This both reapplies #118734, the initial attempt at this, and updates it
significantly.
First, it uses the newly added `StringTable` abstraction for string
tables, and simplifies the construction to build the string table and
info arrays separately. This should reduce any `constexpr` compile time
memory or CPU cost of the original PR while significantly improving the
APIs throughout.
It also restructures the builtins to support sharding across several
independent tables. This accomplishes two improvements from the
original PR:
1) It improves the APIs used significantly.
2) When builtins are defined from different sources (like SVE vs MVE in
AArch64), this allows each of them to build their own string table
independently rather than having to merge the string tables and info
structures.
3) It allows each shard to factor out a common prefix, often cutting the
size of the strings needed for the builtins by a factor two.
The second point is important both to allow different mechanisms of
construction (for example a `.def` file and a tablegen'ed `.inc` file,
or different tablegen'ed `.inc files), it also simply reduces the sizes
of these tables which is valuable given how large they are in some
cases. The third builds on that size reduction.
Initially, we use this new sharding rather than merging tables in
AArch64, LoongArch, RISCV, and X86. Mostly this helps ensure the system
works, as without further changes these still push scaling limits.
Subsequent commits will more deeply leverage the new structure,
including using the prefix capabilities which cannot be easily factored
out here and requires deep changes to the targets.
Reverts llvm/llvm-project#118734
There are currently some specific versions of MSVC that are miscompiling
this code (we think). We don't know why as all the other build bots and
at least some folks' local Windows builds work fine.
This is a candidate revert to help the relevant folks catch their
builders up and have time to debug the issue. However, the expectation
is to roll forward at some point with a workaround if at all possible.
The Clang binary (and any binary linking Clang as a library), when built
using PIE, ends up with a pretty shocking number of dynamic relocations
to apply to the executable image: roughly 400k.
Each of these takes up binary space in the executable, and perhaps most
interestingly takes start-up time to apply the relocations.
The largest pattern I identified were the strings used to describe
target builtins. The addresses of these string literals were stored into
huge arrays, each one requiring a dynamic relocation. The way to avoid
this is to design the target builtins to use a single large table of
strings and offsets within the table for the individual strings. This
switches the builtin management to such a scheme.
This saves over 100k dynamic relocations by my measurement, an over 25%
reduction. Just looking at byte size improvements, using the `bloaty`
tool to compare a newly built `clang` binary to an old one:
```
FILE SIZE VM SIZE
-------------- --------------
+1.4% +653Ki +1.4% +653Ki .rodata
+0.0% +960 +0.0% +960 .text
+0.0% +197 +0.0% +197 .dynstr
+0.0% +184 +0.0% +184 .eh_frame
+0.0% +96 +0.0% +96 .dynsym
+0.0% +40 +0.0% +40 .eh_frame_hdr
+114% +32 [ = ] 0 [Unmapped]
+0.0% +20 +0.0% +20 .gnu.hash
+0.0% +8 +0.0% +8 .gnu.version
+0.9% +7 +0.9% +7 [LOAD #2 [R]]
[ = ] 0 -75.4% -3.00Ki .relro_padding
-16.1% -802Ki -16.1% -802Ki .data.rel.ro
-27.3% -2.52Mi -27.3% -2.52Mi .rela.dyn
-1.6% -2.66Mi -1.6% -2.66Mi TOTAL
```
We get a 16% reduction in the `.data.rel.ro` section, and nearly 30%
reduction in `.rela.dyn` where those reloctaions are stored.
This is also visible in my benchmarking of binary start-up overhead at
least:
```
Benchmark 1: ./old_clang --version
Time (mean ± σ): 17.6 ms ± 1.5 ms [User: 4.1 ms, System: 13.3 ms]
Range (min … max): 14.2 ms … 22.8 ms 162 runs
Benchmark 2: ./new_clang --version
Time (mean ± σ): 15.5 ms ± 1.4 ms [User: 3.6 ms, System: 11.8 ms]
Range (min … max): 12.4 ms … 20.3 ms 216 runs
Summary
'./new_clang --version' ran
1.13 ± 0.14 times faster than './old_clang --version'
```
We get about 2ms faster `--version` runs. While there is a lot of noise
in binary execution time, this delta is pretty consistent, and
represents over 10% improvement. This is particularly interesting to me
because for very short source files, repeatedly starting the `clang`
binary is actually the dominant cost. For example, `configure` scripts
running against the `clang` compiler are slow in large part because of
binary start up time, not the time to process the actual inputs to the
compiler.
