Merge clang 7.0.1 and several follow-up changes

MFC r318594:

Add libc++experimental.a for std::experimental support

This adds a separate library for supporting std::experimental features.
It is purposefully static, and must be explicitly linked into programs
using -lc++experimental.

PLEASE NOTE: there is NO WARRANTY as to any stability or continuing
existence of the features in the std::experimental parts of the C++
library!

Reviewed by: ed
Differential Revision: https://reviews.freebsd.org/D10840

MFC r318598:

Add PICFLAG to build libc++experimental.a, so it can be used in all
situations.

Noticed by: kib

r336969 | emaste | 2018-07-31 16:12:09 +0200 (Tue, 31 Jul 2018) | 13 lines

llvm: [ELF][ARM] Add Arm ABI names for float ABI ELF Header flags

The ELF for the Arm architecture document defines, for EF_ARM_EABI_VER5
and above, the flags EF_ARM_ABI_FLOAT_HARD and EF_ARM_ABI_FLOAT_SOFT.
These have been defined to be compatible with the existing
EF_ARM_VFP_FLOAT and EF_ARM_SOFT_FLOAT used by gcc for
EF_ARM_EABI_UNKNOWN.

This patch adds the flags in addition to the existing ones so that any
code depending on the old names will still work.

Obtained from: llvm r338370 by Peter Smith

r336970 | emaste | 2018-07-31 16:14:41 +0200 (Tue, 31 Jul 2018) | 9 lines

llvm: [ARM] Complete enumeration values for Tag_ABI_VFP_args

The LLD implementation of Tag_ABI_VFP_args needs to check the rarely
seen values of 3 (toolchain specific) and 4 compatible with both Base
and VFP. Add the missing enumeration values so that LLD can refer to
them without having to use the raw numbers.

Obtained from: llvm r338373 by Peter Smith

r336972 | emaste | 2018-07-31 17:25:03 +0200 (Tue, 31 Jul 2018) | 37 lines

lld: [ELF][ARM] Implement support for Tag_ABI_VFP_args

The Tag_ABI_VFP_args build attribute controls the procedure call
standard used for floating point parameters on ARM. The values are:

0 - Base AAPCS (FP Parameters passed in Core (Integer) registers
1 - VFP AAPCS (FP Parameters passed in FP registers)
2 - Toolchain specific (Neither Base or VFP)
3 - Compatible with all (No use of floating point parameters)

If the Tag_ABI_VFP_args build attribute is missing it has an implicit
value of 0.

We use the attribute in two ways:

• Detect a clash in calling convention between Base, VFP and Toolchain.

we follow ld.bfd's lead and do not error if there is a clash between an
implicit Base AAPCS caused by a missing attribute. Many projects
including the hard-float (VFP AAPCS) version of glibc contain assembler
files that do not use floating point but do not have Tag_ABI_VFP_args.

• Set the EF_ARM_ABI_FLOAT_SOFT or EF_ARM_ABI_FLOAT_HARD ELF header flag

for Base or VFP AAPCS respectively. This flag is used by some ELF
loaders.

References:

• Addenda to, and Errata in, the ABI for the ARM Architecture for Tag_ABI_VFP_args
• Elf for the ARM Architecture for ELF header flags

Fixes LLVM PR36009

PR: 229050
Obtained from: llvm r338377 by Peter Smith

r337282 | alc | 2018-08-04 04:30:51 +0200 (Sat, 04 Aug 2018) | 7 lines

Set the default image base on arm64 and i386 to a superpage-aligned
address.

Reviewed by: emaste, markj
Discussed with: dim
Differential Revision: https://reviews.freebsd.org/D16385

r339304 | emaste | 2018-10-11 15:19:17 +0200 (Thu, 11 Oct 2018) | 13 lines

lld: set sh_link and sh_info for .rela.plt sections

ELF spec says that for SHT_REL and SHT_RELA sh_link should reference the
associated string table and sh_info should reference the "section to
which the relocation applies." ELF Tool Chain's elfcopy / strip use
this (in part) to control whether or not the relocation entry is copied
to the output.

LLVM PR 37538 https://bugs.llvm.org/show_bug.cgi?id=37538

Approved by: re (kib)
Obtained from: llvm r344226 (backported for 6.0)

MFC r341825:

Upgrade our copies of clang, llvm, lld, lldb, compiler-rt and libc++ to
the upstream release_70 branch r348686 (effectively, 7.0.1 rc3). The
release will follow very soon, but no more functional changes are
expected.

