[AArch64] Fix PR34625 -mtune without -mcpu should not set -target-cpu
When -mtune is used on AArch64 the -target-cpu is passed the value of the
cpu given to -mtune. As well as setting micro-architectural features of the
-mtune cpu, this will also add the architectural features such as support
for instructions. This can result in the backend using instructions that
are supported in the -mtune cpu but not supported in the target
architecture. For example use of the v8.1-a LSE extensions with -march=v8.
This change removes the setting of -target-cpu for -mtune, the -mcpu must
be used to set -target-cpu. This has the effect of removing all non-hard
coded benefits of mtune but it does produce correct output when -mtune cpu
with a later architecture than v8 is used.
Fixes PR34625
Differential Revision: https://reviews.llvm.org/D39179
llvm-svn: 316424
diff --git a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
index 36186f0..ad04aed 100644
--- a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
@@ -20,14 +20,12 @@
using namespace llvm::opt;
/// getAArch64TargetCPU - Get the (LLVM) name of the AArch64 cpu we are
-/// targeting. Set \p A to the Arg corresponding to the -mcpu or -mtune
-/// arguments if they are provided, or to nullptr otherwise.
+/// targeting. Set \p A to the Arg corresponding to the -mcpu argument if it is
+/// provided, or to nullptr otherwise.
std::string aarch64::getAArch64TargetCPU(const ArgList &Args, Arg *&A) {
std::string CPU;
- // If we have -mtune or -mcpu, use that.
- if ((A = Args.getLastArg(clang::driver::options::OPT_mtune_EQ))) {
- CPU = StringRef(A->getValue()).lower();
- } else if ((A = Args.getLastArg(options::OPT_mcpu_EQ))) {
+ // If we have -mcpu, use that.
+ if ((A = Args.getLastArg(options::OPT_mcpu_EQ))) {
StringRef Mcpu = A->getValue();
CPU = Mcpu.split("+").first.lower();
}
@@ -122,6 +120,12 @@
const ArgList &Args,
std::vector<StringRef> &Features) {
std::string MtuneLowerCase = Mtune.lower();
+ // Check CPU name is valid
+ std::vector<StringRef> MtuneFeatures;
+ StringRef Tune;
+ if (!DecodeAArch64Mcpu(D, MtuneLowerCase, Tune, MtuneFeatures))
+ return false;
+
// Handle CPU name is 'native'.
if (MtuneLowerCase == "native")
MtuneLowerCase = llvm::sys::getHostCPUName();