Improve the widening of integral binary vector operations

- split WidenVecRes_Binary into WidenVecRes_Binary and WidenVecRes_BinaryCanTrap
  - WidenVecRes_BinaryCanTrap preserves the original behaviour for operations
    that can trap
  - WidenVecRes_Binary simply widens the operation and improves codegen for
    3-element vectors by allowing widening and promotion on x86 (matches the
    behaviour of unary and ternary operation widening)
- use WidenVecRes_Binary for operations on integers.

Reviewed by: nrotem



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@188699 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/X86/widen_load-2.ll

@@ -73,9 +73,7 @@ define void @add12i32(%i32vec12*  sret %ret, %i32vec12* %ap, %i32vec12* %bp)  {
 ; CHECK: add3i16
 %i16vec3 = type <3 x i16>
 define void @add3i16(%i16vec3* nocapture sret %ret, %i16vec3* %ap, %i16vec3* %bp) nounwind {
-; CHECK: addl
-; CHECK: addl
-; CHECK: addl
+; CHECK: paddd
 ; CHECK: ret
 	%a = load %i16vec3* %ap, align 16
 	%b = load %i16vec3* %bp, align 16
@@ -135,9 +133,7 @@ define void @add18i16(%i16vec18* nocapture sret %ret, %i16vec18* %ap, %i16vec18*
 ; CHECK: add3i8
 %i8vec3 = type <3 x i8>
 define void @add3i8(%i8vec3* nocapture sret %ret, %i8vec3* %ap, %i8vec3* %bp) nounwind {
-; CHECK: addb
-; CHECK: addb
-; CHECK: addb
+; CHECK: paddd
 ; CHECK: ret
 	%a = load %i8vec3* %ap, align 16
 	%b = load %i8vec3* %bp, align 16