[PGO][PGSO] Temporarily disable the large working set size behavior.

[hjyamauchi]

Summary

This temporarily disables the large working set size behavior in profile guided
size optimization due to internal benchmark regressions.

[davidxl]

lgtm

llvm/include/llvm/Transforms/Utils/SizeOpts.h

 #include "llvm/Analysis/BlockFrequencyInfo.h"
 #include "llvm/Analysis/ProfileSummaryInfo.h"
 #include "llvm/Support/CommandLine.h"
 
 using namespace llvm;
 
 extern cl::opt<bool> EnablePGSO;
 extern cl::opt<bool> PGSOLargeWorkingSetSizeOnly;
+extern cl::opt<bool> PGSOColdCodeOnly;
 extern cl::opt<bool> ForcePGSO;
 extern cl::opt<int> PgsoCutoffInstrProf;
 extern cl::opt<int> PgsoCutoffSampleProf;
 
 namespace llvm {
 
 class BasicBlock;
 class BlockFrequencyInfo;
 class Function;
 class ProfileSummaryInfo;
 
 template<typename AdapterT, typename FuncT, typename BFIT>
 bool shouldFuncOptimizeForSizeImpl(const FuncT *F, ProfileSummaryInfo *PSI,
                                    BFIT *BFI) {
   assert(F);
   if (!PSI || !BFI || !PSI->hasProfileSummary())
     return false;
   if (ForcePGSO)
     return true;
   if (!EnablePGSO)
     return false;
-  if (PGSOLargeWorkingSetSizeOnly && !PSI->hasLargeWorkingSetSize()) {
+  if (PGSOColdCodeOnly ||
+      (PGSOLargeWorkingSetSizeOnly && !PSI->hasLargeWorkingSetSize())) {
     // Even if the working set size isn't large, size-optimize cold code.
     return AdapterT::isFunctionColdInCallGraph(F, PSI, *BFI);
   }
   return !AdapterT::isFunctionHotInCallGraphNthPercentile(
       PSI->hasSampleProfile() ? PgsoCutoffSampleProf : PgsoCutoffInstrProf,
       F, PSI, *BFI);
 }
 
 template<typename AdapterT, typename BlockT, typename BFIT>
 bool shouldOptimizeForSizeImpl(const BlockT *BB, ProfileSummaryInfo *PSI,
                                BFIT *BFI) {
   assert(BB);
   if (!PSI || !BFI || !PSI->hasProfileSummary())
     return false;
   if (ForcePGSO)
     return true;
   if (!EnablePGSO)
     return false;
-  if (PGSOLargeWorkingSetSizeOnly && !PSI->hasLargeWorkingSetSize()) {
+  if (PGSOColdCodeOnly ||
+      (PGSOLargeWorkingSetSizeOnly && !PSI->hasLargeWorkingSetSize())) {
     // Even if the working set size isn't large, size-optimize cold code.
     return AdapterT::isColdBlock(BB, PSI, BFI);
   }
   return !AdapterT::isHotBlockNthPercentile(
       PSI->hasSampleProfile() ? PgsoCutoffSampleProf : PgsoCutoffInstrProf,
       BB, PSI, BFI);
 }
 

llvm/lib/Transforms/Utils/SizeOpts.cpp

cl::opt<bool> EnablePGSO(
     "pgso", cl::Hidden, cl::init(true),
     cl::desc("Enable the profile guided size optimizations. "));
 
 cl::opt<bool> PGSOLargeWorkingSetSizeOnly(
     "pgso-lwss-only", cl::Hidden, cl::init(true),
     cl::desc("Apply the profile guided size optimizations only "
              "if the working set size is large (except for cold code.)"));
 
+cl::opt<bool> PGSOColdCodeOnly(
+    "pgso-cold-code-only", cl::Hidden, cl::init(true),
+    cl::desc("Apply the profile guided size optimizations only "
+             "to cold code."));
+
 cl::opt<bool> ForcePGSO(
     "force-pgso", cl::Hidden, cl::init(false),
     cl::desc("Force the (profiled-guided) size optimizations. "));
 
 cl::opt<int> PgsoCutoffInstrProf(
     "pgso-cutoff-instr-prof", cl::Hidden, cl::init(250000), cl::ZeroOrMore,
     cl::desc("The profile guided size optimization profile summary cutoff "
              "for instrumentation profile."));