rudimentary midipix port (#13896)

Fix linking library for POSIX shared memory functions (#13822)

The POSIX shared memory object operations functions (shm_open,
shm_unlink...) are in:
* C library on most systems (newe

Fix linking library for POSIX shared memory functions (#13822)

The POSIX shared memory object operations functions (shm_open,
shm_unlink...) are in:
* C library on most systems (newer Linux, Solaris 11.4, illumos, BSD*,
macOS, Haiku, etc.)
* real-time (rt) library on older Linux distributions and Solaris <= 10.

Haiku C library (called root library) on Haiku is linked in by default.

Previous check always added additional rt or root library to global LIBS
and rt to OPCACHE_SHARED_LIBADD. Now, the library containing shm_open is
linked as needed to the always shared opcache extension.

This also removes unused HAVE_SHM_OPEN and HAVE_LIBROOT symbols.

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Fix GH-13727: macro generating invalid call test prototypes fixes.

autoconf/libtool generating code to test features missed `void` for
C calls prototypes w/o arguments.
Note that spe

Fix GH-13727: macro generating invalid call test prototypes fixes.

autoconf/libtool generating code to test features missed `void` for
C calls prototypes w/o arguments.
Note that specific changes related to libtool have to be upstreamed.

Co-authored-by: Peter Kokot <petk@php.net>

close GH-13732

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Fix string concatenation in ZEND_JIT_SRC variable (#13740)

The += operator only works in bash shells and when using /bin/sh, for
example in Alpine Linux, the warning is thrown during con

Fix string concatenation in ZEND_JIT_SRC variable (#13740)

The += operator only works in bash shells and when using /bin/sh, for
example in Alpine Linux, the warning is thrown during configuration step

./configure: line 51396: ZEND_JIT_SRC+= jit/ir/ir_disasm.c: not found

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Add missing memfd_create Autoconf check for bundled pcre2lib (#13561)

This moves memfd_create (HAVE_MEMFD_CREATE) to configure.ac. Since
ext/pcre is always enabled and check can be done

Add missing memfd_create Autoconf check for bundled pcre2lib (#13561)

This moves memfd_create (HAVE_MEMFD_CREATE) to configure.ac. Since
ext/pcre is always enabled and check can be done in this case for
ext/pcre and ext/opcache at once.

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Disable JIT on Apple Silicon + ZTS

Apple Silicon has stricter rules about rwx mmap regions. They need to be created
using the MAP_JIT flag. However, the MAP_JIT seems to be incompatible

Disable JIT on Apple Silicon + ZTS

Apple Silicon has stricter rules about rwx mmap regions. They need to be created
using the MAP_JIT flag. However, the MAP_JIT seems to be incompatible with
MAP_SHARED. ZTS requires MAP_SHARED so that some threads may execute code from a
page while another writes/appends to it. We did not find another solution, other
than completely disabling JIT for Apple Silicon + ZTS.

See discussion in https://github.com/php/php-src/pull/13351.

Co-authored-by: Peter Kokot <peterkokot@gmail.com>
Fixes GH-13400
Closes GH-13396

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Align configure check message results together

Add host_cpu type for FreeBSD

In FreeBSD world x86_64 host type is identified as amd64 so add proper
checks for FreeBSD amd64 hosts.

Close GH-12736

Remove old JIT implementation (#12498)

* Remove old JIT implementation

* Remove ext/opcache/jit/zend_jit_vtune.c

A new PHP JIT implementation based on IR JIT framework (#12079)

* IR update

* Use folding to allow constant folding and common subexpression elimination

* Implement IR JIT

A new PHP JIT implementation based on IR JIT framework (#12079)

* IR update

* Use folding to allow constant folding and common subexpression elimination

* Implement IR JIT for INIT_FCALL, INIT_FCALL_BY_NAME and INIT_NS_FCALL_BY_NAME

* Implement IR JIT for SEND_VAL and SEND_VAL_EX

* Implement IR JIT for SEND_REF

* Implement IR JIT for SEND_VAR* instructions (incompltere - few tests failures)

