at the _cas0 label, the linker would generate spurious stack
adjustment before the return:
atexitdont+0x84 0x000000000003614c CLREX $0xf
atexitdont+0x88 0x0000000000036150 MOVW R31,R0
atexitdont+0x8c 0x0000000000036154 MOV (SP)16!,R30 <- ????????????
atexitdont+0x90 0x0000000000036158 RETURN
the work arround is to move the code into its own cas0
text symbol.
this fixes impossible cwfs crashes in srvi().
0002fd0cf7