Support SCoPs with multiple entry edges.

Regions that have multiple entry edges are very common. A simple if condition
yields e.g. such a region:

  if
 /   \
then  else
 \   /
for_region

This for_region contains two entry edges 'then' -> 'for_region' and 'else' -> 'for_region'.

Previously we scheduled the RegionSimplify pass to translate such regions into
simple regions. With this patch, we now support them natively when the region is
in -loop-simplify form, which means the entry block should not be a loop header.

Contributed by:  Star Tan <tanmx_star@yeah.net>

llvm-svn: 179586

1 files changed, 9 insertions, 0 deletions

diff --git a/polly/include/polly/Support/ScopHelper.h b/polly/include/polly/Support/ScopHelper.h
index 4c2336591ff..4f275b2f74b 100755
--- a/polly/include/polly/Support/ScopHelper.h
+++ b/polly/include/polly/Support/ScopHelper.h
@@ -28,6 +28,7 @@ class BasicBlock;
 }
 
 namespace polly {
+class Scop;
 /// Temporary Hack for extended regiontree.
 ///
 /// @brief Cast the region to loop.
@@ -51,6 +52,14 @@ bool hasInvokeEdge(const llvm::PHINode *PN);
 llvm::Value *getPointerOperand(llvm::Instruction &Inst);
 llvm::BasicBlock *createSingleExitEdge(llvm::Region *R, llvm::Pass *P);
 
+/// @brief Simplify the region in a scop to have a single entry edge
+///        and a single exit edge.
+///
+/// @param S  The scop that is simplified.
+/// @param P  The pass that is currently running.
+///
+void simplifyRegion(polly::Scop *S, llvm::Pass *P);
+
 /// @brief Split the entry block of a function to store the newly inserted
 ///        allocations outside of all Scops.
 ///