[LVI][CVP] Calculate with.overflow result range

In LVI, calculate the range of extractvalue(op.with.overflow(%x, %y), 0)
as the range of op(%x, %y). This is mainly useful in conjunction with
D60650: If the result of the operation is extracted in a branch guarded
against overflow, then the value of %x will be appropriately constrained
and the result range of the operation will be calculated taking that
into account.

Differential Revision: https://reviews.llvm.org/D60656

llvm-svn: 361693

1 files changed, 15 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/LazyValueInfo.cpp b/llvm/lib/Analysis/LazyValueInfo.cpp
index fab2bad16ff..4feff1c7764 100644
--- a/llvm/lib/Analysis/LazyValueInfo.cpp
+++ b/llvm/lib/Analysis/LazyValueInfo.cpp
@@ -430,6 +430,8 @@ namespace {
                                BasicBlock *BB);
   bool solveBlockValueCast(ValueLatticeElement &BBLV, CastInst *CI,
                            BasicBlock *BB);
+  bool solveBlockValueOverflowIntrinsic(
+      ValueLatticeElement &BBLV, WithOverflowInst *WO, BasicBlock *BB);
   void intersectAssumeOrGuardBlockValueConstantRange(Value *Val,
                                                      ValueLatticeElement &BBLV,
                                                      Instruction *BBI);
@@ -642,6 +644,11 @@ bool LazyValueInfoImpl::solveBlockValueImpl(ValueLatticeElement &Res,
 
     if (BinaryOperator *BO = dyn_cast<BinaryOperator>(BBI))
       return solveBlockValueBinaryOp(Res, BO, BB);
+
+    if (auto *EVI = dyn_cast<ExtractValueInst>(BBI))
+      if (auto *WO = dyn_cast<WithOverflowInst>(EVI->getAggregateOperand()))
+        if (EVI->getNumIndices() == 1 && *EVI->idx_begin() == 0)
+          return solveBlockValueOverflowIntrinsic(Res, WO, BB);
   }
 
   LLVM_DEBUG(dbgs() << " compute BB '" << BB->getName()
@@ -1097,6 +1104,14 @@ bool LazyValueInfoImpl::solveBlockValueBinaryOp(ValueLatticeElement &BBLV,
   };
 }
 
+bool LazyValueInfoImpl::solveBlockValueOverflowIntrinsic(
+    ValueLatticeElement &BBLV, WithOverflowInst *WO, BasicBlock *BB) {
+  return solveBlockValueBinaryOpImpl(BBLV, WO, BB,
+      [WO](const ConstantRange &CR1, const ConstantRange &CR2) {
+        return CR1.binaryOp(WO->getBinaryOp(), CR2);
+      });
+}
+
 static ValueLatticeElement getValueFromICmpCondition(Value *Val, ICmpInst *ICI,
                                                      bool isTrueDest) {
   Value *LHS = ICI->getOperand(0);