* Implement IR JIT for CHECK_FUNC_ARG

* Implement IR JIT for CHECK_UNDEF_ARGS

* Implement IR JIT for ROPE_INIT, ROPE_ADD and ROPE_END

* Implement IR JIT for FREE, FE_FREE, ECHO, STRLEN and COUNT

* Implement IR JIT for IN_ARRAY

* Implement IR JIT support for separate VM stack overflow check

* Implement IR JIT for INIT_DYNAMIC_CALL

* Implemenr IR JIT for INIT_METHOD_CALL

* Fix IR JIT for IN_ARRAY and COUNT

* Implement IR JIT for VERIFY_RETURN_TYPE

* Force C compiler to store preserved registers to allow JIT using them

* Implement IR JIT for DO_FCALL, DO_UCALL, DO_ICALL and DO_FCALL_BY_NAME

* Implement IR JIT for FETCH_CONSTANT

* Fix (reverse) guard conditions

* Implement IR JIT for RECV and RECV_INIT

* Implement IR JIT for RETURN

* Implement IR JIT for BIND_GLOBAL

* Fix guard for: int++ => double

* Fix exception handling

* Allow deoptimization of zval type only (if some register is spilled by the IR engine)

* Fix overflow handling

* Implement IR JIT for FE_RESET_R and FE_FETCH_R

* Eliminate extra temporary register

* Better registers usage

* Implement IR JIT for FETCH_DIM_* and ISSET_DIM

* Implement IR JIT for ASSIGN_DIM and ASSIGN_DIM_OP

* cleanup

* Generae IR that produces a better x86[_64] code

* Allow trace register allocation for live ranges terminated before entering a called function

* Remove following END->BEGIN nodes during IR construction

* Remove useless (duplicate) guard

* Avoid useless exception check

* Prevent duplicate store

* Eliminate repatable re-assignment of stack zval types

* Enable combination of some instructions with the following SEND_VAL for IR JIT

* Avoid generation of useless RLOADs

* Eliminatare refcouting in a sequence of FETCH_DIM_R

* Fix assertion

* Remove ZREG_ZVAL_ADDREF flag from an element of abstract stack

* Implement IR JIT for FETCH_OBJ_*

* Implement IR JIT for ASSIGN_OBJ

* Implement IR JIT for ASSIGN_OBJ_OP

* cleanup

* Implement IR JIT for (PRE/POST)_(INC/DEC)_OBJ

* ws

* cleanup

* Fix IR JIT for constructor call

* Fix opcache.jit=1201 IR JIT.

With opcache.jit=1201 we still have to generate code for follow and target basic blocks with single exiting VM instruction. We mat just omit the entry point.

* Fix IR construction for the case when both IF targets are the same

* Avoid PHP LEAVE code duplication in function IR JIT.

* Reload operands from memeory when overflow (this improves hot code)

* Implement IR JIT for SWITCH_LONG, SWITCH_STRING and MATCH

* Initialize result to IS_UNDEF

* Fix JIT integraion with observer (Zend/tests/gh10346.phpt failure)

* Fix incorrect compilation of FE_FETCH with predicted empty array

* Fix register allocation

* Use sign extension inxted of zero

* Fix trace register allocator

* cleanp

* Fix address sanitizer warning

* Calculate JIT trace prologue sixe on startup (to avoid magic constants).

* Add cgecks for merge arrays overflow (this should be refactored using lists)

* Cache TLS access to perform corresponding read once per basic block

* cleanup unused variable

* Fix IR JIT support for CLANG build (CALL VM without global register variables)

* Fix IR JIT for CALL VM with global register variables

* Allow %rpb ysage in JIT for CALL VM (we save and restore it in prologue/epilogue anyway)

* cleanup

* Allocate enough fixed stack to keep preserved registers

* We don't have to care about x29 and x30

* cleanup (JMPZ/NZ_EX work fine)

* Revert "cleanup (JMPZ/NZ_EX work fine)"

This reverts commit cf8dd74a040e225d290d8ac4f5e33df638e6f8b8.

