[InlineCost] cleanup calculations of Cost and Threshold

Summary:
Doing better separation of Cost and Threshold.
Cost counts the abstract complexity of live instructions, while Threshold is an upper bound of complexity that inlining is comfortable to pay.
There are two parts:
     - huge 15K last-call-to-static bonus is no longer subtracted from Cost
       but rather is now added to Threshold.

       That makes much more sense, as the cost of inlining (Cost) is not changed by the fact
       that internal function is called once. It only changes the likelyhood of this inlining
       being profitable (Threshold).

     - bonus for calls proved-to-be-inlinable into callee is no longer subtracted from Cost
       but added to Threshold instead.

While calculations are somewhat different,  overall InlineResult should stay the same since Cost >= Threshold compares the same.

Reviewers: eraman, greened, chandlerc, yrouban, apilipenko
Reviewed By: apilipenko
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D60740

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@364422 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Analysis/InlineCost.cpp b/lib/Analysis/InlineCost.cpp
index 3cb56f8cccf59c7184f3be7b3a60e1969df2c7fb..b7b58d8aca3aebf25aca703cadf37dcdd1c70139 100644 (file)
--- a/lib/Analysis/InlineCost.cpp
+++ b/lib/Analysis/InlineCost.cpp
@@ -897,7 +897,15 @@ void CallAnalyzer::updateThreshold(CallBase &Call, Function &Callee) {
   // and the callsite.
   int SingleBBBonusPercent = 50;
   int VectorBonusPercent = 150;
-  int LastCallToStaticBonus = InlineConstants::LastCallToStaticBonus;
+
+  int LastCallToStaticBonus = 0;
+  bool OnlyOneCallAndLocalLinkage =
+      F.hasLocalLinkage() && F.hasOneUse() && &F == Call.getCalledFunction();
+  // If there is only one call of the function, and it has internal linkage,
+  // we can allow to inline pretty anything as it will lead to size reduction
+  // anyway.
+  if (OnlyOneCallAndLocalLinkage)
+    LastCallToStaticBonus = InlineConstants::LastCallToStaticBonus;
 
   // Lambda to set all the above bonus and bonus percentages to 0.
   auto DisallowAllBonuses = [&]() {
@@ -970,20 +978,13 @@ void CallAnalyzer::updateThreshold(CallBase &Call, Function &Callee) {
     }
   }
 
-  // Finally, take the target-specific inlining threshold multiplier into
-  // account.
+  // Take the target-specific inlining threshold multiplier into account.
   Threshold *= TTI.getInliningThresholdMultiplier();
 
   SingleBBBonus = Threshold * SingleBBBonusPercent / 100;
   VectorBonus = Threshold * VectorBonusPercent / 100;
 
-  bool OnlyOneCallAndLocalLinkage =
-      F.hasLocalLinkage() && F.hasOneUse() && &F == Call.getCalledFunction();
-  // If there is only one call of the function, and it has internal linkage,
-  // the cost of inlining it drops dramatically. It may seem odd to update
-  // Cost in updateThreshold, but the bonus depends on the logic in this method.
-  if (OnlyOneCallAndLocalLinkage)
-    Cost -= LastCallToStaticBonus;
+  Threshold += LastCallToStaticBonus;
 }
 
 bool CallAnalyzer::visitCmpInst(CmpInst &I) {
@@ -1330,9 +1331,10 @@ bool CallAnalyzer::visitCallBase(CallBase &Call) {
   CallAnalyzer CA(TTI, GetAssumptionCache, GetBFI, PSI, ORE, *F, Call,
                   IndirectCallParams);
   if (CA.analyzeCall(Call)) {
-    // We were able to inline the indirect call! Subtract the cost from the
-    // threshold to get the bonus we want to apply, but don't go below zero.
-    Cost -= std::max(0, CA.getThreshold() - CA.getCost());
+    // We were able to inline the indirect call! Increase the threshold
+    // with the bonus we want to apply (less the cost of inlinee).
+    // Make sure the bonus doesn't go below zero.
+    Threshold += std::max(0, CA.getThreshold() - CA.getCost());
   }
 
   if (!F->onlyReadsMemory())

