[llvm] r291487 - Refactor inline threshold update code.

[Easwaran Raman via llvm-commits]

Author: eraman
Date: Mon Jan  9 15:56:26 2017
New Revision: 291487

URL: http://llvm.org/viewvc/llvm-project?rev=291487&view=rev
Log:
Refactor inline threshold update code.

Functional change: Previously, if a callee is cold, we used ColdThreshold if it minimizes the existing threshold. This was irrespective of whether we were optimizing for minsize (-Oz) or not. But -Oz uses very low threshold to begin with and the inlining with -Oz is expected to be tuned for lowering code size, so there is no good reason to set an even lower threshold for cold callees. We now lower the threshold for cold callees only when -Oz is not used. For default values of -inlinethreshold and -inlinecold-threshold, this change has no effect and this simplifies the code.

NFC changes: Group all threshold updates that are guarded by !Caller->optForMinSize() and within that group threshold updates that require profile summary info.

Differential revision: https://reviews.llvm.org/D28369


Modified:
    llvm/trunk/lib/Analysis/InlineCost.cpp

Modified: llvm/trunk/lib/Analysis/InlineCost.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Analysis/InlineCost.cpp?rev=291487&r1=291486&r2=291487&view=diff
==============================================================================
--- llvm/trunk/lib/Analysis/InlineCost.cpp (original)
+++ llvm/trunk/lib/Analysis/InlineCost.cpp Mon Jan  9 15:56:26 2017
@@ -636,30 +636,27 @@ void CallAnalyzer::updateThreshold(CallS
   else if (Caller->optForSize())
     Threshold = MinIfValid(Threshold, Params.OptSizeThreshold);
 
-  bool HotCallsite = false;
-  uint64_t TotalWeight;
-  if (PSI && CS.getInstruction()->extractProfTotalWeight(TotalWeight) &&
-      PSI->isHotCount(TotalWeight)) {
-    HotCallsite = true;
+  // Adjust the threshold based on inlinehint attribute and profile based
+  // hotness information if the caller does not have MinSize attribute.
+  if (!Caller->optForMinSize()) {
+    if (Callee.hasFnAttribute(Attribute::InlineHint))
+      Threshold = MaxIfValid(Threshold, Params.HintThreshold);
+    if (PSI) {
+      uint64_t TotalWeight;
+      if (CS.getInstruction()->extractProfTotalWeight(TotalWeight) &&
+          PSI->isHotCount(TotalWeight)) {
+        Threshold = MaxIfValid(Threshold, Params.HotCallSiteThreshold);
+      } else if (PSI->isFunctionEntryHot(&Callee)) {
+        // If callsite hotness can not be determined, we may still know
+        // that the callee is hot and treat it as a weaker hint for threshold
+        // increase.
+        Threshold = MaxIfValid(Threshold, Params.HintThreshold);
+      } else if (PSI->isFunctionEntryCold(&Callee)) {
+        Threshold = MinIfValid(Threshold, Params.ColdThreshold);
+      }
+    }
   }
 
-  // Listen to the inlinehint attribute or profile based hotness information
-  // when it would increase the threshold and the caller does not need to
-  // minimize its size.
-  bool InlineHint = Callee.hasFnAttribute(Attribute::InlineHint) ||
-                    (PSI && PSI->isFunctionEntryHot(&Callee));
-  if (InlineHint && !Caller->optForMinSize())
-    Threshold = MaxIfValid(Threshold, Params.HintThreshold);
-
-  if (HotCallsite && !Caller->optForMinSize())
-    Threshold = MaxIfValid(Threshold, Params.HotCallSiteThreshold);
-
-  bool ColdCallee = PSI && PSI->isFunctionEntryCold(&Callee);
-  // For cold callees, use the ColdThreshold knob if it is available and reduces
-  // the threshold.
-  if (ColdCallee)
-    Threshold = MinIfValid(Threshold, Params.ColdThreshold);
-
   // Finally, take the target-specific inlining threshold multiplier into
   // account.
   Threshold *= TTI.getInliningThresholdMultiplier();