https://gcc.gnu.org/bugzilla/show_bug.cgi?id=112648
Bug ID: 112648
Summary: RISC-V Vector parameter riscv-autovec-lmul value is
ineffective
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: jeremy.bennett at embecosm dot com
Target Milestone: ---
Created attachment 56656
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=56656&action=edit
Reproducer source
The GCC parameter riscv-autovec-lmul is used to force LMUL to be held to a
particular value. Vital for processors which do not support changing LMUL. The
parameter is not always effective.
Reproducer (test.c):
int a[8];
int b;
int c() {
for (; b; b++)
a[b] = (float)b;
}
Compile with:
riscv64-unknown-linux-gnu-gcc -march=rv64gcv -mabi=lp64d -O2
--param=riscv-autovec-lmul=m1 -S test.c
Detect value of LMUL != m1 using grep:
grep 'vsetvli.*\(\(m8\)\|\(m4\)\|\(m2\)\|\(mf2\)\|\(mf4\)\|\(mf8\)\)' test.s
Output is:
vsetvli a4,a3,e8,mf4,ta,ma
System information
==================
Using built-in specs.
COLLECT_GCC=riscv64-unknown-linux-gnu-gcc
COLLECT_LTO_WRAPPER=/home/jeremy/gittrees/mustang/install/libexec/gcc/riscv64-unknown-linux-gnu/14.0.0/lto-wrapper
Target: riscv64-unknown-linux-gnu
Configured with: /home/jeremy/gittrees/mustang/gcc/configure
--target=riscv64-unknown-linux-gnu
--prefix=/home/jeremy/gittrees/mustang/install
--with-sysroot=/home/jeremy/gittrees/mustang/install/sysroot
--with-pkgversion=g41aacdea55c --with-system-zlib --enable-shared --enable-tls
--enable-languages=c,c++,fortran --disable-libmudflap --disable-libssp
--disable-libquadmath --disable-libsanitizer --disable-nls --disable-bootstrap
--src=/home/jeremy/gittrees/mustang/gcc --enable-multilib --with-abi=lp64d
--with-arch=rv64gc --with-tune= --with-isa-spec=20191213 'CFLAGS_FOR_TARGET=-O2
-mcmodel=medany' 'CXXFLAGS_FOR_TARGET=-O2 -mcmodel=medany'
Thread model: posix
Supported LTO compression algorithms: zlib
gcc version 14.0.0 20231121 (experimental) (g41aacdea55c)
