Add an isLoopSimplifyForm() predicate, following the example of
isLCSSAForm(), to test whether a loop is in the form guaranteed
by the LoopSimplify pass.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@76077 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/include/llvm/Analysis/LoopInfo.h b/include/llvm/Analysis/LoopInfo.h
index 60c9564..7ce6a4e 100644
--- a/include/llvm/Analysis/LoopInfo.h
+++ b/include/llvm/Analysis/LoopInfo.h
@@ -551,6 +551,11 @@
/// isLCSSAForm - Return true if the Loop is in LCSSA form
bool isLCSSAForm() const;
+ /// isLoopSimplifyForm - Return true if the Loop is in the form that
+ /// the LoopSimplify form transforms loops to, which is sometimes called
+ /// normal form.
+ bool isLoopSimplifyForm() const;
+
private:
friend class LoopInfoBase<BasicBlock, Loop>;
explicit Loop(BasicBlock *BB) : LoopBase<BasicBlock, Loop>(BB) {}
diff --git a/lib/Analysis/LoopInfo.cpp b/lib/Analysis/LoopInfo.cpp
index 63de1aa..d350fa6 100644
--- a/lib/Analysis/LoopInfo.cpp
+++ b/lib/Analysis/LoopInfo.cpp
@@ -276,6 +276,30 @@
return true;
}
+
+/// isLoopSimplifyForm - Return true if the Loop is in the form that
+/// the LoopSimplify form transforms loops to, which is sometimes called
+/// normal form.
+bool Loop::isLoopSimplifyForm() const {
+ // Normal-form loops have a preheader.
+ if (!getLoopPreheader())
+ return false;
+ // Normal-form loops have a single backedge.
+ if (!getLoopLatch())
+ return false;
+ // Each predecessor of each exit block of a normal loop is contained
+ // within the loop.
+ SmallVector<BasicBlock *, 4> ExitBlocks;
+ getExitBlocks(ExitBlocks);
+ for (unsigned i = 0, e = ExitBlocks.size(); i != e; ++i)
+ for (pred_iterator PI = pred_begin(ExitBlocks[i]),
+ PE = pred_end(ExitBlocks[i]); PI != PE; ++PI)
+ if (!contains(*PI))
+ return false;
+ // All the requirements are met.
+ return true;
+}
+
//===----------------------------------------------------------------------===//
// LoopInfo implementation
//