© CyberThor Studios Ltd.
Release Notes: LLVM FOR RENESAS RL78 10.0.0.202209
Release Notes: LLVM FOR RENESAS RL78 10.0.0.202209
30th of September, 2022
CyberThor Studios Ltd. is releasing the LLVM for Renesas RL78 10.0.0.202209, a cross compiler tool for
Renesas RL78 micro-controllers.

SALIENT FEATURES
The LLVM for Renesas RL78 10.0.0.202209 toolchain is based on:❖ LLVM 10.0.0 [released]❖ Compiler-rt 10.0.0 [released]❖ Libcxx 10.0.0 [released]❖ Libcxx-abi 10.0.0 [released]❖ Newlib 4.1.0 [released]❖ GDB 7.8.2 [released]
LLVM RL78 comes with significant performance improvements (both code size and speed) compared to
GCC RL78. It also comes with support for latest language standards: full support for C17 and C++17 andexperimental support for the C2x (next C standard) and partial support for C++20.
The latest patches are applied to the LLVM sources.

ABOUT LLVM FOR RENESAS RL78 10.0.0.202209
Release Version:

LLVM for Renesas RL78 10.0.0.202209

Release Date:

30th of September, 2022
Ubuntu 18.04 or later (or compatible distribution)

Platforms Supported:
Windows 7 or later
Language:

C, C++

Targets:

G23, G1X, I1X, D1X, LIN MCP, F1X, and L1X

Object File Format:

ELF

CHANGES IN LLVM FOR RENESAS RL78 10.0.0.202209
This toolchain is the successor of GCC RL78 toolchain, and it is meant as a direct replacement to GCC RL78.
This section describes the fixes made in the LLVM for Renesas RL78 10.0.0.202209 release.
1. [Improvement] Various codegen optimizations
Code speed and size optimizations were made in the compiler.
2. [Bug Fix] Fixed assembly parser allowing MULH/MACH instructions for S1/S2 cores
The assembler did not generate an error when parsing assembly files and encountering the MULH/MACH
instructions while having the -mcpu=S1/-mcpu=S2 option specified.
This was fixed in the current release: the assembler will generate an error message when the selected coredoes not support a parsed instruction.

Notes:
This installer does not provide an option to integrate the LLVM RL78 toolchain with e2 studio, as the e2studio IDE will automatically detect the LLVM RL78 toolchain installation on start-up for integration.
Alternatively, you may use the 'Toolchain Management' feature in e2 studio to achieve this.
For details on e2 studio please visit the following link below:
https://www.renesas.com/eu/en/software-tool/e-studio
There is no support in this installer to integrate the toolchain with the HEW IDE.

KNOWN ISSUES IN LLVM FOR RENESAS RL78 10.0.0.202209
The following is a list of known issues for the tools we include for the LLVM for Renesas RL78
10.0.0.202209 toolchain:
1. Assembly parsing issue of callt instruction operand.
The assembly parser cannot handle any complex expressions as operands for callt instruction, only
constant values are allowed at the moment.
2. Assembly parsing of %lo16, %hi16 limited support.
When using %lo16, %hi16 operators only 2 basic operations are currently allowed, symbol + constant andsymbol - constant.
For example:.short %lo16(_my_symbol) + %lo16(my_const)
The parse will be enhanced in future versions to support more complex expressions.
3. Assembly parsing missing operand.
There is currently no assembly operand to extract 8-bit data from symbols in order to be used with MOV
ES, #byte, MOV CS, #byte etc. Only immediate values can be used with those instructions at the moment.
The current workaround is to use %lo16, %hi16 to set the value in the 16-bit register and then move therelevant part in ES/CS. A new operand will be implemented in the next release.

4. Missing assembly listing support (-a[cdhlns] option in GNU AS).
There’s no equivalent in the LLVM for the -a[cdhlns] GNU AS option.
The alternative solution is to use llvm-objdump to obtain source code interleaved with assembly (-S, -source option).
5. Binding of references to packed fields.
Creating references to struct members which are declared as packed, e.q. __attribute__ ((packed)), isincorrect as it can cause unaligned access issues. The compiler should return an error in this case however
this is not currently the case. This will be fixed in a future release.
6. Inline assembly missing constraints and modifiers support for parameters.
Clang supports, in the case of RL78, inline assembly constructs without parameters, e.q. asm(AssembleTemplate).

