[ARM] Fix recent breakage of -mfpu=none.
The recent change D60691 introduced a bug in clang when handling
option combinations such as `-mcpu=cortex-m4 -mfpu=none`. Those
options together should select Cortex-M4 but disable all use of
hardware FP, but in fact, now hardware FP instructions can still be
generated in that mode.
The reason is because the handling of FPUVersion::NONE disables all
the same feature names it used to, of which the base one is `vfp2`.
But now there are further features below that, like `vfp2d16fp` and
(following D60694) `fpregs`, which also need to be turned off to
disable hardware FP completely.
Added a tiny test which double-checks that compiling a simple FP
function doesn't access the FP registers.
Reviewers: SjoerdMeijer, dmgreen
Reviewed By: dmgreen
Subscribers: lebedev.ri, javed.absar, kristof.beyls, hiraditya, cfe-commits, llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D62729
llvm-svn: 362380
diff --git a/llvm/lib/Support/ARMTargetParser.cpp b/llvm/lib/Support/ARMTargetParser.cpp
index a33f602..8806ea52 100644
--- a/llvm/lib/Support/ARMTargetParser.cpp
+++ b/llvm/lib/Support/ARMTargetParser.cpp
@@ -198,6 +198,7 @@
Features.push_back("-fp-armv8");
break;
case FPUVersion::NONE:
+ Features.push_back("-fpregs");
Features.push_back("-vfp2");
Features.push_back("-vfp3");
Features.push_back("-fp16");