[PGO] Add ability to mark cold functions as optsize/minsize/optnone (#69030)

The performance of cold functions shouldn't matter too much, so if we
care about binary sizes, add an option to mark cold functions as
optsize/minsize for binary size, or optnone for compile times [1]. Clang
patch will be in a future patch.

This is intended to replace `shouldOptimizeForSize(Function&, ...)`.
We've seen multiple cases where calls to this expensive function, if not
careful, can blow up compile times. I will clean up users of that
function in a followup patch.

Initial version: https://reviews.llvm.org/D149800

[1]
https://discourse.llvm.org/t/rfc-new-feature-proposal-de-optimizing-cold-functions-using-pgo-info/56388

1 files changed, 12 insertions, 6 deletions

diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
index e2511aa..a310825 100644
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -748,7 +748,8 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
         CodeGenOpts.InstrProfileOutput.empty() ? getDefaultProfileGenName()
                                                : CodeGenOpts.InstrProfileOutput,
         "", "", CodeGenOpts.MemoryProfileUsePath, nullptr, PGOOptions::IRInstr,
-        PGOOptions::NoCSAction, CodeGenOpts.DebugInfoForProfiling,
+        PGOOptions::NoCSAction, PGOOptions::ColdFuncOpt::Default,
+        CodeGenOpts.DebugInfoForProfiling,
         /*PseudoProbeForProfiling=*/false, CodeGenOpts.AtomicProfileUpdate);
   else if (CodeGenOpts.hasProfileIRUse()) {
     // -fprofile-use.
@@ -757,28 +758,32 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
     PGOOpt = PGOOptions(
         CodeGenOpts.ProfileInstrumentUsePath, "",
         CodeGenOpts.ProfileRemappingFile, CodeGenOpts.MemoryProfileUsePath, VFS,
-        PGOOptions::IRUse, CSAction, CodeGenOpts.DebugInfoForProfiling);
+        PGOOptions::IRUse, CSAction, PGOOptions::ColdFuncOpt::Default,
+        CodeGenOpts.DebugInfoForProfiling);
   } else if (!CodeGenOpts.SampleProfileFile.empty())
     // -fprofile-sample-use
     PGOOpt = PGOOptions(
         CodeGenOpts.SampleProfileFile, "", CodeGenOpts.ProfileRemappingFile,
         CodeGenOpts.MemoryProfileUsePath, VFS, PGOOptions::SampleUse,
-        PGOOptions::NoCSAction, CodeGenOpts.DebugInfoForProfiling,
-        CodeGenOpts.PseudoProbeForProfiling);
+        PGOOptions::NoCSAction, PGOOptions::ColdFuncOpt::Default,
+        CodeGenOpts.DebugInfoForProfiling, CodeGenOpts.PseudoProbeForProfiling);
   else if (!CodeGenOpts.MemoryProfileUsePath.empty())
     // -fmemory-profile-use (without any of the above options)
     PGOOpt = PGOOptions("", "", "", CodeGenOpts.MemoryProfileUsePath, VFS,
                         PGOOptions::NoAction, PGOOptions::NoCSAction,
+                        PGOOptions::ColdFuncOpt::Default,
                         CodeGenOpts.DebugInfoForProfiling);
   else if (CodeGenOpts.PseudoProbeForProfiling)
     // -fpseudo-probe-for-profiling
     PGOOpt = PGOOptions("", "", "", /*MemoryProfile=*/"", nullptr,
                         PGOOptions::NoAction, PGOOptions::NoCSAction,
+                        PGOOptions::ColdFuncOpt::Default,
                         CodeGenOpts.DebugInfoForProfiling, true);
   else if (CodeGenOpts.DebugInfoForProfiling)
     // -fdebug-info-for-profiling
     PGOOpt = PGOOptions("", "", "", /*MemoryProfile=*/"", nullptr,
-                        PGOOptions::NoAction, PGOOptions::NoCSAction, true);
+                        PGOOptions::NoAction, PGOOptions::NoCSAction,
+                        PGOOptions::ColdFuncOpt::Default, true);
 
   // Check to see if we want to generate a CS profile.
   if (CodeGenOpts.hasProfileCSIRInstr()) {
@@ -801,7 +806,8 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
                          ? getDefaultProfileGenName()
                          : CodeGenOpts.InstrProfileOutput,
                      "", /*MemoryProfile=*/"", nullptr, PGOOptions::NoAction,
-                     PGOOptions::CSIRInstr, CodeGenOpts.DebugInfoForProfiling);
+                     PGOOptions::CSIRInstr, PGOOptions::ColdFuncOpt::Default,
+                     CodeGenOpts.DebugInfoForProfiling);
   }
   if (TM)
     TM->setPGOOption(PGOOpt);