[SCEV] Introduce add operation inlining limit

Inlining in getAddExpr() can cause abnormal computational time in some cases.
New parameter -scev-addops-inline-threshold is intruduced with default value 500.

Reviewers: sanjoy

Subscribers: mzolotukhin, llvm-commits

Differential Revision: https://reviews.llvm.org/D28812

llvm-svn: 293176

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolution.cpp b/llvm/lib/Analysis/ScalarEvolution.cpp
index 18fcb0e85b6..ee09c8f3c01 100644
--- a/llvm/lib/Analysis/ScalarEvolution.cpp
+++ b/llvm/lib/Analysis/ScalarEvolution.cpp
@@ -127,6 +127,11 @@ static cl::opt<unsigned> MulOpsInlineThreshold(
     cl::desc("Threshold for inlining multiplication operands into a SCEV"),
     cl::init(1000));
 
+static cl::opt<unsigned> AddOpsInlineThreshold(
+    "scev-addops-inline-threshold", cl::Hidden,
+    cl::desc("Threshold for inlining multiplication operands into a SCEV"),
+    cl::init(500));
+
 static cl::opt<unsigned>
     MaxCompareDepth("scalar-evolution-max-compare-depth", cl::Hidden,
                     cl::desc("Maximum depth of recursive compare complexity"),
@@ -2219,6 +2224,9 @@ const SCEV *ScalarEvolution::getAddExpr(SmallVectorImpl<const SCEV *> &Ops,
   if (Idx < Ops.size()) {
     bool DeletedAdd = false;
     while (const SCEVAddExpr *Add = dyn_cast<SCEVAddExpr>(Ops[Idx])) {
+      if (Ops.size() > AddOpsInlineThreshold ||
+          Add->getNumOperands() > AddOpsInlineThreshold)
+        break;
       // If we have an add, expand the add operands onto the end of the operands
       // list.
       Ops.erase(Ops.begin()+Idx);