Driver: add -m{,no-}long-calls support
This mirrors the GCC option for the ARM backend. This option enables the
backend option "-enable-arm-long-calls". The default behaviour is that this is
disabled due to the slight overhead of the generated calls.
If the target of jumps are greater than 64M range of offset-based jumps, then
the target address must be loaded into a register to make an indirect jump. The
backend support for this has been present, but was not previously controllable
by the proper flag.
llvm-svn: 210398
diff --git a/clang/lib/Driver/Tools.cpp b/clang/lib/Driver/Tools.cpp
index 0316357..dfbc280 100644
--- a/clang/lib/Driver/Tools.cpp
+++ b/clang/lib/Driver/Tools.cpp
@@ -3469,6 +3469,17 @@
CmdArgs.push_back("-arm-restrict-it");
}
+ if (TT.getArch() == llvm::Triple::arm ||
+ TT.getArch() == llvm::Triple::thumb) {
+ if (Arg *A = Args.getLastArg(options::OPT_mlong_calls,
+ options::OPT_mno_long_calls)) {
+ if (A->getOption().matches(options::OPT_mlong_calls)) {
+ CmdArgs.push_back("-backend-option");
+ CmdArgs.push_back("-enable-arm-long-calls");
+ }
+ }
+ }
+
// Forward -f options with positive and negative forms; we translate
// these by hand.
if (Arg *A = Args.getLastArg(options::OPT_fprofile_sample_use_EQ)) {