The extended syntax available in GCC, asm (AssemblerTemplate : OutputOperands : InputOperands :Clobbers : GotoLabels), is not currently supported. This will be fixed in the next release, however theconstraints will not be the same as in GCC.

7. Other issues, non-specific to RL78
LLVM tries to be a complete replacement. As such there are still a couple of missing features from GCC
which will be implemented in future releases. In particular, the following issues should be noted:
lld: Information printed using --print-gc-sections is not as nice as when using the GNU ld. Bug 46783
llvm-ar: Errors when printing multiple members with the same name. Bug 42521
llvm-dwarfdump: Does not print section attribute flags yet. Bug 38488
llvm-nm: Unable to understand symbols built with gcc-lto Bug 41437
llvm-nm: Needs support for --line-numbers to llvm-nm Bug 40001
llvm-objcopy: Unknown argument '--change-section-address'. Bug 45217
llvm-objcopy: Objcopy zero-size section might cause huge binaries. Bug 46299
llvm-objdump: Prints wrong line number info for obj file compiled with -ffunction-sections. Bug 40703
llvm-objdump: Wrong behavior for non-relocatable objects when suing llvm-objdump with -r option. Bug
Bug 41901
llvm-readobj: Make GNU style symbol printing invalid symbol section indexes match GNU readelf Bug
43850
llvm-readelf: Relocation addends printed style does not match GNU readelf Bug 45235
llvm-string: Short option with argument grouping not GNU compatible Bug 42942
llvm-string: Allow "-<integer>" as an alias for "-n <integer>" Bug 42964
llvm-symbolizer: Shows incorrect source line info if --gc-sections used Bug 41124
llvm-symbolizer: llvm-addr2line does not exit when passed a non-existent file Bug 42754
8. Other issues
Finally, for better understanding regarding the status of the toolchain please visit https://bugs.llvm.org/ .

In particular, the following queries will help better understand the status of each tool.
https://bugs.llvm.org/buglist.cgi?bug_status=UNCONFIRMED&bug_status=NEW&bug_status=CONFIRMED&bug_status=REOPENED&component=ELF&product=lld&query_format=advanced&resolution=--https://bugs.llvm.org/buglist.cgi?bug_status=UNCONFIRMED&bug_status=NEW&bug_status=CONFIRMED&bug_status=REOPENED&component=llvm-ar&product=tools&query_format=advanced&resolution=--https://bugs.llvm.org/buglist.cgi?bug_status=UNCONFIRMED&bug_status=NEW&bug_status=CONFIRMED&bug_status=REOPENED&component=llvmdwarfdump&product=tools&query_format=advanced&resolution=--https://bugs.llvm.org/buglist.cgi?bug_status=UNCONFIRMED&bug_status=NEW&bug_status=CONFIRMED&bug_status=REOPENED&component=llvm-nm&product=tools&query_format=advanced&resolution=--https://bugs.llvm.org/buglist.cgi?bug_status=UNCONFIRMED&bug_status=NEW&bug_status=CONFIRMED&bug_status=REOPENED&component=llvmobjcopy%2Fstrip&product=tools&query_format=advanced&resolution=--https://bugs.llvm.org/buglist.cgi?bug_status=UNCONFIRMED&bug_status=NEW&bug_status=CONFIRMED&bug_status=REOPENED&component=llvmobjdump&product=tools&query_format=advanced&resolution=--https://bugs.llvm.org/buglist.cgi?bug_status=UNCONFIRMED&bug_status=NEW&bug_status=CONFIRMED&bug_status=REOPENED&component=llvmreadobj&product=tools&query_format=advanced&resolution=--https://bugs.llvm.org/buglist.cgi?bug_status=UNCONFIRMED&bug_status=NEW&bug_status=CONFIRMED&bug_status=REOPENED&component=llvm-size&product=tools&query_format=advanced&resolution=--https://bugs.llvm.org/buglist.cgi?bug_status=NEW&bug_status=CONFIRMED&bug_status=REOPENED&co
mponent=llvm-symbolizer&product=tools&query_format=advanced&resolution=---

FREE SUPPORT FOR LLVM FOR RENESAS RL78 10.0.0.202209
For free technical support, please register athttps://llvm-gcc-renesas.com
For your feedback and suggestions, please visit
https://llvm-gcc-renesas.com/help/contact-us/