It appears that gcc configured for mipsel-linux will execute a "break 7"
instruction on integer division by zero.
This causes the kernel (I am using 2.4.25) to send SIGTRAP.
Gcj when configured for this platform uses the -f-use-divide-subroutine
option, causing it to never generate inline division instructions (nor
the accompanying break 7), but instead call a runtime function that
properly handles throwing ArithmeticException.
Q1: Is this behavior (use of break 7 and SIGTRAP) part of some ABI
specification? I'll admit a bit of ignorance in this area.
Q2: Does anyone see any reason that libgcj should not be configured to
handle the SIGTRAP and throw the ArithmeticException from the signal
handler (similar to what is done on i386).
Q3: Will using SIGTRAP in this manner make debugging programs that
divide things by zero very difficult to debug under gdb?
Q4: I appears that on the i386, a divide overflow causes SIGFPE. Why
doesn't the mips-linux kernel sent SIGFPE on "break 7"
Q5: prims.cc in libgcj implies that we should be handling SIGFPE to do
all this. If I make these changes, won't it be a little confusing that
all references to SIGFPE are really SIGTRAP?
David Daney