diff --git a/test/LTO/Resolution/X86/diagnostic-handler-remarks-with-hotness.ll b/test/LTO/Resolution/X86/diagnostic-handler-remarks-with-hotness.ll
index 9932f527dc602a485a5ca923b149ba5d2d410592..6b5a338e412ef0fa9ad8ccda779ef5c152eee25e 100644 (file)
--- a/test/LTO/Resolution/X86/diagnostic-handler-remarks-with-hotness.ll
+++ b/test/LTO/Resolution/X86/diagnostic-handler-remarks-with-hotness.ll
@@ -27,13 +27,13 @@
 ; YAML-NEXT:   - Caller:          main
 ; YAML-NEXT:   - String:          ' with '
 ; YAML-NEXT:   - String:          '(cost='
-; YAML-NEXT:   - Cost:            '-15000'
+; YAML-NEXT:   - Cost:            '0'
 ; YAML-NEXT:   - String:          ', threshold='
-; YAML-NEXT:   - Threshold:       '337'
+; YAML-NEXT:   - Threshold:       '15337'
 ; YAML-NEXT:   - String:          ')'
 ; YAML-NEXT: ...
 
-; CHECK: tinkywinky inlined into main with (cost=-15000, threshold=337) (hotness: 300)
+; CHECK: tinkywinky inlined into main with (cost=0, threshold=15337) (hotness: 300)
 
 target datalayout = "e-m:e-i64:64-f80:128-n8:16:32:64-S128"
 target triple = "x86_64-scei-ps4"

diff --git a/test/LTO/Resolution/X86/diagnostic-handler-remarks.ll b/test/LTO/Resolution/X86/diagnostic-handler-remarks.ll
index beb0f4fa49b8663364e3457f744828dd5ef173ec..72f10235a81f261df7926d506933e82f92bfcdb4 100644 (file)
--- a/test/LTO/Resolution/X86/diagnostic-handler-remarks.ll
+++ b/test/LTO/Resolution/X86/diagnostic-handler-remarks.ll
@@ -30,9 +30,9 @@
 ; YAML-NEXT:   - Caller:          main
 ; YAML-NEXT:   - String:          ' with '
 ; YAML-NEXT:   - String:          '(cost='
-; YAML-NEXT:   - Cost:            '-15000'
+; YAML-NEXT:   - Cost:            '0'
 ; YAML-NEXT:   - String:          ', threshold='
-; YAML-NEXT:   - Threshold:       '337'
+; YAML-NEXT:   - Threshold:       '15337'
 ; YAML-NEXT:   - String:          ')'
 ; YAML-NEXT: ...
 

diff --git a/test/LTO/X86/diagnostic-handler-remarks-with-hotness.ll b/test/LTO/X86/diagnostic-handler-remarks-with-hotness.ll
index d1dddf1a71f01778b5bec260462b1264b0ecf69b..ab4003d0e09b5c6d6f77eda31ea60ec6e0d6888d 100644 (file)
--- a/test/LTO/X86/diagnostic-handler-remarks-with-hotness.ll
+++ b/test/LTO/X86/diagnostic-handler-remarks-with-hotness.ll
@@ -19,9 +19,9 @@
 ; YAML-NEXT:   - Caller:          main
 ; YAML-NEXT:   - String:          ' with '
 ; YAML-NEXT:   - String:          '(cost='
-; YAML-NEXT:   - Cost:            '-15000'
+; YAML-NEXT:   - Cost:            '0'
 ; YAML-NEXT:   - String:          ', threshold='
-; YAML-NEXT:   - Threshold:       '337'
+; YAML-NEXT:   - Threshold:       '15337'
 ; YAML-NEXT:   - String:          ')'
 ; YAML-NEXT: ...
 

diff --git a/test/LTO/X86/diagnostic-handler-remarks.ll b/test/LTO/X86/diagnostic-handler-remarks.ll
index 94f88ec43c5c71ffc83c9804c8c92d4c3c8834f9..dd4086fb58793d0ae55fcfc7bcdf6e428001fac6 100644 (file)
--- a/test/LTO/X86/diagnostic-handler-remarks.ll
+++ b/test/LTO/X86/diagnostic-handler-remarks.ll
@@ -55,9 +55,9 @@
 ; YAML-NEXT:   - Caller:          main
 ; YAML-NEXT:   - String:          ' with '
 ; YAML-NEXT:   - String:          '(cost='
-; YAML-NEXT:   - Cost:            '-15000'
+; YAML-NEXT:   - Cost:            '0'
 ; YAML-NEXT:   - String:          ', threshold='
-; YAML-NEXT:   - Threshold:       '337'
+; YAML-NEXT:   - Threshold:       '15337'
 ; YAML-NEXT:   - String:          ')'
 ; YAML-NEXT: ...
 

