Add option to choose where in the pass pipeline polly is run

These options are useful to play with the location of Polly within LLVM's
pass manager.

llvm-svn: 242390

1 files changed, 70 insertions, 6 deletions

diff --git a/polly/lib/Support/RegisterPasses.cpp b/polly/lib/Support/RegisterPasses.cpp
index 13049300624..f0c611b90b6 100644
--- a/polly/lib/Support/RegisterPasses.cpp
+++ b/polly/lib/Support/RegisterPasses.cpp
@@ -49,8 +49,26 @@ static cl::opt<bool> PollyDetectOnly(
     cl::desc("Only run scop detection, but no other optimizations"),
     cl::init(false), cl::ZeroOrMore, cl::cat(PollyCategory));
 
+enum PassPositionChoice {
+  POSITION_EARLY,
+  POSITION_AFTER_LOOPOPT,
+  POSITION_BEFORE_VECTORIZER
+};
+
 enum OptimizerChoice { OPTIMIZER_NONE, OPTIMIZER_ISL };
 
+static cl::opt<PassPositionChoice> PassPosition(
+    "polly-position", cl::desc("Where to run polly in the pass pipeline"),
+    cl::values(
+        clEnumValN(POSITION_EARLY, "early", "Before everything"),
+        clEnumValN(POSITION_AFTER_LOOPOPT, "after-loopopt",
+                   "After the loop optimizer (but within the inline zycle)"),
+        clEnumValN(POSITION_BEFORE_VECTORIZER, "before-vectorizer",
+                   "Right before the vectorizer"),
+        clEnumValEnd),
+    cl::Hidden, cl::init(POSITION_EARLY), cl::ZeroOrMore,
+    cl::cat(PollyCategory));
+
 static cl::opt<OptimizerChoice> Optimizer(
     "polly-optimizer", cl::desc("Select the scheduling optimizer"),
     cl::values(clEnumValN(OPTIMIZER_NONE, "none", "No optimizer"),
@@ -167,8 +185,6 @@ void initializePollyPasses(PassRegistry &Registry) {
 ///
 /// Polly supports the isl internal code generator.
 void registerPollyPasses(llvm::legacy::PassManagerBase &PM) {
-  registerCanonicalicationPasses(PM);
-
   PM.add(polly::createScopDetectionPass());
 
   if (PollyDetectOnly)
@@ -232,13 +248,48 @@ registerPollyEarlyAsPossiblePasses(const llvm::PassManagerBuilder &Builder,
   if (!polly::shouldEnablePolly())
     return;
 
+  if (PassPosition != POSITION_EARLY)
+    return;
+
+  registerCanonicalicationPasses(PM);
+  polly::registerPollyPasses(PM);
+}
+
+static void
+registerPollyLoopOptimizerEndPasses(const llvm::PassManagerBuilder &Builder,
+                                    llvm::legacy::PassManagerBase &PM) {
+  if (!polly::shouldEnablePolly())
+    return;
+
+  if (PassPosition != POSITION_AFTER_LOOPOPT)
+    return;
+
   polly::registerPollyPasses(PM);
+  // TODO: Add some cleanup passes
+}
+
+static void
+registerPollyScalarOptimizerLatePasses(const llvm::PassManagerBuilder &Builder,
+                                       llvm::legacy::PassManagerBase &PM) {
+  if (!polly::shouldEnablePolly())
+    return;
+
+  if (PassPosition != POSITION_BEFORE_VECTORIZER)
+    return;
+
+  polly::registerPollyPasses(PM);
+  // TODO: Add some cleanup passes
 }
 
 /// @brief Register Polly to be available as an optimizer
 ///
-/// We currently register Polly such that it runs as early as possible. This has
-/// several implications:
+///
+/// We can currently run Polly at three different points int the pass manager.
+/// a) very early, b) after the canonicalizing loop transformations and c) right
+/// before the vectorizer.
+///
+/// The default is currently a), to register Polly such that it runs as early as
+/// possible. This has several implications:
 ///
 ///   1) We need to schedule more canonicalization passes
 ///
@@ -262,7 +313,20 @@ registerPollyEarlyAsPossiblePasses(const llvm::PassManagerBuilder &Builder,
 ///   Polly before all other passes, we have the full sequence of -O3
 ///   optimizations behind us, such that inefficiencies on the low level can
 ///   be optimized away.
+///
+/// We are currently evaluating the benefit or running Polly at position b) or
+/// c). b) is likely to early as it interacts with the inliner. c) is nice
+/// as everything is fully inlined and canonicalized, but we need to be able
+/// to handle LICMed code to make it useful.
+static llvm::RegisterStandardPasses
+    RegisterPollyOptimizerEarly(llvm::PassManagerBuilder::EP_EarlyAsPossible,
+                                registerPollyEarlyAsPossiblePasses);
+
 static llvm::RegisterStandardPasses
-    RegisterPollyOptimizer(llvm::PassManagerBuilder::EP_EarlyAsPossible,
-                           registerPollyEarlyAsPossiblePasses);
+    RegisterPollyOptimizerLoopEnd(llvm::PassManagerBuilder::EP_LoopOptimizerEnd,
+                                  registerPollyLoopOptimizerEndPasses);
+
+static llvm::RegisterStandardPasses RegisterPollyOptimizerScalarLate(
+    llvm::PassManagerBuilder::EP_VectorizerStart,
+    registerPollyScalarOptimizerLatePasses);
 }