----
This PR implements the string tables using `constexpr` code and the
existing macro system. I understand that the builtins are moving towards
a TableGen model, and if complete that would provide more options for
modeling this. Unfortunately, that migration isn't complete, and even
the parts that are migrated still rely on the ability to break out of
the TableGen model and directly expand an X-macro style `BUILTIN(...)`
textually. I looked at trying to complete the move to TableGen, but it
would both require the difficult migration of the remaining targets, and
solving some tricky problems with how to move away from any macro-based
expansion.
I was also able to find a reasonably clean and effective way of doing
this with the existing macros and some `constexpr` code that I think is
clean enough to be a pretty good intermediate state, and maybe give a
good target for the eventual TableGen solution. I was also able to
factor the macros into set of consistent patterns that avoids a
significant regression in overall boilerplate.
We emit an error when -msoft-float and -maltivec/-mvsx is used together,
but when -msoft-float is used on its own, there is still +altivec and
+vsx in the IR attributes. This patch disables altivec and vsx and all
related sub features when -msoft-float is used.
Implement BCD assist builtins for XL and GCC compatibility.
GCC compat:
```
unsigned int __builtin_cdtbcd (unsigned int);
unsigned int __builtin_cbcdtd (unsigned int);
unsigned int __builtin_addg6s (unsigned int, unsigned int);
```
64BIT XL compat:
```
long long __cdtbcd (long long);
long long __cbcdtd (long long);
long long __addg6s (long long source1, long long source2)
```
For now only focus on the CPU type, will work on the CPU features part
later.
With the CPU handling in TargetParser, clang and llc/opt are able to
query common interfaces.
So we can set same default CPU and CPU features with same interfaces.
musttail is not often possible to be generated on PPC targets as when
calling to a function defined in another module, PPC needs to restore
the TOC pointer. To restore the TOC pointer, compiler needs to emit a
nop after the call to let linker generate codes to restore TOC pointer.
Tail call cannot generate expected call sequence for this case.
To avoid the crash inside the compiler backend, a diagnosis is added in
the frontend.
Fixes#63214
Under some circumstance (library loaded with the main program), TLS
initial-exec model can be applied to local-dynamic access(es). We
could use some simple heuristic to decide the update at function level:
* If there is equal or less than a number of TLS local-dynamic access(es)
in the function, use TLS initial-exec model. (the threshold which default to
1 is controlled by hidden option)
The PR implements a subset of features of function
__builtin_cpu_support() for AIX OS based on the information which AIX
kernel runtime variable `_system_configuration` and function call `getsystemcfg()` of
/usr/include/sys/systemcfg.h in AIX OS can provide.
Following subset of features are supported in the PR
"arch_3_00", "arch_3_1","booke","cellbe","darn","dfp","dscr" ,"ebb","efpsingle","efpdouble","fpu","htm","isel",
"mma","mmu","pa6t","power4","power5","power5+","power6x","ppc32","ppc601","ppc64","ppcle","smt",
"spe","tar","true_le","ucache","vsx"
This patch adds the clang portion of an AIX-specific option to inform
the
compiler that it can use a faster access sequence for the local-dynamic
TLS model (formally named aix-small-local-dynamic-tls).
This patch mainly references Amy's work on small local-exec TLS support.
This patch disallows the use of the -maix-small-local-exec-tls and
-fno-data-sections options within clang, and also disallows the use of
the aix-small-local-exec-tls attribute with the -data-sections=false
option in llc.
This is because having data sections off when using the
aix-small-local-exec-tls feature is not ideal for performance. As the
small-local-exec-tls region is a limited resource, this space should not
used for variables that may be replaced.
Note, that on AIX, data sections is turned on by default, so this patch
makes it so that a diagnostic is emitted when users explicitly turn off
data sections while using the aix-small-local-exec-tls feature.
Make __builtin_cpu_{init|supports|is} target independent and provide an
opt-in query for targets that want to support it. Each target is still
responsible for their specific lowering/code-gen. Also provide code-gen
for PowerPC.
I originally proposed this in https://reviews.llvm.org/D152914 and this
addresses the comments I received there.
