[llvm] 9d375a4 - Reapply [InlineCost] Enable the cost benefit analysis on FDO

[Kazu Hirata via llvm-commits]

Author: Kazu Hirata
Date: 2021-03-25T21:51:38-07:00
New Revision: 9d375a40c3df90dd48edc0e1b1115c702c55d716

URL: https://github.com/llvm/llvm-project/commit/9d375a40c3df90dd48edc0e1b1115c702c55d716
DIFF: https://github.com/llvm/llvm-project/commit/9d375a40c3df90dd48edc0e1b1115c702c55d716.diff

LOG: Reapply [InlineCost] Enable the cost benefit analysis on FDO

This patch enables the cost-benefit-analysis-based inliner by default
if we have instrumentation profile.

- SPEC CPU 2017 shows a 0.4% improvement.

- An internal large benchmark shows a 0.9% reduction in the cycle
  count along with 14.6% reduction in the number of call instructions
  executed.

Differential Revision: https://reviews.llvm.org/D98213

Added: 
    

Modified: 
    llvm/lib/Analysis/InlineCost.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index 538dfacdaa5b..f4e22d47b98a 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -675,15 +675,22 @@ class InlineCostCallAnalyzer final : public CallAnalyzer {
   }
 
   bool isCostBenefitAnalysisEnabled() {
-    if (!InlineEnableCostBenefitAnalysis)
-      return false;
-
     if (!PSI || !PSI->hasProfileSummary())
       return false;
 
     if (!GetBFI)
       return false;
 
+    if (InlineEnableCostBenefitAnalysis.getNumOccurrences()) {
+      // Honor the explicit request from the user.
+      if (!InlineEnableCostBenefitAnalysis)
+        return false;
+    } else {
+      // Otherwise, require instrumentation profile.
+      if (!PSI->hasInstrumentationProfile())
+        return false;
+    }
+
     auto *Caller = CandidateCall.getParent()->getParent();
     if (!Caller->getEntryCount())
       return false;