[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 2f48cf7403652799227210bdc432ebed153324be Mon Sep 17 00:00:00 2001
From: laichunfeng <laichunfeng at tencent.com>
Date: Fri, 22 Sep 2023 09:51:31 +0800
Subject: [PATCH 1/2] [Passes] Add option for LoopVersioningLICM pass.

This option was deleted before when removing cl::opts
controling optimization pass manager passes in
https://reviews.llvm.org/D137915
---
 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 5f5d92d277c1bfc..1cad0697927064e 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"));
@@ -1293,6 +1298,21 @@ PassBuilder::buildModuleOptimizationPipeline(OptimizationLevel Level,
   if (RunPartialInlining)
     MPM.addPass(PartialInlinerPass());
 
+  // 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. By placing it just after inlining other optimizations which runs
+  // later might get benefit of no-alias assumption in clone loop.
+  if (UseLoopVersioningLICM) {
+    MPM.addPass(createModuleToFunctionPassAdaptor(
+        createFunctionToLoopPassAdaptor(LoopVersioningLICMPass())));
+    MPM.addPass(
+        createModuleToFunctionPassAdaptor(createFunctionToLoopPassAdaptor(
+            LICMPass(PTO.LicmMssaOptCap, PTO.LicmMssaNoAccForPromotionCap,
+                     /*AllowSpeculation=*/true),
+            /*USeMemorySSA=*/true, /*UseBlockFrequencyInfo=*/false)));
+  }
+
   // Remove avail extern fns and globals definitions since we aren't compiling
   // an object file for later LTO. For LTO we want to preserve these so they
   // are eligible for inlining at link-time. Note if they are unreferenced they

>From 7b099488af8894215ba0ea0c5ccebb986f1759f1 Mon Sep 17 00:00:00 2001
From: laichunfeng <laichunfeng at tencent.com>
Date: Tue, 26 Sep 2023 22:16:47 +0800
Subject: [PATCH 2/2] [Passes] Mov licm pass into OptimizePM.

---
 llvm/lib/Passes/PassBuilderPipelines.cpp | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/llvm/lib/Passes/PassBuilderPipelines.cpp b/llvm/lib/Passes/PassBuilderPipelines.cpp
index 1cad0697927064e..48f272492bbf5f9 100644
--- a/llvm/lib/Passes/PassBuilderPipelines.cpp
+++ b/llvm/lib/Passes/PassBuilderPipelines.cpp
@@ -1303,15 +1303,9 @@ PassBuilder::buildModuleOptimizationPipeline(OptimizationLevel Level,
   // early versioning may prevent further inlining due to increase of code
   // size. By placing it just after inlining other optimizations which runs
   // later might get benefit of no-alias assumption in clone loop.
-  if (UseLoopVersioningLICM) {
+  if (UseLoopVersioningLICM)
     MPM.addPass(createModuleToFunctionPassAdaptor(
         createFunctionToLoopPassAdaptor(LoopVersioningLICMPass())));
-    MPM.addPass(
-        createModuleToFunctionPassAdaptor(createFunctionToLoopPassAdaptor(
-            LICMPass(PTO.LicmMssaOptCap, PTO.LicmMssaNoAccForPromotionCap,
-                     /*AllowSpeculation=*/true),
-            /*USeMemorySSA=*/true, /*UseBlockFrequencyInfo=*/false)));
-  }
 
   // Remove avail extern fns and globals definitions since we aren't compiling
   // an object file for later LTO. For LTO we want to preserve these so they
@@ -1363,6 +1357,12 @@ PassBuilder::buildModuleOptimizationPipeline(OptimizationLevel Level,
   invokeOptimizerEarlyEPCallbacks(MPM, Level);
 
   FunctionPassManager OptimizePM;
+  // LoopVersioningLICM pass may increase new LICM opportunities.
+  if (UseLoopVersioningLICM)
+    OptimizePM.addPass(createFunctionToLoopPassAdaptor(
+        LICMPass(PTO.LicmMssaOptCap, PTO.LicmMssaNoAccForPromotionCap,
+                 /*AllowSpeculation=*/true),
+        /*USeMemorySSA=*/true, /*UseBlockFrequencyInfo=*/false));
   OptimizePM.addPass(Float2IntPass());
   OptimizePM.addPass(LowerConstantIntrinsicsPass());