---------
Co-authored-by: Nemanja Ivanovic <nemanjaivanovic@nemanjas-air.kpn>
Co-authored-by: Nemanja Ivanovic <nemanja@synopsys.com>
Moved from https://reviews.llvm.org/D126302
The current behaviour with these three options is quite undesirable:
-mno-altivec -mvsx allows VSX to override no Altivec, thereby turning on
both
-msoft-float -maltivec causes a crash if an actual Altivec instruction
is required because soft float turns of Altivec
-msoft-float -mvsx is also accepted with both Altivec and VSX turned off
(potentially causing crashes as above)
This patch diagnoses these impossible combinations in the driver so the
user does not end up with surprises in terms of their options being
ignored or silently overridden.
Fixes https://github.com/llvm/llvm-project/issues/55556
---------
Co-authored-by: Nemanja Ivanovic <nemanja.i.ibm@gmail.com>
PowerPC AIX backend does not support float128 at all. Diagnose even when
specifying -mfloat128 to avoid backend crash.
---------
Co-authored-by: Kai Luo <gluokai@gmail.com>
smmintrin.h uses __builtin_mffs, __builtin_mffsl, __builtin_mtfsf and
__builtin_set_fpscr_rn. This patch replaces the uses with ppc prefix
and implement the missing ones.
This patch adds the clang portion of an AIX-specific option to inform
the compiler that it can use a faster access sequence for the local-exec
TLS model (formally named aix-small-local-exec-tls).
This patch only adds the frontend portion of the option, building upon:
Backend portion of the option (D156203)
Backend patch that utilizes this option to actually produce the faster access sequence (D155600)
Differential Revision: https://reviews.llvm.org/D155544
Clang has mechanism to specify required target features of a built-in
function. This patch adds such definitions to Altivec, VSX, HTM,
PairedVec and MMA builtins.
This will help frontend to detect incompatible target features of
bulitin when using target attribute syntax.
Reviewed By: nemanjai, kamaub
Differential Revision: https://reviews.llvm.org/D143467
POWER Darwin support in the backend has been removed for some time: https://discourse.llvm.org/t/rfc-remove-darwin-support-from-power-backends
but Clang still has the TargetInfo and other remnants lying around.
This patch does some cleanup and removes those and other related frontend support still remaining. We adjust any tests using the triple to either remove
the test if unneeded or switch to another Power triple.
Reviewed By: MaskRay, nemanjai
Differential Revision: https://reviews.llvm.org/D146459
Reorganize clang::Builtin::Info to have them naturally align on 4 bytes
boundaries.
Instead of storing builtin headers as a straight char pointer, enumerate
them and store the enum. It allows to use a small enum instead of a
pointer to reference them.
On a 64 bit machine, this brings sizeof(clang::Builtin::Info) from 56
down to 48 bytes.
On a release build on my Linux 64 bit machine, it shrinks the size of
libclang-cpp.so by 193kB.
The impact on performance is negligible in terms of instruction count,
but the wall time seems better, see
https://llvm-compile-time-tracker.com/compare.php?from=b3d8639f3536a4876b511aca9fb7948ff9266cee&to=a89b56423f98b550260a58c41e64aff9e56b76be&stat=task-clock
Differential Revision: https://reviews.llvm.org/D142024
This avoids recomputing string length that is already known at compile time.
It has a slight impact on preprocessing / compile time, see
https://llvm-compile-time-tracker.com/compare.php?from=3f36d2d579d8b0e8824d9dd99bfa79f456858f88&to=e49640c507ddc6615b5e503144301c8e41f8f434&stat=instructions:u
This a recommit of e953ae5bbc313fd0cc980ce021d487e5b5199ea4 and the subsequent fixes caa713559bd38f337d7d35de35686775e8fb5175 and 06b90e2e9c991e211fecc97948e533320a825470.
The above patchset caused some version of GCC to take eons to compile clang/lib/Basic/Targets/AArch64.cpp, as spotted in aa171833ab0017d9732e82b8682c9848ab25ff9e.
The fix is to make BuiltinInfo tables a compilation unit static variable, instead of a private static variable.
Differential Revision: https://reviews.llvm.org/D139881
GCC only defines `__ppc64__` for darwin while the darwin support has been
removed from llvm-project. The existence of `__ppc64__` makes some software
think we are compiling for big-endian PowerPC Mac; also it lures users to write
code which is not portable to GCC.
It is straightforward if a distro wants to keep the macro: add
`-D__ppc64__=1` to a Clang configuration file.
