Prevent clang from using the x18 register on arm64.
This is achieved via the compiler flag -ffixed-x18 for non-LTO builds
and the linker flag -plugin-opt -mattr=+reserve-x18 for LTO builds.
This change should be reverted once we upgrade past LLVM r340889
which does this by default on Android.
Bug: 112907825
Bug: 111759196
Change-Id: I05473ddbb98319d87d442425b4d715647eae3a38
diff --git a/cc/lto.go b/cc/lto.go
index 52b9a34..d9d2662 100644
--- a/cc/lto.go
+++ b/cc/lto.go
@@ -113,6 +113,13 @@
flags.LdFlags = append(flags.LdFlags, "-Wl,-plugin-opt,-inline-threshold=0")
flags.LdFlags = append(flags.LdFlags, "-Wl,-plugin-opt,-unroll-threshold=0")
}
+
+ if ctx.Arch().ArchType == android.Arm64 {
+ // Prevent use of x18 register on arm64.
+ // TODO(pcc): Remove this flag once we upgrade past LLVM r340889
+ // which does this by default on Android.
+ flags.LdFlags = append(flags.LdFlags, "-Wl,-plugin-opt,-mattr=+reserve-x18")
+ }
}
return flags
}