Strip constant factors from SCoP parameters

  This will strip the constant factor of a parameter befor we add it to
  the SCoP. As a result the access functions are simplified, e.g., for
  the attached test case.

llvm-svn: 233501

1 files changed, 19 insertions, 0 deletions

diff --git a/polly/lib/Support/SCEVValidator.cpp b/polly/lib/Support/SCEVValidator.cpp
index 5a3706b2fac..048fdc32aa1 100644
--- a/polly/lib/Support/SCEVValidator.cpp
+++ b/polly/lib/Support/SCEVValidator.cpp
@@ -562,4 +562,23 @@ std::vector<const SCEV *> getParamsInAffineExpr(const Region *R,
 
   return Result.getParameters();
 }
+
+std::pair<const SCEV *, const SCEV *>
+extractConstantFactor(const SCEV *S, ScalarEvolution &SE) {
+
+  const SCEV *LeftOver = SE.getConstant(S->getType(), 1);
+  const SCEV *ConstPart = SE.getConstant(S->getType(), 1);
+
+  const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(S);
+  if (!M)
+    return std::make_pair(ConstPart, S);
+
+  for (const SCEV *Op : M->operands())
+    if (isa<SCEVConstant>(Op))
+      ConstPart = SE.getMulExpr(ConstPart, Op);
+    else
+      LeftOver = SE.getMulExpr(LeftOver, Op);
+
+  return std::make_pair(ConstPart, LeftOver);
+}
 }