueSaturatingIntrinsic(
-      SaturatingInst *SI, BasicBlock *BB);
   Optional<ValueLatticeElement> solveBlockValueIntrinsic(IntrinsicInst *II,
                                                          BasicBlock *BB);
   Optional<ValueLatticeElement> solveBlockValueExtractValue(
@@ -1035,43 +1033,24 @@ LazyValueInfoImpl::solveBlockValueOverflowIntrinsic(WithOverflowInst *WO,
       });
 }
 
-Optional<ValueLatticeElement>
-LazyValueInfoImpl::solveBlockValueSaturatingIntrinsic(SaturatingInst *SI,
-                                                      BasicBlock *BB) {
-  switch (SI->getIntrinsicID()) {
-  case Intrinsic::uadd_sat:
-    return solveBlockValueBinaryOpImpl(
-        SI, BB, [](const ConstantRange &CR1, const ConstantRange &CR2) {
-          return CR1.uadd_sat(CR2);
-        });
-  case Intrinsic::usub_sat:
-    return solveBlockValueBinaryOpImpl(
-        SI, BB, [](const ConstantRange &CR1, const ConstantRange &CR2) {
-          return CR1.usub_sat(CR2);
-        });
-  case Intrinsic::sadd_sat:
-    return solveBlockValueBinaryOpImpl(
-        SI, BB, [](const ConstantRange &CR1, const ConstantRange &CR2) {
-          return CR1.sadd_sat(CR2);
-        });
-  case Intrinsic::ssub_sat:
-    return solveBlockValueBinaryOpImpl(
-        SI, BB, [](const ConstantRange &CR1, const ConstantRange &CR2) {
-          return CR1.ssub_sat(CR2);
-        });
-  default:
-    llvm_unreachable("All llvm.sat intrinsic are handled.");
-  }
-}
-
 Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueIntrinsic(
     IntrinsicInst *II, BasicBlock *BB) {
-  if (auto *SI = dyn_cast<SaturatingInst>(II))
-    return solveBlockValueSaturatingIntrinsic(SI, BB);
+  if (!ConstantRange::isIntrinsicSupported(II->getIntrinsicID())) {
+    LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()
+                      << "' - overdefined (unknown intrinsic).\n");
+    return ValueLatticeElement::getOverdefined();
+  }
 
-  LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()
-                    << "' - overdefined (unknown intrinsic).\n");
-  return ValueLatticeElement::getOverdefined();
+  SmallVector<ConstantRange, 2> OpRanges;
+  for (Value *Op : II->args()) {
+    Optional<ConstantRange> Range = getRangeFor(Op, II, BB);
+    if (!Range)
+      return None;
+    OpRanges.push_back(*Range);
+  }
+
+  return ValueLatticeElement::getRange(
+      ConstantRange::intrinsic(II->getIntrinsicID(), OpRanges));
 }
 
 Optional<ValueLatticeElement> LazyValueInfoImpl::solveBlockValueExtractValue(

llvm/lib/IR/ConstantRange.cpp

@@ -26,6 +26,7 @@
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/InstrTypes.h"
 #include "llvm/IR/Instruction.h"
+#include "llvm/IR/Intrinsics.h"
 #include "llvm/IR/Metadata.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/Support/Compiler.h"
@@ -835,6 +836,35 @@ ConstantRange ConstantRange::overflowingBinaryOp(Instruction::BinaryOps BinOp,
   }
 }
 
+bool ConstantRange::isIntrinsicSupported(Intrinsic::ID IntrinsicID) {
+  switch (IntrinsicID) {
+  case Intrinsic::uadd_sat:
+  case Intrinsic::usub_sat:
+  case Intrinsic::sadd_sat:
+  case Intrinsic::ssub_sat:
+    return true;
+  default:
+    return false;
+  }
+}
+
+ConstantRange ConstantRange::intrinsic(Intrinsic::ID IntrinsicID,
+                                       ArrayRef<ConstantRange> Ops) {
+  switch (IntrinsicID) {
+  case Intrinsic::uadd_sat:
+    return Ops[0].uadd_sat(Ops[1]);
+  case Intrinsic::usub_sat:
+    return Ops[0].usub_sat(Ops[1]);
+  case Intrinsic::sadd_sat:
+    return Ops[0].sadd_sat(Ops[1]);
+  case Intrinsic::ssub_sat:
+    return Ops[0].ssub_sat(Ops[1]);
+  default:
+    assert(!isIntrinsicSupported(IntrinsicID) && "Shouldn't be supported");
+    llvm_unreachable("Unsupported intrinsic");
+  }
+}
+
 ConstantRange
 ConstantRange::add(const ConstantRange &Other) const {
   if (isEmptySet() || Other.isEmptySet())