Change D60691 caused some knock-on failures that weren't caught by the
existing tests. Firstly, selecting a CPU that should have had a
restricted FPU (e.g. -mcpu=cortex-m4, which should have 16 d-regs
and no double precision) could give the unrestricted version, because
ARM::getFPUFeatures returned a list of features including subtracted
ones (here -fp64,-d32), but ARMTargetInfo::initFeatureMap threw
away all the ones that didn't start with +. Secondly, the
preprocessor macros didn't reliably match the actual compilation
settings: for example, -mfpu=softvfp could still set __ARM_FP as
if hardware FP was available, because the list of features on the cc1
command line would include things like +vfp4,-vfp4d16 and clang
didn't realise that one of those cancelled out the other.
I've fixed both of these issues by rewriting ARM::getFPUFeatures so
that it returns a list that enables every FP-related feature
compatible with the selected FPU and disables every feature not
compatible, which is more verbose but means clang doesn't have to
understand the dependency relationships between the backend features.
Meanwhile, ARMTargetInfo::handleTargetFeatures is testing for all
the various forms of the FP feature names, so that it won't miss cases
where it should have set HW_FP to feed into feature test macros.
That in turn caused an ordering problem when handling -mcpu=foo+bar
together with -mfpu=something_that_turns_off_bar. To fix that, I've
arranged that the +bar suffixes on the end of -mcpu and -march
cause feature names to be put into a separate vector which is
concatenated after the output of getFPUFeatures.
Another side effect of all this is to fix a bug where `clang -target
armv8-eabi` by itself would fail to set __ARM_FEATURE_FMA, even
though armv8 (aka Arm v8-A) implies FP-Armv8 which has FMA. That was
because HW_FP was being set to a value including only the FPARMV8
bit, but that feature test macro was testing only the VFP4FPU bit.
Now HW_FP ends up with all the bits set, so it gives the right
Changes to tests included in this patch:
- arm-target-features.c: I had to change basically all the expected results. (The Cortex-M4 test in there should function as a regression test for the accidental double-precision bug.)
- arm-mfpu.c, armv8.1m.main.c: switched to using CHECK-DAG everywhere so that those tests are no longer sensitive to the order of cc1 feature options on the command line.
- arm-acle-6.5.c: been updated to expect the right answer to that FMA test.
- Preprocessor/arm-target-features.c: added a regression test for the mfpu=softvfp issue.