This change addresses a problem where QEMU incorrectly traps on
floating-point MADD group instructions with SIGILL, at least while
emulating MIPS32r2 processors. These instructions use the COP1X major
opcode and include ones like:
madd.d $f2,$f4,$f2,$f6
Here's Nathan's original analysis of the problem:
"QEMU essentially does:
d = find_cpu (cpu_string) // get CPU definition
fpu_init (env, d) // initialize fpu state (init FCR0, basically)
cpu_reset (env)
...and the cpu_reset call clears all interesting state that fpu_init
setup, then proceeds to reinitialize all the CP0 registers...but not
FCR0."
I have verified this change with system emulation running the GDB test
suite for the mips-sde-elf target (o32, big endian, 24Kf CPU emulated),
there were 55 progressions and no regressions.
Signed-off-by: Maciej W. Rozycki <macro@codesourcery.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
f1cb0951c5