* Don't allocate register for PHP variables that are loaded from memory and used once

* Eliminate redundand deoptimization stores

* cleanup

* cleanup

* cleanup

* Optimization for constant comparison

* Cleanup and elimination of dead deoptimization stores

* Eliminate duplicate constant loading

* Set proper initial SP offset info for GDB backtraces

This doesn't take into account the following SP/FP modifications

* Add spill stores

* Remove low limit on number of deoptimization constants

* Emit dead code only when it's really necessary for IR graph

* cleanup

* cleanup

* Prefer loading long constants from memory (instead of loading immediate value)

* Regiter disasm labels using macros (add missing helpers)

* Make IR franework to care about GUARD JMP reordering

* Avoid reloading

* Improve register allocation for IR tracing JIT

* Add comment

* Fix deoptimization on result type guard of FETCH_DIM_R and FETCH_OBJ_R

* If HYBRID VM can't provide some stack space for JIT code in "red zone" then JIT has to reserve stack space itself

* Dump IR for stubs only if disassembling of stubs is requested

* Revert "Dump IR for stubs only if disassembling of stubs is requested"

This reverts commit d8b56bec129bc23c2b16f1f3c6367190181b6fdb.

* Dump IR for stubs only if disassembling of stubs is requested (another approach)

* Improve overflow deoptimization for ADD(_,1) and SUB(_,1)

Now we deoptimize to the next instruction, load constant result, and remove op1 from SNAPSHOT

* Switch to IR Builder API

* Switch to new IR builder macros

* Fix jit_set_Z_TYPE_INFO() call. op3 is a simple constant (not a ir_ref).

* Generate better code

* Enable empty ENTRY block merging

* Improve code generated for array separation/creation before an update

(ASSIGN_DIM, ASSING_DIM_OP, etc)

* Fix incorrect deleteion of PHI source (op1 is used for control link)

* Load constant once

* cleanup

* Improve control-flow to avoid two IS_ARRAY checks for REFERENCEs

* Update comments

* cleanup

* Clenup comments

* Fix AAarch 64 build (disable stack adjustment auto-detection)

* Add filename and line number to closure names

* Reserve stack for parameter passing

* Increase size of CPU stack reserved for JIT-ed code

* Fix addess sanitizer warnings

* Clenup: introduce OPTIMIZE_FOR_SIZE macro (disabled by default)

* Port 08e759120690520e99f9f2d38afeb21bcd1de197 to IR JIT

Fix (at lease part of the) #GH-10635: ARM64 function JIT causes impossible assertion

* cleanup

* Preload constant and use tests that may be compiled into better code

* Convert helpers to stubs

* Introduce a helper data structure (ir_refs) to collect references for the following use in (MERGE/PHI)_N

* Use ir_refs

* Improve code generated by zend_jit_zval_copy_deref()

* Use "cold" attribute to influence IR block scheduler and achieve better code layout

* Keep info collected by recursion analyzer

* Use HTTPS URL to allow fetching without a SSH key

* Update IR

* Update IR

* Add IR JIT support for Wondows (Win64 support is incomplete)

* Update IR

* Update IR

* Fix support for Windows ZTS build

* Fix stack alignment

* Cleanup ir_ctx.control usage

* Fixed support for irreducable (incomplete) and merged loops

* Revert "Fixed support for irreducable (incomplete) and merged loops"

This reverts commit 672b5b89f47e8b81745fb73c86e0bcb0937daf16.

