[PATCH] D109102: [CSSPGO] Allow inlining recursive call for preinliner

[Wenlei He via Phabricator via llvm-commits]

wenlei created this revision.
Herald added subscribers: ormris, hoy, modimo, lxfind, haicheng, hiraditya, eraman.
wenlei requested review of this revision.
Herald added a project: LLVM.
Herald added a subscriber: llvm-commits.

Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D109102

Files:
  llvm/include/llvm/Analysis/InlineCost.h
  llvm/lib/Analysis/InlineCost.cpp
  llvm/lib/Transforms/IPO/SampleProfile.cpp


Index: llvm/lib/Transforms/IPO/SampleProfile.cpp
===================================================================
--- llvm/lib/Transforms/IPO/SampleProfile.cpp
+++ llvm/lib/Transforms/IPO/SampleProfile.cpp
@@ -1283,7 +1283,11 @@
   assert(Callee && "Expect a definition for inline candidate of direct call");
 
   InlineParams Params = getInlineParams();
+  // We will ignore the threshold from inline cost, so always get full cost.
   Params.ComputeFullInlineCost = true;
+  // If preinline decision is used we want to allow inline recursive call.
+  // TODO: Evaluate if this is helpful for AutoFDO too in general.
+  Params.AllowRecursiveCall = ProfileIsCS && UsePreInlinerDecision;
   // Checks if there is anything in the reachable portion of the callee at
   // this callsite that makes this inlining potentially illegal. Need to
   // set ComputeFullInlineCost, otherwise getInlineCost may return early
Index: llvm/lib/Analysis/InlineCost.cpp
===================================================================
--- llvm/lib/Analysis/InlineCost.cpp
+++ llvm/lib/Analysis/InlineCost.cpp
@@ -333,6 +333,10 @@
   /// whenever we simplify away the stores that would otherwise cause them to be
   /// loads.
   bool EnableLoadElimination;
+
+  /// Whether we allow inlining for recursive call.
+  bool AllowRecursiveCall;
+
   SmallPtrSet<Value *, 16> LoadAddrSet;
 
   AllocaInst *getSROAArgForValueOrNull(Value *V) const {
@@ -421,7 +425,8 @@
                OptimizationRemarkEmitter *ORE = nullptr)
       : TTI(TTI), GetAssumptionCache(GetAssumptionCache), GetBFI(GetBFI),
         PSI(PSI), F(Callee), DL(F.getParent()->getDataLayout()), ORE(ORE),
-        CandidateCall(Call), EnableLoadElimination(true) {}
+        CandidateCall(Call), EnableLoadElimination(true),
+        AllowRecursiveCall(false) {}
 
   InlineResult analyze();
 
@@ -930,7 +935,9 @@
         Params(Params), Threshold(Params.DefaultThreshold),
         BoostIndirectCalls(BoostIndirect), IgnoreThreshold(IgnoreThreshold),
         CostBenefitAnalysisEnabled(isCostBenefitAnalysisEnabled()),
-        Writer(this) {}
+        Writer(this) {
+    AllowRecursiveCall = Params.AllowRecursiveCall.getValue();
+  }
 
   /// Annotation Writer for instruction details
   InlineCostAnnotationWriter Writer;
@@ -2098,7 +2105,8 @@
     // This flag will fully abort the analysis, so don't bother with anything
     // else.
     IsRecursiveCall = true;
-    return false;
+    if (!AllowRecursiveCall)
+      return false;
   }
 
   if (TTI.isLoweredToCall(F)) {
@@ -2336,7 +2344,7 @@
     using namespace ore;
     // If the visit this instruction detected an uninlinable pattern, abort.
     InlineResult IR = InlineResult::success();
-    if (IsRecursiveCall)
+    if (IsRecursiveCall && !AllowRecursiveCall)
       IR = InlineResult::failure("recursive");
     else if (ExposesReturnsTwice)
       IR = InlineResult::failure("exposes returns twice");
Index: llvm/include/llvm/Analysis/InlineCost.h
===================================================================
--- llvm/include/llvm/Analysis/InlineCost.h
+++ llvm/include/llvm/Analysis/InlineCost.h
@@ -213,6 +213,9 @@
 
   /// Indicate whether we should allow inline deferral.
   Optional<bool> EnableDeferral = true;
+
+  /// Indicate whether we allow inlining for recursive call.
+  Optional<bool> AllowRecursiveCall = false;
 };
 
 /// Generate the parameters to tune the inline cost analysis based only on the


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