/volatileMetadata (Generate metadata on volatile memory accesses)
Generate metadata for volatile memory accesses to improve performance when running x64 code on ARM64.
Syntax
/volatileMetadata[-]
Arguments
-
Turns off /volatileMetadata. This may result in worse performance when your code runs in emulation mode on ARM64 because the emulator pessimistically assumes that every load/store needs a barrier.
Remarks
Starting with Visual Studio 2019 16.10, /volatileMetadata is on by default when generating x64 code. It improves the emulation performance of x64 code on ARM64 by generating metadata that identifies volatile memory addresses. An emulator can use this metadata to improve performance by not using acquire/release semantics on those accesses it knows aren't volatile. Without this metadata, the emulator assumes that all addresses are volatile and uses acquire and release semantics.
One side effect of /volatileMetadata is you may see npad macros used in the generated code. This macro expands to a specified number of NOP instructions that create an address to associate with a memory barrier. That address is then recorded in the metadata to indicate that acquire/release semantics should be used to access it.
/volatileMetadata is ignored when targeting x86.
/volatileMetadata can be disabled by using /volatileMetadata-.
Requirements
Visual Studio 2019 version 16.10 or later.