* Generate better code for RECV_ENTRies

* Use simpler and more efficient checks

* Switch to new ENTRY node concept

* Limit register usage across the OSR ENTRY point

* Upate MEM type only if we write to memory

* Use LOOP_END without a reference edge

* Use new ir_init() prototype

* Delay LOAD for better LOAD fusion

* Fix RECV/RECV_INIT compilation with opcache.jit=1235

* iPtoperly compile fake closures (they mau be called as regular functions)

* Fix reabase

* Fix rebase and add --with-capstone support for IR JIT

* Replace zend_uchar -> uint8_t

* IR JIT support for delayed destructor for zend_assign_to_typed_ref/prop

* Handle zend_execute_internal in IR JIT

* Fix readonly+clone IR JIT issues

* Switch to ir_ctx.mflags

* Ckeanup "inputs_count" access

* Disable CSE for nodes bound to PHP local varibles

The stack slots for temporaty variables may be reused and in case of
spilling this may cause clobbering of the value.

(ext/standard/tests/strings/htmlentities20.phpt on x86 with tracing JIT)

* Fix deoptimization code when link traces

See ext/zlib/tests/bug75273.phpt failure

* Fix missing type store

This fixes ext/openssl/tests/openssl_error_string_basic_openssl3.phpt

* Fix tracing JIT for overflowing INC/DEC

Fixes tests/lang/operators/preinc_basiclong_64bit.phpt

* Remove ir_remove_unreachable_blocks() call. Now it's called by ir_build_cfg(), when necessary.

* IR JIT: Fixed inaccurate range inference usage for UNDEF/NULL/FALSE

* IR JIT: Fixed GH-11127 (JIT fault)

* Avoid allocation of unused exit point

* Don't record already stored PHP variables in SNAPSHOTs

* Delay variable load

* Disable CSE across ENTRY

* Fixed disabling CSE

* Fix deoptimization

* Fixed deoptimization

* Disable incorrect register allocation

* Fix JIT for INDENTICAL+JMPZ_EX

* Add comments

* Fixed missed type stores

* IR JIT: added support for CLDEMOTE

* Fixed incorrect constant usage

* Disable compilation of PHP functions with irreducible CGF

* Fixed liveness check

* Fixed code for constant conditional jump

* Add type store to avoid use-after-free

* Fixed liveness analyses

* Gnerate SNAPSHOT for virtual method calls

* More accurate search for staticaly inferred info about a trace SSA vaiable

* Fix incorrect result use type_info

* Fix JMPZ/NZ_EX support and missing type store

* Fixed trace type inference and missing type store

* Store type of unused CV to prevent possible following use after free

* Fixed deoptimizaton info

* Fixed stack layout

* Implemented support for veneers on AArch64

* Dsable CSE to avoid over-optimization

* Don't bind nodes for TMP PHP variables

* Re-enable CSE for temporary variables as we don't bind them anymore

* Switch to CPU stack spill slots

* Add codegen info dump

* Initialize CV variables through FP (this enables some folding optimizatios)

* Use zero-extension that can be eliminated

* Avoid generation of dead PHIs

* Increase preallocated spill stack size

* Enable IR based JIT by default

* Fixed build with -disable-opcache-jit

* Use explicit type conversion & force load values to registerts

* Fix IR build

* Checkout submodules in github actions

* Fixed Windows build

* Fixed Windows build

* Fixed reattach to IR JIT SHM

* Update IR

* Checkout submodules in nightly CI

* Fix MACOS ZTS in IR JIT

* Update ir

* Fixed incorrect register allocation

* Fixed incorect code generation

* Fixed tracing jit for BIND_INIT_STATIC_OR_JMP

* Update README

* Typos

* Revert JIT disabling for run-tests.php workers

* Fixed code review issues

* Update IR

* Update IR

* Update IR

* Allow exit_point duplication, when the deoptimization info differs because of spilling

* Use bound spill slots for CV (once again)

* Improve error handling

* Removed IR submodule

* Remove IR submodule from workflows

* Embed IR

IR commit: 8977307f4e96ee03847d7f2eb809b3080f9ed662

* Add .gitignore

* Fixed according to feedback

* Force C saving preserved registers only for HYBRID VM

* Update IR

IR commit: a2f8452b3d35a756cba38924f5c51a48a7207494

* cleanup

* Replace ZEND_ASSERT(0) by ZEND_UNREACHABLE()

