This patch mechanically replaces None with std::nullopt where the
compiler would warn if None were deprecated. The intent is to reduce
the amount of manual work required in migrating from Optional to
std::optional.
This is part of an effort to migrate from llvm::Optional to
std::optional:
https://discourse.llvm.org/t/deprecating-llvm-optional-x-hasvalue-getvalue-getvalueor/63716
Most notably, Pass.h is no longer included by TargetMachine.h
before: 1063570306
after: 1063332844
Differential Revision: https://reviews.llvm.org/D121168
Delay reading global metadata until the first function or the end of
the file is emitted. That way, earlier module passes can set metadata
that is emitted in the ELF.
`emitStartOfAsmFile` gets called when the passes are initialized,
which prevented earlier passes from changing the metadata.
This fixes issues encountered after converting
AMDGPUResourceUsageAnalysis to a Module pass in D117504.
Differential Revision: https://reviews.llvm.org/D118492
Kazu Hirata