https://gcc.gnu.org/bugzilla/show_bug.cgi?id=119267
Bug ID: 119267
Summary: RISC-V: gcc generates vsetvli with wrong LMUL with
extended assembly
Product: gcc
Version: 14.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: mperotti at iis dot ee.ethz.ch
Target Milestone: ---
Created attachment 60739
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=60739&action=edit
Content of "a-bug.i"
I experienced an issue when writing RISC-V V assembly code in a .c file.
Function content:
```
asm volatile ("vsetvli t0, %0, e8, m1, ta, ma" :: "r" (16) : "t0", "vtype",
"vl");
volatile unsigned char Va[] = {1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8};
asm volatile ("vle8.v v1, (%0)":: "r"(Va));
volatile unsigned char Vb[] = {1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8};
asm volatile ("vle8.v v2, (%0)":: "r"(Vb));
asm volatile ("vsetvli t0, %0, e16, m1, ta, ma" :: "r" (16) : "t0", "vtype",
"vl");
volatile unsigned short int Vc[] = {1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6,
7, 8};
asm volatile ("vle16.v v1, (%0)":: "r"(Vc));
volatile unsigned short int Vd[] = {1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6,
7, 8};
asm volatile ("vle16.v v2, (%0)":: "r"(Vd));
```
Fragment of the objdump:
```
vsetvli t0,a5,e16,m1,ta,ma
lui a5,0x10
addi a4,a5,488 # 101e8 <_start+0x40>
addi a5,s0,-80
vsetivli zero,4,e64,m8,ta,ma
vle64.v v8,(a4)
vsetivli zero,4,e64,m8,ta,ma
vse64.v v8,(a5)
addi a5,s0,-80
vle16.v v1,(a5)
```
gcc inserts vsetivli instructions that overwrite the LMUL I previously set
without setting it back so that my "vle16.v v1" instruction becomes illegal.
The code of a-bug.i is attached.
-------------------------------------------------
Command line:
${path1}/riscv64-unknown-elf-gcc -v -save-temps -Wall -Wextra -nostartfiles
-march=rv64gv -mabi=lp64 bug.c
Warning:
No warnings
-------------------------------------------------
Target: riscv64-unknown-elf
Configured with: ${path0}/configure --target=riscv64-unknown-elf
--prefix=${path1}/riscv-gcc --disable-shared --disable-threads
--enable-languages=c,c++ --with-pkgversion=g04696df09 --with-system-zlib
--enable-tls --with-newlib
--with-sysroot=${path1}/riscv-gcc/riscv64-unknown-elf
--with-native-system-header-dir=/include --disable-libmudflap --disable-libssp
--disable-libquadmath --disable-libgomp --disable-nls
--disable-tm-clone-registry --src=../../gcc --enable-multilib --with-abi=lp64d
--with-arch=rv64gcv --with-tune=rocket --with-isa-spec=20191213
'CFLAGS_FOR_TARGET=-Os -mcmodel=medany' 'CXXFLAGS_FOR_TARGET=-Os
-mcmodel=medany'
gcc version 14.2.0 (g04696df09)
-------------------------------------------------
Extended command output:
Using built-in specs.
COLLECT_GCC=../../install/riscv-gcc/bin/riscv64-unknown-elf-gcc
COLLECT_LTO_WRAPPER=${path}/install/riscv-gcc/libexec/gcc/riscv64-unknown-elf/14.2.0/lto-wrapper
Target: riscv64-unknown-elf
Configured with: ${path}/toolchain/riscv-gnu-toolchain/build/../gcc/configure
--target=riscv64-unknown-elf --prefix=${path}/install/riscv-gcc
--disable-shared --disable-threads --enable-languages=c,c++
--with-pkgversion=g04696df09 --with-system-zlib --enable-tls --with-newlib
--with-sysroot=${path}/install/riscv-gcc/riscv64-unknown-elf
--with-native-system-header-dir=/include --disable-libmudflap --disable-libssp
--disable-libquadmath --disable-libgomp --disable-nls
--disable-tm-clone-registry --src=../../gcc --enable-multilib --with-abi=lp64d
--with-arch=rv64gcv --with-tune=rocket --with-isa-spec=20191213
'CFLAGS_FOR_TARGET=-Os -mcmodel=medany' 'CXXFLAGS_FOR_TARGET=-Os
-mcmodel=medany'
Thread model: single
Supported LTO compression algorithms: zlib
gcc version 14.2.0 (g04696df09)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-nostartfiles' '-march=rv64gv'
'-mabi=lp64' '-Wall' '-Wextra' '-mtune=rocket' '-misa-spec=20191213'
'-march=rv64imafdv_zicsr_zifencei_zve32f_zve32x_zve64d_zve64f_zve64x_zvl128b_zvl32b_zvl64b'
'-dumpdir' 'a-'
${path}/install/riscv-gcc/libexec/gcc/riscv64-unknown-elf/14.2.0/cc1 -E -quiet
-v bug.c -march=rv64gv -mabi=lp64 -mtune=rocket -misa-spec=20191213
