allow LazyValueInfo::getEdgeValue() to reason about multiple edges from the same switch instruction by doing union of ranges (which may still be conservative, but it's more aggressive than before)

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@157071 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 28 insertions, 0 deletions

diff --git a/test/Transforms/CorrelatedValuePropagation/range.ll b/test/Transforms/CorrelatedValuePropagation/range.ll
index 2bb21874ce..4ac478b0d5 100644
--- a/test/Transforms/CorrelatedValuePropagation/range.ll
+++ b/test/Transforms/CorrelatedValuePropagation/range.ll
@@ -70,3 +70,31 @@ if.then4:
 if.end8:
   ret i32 4
 }
+
+; CHECK: @test4
+define i32 @test4(i32 %c) nounwind {
+  switch i32 %c, label %sw.default [
+    i32 1, label %sw.bb
+    i32 2, label %sw.bb
+    i32 4, label %sw.bb
+  ]
+
+; CHECK: sw.bb
+sw.bb:
+  %cmp = icmp sge i32 %c, 1
+; CHECK: br i1 true
+  br i1 %cmp, label %if.then, label %if.end
+
+if.then:
+  br label %return
+
+if.end:
+  br label %return
+
+sw.default:
+  br label %return
+
+return:
+  %retval.0 = phi i32 [ 42, %sw.default ], [ 4, %if.then ], [ 9, %if.end ]
+  ret i32 %retval.0
+}