Use "code size reduction extensions"

[tasasao]

Hello everyone, I'm new to posting on this Discussion and I have a few questions about xPack GNU RISC-V Embedded GCC v14.2.0-1. Could you please help me with it? Thank you in advance for your assistance!

---

Since GCC version 14 supports "code size reduction extensions" of the RISC-V specification, I am trying to build my software using this feature. First, I tried using zca and zcb extensions, and the build was successful without any issues. However, when I added zcmp extension and tried to build, I encountered an error during the execution of the Assembler.

Here are the detailed options and results. I would appreciate any advice on how to resolve this error and enable successful builds using zcmp.

[Case 1]
-march=rv32imc_zicsr_zca_zcb_zba_zbb_zbs
-mabi=ilp32

=>Completed both the compilation and assembly without any issues.

[Case 2]
-march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs
-mabi=ilp32

=>Completed the compilation, but I encountered the following error during the assembly.

  Assembler messages:
  Error: rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs: unknown prefixed ISA extension `zcmp'
  ...\tmp\cc62kIPH.s:3: Error: rv32i2p1_m2p0_c2p0_zicsr2p0_zca1p0_zcb1p0_zcmp1p0_zba1p0_zbb1p0_zbs1p0: unknown prefixed ISA extension `zcmp'
  ...\tmp\cc62kIPH.s:23: Error: unrecognized opcode `cm.push {ra,s0},-16'
  ...\tmp\cc62kIPH.s:68: Error: unrecognized opcode `cm.popret {ra,s0},16'

I'm not sure if this is related, but I have a question about the version of the GNU assembler included in this xPack. I understand that the latest version of GNU assembler is version 2.43, but it seems that the current version included in this xPack is version 2.42. Is there any plan to release an xPack that supports version 2.43 in the future?

Thank you all for taking the time to read my question. I appreciate any insights or suggestions you can provide. Looking forward to your responses. Have a great day!

[ilg-ul]

binutils 2.43 was just released a few days ago; it'll be part of the next xPack release.

[ilg-ul]

Since GCC version 14 supports "code size reduction extensions" of the RISC-V specification, ... However, when I added zcmp extension and tried to build, I encountered an error

Can you confirm that the assembler in binutils 2.43 accepts the zcmp extension?

@TommyMurphyTM1234, Tommy, do you know something about this?

[TommyMurphyTM1234]

Since GCC version 14 supports "code size reduction extensions" of the RISC-V specification, ... However, when I added zcmp extension and tried to build, I encountered an error

Can you confirm that the assembler in binutils 2.43 accepts the zcmp extension?

@TommyMurphyTM1234, Tommy, do you know something about this?

Sorry, not offhand - and I constantly struggle to keep up with the plethora and increasing number of RISC-V extensions and support for same in GCC/Binutils etc.

[TommyMurphyTM1234]

Since GCC version 14 supports "code size reduction extensions" of the RISC-V specification, ... However, when I added zcmp extension and tried to build, I encountered an error

Can you confirm that the assembler in binutils 2.43 accepts the zcmp extension?
@TommyMurphyTM1234, Tommy, do you know something about this?

Sorry, not offhand - and I constantly struggle to keep up with the plethora and increasing number of RISC-V extensions and support for same in GCC/Binutils etc.

According to this GCC 14 supports the Zcmp extension:

• https://gcc.gnu.org/gcc-14/changes.html

And Binutils seems to have been updated with Zcmp support earlier this year:

• https://marc.info/?w=2&r=1&s=zcmp+push+pop&q=t

Unfortunately I can't seem to tell what (if any) release of Binutils includes this support.

Maybe @kito-cheng might know?

[TommyMurphyTM1234]

For what it's worth I built the toolchain with GCC 14 and Binutils 2.43 sources and the assembler did not complain when the -march option passed included zcmp:

git clone https://github.com/riscv-collab/riscv-gnu-toolchain
cd riscv-gnu-toolchain
git clone https://github.com/gcc-mirror/gcc -b releases/gcc-14 gcc-14 --depth=1
git clone https://github.com/bminor/binutils-gdb -b binutils-2_43-branch binutils-2.43 --depth=1
./configure --prefix=`pwd`/installed-tools --disable-gdb --with-gcc-src=`pwd`/gcc-14 --with-binutils-src=`pwd`/binutils-2.43
make 2>&1 | tee build.log

