[llvm-commits] [llvm] r76077 - in /llvm/trunk: include/llvm/Analysis/LoopInfo.h lib/Analysis/LoopInfo.cpp

[Dan Gohman]

Author: djg
Date: Thu Jul 16 11:16:23 2009
New Revision: 76077

URL: http://llvm.org/viewvc/llvm-project?rev=76077&view=rev
Log:
Add an isLoopSimplifyForm() predicate, following the example of
isLCSSAForm(), to test whether a loop is in the form guaranteed
by the LoopSimplify pass.

Modified:
    llvm/trunk/include/llvm/Analysis/LoopInfo.h
    llvm/trunk/lib/Analysis/LoopInfo.cpp

Modified: llvm/trunk/include/llvm/Analysis/LoopInfo.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/Analysis/LoopInfo.h?rev=76077&r1=76076&r2=76077&view=diff

==============================================================================
--- llvm/trunk/include/llvm/Analysis/LoopInfo.h (original)
+++ llvm/trunk/include/llvm/Analysis/LoopInfo.h Thu Jul 16 11:16:23 2009
@@ -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) {}

Modified: llvm/trunk/lib/Analysis/LoopInfo.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/LoopInfo.cpp?rev=76077&r1=76076&r2=76077&view=diff

==============================================================================
--- llvm/trunk/lib/Analysis/LoopInfo.cpp (original)
+++ llvm/trunk/lib/Analysis/LoopInfo.cpp Thu Jul 16 11:16:23 2009
@@ -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
 //