Reviewed By: thesamesam, nemanjai
Differential Revision: https://reviews.llvm.org/D137511
We are supporting quadword lock free atomics on AIX. For the situation that users on AIX are using a libatomic that is lock-based for quadword types, we can't enable quadword lock free atomics by default on AIX in case user's new code and existing code accessing the same shared atomic quadword variable, we can't guarentee atomicity. So we need an option to enable quadword lock free atomics on AIX, thus we can build a quadword lock-free libatomic(also for advanced users considering atomic performance critical) for users to make the transition smooth.
Reviewed By: shchenz
Differential Revision: https://reviews.llvm.org/D127189
This patch implements the following floating point negative absolute value
builtins that required for compatibility with the XL compiler:
```
double __fnabs(double);
float __fnabss(float);
```
These builtins will emit :
- fnabs on PWR6 and below, or if VSX is disabled.
- xsnabsdp on PWR7 and above, if VSX is enabled.
Differential Revision: https://reviews.llvm.org/D125506
This patch turns on support for CR bit accesses for Power8 and above. The reason
why CR bits are turned on as the default for Power8 and above is that because
later architectures make use of builtins and instructions that require CR bit
accesses (such as the use of setbc in the vector string isolate predicate
and bcd builtins on Power10).
This patch also adds the clang portion to allow for turning on CR bits in the
front end if the user so desires to.
Differential Revision: https://reviews.llvm.org/D124060
Make 16-byte atomic type aligned to 16-byte on PPC64, thus consistent with GCC. Also enable inlining 16-byte atomics on non-AIX targets on PPC64.
Reviewed By: hubert.reinterpretcast
Differential Revision: https://reviews.llvm.org/D122377
Add support for builtin_[max|min] which has below prototype:
A builtin_max (A1, A2, A3, ...)
All arguments must have the same type; they must all be float, double, or long double.
Internally use SelectCC to get the result.
Reviewed By: qiucf
Differential Revision: https://reviews.llvm.org/D122478
This patch emits a warning when the stack pointer register (`R1`) is found in
the clobber list of an inline asm statement. Clobbering the stack pointer is
not supported.
Reviewed By: #powerpc, nemanjai
Differential Revision: https://reviews.llvm.org/D112073
Targets with VSX feature but without native float128 instructions can
also use that type with supplementary libcalls. We don't enable it by
default now because Glibc assumes long double and float128 can be
implicitly converted in between, which is not available under default
'ibmlongdouble' semantics in clang.
This commit partly relands cbd93ce.
This patch attempts to restrict the following P10 options:
```
-mprefixed
-mpcrel
-mpaired-vector-memops
```
To P10 only. This will prevent the use of these options on P9 and earlier.
The behaviour of this patch looks like the following on pre-P10:
```
$ clang -mcpu=pwr9 -mpaired-vector-memops test.c -o test
error: option '-mpaired-vector-memops' cannot be specified without '-mcpu=pwr10'
$ clang -mcpu=pwr9 -mprefixed test.c -o test
error: option '-mprefixed' cannot be specified without '-mcpu=pwr10'
$ clang -mcpu=pwr9 -mprefixed -mpcrel test.c -o test
error: option '-mpcrel' cannot be specified without '-mcpu=pwr10 -mprefixed'
$ clang -mcpu=pwr9 -mpcrel -mprefixed test.c -o test
error: option '-mpcrel' cannot be specified without '-mcpu=pwr10 -mprefixed'
$ clang -mcpu=pwr9 -mpcrel test.c -o test
error: option '-mpcrel' cannot be specified without '-mcpu=pwr10 -mprefixed'
```
Differential Revision: https://reviews.llvm.org/D109652
This patch makes sure that the builtins __builtin_ppc_load8r and
__ builtin_ppc_store8r are only available for Power 7 and up.
Currently the builtins seem to produce incorrect code if used for
Power 6 or before.
Reviewed By: nemanjai, #powerpc
Differential Revision: https://reviews.llvm.org/D110653
This patch is in a series of patches to provide builtins for compatibility with
the XL compiler. This patch implements the software divide builtin as
wrappers for a floating point divide. XL provided these builtins because it
didn't produce software estimates by default at `-Ofast`. When compiled
with `-Ofast` these builtins will produce the software estimate for divide.
Reviewed By: #powerpc, nemanjai
Differential Revision: https://reviews.llvm.org/D106959
Since XLC only ever shipped on PowerPC AIX and Linux, it is not reasonable to
provide the compatibility macros on any target other than those two. This patch
restricts those macros to AIX/Linux.
Differential revision: https://reviews.llvm.org/D110213
