add uadd_ov/usub_ov to apint, consolidate constant folding
logic to use the new APInt methods.  Among other things this
implements rdar://8501501 - llvm.smul.with.overflow.i32 should constant fold

which comes from "clang -ftrapv", originally brought to my attention from PR8221.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116457 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/test/Transforms/ConstProp/overflow-ops.ll b/test/Transforms/ConstProp/overflow-ops.ll
index 1547a4d..5587e9b 100644
--- a/test/Transforms/ConstProp/overflow-ops.ll
+++ b/test/Transforms/ConstProp/overflow-ops.ll
@@ -170,3 +170,14 @@
 
 declare {i8, i1} @llvm.sadd.with.overflow.i8(i8, i8)
 declare {i8, i1} @llvm.ssub.with.overflow.i8(i8, i8)
+declare {i8, i1} @llvm.smul.with.overflow.i8(i8, i8)
+
+; rdar://8501501
+define {i8, i1} @smul_1() nounwind {
+entry:
+  %t = call {i8, i1} @llvm.smul.with.overflow.i8(i8 -20, i8 -10)
+  ret {i8, i1} %t
+
+; CHECK: @smul_1
+; CHECK: ret %i8i1 { i8 -56, i1 true }
+}