"remove -mrvv compile option" make newlib library code has side effect....

[chihinko]

library newlib is built with -O2 by default, the -O2 option imply auto-vectorization -mriscv-vector-bits=128,
this would make library code generate vector code that only work for spike --varch=vlen:128,elen:64,slen:128
when execute.

Here is an example:
riscv64-unknown-elf-gcc -O2 -mriscv-vector-bits=64 tmp.c -o tmp.64.x
spike --varch=vlen:64,elen:32,slen:64 --isa=RV64IMAFDCV pk tmp.64.x
b = 0.000 c = 0.000
b = 1.380 c = 1.380
b = 1.380 c = 1.380
b = 1.380 c = 1.380
b = 1.380 c = 1.380
b = 1.380 c = 1.380
b = 1.380 c = 1.380
b = 1.380 c = 1.380
b = 1.380 c = 1.380
b = 1.380 c = 1.380
should be
b = 0.000 c = 0.000
b = 1.000 c = 2.000
b = 2.000 c = 4.000
b = 3.000 c = 6.000
b = 4.000 c = 8.000
b = 5.000 c = 10.000
b = 6.000 c = 12.000
b = 7.000 c = 14.000
b = 8.000 c = 16.000
b = 9.000 c = 18.000

tmp.c.gz

[zhongjuzhe]

Yeah, rvv-next currently by default VLA autovectorization with -O2 which should run on VLENB >= 128. Since the original framework base on ARM SVE which only support vector length >= 128. Well, it has been fixed by me in the latest upstream GCC13 and I working on pushing && refining codes of rvv-next into GCC upstream. It will not be an issue in upstream GCC. However, upstream GCC is far from support all RVV features. sifive@kito-cheng is helping me with reviewing && merging RVV codes in upstream GCC. To solve your problem, would you mind send a PR adding -mrvv compile option back ? Then I merge it. It's simple add MASK (RVV) in riscv.opt and disable them in TARGET_VECTORIZE_PREFERRED_SIMD_MODE target hook implementation.

[chihinko]

There is another problem:
Since -O2 means generating vector codes, I used -O1 to build newlib library, it works fine, no vector assembly codes in newlib
library. I was able to run tests with spike.
But used same idea to build glibc, there are a lot of vector assembly codes generated in glibc library:
grep csrr *.dump
10546: c20026f3 csrr a3,vl
116b0: c22022f3 csrr t0,vlenb
122be: c20026f3 csrr a3,vl
122fe: c20026f3 csrr a3,vl

I tried -O0, but build failed when compiling glibc/time/tzfile.c
How can I work around this problem ?