The change for PR9190 wasn't quite right. We need to avoid making the

transformation if we can't legally create a build vector of the correct
type. Check that we can make the transformation first, and add a TODO to
refactor this code with similar cases.

Fixes: PR9223 and rdar://9000350


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@125631 91177308-0d34-0410-b5e6-96231b3b80d8

test/CodeGen/X86/legalize-sub-zero-2.ll

@@ -0,0 +1,41 @@
+; RUN: llc < %s -mtriple=i386-apple-darwin
+
+define fastcc void @foo(i32 %type) nounwind optsize {
+entry:
+  switch i32 %type, label %bb26 [
+    i32 33634, label %bb11
+    i32 5121, label %bb27
+  ]
+
+bb11:                                             ; preds = %entry
+  br label %bb27
+
+bb26:                                             ; preds = %entry
+  unreachable
+
+bb27:                                             ; preds = %bb11, %entry
+  %srcpb.0 = phi i32 [ 1, %bb11 ], [ 0, %entry ]
+  br i1 undef, label %bb348, label %bb30.lr.ph
+
+bb30.lr.ph:                                       ; preds = %bb27
+  %.sum743 = shl i32 %srcpb.0, 1
+  %0 = mul i32 %srcpb.0, -2
+  %.sum745 = add i32 %.sum743, %0
+  br i1 undef, label %bb70, label %bb71
+
+bb70:                                             ; preds = %bb30.lr.ph
+  unreachable
+
+bb71:                                             ; preds = %bb30.lr.ph
+  br i1 undef, label %bb92, label %bb80
+
+bb80:                                             ; preds = %bb71
+  unreachable
+
+bb92:                                             ; preds = %bb71
+  %1 = getelementptr inbounds i8* undef, i32 %.sum745
+  unreachable
+
+bb348:                                            ; preds = %bb27
+  ret void
+}