diff --git a/test/Transforms/Inline/ARM/inline-fp.ll b/test/Transforms/Inline/ARM/inline-fp.ll
index 1d74dfd15b187a790bf10129e315e197bf73ca4d..a8e486eb0a538a6abe22cbda550eec4d0bc1281e 100644 (file)
--- a/test/Transforms/Inline/ARM/inline-fp.ll
+++ b/test/Transforms/Inline/ARM/inline-fp.ll
@@ -7,7 +7,7 @@
 ; NOFP-DAG: single not inlined into test_single because too costly to inline (cost=125, threshold=75)
 ; NOFP-DAG: single not inlined into test_single because too costly to inline (cost=125, threshold=75)
 ; NOFP-DAG: single_cheap inlined into test_single_cheap with (cost=-15, threshold=75)
-; NOFP-DAG: single_cheap inlined into test_single_cheap with (cost=-15015, threshold=75)
+; NOFP-DAG: single_cheap inlined into test_single_cheap with (cost=-15, threshold=15075)
 ; NOFP-DAG: double not inlined into test_double because too costly to inline (cost=125, threshold=75)
 ; NOFP-DAG: double not inlined into test_double because too costly to inline (cost=125, threshold=75)
 ; NOFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125, threshold=75)
@@ -16,20 +16,20 @@
 ; NOFP-DAG: single_force_soft_fneg not inlined into test_single_force_soft_fneg because too costly to inline (cost=100, threshold=75)
 
 ; FULLFP-DAG: single inlined into test_single with (cost=0, threshold=75)
-; FULLFP-DAG: single inlined into test_single with (cost=-15000, threshold=75)
+; FULLFP-DAG: single inlined into test_single with (cost=0, threshold=15075)
 ; FULLFP-DAG: single_cheap inlined into test_single_cheap with (cost=-15, threshold=75)
-; FULLFP-DAG: single_cheap inlined into test_single_cheap with (cost=-15015, threshold=75)
+; FULLFP-DAG: single_cheap inlined into test_single_cheap with (cost=-15, threshold=15075)
 ; FULLFP-DAG: double inlined into test_double with (cost=0, threshold=75)
-; FULLFP-DAG: double inlined into test_double with (cost=-15000, threshold=75)
+; FULLFP-DAG: double inlined into test_double with (cost=0, threshold=15075)
 ; FULLFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125, threshold=75)
 ; FULLFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125, threshold=75)
 ; FULLFP-DAG: single_force_soft_fneg not inlined into test_single_force_soft_fneg because too costly to inline (cost=100, threshold=75)
 ; FULLFP-DAG: single_force_soft_fneg not inlined into test_single_force_soft_fneg because too costly to inline (cost=100, threshold=75)
 
 ; SINGLEFP-DAG: single inlined into test_single with (cost=0, threshold=75)
-; SINGLEFP-DAG: single inlined into test_single with (cost=-15000, threshold=75)
+; SINGLEFP-DAG: single inlined into test_single with (cost=0, threshold=15075)
 ; SINGLEFP-DAG: single_cheap inlined into test_single_cheap with (cost=-15, threshold=75)
-; SINGLEFP-DAG: single_cheap inlined into test_single_cheap with (cost=-15015, threshold=75)
+; SINGLEFP-DAG: single_cheap inlined into test_single_cheap with (cost=-15, threshold=15075)
 ; SINGLEFP-DAG: double not inlined into test_double because too costly to inline (cost=125, threshold=75)
 ; SINGLEFP-DAG: double not inlined into test_double because too costly to inline (cost=125, threshold=75)
 ; SINGLEFP-DAG: single_force_soft not inlined into test_single_force_soft because too costly to inline (cost=125, threshold=75)