Generalize ScalarEvolution's PHI analysis to handle loops that don't

have preheaders or dedicated exit blocks, as clients may not otherwise
need to run LoopSimplify.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@101030 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 29 insertions, 0 deletions

diff --git a/test/Analysis/ScalarEvolution/unsimplified-loop.ll b/test/Analysis/ScalarEvolution/unsimplified-loop.ll
new file mode 100644
index 0000000000..a3175077b6
--- /dev/null
+++ b/test/Analysis/ScalarEvolution/unsimplified-loop.ll
@@ -0,0 +1,29 @@
+; RUN: opt -analyze -scalar-evolution < %s | FileCheck %s
+
+; This loop has no preheader, multiple backedges, etc., but ScalarEvolution
+; should still be able to analyze it.
+
+; CHECK: %i = phi i64 [ 5, %entry ], [ 5, %alt ], [ %i.next, %loop.a ], [ %i.next, %loop.b ]
+; CHECK-NEXT: -->  {5,+,1}<%loop>
+
+define void @foo(i1 %p, i1 %q, i1 %s, i1 %u) {
+entry:
+  br i1 %p, label %loop, label %alt
+
+alt:
+  br i1 %s, label %loop, label %exit
+
+loop:
+  %i = phi i64 [ 5, %entry ], [ 5, %alt ], [ %i.next, %loop.a ], [ %i.next, %loop.b ]
+  %i.next = add i64 %i, 1
+  br i1 %q, label %loop.a, label %loop.b
+
+loop.a:
+  br label %loop
+
+loop.b:
+  br i1 %u, label %loop, label %exit
+
+exit:
+  ret void
+}