Release notes for llvm, clang and lld 7.0.0 are available here:
http://releases.llvm.org/7.0.0/docs/ReleaseNotes.html
http://releases.llvm.org/7.0.0/tools/clang/docs/ReleaseNotes.html
http://releases.llvm.org/7.0.0/tools/lld/docs/ReleaseNotes.html

PR: 230240, 230355
Relnotes: yes

MFC r342123:

Update clang, llvm, lld, lldb, compiler-rt and libc++ version number to
7.0.1 release r349250. There were no functional changes since the 7.0.1
rc3 import.

PR: 230240, 230355
Relnotes: yes

r343429 | emaste | 2019-01-25 15:46:13 +0100 (Fri, 25 Jan 2019) | 16 lines

clang: default to DWARF 4 as of FreeBSD 13

FreeBSD previously defaulted to DWARF 2 because several tools (gdb,
ctfconvert, etc.) did not support later versions. These have either
been fixed or are deprecated.

Note that gdb 6 still exists but has been moved out of $PATH into
/usr/libexec and is intended only for use by crashinfo(8). The kernel
build sets the DWARF version explicitly via -gdwarf2, so this should
have no effect there.

PR: 234887 [exp-run]
Reviewed by: markj
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D17930

MFC r343916:

Pull in r352607 from upstream llvm trunk (by Craig Topper):

[X86] Add FPSW as a Def on some FP instructions that were missing it.

Pull in r353141 from upstream llvm trunk (by Craig Topper):

[X86] Connect the default fpsr and dirflag clobbers in inline
assembly to the registers we have defined for them.

Summary:
We don't currently map these constraints to physical register numbers
so they don't make it to the MachineIR representation of inline
assembly.

This could have problems for proper dependency tracking in the
machine schedulers though I don't have a test case that shows that.

Reviewers: rnk

Reviewed By: rnk

Subscribers: eraman, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57641

Pull in r353489 from upstream llvm trunk (by Craig Topper):

[X86] Add FPCW as a register and start using it as an implicit use on
floating point instructions.

Summary:
FPCW contains the rounding mode control which we manipulate to
implement fp to integer conversion by changing the roudning mode,
storing the value to the stack, and then changing the rounding mode
back. Because we didn't model FPCW and its dependency chain, other
instructions could be scheduled into the middle of the sequence.

This patch introduces the register and adds it as an implciit def of
FLDCW and implicit use of the FP binary arithmetic instructions and
store instructions. There are more instructions that need to be
updated, but this is a good start. I believe this fixes at least the
reduced test case from PR40529.

Reviewers: RKSimon, spatel, rnk, efriedma, andrew.w.kaylor

Subscribers: dim, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D57735

These should fix a problem in clang 7.0 where it would sometimes emit
long double floating point instructions in a slightly wrong order,
leading to failures in our libm tests. In particular, the cbrt_test
test case 'cbrtl_powl' and the trig_test test case 'reduction'.

Also bump __FreeBSD_cc_version, to be able to detect this in our test
suite.

Reported by: lwhsu
PR: 234040
Upstream PR: https://bugs.llvm.org/show_bug.cgi?id=40206

MFC r344056:

Pull in r339734 from upstream llvm trunk (by Eli Friedman):

[ARM] Make PerformSHLSimplify add nodes to the DAG worklist correctly.

Intentionally excluding nodes from the DAGCombine worklist is likely
to lead to weird optimizations and infinite loops, so it's generally
a bad idea.

To avoid the infinite loops, fix DAGCombine to use the
isDesirableToCommuteWithShift target hook before performing the
transforms in question, and implement the target hook in the ARM
backend disable the transforms in question.

Fixes https://bugs.llvm.org/show_bug.cgi?id=38530 . (I don't have a
reduced testcase for that bug. But we should have sufficient test
coverage for PerformSHLSimplify given that we're not playing weird
tricks with the worklist. I can try to bugpoint it if necessary,
though.)

Differential Revision: https://reviews.llvm.org/D50667

This should fix a possible hang when compiling sys/dev/nxge/if_nxge.c
(which exists now only in the stable/11 branch) for arm.