[IR] Add WithOverflowInst class

This adds a WithOverflowInst class with a few helper methods to get
the underlying binop, signedness and nowrap type and makes use of it
where sensible. There will be two more uses in D60650/D60656.

The refactorings are all NFC, though I left some TODOs where things
could be improved. In particular we have two places where add/sub are
handled but mul isn't.

Differential Revision: https://reviews.llvm.org/D60668

llvm-svn: 358512

1 files changed, 34 insertions, 0 deletions

diff --git a/llvm/lib/IR/IntrinsicInst.cpp b/llvm/lib/IR/IntrinsicInst.cpp
index 8d371aabb21..2e2da0edb08 100644
--- a/llvm/lib/IR/IntrinsicInst.cpp
+++ b/llvm/lib/IR/IntrinsicInst.cpp
@@ -21,6 +21,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Operator.h"
 #include "llvm/ADT/StringSwitch.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/DebugInfoMetadata.h"
@@ -168,3 +169,36 @@ bool ConstrainedFPIntrinsic::isTernaryOp() const {
   }
 }
 
+Instruction::BinaryOps WithOverflowInst::getBinaryOp() const {
+  switch (getIntrinsicID()) {
+    case Intrinsic::uadd_with_overflow:
+    case Intrinsic::sadd_with_overflow:
+      return Instruction::Add;
+    case Intrinsic::usub_with_overflow:
+    case Intrinsic::ssub_with_overflow:
+      return Instruction::Sub;
+    case Intrinsic::umul_with_overflow:
+    case Intrinsic::smul_with_overflow:
+      return Instruction::Mul;
+    default:
+      llvm_unreachable("Invalid intrinsic");
+  }
+}
+
+bool WithOverflowInst::isSigned() const {
+  switch (getIntrinsicID()) {
+    case Intrinsic::sadd_with_overflow:
+    case Intrinsic::ssub_with_overflow:
+    case Intrinsic::smul_with_overflow:
+      return true;
+    default:
+      return false;
+  }
+}
+
+unsigned WithOverflowInst::getNoWrapKind() const {
+  if (isSigned())
+    return OverflowingBinaryOperator::NoSignedWrap;
+  else
+    return OverflowingBinaryOperator::NoUnsignedWrap;
+}