* Update IR and remove unused IR files

IR commit: 399a38771393c202a741336643118991290b4b1b

* Fixed inconsistency between IR code-generation and register-allocation

* Update IR

IR commit: 86685504274b0c71d9985b3c926dccaca2cacf9b

* Update ir_PHI*() according to IR construction API changes

* Fixed 32-bit build

* Update IR

IR commit: d0686408e20cd8c8640e37ed52ab81403a2383cb

* Support for ir_TAILCALL() prototype changes

* Update IR

IR commit: d72ae866e09d17e879378767aceb91d51894818c

* Fixed incorrect extension (ZEXT->SEXT)

* Fix SSA dominance

* Update IR

IR commit: d60d92516dc5f89b93cdf1df7a54141e83226b07

* Fixed support ir_ctx.ret_type

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opcache posix creating special shared segments for FreeBSD 13 and above.

From this release, it is permitted to create shared memory blocks tagged
as large for faster accesses for a size

opcache posix creating special shared segments for FreeBSD 13 and above.

From this release, it is permitted to create shared memory blocks tagged
as large for faster accesses for a size compatible with otherwise
we fallback to a classic creation.

Close GH-8037

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Rename --with-opcache-capstone to --with-capstone (#10952)

Use capstone explicitly, drop oprofile (GH 10876) (#10918)

* ext/opcache/config.m4: new --with-opcache-capstone flag.

Until now, libcapstone has been detected "automagically" and us

Use capstone explicitly, drop oprofile (GH 10876) (#10918)

* ext/opcache/config.m4: new --with-opcache-capstone flag.

Until now, libcapstone has been detected "automagically" and used for
JIT disassembly whenever it is available on the system used to compile
PHP. This can have some unintended consequences, however: many users
have capstone installed for some other purpose, and are surprised to
find that PHP breaks when capstone is later uninstalled.

To address this, we have introduced a new --with-opcache-capstone flag
that is disabled by default, and that makes the user's preference
explicit. It is ignored unless the JIT is enabled.

* ext/opcache: drop support for the oprofile JIT profiler.

Recently we have replaced the "automagic" detection of capstone at
build time with a --with-opcache-capstone flag. The detection of
oprofile causes similar problems and would likely have the same
solution; however, it was suggested that we might remove oprofile
altogether. So, this commit removes it:

* Remove the detection bits from ext/opcache/config.m4.
* Drop HAVE_OPROFILE ifdef blocks.
* Delete ext/opcache/jit/zend_jit_oprofile.c.
* Undefine the ZEND_JIT_DEBUG_OPROFILE constant.

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*/*.m4: update main() signatures.

The next generation of C compilers is going to enforce the C standard
more strictly:

https://wiki.gentoo.org/wiki/Modern_C_porting

O

*/*.m4: update main() signatures.

The next generation of C compilers is going to enforce the C standard
more strictly:

https://wiki.gentoo.org/wiki/Modern_C_porting

One warning that will soon become an error is -Wstrict-prototypes.
This is relatively easy to catch in most code (it will fail to
compile), but inside of autoconf tests it can go unnoticed because
many feature-test compilations fail by design. For example,

$ export CFLAGS="$CFLAGS -Werror=strict-prototypes"
$ ./configure
...
checking if iconv supports errno... no
configure: error: iconv does not support errno

(this is on a system where iconv *does* support errno). If errno
support were optional, that test would have "silently" disabled
it. The underlying issue here, from config.log, is

conftest.c:211:5: error: function declaration isn't a prototype
[-Werror=strict-prototypes]
211 | int main() {

This commit goes through all of our autoconf tests, replacing main()
with main(void). Up to equivalent types and variable renamings, that's
one of the two valid signatures, and satisfies the compiler (gcc-12 in
this case).

