[InstCombine] Refactor OptimizeOverflowCheck; NFCI

Extract method to compute overflow based on binop and signedness,
and then make the result handling code generic. This extends the
always-overflow handling to signed muls, but has currently no effect,
as we don't compute always overflow for them (thus NFC).

llvm-svn: 361721

1 files changed, 5 insertions, 1 deletions

diff --git a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
index 123025bbccf..434b0d59121 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
+++ b/llvm/lib/Transforms/InstCombine/InstCombineInternal.h
@@ -692,7 +692,7 @@ public:
   }
 
   OverflowResult computeOverflowForSignedMul(const Value *LHS,
-	                                         const Value *RHS,
+                                             const Value *RHS,
                                              const Instruction *CxtI) const {
     return llvm::computeOverflowForSignedMul(LHS, RHS, DL, &AC, CxtI, &DT);
   }
@@ -720,6 +720,10 @@ public:
     return llvm::computeOverflowForSignedSub(LHS, RHS, DL, &AC, CxtI, &DT);
   }
 
+  OverflowResult computeOverflow(
+      Instruction::BinaryOps BinaryOp, bool IsSigned,
+      Value *LHS, Value *RHS, Instruction *CxtI) const;
+
   /// Maximum size of array considered when transforming.
   uint64_t MaxArraySizeForCombine;