-march=rv64imafdv_zicsr_zifencei_zve32f_zve32x_zve64d_zve64f_zve64x_zvl128b_zvl32b_zvl64b
-Wall -Wextra -fpch-preprocess -o a-bug.i
ignoring nonexistent directory
"${path}/install/riscv-gcc/riscv64-unknown-elf/usr/local/include"
ignoring duplicate directory
"${path}/install/riscv-gcc/riscv64-unknown-elf/include"
#include "..." search starts here:
#include <...> search starts here:
${path}/install/riscv-gcc/lib/gcc/riscv64-unknown-elf/14.2.0/include
${path}/install/riscv-gcc/lib/gcc/riscv64-unknown-elf/14.2.0/include-fixed
${path}/install/riscv-gcc/lib/gcc/riscv64-unknown-elf/14.2.0/../../../../riscv64-unknown-elf/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-nostartfiles' '-march=rv64gv'
'-mabi=lp64' '-Wall' '-Wextra' '-mtune=rocket' '-misa-spec=20191213'
'-march=rv64imafdv_zicsr_zifencei_zve32f_zve32x_zve64d_zve64f_zve64x_zvl128b_zvl32b_zvl64b'
'-dumpdir' 'a-'
${path}/install/riscv-gcc/libexec/gcc/riscv64-unknown-elf/14.2.0/cc1
-fpreprocessed a-bug.i -quiet -dumpdir a- -dumpbase bug.c -dumpbase-ext .c
-march=rv64gv -mabi=lp64 -mtune=rocket -misa-spec=20191213
-march=rv64imafdv_zicsr_zifencei_zve32f_zve32x_zve64d_zve64f_zve64x_zvl128b_zvl32b_zvl64b
-Wall -Wextra -version -o a-bug.s
GNU C17 (g04696df09) version 14.2.0 (riscv64-unknown-elf)
compiled by GNU C version 14.2.0, GMP version 6.2.1, MPFR version
4.1.0, MPC version 1.2.1, isl version isl-0.24-GMP
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: bba804f6629957e309ef1ba78c198dd2
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-nostartfiles' '-march=rv64gv'
'-mabi=lp64' '-Wall' '-Wextra' '-mtune=rocket' '-misa-spec=20191213'
'-march=rv64imafdv_zicsr_zifencei_zve32f_zve32x_zve64d_zve64f_zve64x_zvl128b_zvl32b_zvl64b'
'-dumpdir' 'a-'
${path}/install/riscv-gcc/lib/gcc/riscv64-unknown-elf/14.2.0/../../../../riscv64-unknown-elf/bin/as
-v --traditional-format -march=rv64gv
-march=rv64imafdv_zicsr_zifencei_zve32f_zve32x_zve64d_zve64f_zve64x_zvl128b_zvl32b_zvl64b
-mabi=lp64 -misa-spec=20191213 -o a-bug.o a-bug.s
GNU assembler version 2.43.1 (riscv64-unknown-elf) using BFD version (GNU
Binutils) 2.43.1
COMPILER_PATH=${path}/install/riscv-gcc/libexec/gcc/riscv64-unknown-elf/14.2.0/:${path}/install/riscv-gcc/libexec/gcc/riscv64-unknown-elf/14.2.0/:${path}/install/riscv-gcc/libexec/gcc/riscv64-unknown-elf/:${path}/install/riscv-gcc/lib/gcc/riscv64-unknown-elf/14.2.0/:${path}/install/riscv-gcc/lib/gcc/riscv64-unknown-elf/:${path}/install/riscv-gcc/lib/gcc/riscv64-unknown-elf/14.2.0/../../../../riscv64-unknown-elf/bin/
LIBRARY_PATH=${path}/install/riscv-gcc/lib/gcc/riscv64-unknown-elf/14.2.0/:${path}/install/riscv-gcc/lib/gcc/riscv64-unknown-elf/14.2.0/../../../../riscv64-unknown-elf/lib/:${path}/install/riscv-gcc/riscv64-unknown-elf/lib/
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-nostartfiles' '-march=rv64gv'
'-mabi=lp64' '-Wall' '-Wextra' '-mtune=rocket' '-misa-spec=20191213'
'-march=rv64imafdv_zicsr_zifencei_zve32f_zve32x_zve64d_zve64f_zve64x_zvl128b_zvl32b_zvl64b'
'-dumpdir' 'a.'
${path}/install/riscv-gcc/libexec/gcc/riscv64-unknown-elf/14.2.0/collect2
-plugin
${path}/install/riscv-gcc/libexec/gcc/riscv64-unknown-elf/14.2.0/liblto_plugin.so
-plugin-opt=${path}/install/riscv-gcc/libexec/gcc/riscv64-unknown-elf/14.2.0/lto-wrapper
-plugin-opt=-fresolution=a.res -plugin-opt=-pass-through=-lgcc
-plugin-opt=-pass-through=-lc -plugin-opt=-pass-through=-lgloss
-plugin-opt=-pass-through=-lgcc
--sysroot=${path}/install/riscv-gcc/riscv64-unknown-elf -melf64lriscv -X
-L${path}/install/riscv-gcc/lib/gcc/riscv64-unknown-elf/14.2.0
-L${path}/install/riscv-gcc/lib/gcc/riscv64-unknown-elf/14.2.0/../../../../riscv64-unknown-elf/lib
-L${path}/install/riscv-gcc/riscv64-unknown-elf/lib a-bug.o -lgcc --start-group
-lc -lgloss --end-group -lgcc
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-nostartfiles' '-march=rv64gv'
'-mabi=lp64' '-Wall' '-Wextra' '-mtune=rocket' '-misa-spec=20191213'
'-march=rv64imafdv_zicsr_zifencei_zve32f_zve32x_zve64d_zve64f_zve64x_zvl128b_zvl32b_zvl64b'
'-dumpdir' 'a.'
-------------------------------------------------
Thank you in advance.
