[Constants] Simplify type checking switch in ConstantExpr::get.

[craig.topper]

Summary

Remove duplicate checks that both operands have the same type. This is checked
before the switch.

Use 'integer' or 'floating-point' instead of 'arithmetic' type. I think this
might be a leftover to the days when floating point and integer operations
shared the same opcodes.

[RKSimon]

LGTM

llvm/lib/IR/Constants.cpp

Constant *ConstantExpr::get(unsigned Opcode, Constant *C1, Constant *C2,
   assert(C1->getType() == C2->getType() &&
          "Operand types in binary constant expression should match");
 
 #ifndef NDEBUG
   switch (Opcode) {
   case Instruction::Add:
   case Instruction::Sub:
   case Instruction::Mul:
-    assert(C1->getType() == C2->getType() && "Op types should be identical!");
+  case Instruction::UDiv:
+  case Instruction::SDiv:
+  case Instruction::URem:
+  case Instruction::SRem:
     assert(C1->getType()->isIntOrIntVectorTy() &&
            "Tried to create an integer operation on a non-integer type!");
     break;
   case Instruction::FAdd:
   case Instruction::FSub:
   case Instruction::FMul:
-    assert(C1->getType() == C2->getType() && "Op types should be identical!");
-    assert(C1->getType()->isFPOrFPVectorTy() &&
-           "Tried to create a floating-point operation on a "
-           "non-floating-point type!");
-    break;
-  case Instruction::UDiv:
-  case Instruction::SDiv:
-    assert(C1->getType() == C2->getType() && "Op types should be identical!");
-    assert(C1->getType()->isIntOrIntVectorTy() &&
-           "Tried to create an arithmetic operation on a non-arithmetic type!");
-    break;
   case Instruction::FDiv:
-    assert(C1->getType() == C2->getType() && "Op types should be identical!");
-    assert(C1->getType()->isFPOrFPVectorTy() &&
-           "Tried to create an arithmetic operation on a non-arithmetic type!");
-    break;
-  case Instruction::URem:
-  case Instruction::SRem:
-    assert(C1->getType() == C2->getType() && "Op types should be identical!");
-    assert(C1->getType()->isIntOrIntVectorTy() &&
-           "Tried to create an arithmetic operation on a non-arithmetic type!");
-    break;
   case Instruction::FRem:
-    assert(C1->getType() == C2->getType() && "Op types should be identical!");
     assert(C1->getType()->isFPOrFPVectorTy() &&
-           "Tried to create an arithmetic operation on a non-arithmetic type!");
+           "Tried to create a floating-point operation on a "
+           "non-floating-point type!");
     break;
   case Instruction::And:
   case Instruction::Or:
   case Instruction::Xor:
-    assert(C1->getType() == C2->getType() && "Op types should be identical!");
     assert(C1->getType()->isIntOrIntVectorTy() &&
            "Tried to create a logical operation on a non-integral type!");
     break;
   case Instruction::Shl:
   case Instruction::LShr:
   case Instruction::AShr:
-    assert(C1->getType() == C2->getType() && "Op types should be identical!");
     assert(C1->getType()->isIntOrIntVectorTy() &&
            "Tried to create a shift operation on a non-integer type!");
     break;
   default:
     break;
   }
 #endif