Fixes GH-10751

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ext/opcache/zend_shared_alloc: use memfd for locking if available

A memfd is a virtual file that has no reachable path, therefore does
not clobber any filesystem. It is deleted automati

ext/opcache/zend_shared_alloc: use memfd for locking if available

A memfd is a virtual file that has no reachable path, therefore does
not clobber any filesystem. It is deleted automatically as soon as
the last handle gets closed. The feature is available since Linux
kernel 3.17.

Closes GH-10589.

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Revert "ext/opcache: use C11 atomics for "restart_in" (#10276)" (#10339)

* Revert "ext/opcache: use C11 atomics for "restart_in" (#10276)"

This reverts commit 061fcdb0a5649572b90cda

Revert "ext/opcache: use C11 atomics for "restart_in" (#10276)" (#10339)

* Revert "ext/opcache: use C11 atomics for "restart_in" (#10276)"

This reverts commit 061fcdb0a5649572b90cdad1be4d457dd3faa301.

While the commit does indeed improve performance, @dstogov complained
that it disables the code path calling kill_all_lockers(), and thus
hanging workers are never killed and restarted.
https://github.com/php/php-src/pull/10276#issuecomment-1383593046

The fact that this feature was not implemented in the existing atomic
code path (i.e. Windows) did not mean that the feature was considered
not strictly necessary, but that the Windows implementation just did
not need the feature because SAPIs that work on Windows do not manage
child processes
https://github.com/php/php-src/pull/10276#issuecomment-1383868696
https://github.com/php/php-src/pull/10276#issuecomment-1384235011

* ext/opcache: document lack of kill_all_lockers() on Windows

kill_all_lockers() is not implemented on Windows, and does not need to
be.

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ext/opcache: use C11 atomics for "restart_in" (#10276)

Cheaper than fcntl(F_SETLK). The same is done already on Windows, so
if that works, why not use it everywhere? (Of course, only i

ext/opcache: use C11 atomics for "restart_in" (#10276)

Cheaper than fcntl(F_SETLK). The same is done already on Windows, so
if that works, why not use it everywhere? (Of course, only if the
compiler supports this C11 feature.)

As a bonus, the code in this commit also works on C++ via C++11
std::atomic, just in case somebody adds some C++ code to the opcache
extension one day.

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Don't directly include zend_jit_gdb.c

Compile the file separately and only include a header. There doesn't
seem to be a good reason to directly include the C file here, and
this ensu

Don't directly include zend_jit_gdb.c

Compile the file separately and only include a header. There doesn't
seem to be a good reason to directly include the C file here, and
this ensures that there are no symbol clashes (see GH-7197).

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Initial support of JIT/arm64

SUMMARY

We implemented a prototype of PHP JIT/arm64. Briefly speaking,

1. build system
Changes to the build system are made so that PHP JIT

Initial support of JIT/arm64

SUMMARY

We implemented a prototype of PHP JIT/arm64. Briefly speaking,

1. build system
Changes to the build system are made so that PHP JIT can be successfully
built and run on ARM-based machine.
Major change lies in file zend_jit_arm64.dasc, where the handler for
each opcode is generated into machine code. Note that this file is just
copied from zend_jit_x86.dasc and the *unimplemented* parts are
substitued with 'brk' instruction for future work.

2. registers
AArch64 registers are defined in file zend_jit_arm64.h. From our
perspectives, the register usage is quite different from the x86
implementation due to the different ABI, number of registers and
addressing modes.
We had many confusions on this part, and will discuss it in details in
the final section.

3. opcodes
Several opcodes are partially supported, including INIT_FCALL, DO_UCALL,
DO_ICALL, RETURN, ADD, PRE_INC, JMP, QM_ASSIGN, etc. Hence, simple use
scenarios such as user function call, loops, addition with integer and
floating point numbers can be supported.
18 micro test cases are added under 'ext/opcache/tests/jit/arm64/'. Note
that majority of these test cases are design for functional JIT, and
cases 'hot_func_*.phpt' and 'loop_002.phpt' can trigger tracing JIT.