./installed-tools/bin/riscv64-unknown-elf-gcc -v -march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs -mabi=ilp32 -c test.c
Using built-in specs.
COLLECT_GCC=./installed-tools/bin/riscv64-unknown-elf-gcc
Target: riscv64-unknown-elf
Configured with: /home/user/Downloads/issue-1529/gcc-14/configure --target=riscv64-unknown-elf --prefix=/home/user/Downloads/issue-1529/installed-tools --disable-shared --disable-threads --enable-languages=c,c++ --with-pkgversion=g897cd794d --with-system-zlib --enable-tls --with-newlib --with-sysroot=/home/user/Downloads/issue-1529/installed-tools/riscv64-unknown-elf --with-native-system-header-dir=/include --disable-libmudflap --disable-libssp --disable-libquadmath --disable-libgomp --disable-nls --disable-tm-clone-registry --src=/home/user/Downloads/issue-1529/gcc-14 --disable-multilib --with-abi=lp64d --with-arch=rv64imafdc --with-tune=rocket --with-isa-spec=20191213 'CFLAGS_FOR_TARGET=-Os    -mcmodel=medlow' 'CXXFLAGS_FOR_TARGET=-Os    -mcmodel=medlow'
Thread model: single
Supported LTO compression algorithms: zlib
gcc version 14.2.1 20240809 (g897cd794d)
COLLECT_GCC_OPTIONS='-v' '-c' '-march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs' '-mabi=ilp32' '-mtune=rocket' '-misa-spec=20191213' '-march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs'
 /home/user/Downloads/issue-1529/installed-tools/libexec/gcc/riscv64-unknown-elf/14.2.1/cc1 -quiet -v test.c -quiet -dumpbase test.c -dumpbase-ext .c -march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs -mabi=ilp32 -mtune=rocket -misa-spec=20191213 -march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs -version -o /tmp/ccagHg8q.s
GNU C17 (g897cd794d) version 14.2.1 20240809 (riscv64-unknown-elf)
        compiled by GNU C version 11.4.0, GMP version 6.2.1, MPFR version 4.1.0, MPC version 1.2.1, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/home/user/Downloads/issue-1529/installed-tools/riscv64-unknown-elf/usr/local/include"
ignoring duplicate directory "/home/user/Downloads/issue-1529/installed-tools/riscv64-unknown-elf/include"
#include "..." search starts here:
#include <...> search starts here:
 /home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/include
 /home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/include-fixed
 /home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/../../../../riscv64-unknown-elf/include
End of search list.
Compiler executable checksum: 08d30ffe2305aad0a26e9765fe0ee5db
COLLECT_GCC_OPTIONS='-v' '-c' '-march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs' '-mabi=ilp32' '-mtune=rocket' '-misa-spec=20191213' '-march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs'
 /home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/../../../../riscv64-unknown-elf/bin/as -v --traditional-format -march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs -march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs -mabi=ilp32 -misa-spec=20191213 -o test.o /tmp/ccagHg8q.s
GNU assembler version 2.43.0 (riscv64-unknown-elf) using BFD version (GNU Binutils) 2.43.0.20240809
COMPILER_PATH=/home/user/Downloads/issue-1529/installed-tools/libexec/gcc/riscv64-unknown-elf/14.2.1/:/home/user/Downloads/issue-1529/installed-tools/libexec/gcc/riscv64-unknown-elf/14.2.1/:/home/user/Downloads/issue-1529/installed-tools/libexec/gcc/riscv64-unknown-elf/:/home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/:/home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/:/home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/../../../../riscv64-unknown-elf/bin/
LIBRARY_PATH=/home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/:/home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/../../../../riscv64-unknown-elf/lib/:/home/user/Downloads/issue-1529/installed-tools/riscv64-unknown-elf/lib/
COLLECT_GCC_OPTIONS='-v' '-c' '-march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs' '-mabi=ilp32' '-mtune=rocket' '-misa-spec=20191213' '-march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs'

[ilg-ul]

Could you do another test with 2.42?

[TommyMurphyTM1234]

Could you do another test with 2.42?

