Speculatively revert commit 121905 since it looks like it might have broken the

dragonegg self-host buildbot.  Original commit message:

Add an InstCombine transform to recognize instances of manual overflow-safe addition
(performing the addition in a wider type and explicitly checking for overflow), and
fold them down to intrinsics.  This currently only supports signed-addition, but could
be generalized if someone works out the magic constant formulas for other operations.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@121965 91177308-0d34-0410-b5e6-96231b3b80d8

test/Transforms/InstCombine/overflow.ll

@@ -1,27 +0,0 @@
-; RUN: opt -S -instcombine < %s | FileCheck %s
-; <rdar://problem/8558713>
-
-; CHECK: @test1
-define i32 @test1(i32 %a, i32 %b) nounwind ssp {
-entry:
-; CHECK-NOT: sext
-  %conv = sext i32 %a to i64
-  %conv2 = sext i32 %b to i64
-  %add = add nsw i64 %conv2, %conv
-  %add.off = add i64 %add, 2147483648
-; CHECK: llvm.sadd.with.overflow
-  %0 = icmp ugt i64 %add.off, 4294967295
-  br i1 %0, label %if.then, label %if.end
-
-if.then:
-  %call = tail call i32 (...)* @throwAnExceptionOrWhatever() nounwind
-  br label %if.end
-
-if.end:
-; CHECK-NOT: trunc
-  %conv9 = trunc i64 %add to i32
-; CHECK: ret i32
-  ret i32 %conv9
-}
-
-declare i32 @throwAnExceptionOrWhatever(...)