4. test
Our local test environment is an ARM-based server with Ubuntu 20.04 and
GCC-10. Note that both HYBRID and CALL VM modes are supported. We
suggest running the JIT test cases using the following command. Out of
all 130 test cases, 66 cases can be passed currently.
```
$ make test TESTS='-d opcache.jit=1203 ext/opcache/tests/jit/'
```

DETAILS

1. I-cache flush
Instruction cache must be flushed for the JIT-ed code on AArch64. See
macro JIT_CACHE_FLUSH in file 'zend_jit_internal.h'.

2. Disassembler
Add initialization and jump target parse operations for AArch64 backed.
See the updates in file 'zend_jit_disasm.c'.

3. redzone
Enable redzone for AArch64. See the update in zend_vm_opcodes.h.
Redzone is designated to prevent 'vm_stack_data' from being optimized
out by compilers. It's worth noting that this 16-byte redzone might be
reused as temporary use(treated as extra stack space) for HYBRID mode.

4. stack space reservation
The definitions of HYBRID_SPAD, SPAD and NR_SPAD are a bit tricky for
x86/64.
In AArch64, HYBRID_SPAD and SPAD are both defined as 16. These 16 bytes
are pre-allocated for tempoerary usage along the exuection of JIT-ed
code. Take line 4185 in file zend_jit_arm64.dasc as an example. NR_SPAD
is defined as 48, out of which 32 bytes to save FP/IP/LR registers.
Note that we choose to always reserve HYBRID_SPAD bytes in HYBRID mode,
no matter whether redzone is used or not, for the sake of safety.

5. stack alignment
In AArch64 the stack pointer should be 16-byte aligned. Since shadow
stack is used for JIT, it's easy to guarantee the stack alignment, via
simply moving SP with an offset like 16 or a multiple of 16. That's why
NR_SPAD is defined as 48 and we use 32 of them to save FP/IP/LR
registers which only occupies 24 bytes.

6. global registers
x27 and x28 are reserved as global registers. See the updates in file
zend_jit_vm_helpers.c

7. function prologue for CALL mode
Two callee-saved registers x27 and x28 should saved in function
zend_jit_prologue() in file zend_jit_arm64.dasc. Besides the LR, i.e.
x30, should also be saved since runtime C helper functions(such as
zend_jit_find_func_helper) might be invoked along the execution of
JIT-ed code.

8. regset
Minor changes are done to regset operations particularly for AArch64.
See the updates in file zend_jit_internal.h.

REGISTER USAGE

In this section, we will first talk about our understanding on register
usage and then demonstrate our design.

1. Register usage for HYBRID/CALL modes
Registers are used similarly between HYBRID mode and CALL mode.

One difference is how FP and IP are saved. In HYBRID mode, they are
assigned to global registers, while in CALL mode they are saved/restored
on the VM stack explicitly in prologue/epilogue.

The other difference is that LR register should also be saved/restored
in CALL mode since JIT-ed code are invoked as normal functions.

2. Register usage for functional/tracing JIT
The way registers are used differs a lot between functional JIT and
tracing JIT.

For functional JIT, runtime C code (e.g. helper functions) would be
invoked along the execution of JIT-ed code. As the operands for *most*
opcodes are accessed via the stack slot, i.e. FP + offset. Hence there
is no need to save/restore local(caller-saved) registers before/after
invoking runtime C code.
Exception lies in Phi node and registers might be allocated for these
nodes. Currently I don't fully understand the reason, why registers are
allocated for Phi functions, because I suppose for different versions of
SSA variables at the Phi function, their postions on the stack slot
should be identical(in other words, access via the stack slot is enough
and there is no need to allocate registers).

For tracing JIT, runtime information are recorded for traces(before the
JIT compilation), and the data types and control flows are concrete as
well. Hence it's would be faster to conduct operations and computations
via registers rather than stack slots(as functional JIT does) for these
collected hot paths. Besides, runtime C code can be invoked for tracing
JIT, however this only happends for deoptimization and all registers are
saved to stack in advance.

