[MIPS] -mno-abicalls is ignored for LTO

[vit9696]

For 2 empty files (t.c and k.S) do the following:

clang -target mips-linux-gnu -c -flto -mno-abicalls t.c -o t.o
clang -target mips-linux-gnu -c -flto -mno-abicalls k.S -o k.o
clang -target mips-linux-gnu  -flto -mno-abicalls -nostdlib -fuse-ld=lld t.o k.o -o t

The following warnings will be generated:

ld.lld: warning: lto.tmp: linking abicalls code with non-abicalls code k.o
ld.lld: warning: cannot find entry symbol __start; not setting start address

The problematic one is the ld.lld: warning: lto.tmp: linking abicalls code with non-abicalls code k.o. The assembly code is correctly generated without ABI calls. However, LTO code apparently is generated with ABI calls despite -mno-abicalls argument present.

Is it a bug or shall one disable mno-abicalls anyhow differently?

[llvmbot]

@llvm/issue-subscribers-lld-elf

[llvmbot]

@llvm/issue-subscribers-backend-mips

[vit9696]

The issue can be worked around by adding -Wl,-mllvm,-mattr=+noabicalls. Apparently the bug is similar to #50505.