[PATCH] D153154: [Inliner]Use a hybrid of cost-benefit and cost-threshold analysis.

[Mingming Liu via Phabricator via llvm-commits]

mingmingl created this revision.
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(WIP) The threshold should be a target-specific number.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D153154

Files:
  llvm/lib/Analysis/InlineCost.cpp


Index: llvm/lib/Analysis/InlineCost.cpp
===================================================================
--- llvm/lib/Analysis/InlineCost.cpp
+++ llvm/lib/Analysis/InlineCost.cpp
@@ -88,6 +88,18 @@
     "inline-enable-cost-benefit-analysis", cl::Hidden, cl::init(false),
     cl::desc("Enable the cost-benefit analysis for the inliner"));
 
+static cl::opt<bool> EnableHybridAnalysis(
+    "inline-hybrid-analysis", cl::init(false), cl::Hidden,
+    cl::desc("If set to true, a hybrid of cost-benefit analysis and "
+             "cost-threshold analysis is used. In parctice, a hybrid model "
+             "should be used when machine-functions-splitter is not enabled."));
+
+static cl::opt<int> AggressiveInlineSavingsMultiplier(
+    "aggressive-inline-savings-multiplier", cl::Hidden, cl::init(3),
+    cl::desc("The multiplier to multiply cycle savings. If a callee's cycle "
+             "saving is greater than cost using this multiplier, it's a "
+             "stronger signal that inlining this callee is useful"));
+
 static cl::opt<int> InlineSavingsMultiplier(
     "inline-savings-multiplier", cl::Hidden, cl::init(8),
     cl::desc("Multiplier to multiply cycle savings by during inlining"));
@@ -898,10 +910,19 @@
     // Note that the left hand side is specific to a call site.  The right hand
     // side is a constant for the entire executable.
     APInt LHS = CycleSavings;
-    LHS *= InlineSavingsMultiplier;
+    LHS *= AggressiveInlineSavingsMultiplier;
     APInt RHS(128, PSI->getOrCompHotCountThreshold());
     RHS *= Size;
-    return LHS.uge(RHS);
+    if (LHS.uge(RHS))
+      return true;
+
+    APInt ConservativeLHS = CycleSavings;
+    ConservativeLHS *= InlineSavingsMultiplier;
+
+    if (!ConservativeLHS.uge(RHS))
+      return false;
+
+    return std::nullopt;
   }
 
   InlineResult finalizeAnalysis() override {


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