3. Candidates for register allocator
1) opcode candidates
Function zend_jit_opline_supports_reg() determines the candidate opcodes
which can use CPU registers.

2) register candidates
Registers in set "ZEND_REGSET_FP + ZEND_REGSET_GP - ZEND_REGSET_FIXED -
ZEND_REGSET_PRESERVED" are available for register allocator.
Note that registers from ZEND_REGSET_FIXED are reserved for special
purpose, such as the stack pointer, and they are excluded from register
allocation process.
Note that registers from ZEND_REGSET_PRESERVED are callee-saved based on
the ABI and it's safe to not use them either.

4. Temporary registers
Temporary registers are needed by some opcodes to save intermediate
computation results.

1) Functions zend_jit_get_def_scratch_regset() and
zend_jit_get_scratch_regset() return which registers might be clobbered
by some opcodes. Hence register allocator would spill these scratch
registers if necessary when encountering these opcodes.

2) Macro ZEND_REGSET_LOW_PRIORITY denotes a set of registers which would
be allocated with low priority, and these registers can be used as
temporary usage to avoid conflicts to its best.

5. Compared to the x86 implementation, in JIT/arm64
1) Called-saved FP registers are included into ZEND_REGSET_PRESERVED for
AArch64.

2) We follow the logic of function zend_jit_opline_supports_reg().

3) We reserve 4 GPRs and 2 FPRs out from register allocator and use them
as temporary registers in particular. Note that these 6 registers are
included in set ZEND_REGSET_FIXED.
Since they are reserved, may-clobbered registers can be removed for most
opcodes except for function calls. Besides, low-priority registers are
defined as empty since all candidate registers are of the same priority.
See the updates in function zend_jit_get_scratch_regset() and macro
ZEND_REGSET_LOW_PRIORITY.

6. Why we reserve registers for temporary usage?
1) Addressing mode in AArch64 needs more temporary registers.
The addressing mode is different from x86 and tempory registers might be
*always* needed for most opcodes. For instance, an immediate must be
first moved into one register before storing into memory in AArch64,
whereas in x86 this immediate can be stored directly.

2) There are more registers in AArch64.
Compared to the solution in JIT/x86(that is, temporary registers are
reserved on demand, i.e. different registers for different opcodes under
different conditions), our solution seems a coarse-granularity and
brute-force solution, and the execution performance might be downgraded
to some extent since the number of candidate registers used for
allocation becomes less.
We suppose the performance loss might be acceptable since there are more
registers in AArch64.

3) Based on my understanding, scratch registers defined in x86 are
excluded from candidates for register allocator with *low possibility*,
and it can still allocate these registers. Special handling should be
conducted, such as checking 'reg != ZREG_R0'.
Hence, as we see it, it's simpler to reserve some temporary registers
exclusively. See the updates in function zend_jit_math_long_long() for
instance. TMP1 can be used directly without checking.

Co-Developed-by: Nick Gasson <Nick.Gasson@arm.com>

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Fixed CPU detection

Drop -Wno-implicit-fallthrough compiler flag

And add it back to ext/date, ext/hash, and ext/opcache

Better support for cross-compilation

Use capstone disassembler, if available.

Merge branch 'PHP-8.0'

* PHP-8.0:
ext/opcache: fix configure output while checking mmap MAP_ANON support

ext/opcache: fix configure output while checking mmap MAP_ANON support

It seems that f3efb9e3fb introduced a "typo" which may result
in the following confusing message:

checking

ext/opcache: fix configure output while checking mmap MAP_ANON support

It seems that f3efb9e3fb introduced a "typo" which may result
in the following confusing message:

checking for mmap() using MAP_ANON shared memory support... no=yes

Let's fix this.

Signed-off-by: Michael Heimpold <mhei@heimpold.de>

Closes GH-6758.

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