[llvm] [Passes] Add option for LoopVersioningLICM pass. (PR #67107)

[via llvm-commits]

https://github.com/lcvon007 updated https://github.com/llvm/llvm-project/pull/67107

>From fca803f35b0b9563786dbce339cfaa272d167876 Mon Sep 17 00:00:00 2001
From: laichunfeng <laichunfeng at tencent.com>
Date: Fri, 22 Sep 2023 09:51:31 +0800
Subject: [PATCH] [Passes] Add option for LoopVersioningLICM pass.

User only can use opt to test LoopVersioningLICM pass before,
and this PR adds the option back(deleted in https://reviews.llvm.org/D137915)
so that it's easy for verifying if it is useful for some benchmarks.
---
 llvm/lib/Passes/PassBuilderPipelines.cpp | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 2cc7d43cfcc71fa..78e0e6353056343 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -105,6 +105,7 @@
 #include "llvm/Transforms/Scalar/LoopSink.h"
 #include "llvm/Transforms/Scalar/LoopUnrollAndJamPass.h"
 #include "llvm/Transforms/Scalar/LoopUnrollPass.h"
+#include "llvm/Transforms/Scalar/LoopVersioningLICM.h"
 #include "llvm/Transforms/Scalar/LowerConstantIntrinsics.h"
 #include "llvm/Transforms/Scalar/LowerExpectIntrinsic.h"
 #include "llvm/Transforms/Scalar/LowerMatrixIntrinsics.h"
@@ -271,6 +272,10 @@ static cl::opt<AttributorRunOption> AttributorRun(
                clEnumValN(AttributorRunOption::NONE, "none",
                           "disable attributor runs")));
 
+static cl::opt<bool> UseLoopVersioningLICM(
+    "enable-loop-versioning-licm", cl::init(false), cl::Hidden,
+    cl::desc("Enable the experimental Loop Versioning LICM pass"));
+
 cl::opt<bool> EnableMemProfContextDisambiguation(
     "enable-memprof-context-disambiguation", cl::init(false), cl::Hidden,
     cl::ZeroOrMore, cl::desc("Enable MemProf context disambiguation"));
@@ -1343,6 +1348,21 @@ PassBuilder::buildModuleOptimizationPipeline(OptimizationLevel Level,
   invokeOptimizerEarlyEPCallbacks(MPM, Level);
 
   FunctionPassManager OptimizePM;
+  // Scheduling LoopVersioningLICM when inlining is over, because after that
+  // we may see more accurate aliasing. Reason to run this late is that too
+  // early versioning may prevent further inlining due to increase of code
+  // size. Other optimizations which runs later might get benefit of no-alias
+  // assumption in clone loop.
+  if (UseLoopVersioningLICM) {
+    OptimizePM.addPass(
+        createFunctionToLoopPassAdaptor(LoopVersioningLICMPass()));
+    // LoopVersioningLICM pass might increase new LICM opportunities.
+    OptimizePM.addPass(createFunctionToLoopPassAdaptor(
+        LICMPass(PTO.LicmMssaOptCap, PTO.LicmMssaNoAccForPromotionCap,
+                 /*AllowSpeculation=*/true),
+        /*USeMemorySSA=*/true, /*UseBlockFrequencyInfo=*/false));
+  }
+
   OptimizePM.addPass(Float2IntPass());
   OptimizePM.addPass(LowerConstantIntrinsicsPass());