1 files changed, 29 insertions, 7 deletions

diff --git a/llvm/lib/CodeGen/MachinePipeliner.cpp b/llvm/lib/CodeGen/MachinePipeliner.cpp
index 3a9651c5cee0..a717d9e4a618 100644
--- a/llvm/lib/CodeGen/MachinePipeliner.cpp
+++ b/llvm/lib/CodeGen/MachinePipeliner.cpp
@@ -110,6 +110,7 @@ STATISTIC(NumFailZeroMII, "Pipeliner abort due to zero MII");
 STATISTIC(NumFailNoSchedule, "Pipeliner abort due to no schedule found");
 STATISTIC(NumFailZeroStage, "Pipeliner abort due to zero stage");
 STATISTIC(NumFailLargeMaxStage, "Pipeliner abort due to too many stages");
+STATISTIC(NumFailTooManyStores, "Pipeliner abort due to too many stores");
 
 /// A command line option to turn software pipelining on or off.
 static cl::opt<bool> EnableSWP("enable-pipeliner", cl::Hidden, cl::init(true),
@@ -193,16 +194,22 @@ static cl::opt<bool>
     MVECodeGen("pipeliner-mve-cg", cl::Hidden, cl::init(false),
                cl::desc("Use the MVE code generator for software pipelining"));
 
-namespace llvm {
+/// A command line argument to limit the number of store instructions in the
+/// target basic block.
+static cl::opt<unsigned> SwpMaxNumStores(
+    "pipeliner-max-num-stores",
+    cl::desc("Maximum number of stores allwed in the target loop."), cl::Hidden,
+    cl::init(200));
 
 // A command line option to enable the CopyToPhi DAG mutation.
-cl::opt<bool> SwpEnableCopyToPhi("pipeliner-enable-copytophi", cl::ReallyHidden,
-                                 cl::init(true),
-                                 cl::desc("Enable CopyToPhi DAG Mutation"));
+cl::opt<bool>
+    llvm::SwpEnableCopyToPhi("pipeliner-enable-copytophi", cl::ReallyHidden,
+                             cl::init(true),
+                             cl::desc("Enable CopyToPhi DAG Mutation"));
 
 /// A command line argument to force pipeliner to use specified issue
 /// width.
-cl::opt<int> SwpForceIssueWidth(
+cl::opt<int> llvm::SwpForceIssueWidth(
     "pipeliner-force-issue-width",
     cl::desc("Force pipeliner to use specified issue width."), cl::Hidden,
     cl::init(-1));
@@ -218,8 +225,6 @@ static cl::opt<WindowSchedulingFlag> WindowSchedulingOption(
                clEnumValN(WindowSchedulingFlag::WS_Force, "force",
                           "Use window algorithm instead of SMS algorithm.")));
 
-} // end namespace llvm
-
 unsigned SwingSchedulerDAG::Circuits::MaxPaths = 5;
 char MachinePipeliner::ID = 0;
 #ifndef NDEBUG
@@ -544,6 +549,23 @@ bool MachinePipeliner::canPipelineLoop(MachineLoop &L) {
     return false;
   }
 
+  unsigned NumStores = 0;
+  for (MachineInstr &MI : *L.getHeader())
+    if (MI.mayStore())
+      ++NumStores;
+  if (NumStores > SwpMaxNumStores) {
+    LLVM_DEBUG(dbgs() << "Too many stores\n");
+    NumFailTooManyStores++;
+    ORE->emit([&]() {
+      return MachineOptimizationRemarkAnalysis(DEBUG_TYPE, "canPipelineLoop",
+                                               L.getStartLoc(), L.getHeader())
+             << "Too many store instructions in the loop: "
+             << ore::NV("NumStores", NumStores) << " > "
+             << ore::NV("SwpMaxNumStores", SwpMaxNumStores) << ".";
+    });
+    return false;
+  }
+
   // Remove any subregisters from inputs to phi nodes.
   preprocessPhiNodes(*L.getHeader());
   return true;