GCC 14 + Binutils 2.42 fails:

git clone https://github.com/riscv-collab/riscv-gnu-toolchain
cd riscv-gnu-toolchain
git clone https://github.com/gcc-mirror/gcc -b releases/gcc-14 gcc-14 --depth=1
git clone https://github.com/bminor/binutils-gdb -b binutils-2_42-branch binutils-2.42 --depth=1
./configure --prefix=`pwd`/installed-tools --disable-gdb --with-gcc-src=`pwd`/gcc-14 --with-binutils-src=`pwd`/binutils-2.42
make 2>&1 | tee build.log

./installed-tools/bin/riscv64-unknown-elf-gcc -v -c -march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs -mabi=ilp32 test.c
Using built-in specs.
COLLECT_GCC=./installed-tools/bin/riscv64-unknown-elf-gcc
Target: riscv64-unknown-elf
Configured with: /home/user/Downloads/issue-1529/gcc-14/configure --target=riscv64-unknown-elf --prefix=/home/user/Downloads/issue-1529/installed-tools --disable-shared --disable-threads --enable-languages=c,c++ --with-pkgversion=g897cd794d --with-system-zlib --enable-tls --with-newlib --with-sysroot=/home/user/Downloads/issue-1529/installed-tools/riscv64-unknown-elf --with-native-system-header-dir=/include --disable-libmudflap --disable-libssp --disable-libquadmath --disable-libgomp --disable-nls --disable-tm-clone-registry --src=/home/user/Downloads/issue-1529/gcc-14 --disable-multilib --with-abi=lp64d --with-arch=rv64imafdc --with-tune=rocket --with-isa-spec=20191213 'CFLAGS_FOR_TARGET=-Os    -mcmodel=medlow' 'CXXFLAGS_FOR_TARGET=-Os    -mcmodel=medlow'
Thread model: single
Supported LTO compression algorithms: zlib
gcc version 14.2.1 20240809 (g897cd794d)
COLLECT_GCC_OPTIONS='-v' '-c' '-march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs' '-mabi=ilp32' '-mtune=rocket' '-misa-spec=20191213' '-march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs'
 /home/user/Downloads/issue-1529/installed-tools/libexec/gcc/riscv64-unknown-elf/14.2.1/cc1 -quiet -v test.c -quiet -dumpbase test.c -dumpbase-ext .c -march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs -mabi=ilp32 -mtune=rocket -misa-spec=20191213 -march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs -version -o /tmp/ccdX2eJX.s
GNU C17 (g897cd794d) version 14.2.1 20240809 (riscv64-unknown-elf)
        compiled by GNU C version 11.4.0, GMP version 6.2.1, MPFR version 4.1.0, MPC version 1.2.1, isl version none
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
ignoring nonexistent directory "/home/user/Downloads/issue-1529/installed-tools/riscv64-unknown-elf/usr/local/include"
ignoring duplicate directory "/home/user/Downloads/issue-1529/installed-tools/riscv64-unknown-elf/include"
#include "..." search starts here:
#include <...> search starts here:
 /home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/include
 /home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/include-fixed
 /home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/../../../../riscv64-unknown-elf/include
End of search list.
Compiler executable checksum: 08d30ffe2305aad0a26e9765fe0ee5db
COLLECT_GCC_OPTIONS='-v' '-c' '-march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs' '-mabi=ilp32' '-mtune=rocket' '-misa-spec=20191213' '-march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs'
 /home/user/Downloads/issue-1529/installed-tools/lib/gcc/riscv64-unknown-elf/14.2.1/../../../../riscv64-unknown-elf/bin/as -v --traditional-format -march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs -march=rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs -mabi=ilp32 -misa-spec=20191213 -o test.o /tmp/ccdX2eJX.s
GNU assembler version 2.42.0 (riscv64-unknown-elf) using BFD version (GNU Binutils) 2.42.0.20240723
Assembler messages:
Error: rv32imc_zicsr_zca_zcb_zcmp_zba_zbb_zbs: unknown prefixed ISA extension `zcmp'
/tmp/ccdX2eJX.s:3: Error: rv32i2p1_m2p0_c2p0_zicsr2p0_zca1p0_zcb1p0_zcmp1p0_zba1p0_zbb1p0_zbs1p0: unknown prefixed ISA extension `zcmp'

[ilg-ul]

Thank you, Tommy, it looks like you reproduced the error reported by @tasasao.

As expected, the solution is a new release 14.2.0-2 based to 2.43.

I'll add it to my (long) TODO list.

[ilg-ul]

#34

[tasasao]

ilg-ul, Tommy, thank you very much for investigating so quickly. It’s a great help.
If there's anything else I can do, such as additional checks, please let me know.