[BOLT] Always run CheckLargeFunctions in non-relocation mode (#80922)

We run CheckLargeFunctions pass in non-relocation mode to prevent the
emission of functions that later could not be written to the output due
to their large size. The main reason behind the pass is to prevent the
emission of metadata for such functions since this metadata becomes
incorrect if the function is left unmodified.

Currently, the pass is enabled in non-relocation mode only when debug
info output is also enabled. As we emit increasingly more kinds of
metadata, e.g. for the Linux kernel, it becomes more challenging to
track metadata that needs to be fixed. Hence, I'm enabling the pass to
always run in non-relocation mode.

Author: maksfb

bolt/lib/Passes/BinaryPasses.cpp

@@ -554,11 +554,8 @@ void CheckLargeFunctions::runOnFunctions(BinaryContext &BC) {
   if (BC.HasRelocations)
     return;
 
-  if (!opts::UpdateDebugSections)
-    return;
-
   // If the function wouldn't fit, mark it as non-simple. Otherwise, we may emit
-  // incorrect debug info.
+  // incorrect meta data.
   ParallelUtilities::WorkFuncTy WorkFun = [&](BinaryFunction &BF) {
     uint64_t HotSize, ColdSize;
     std::tie(HotSize, ColdSize) =

bolt/lib/Rewrite/RewriteInstance.cpp

@@ -3631,6 +3631,7 @@ void RewriteInstance::mapCodeSections(BOLTLinker::SectionMapper MapSection) {
     Function.setImageAddress(FuncSection->getAllocAddress());
     Function.setImageSize(FuncSection->getOutputSize());
     if (Function.getImageSize() > Function.getMaxSize()) {
+      assert(!BC->isX86() && "Unexpected large function.");
       TooLarge = true;
       FailedAddresses.emplace_back(Function.getAddress());
     }
@@ -5367,6 +5368,7 @@ void RewriteInstance::rewriteFile() {
       continue;
 
     if (Function->getImageSize() > Function->getMaxSize()) {
+      assert(!BC->isX86() && "Unexpected large function.");
       if (opts::Verbosity >= 1)
         errs() << "BOLT-WARNING: new function size (0x"
                << Twine::utohexstr(Function->getImageSize())