Only enable MLGO for ARM64 ThinLTO targets
The MLGO model we embed in the Android Clang is trained on ARM64
ThinLTO artefacts. Applying the model across architectures does not
necessarily translate to performance improvement. Therefore only enable
the optimisation on ARM64 ThinLTO for now.
Test: presubmit
Bug: 293827654
Change-Id: Ie64a65c11191cf700a463637a0746c8470d3aa3c
diff --git a/cc/lto.go b/cc/lto.go
index 20e4f24..fb3b485 100644
--- a/cc/lto.go
+++ b/cc/lto.go
@@ -147,10 +147,15 @@
}
}
- // For ML training
- if ctx.Config().IsEnvTrue("THINLTO_EMIT_INDEXES_AND_IMPORTS") {
- ltoLdFlags = append(ltoLdFlags, "-Wl,--save-temps=import")
- ltoLdFlags = append(ltoLdFlags, "-Wl,--thinlto-emit-index-files")
+ // Register allocation MLGO flags for ARM64.
+ if ctx.Arch().ArchType == android.Arm64 {
+ ltoCFlags = append(ltoCFlags, "-mllvm -regalloc-enable-advisor=release")
+ ltoLdFlags = append(ltoLdFlags, "-Wl,-mllvm,-regalloc-enable-advisor=release")
+ // Flags for training MLGO model.
+ if ctx.Config().IsEnvTrue("THINLTO_EMIT_INDEXES_AND_IMPORTS") {
+ ltoLdFlags = append(ltoLdFlags, "-Wl,--save-temps=import")
+ ltoLdFlags = append(ltoLdFlags, "-Wl,--thinlto-emit-index-files")
+ }
}
flags.Local.CFlags = append(flags.Local.CFlags, ltoCFlags...)