with -mabicalls: the gcc/egcs code emits hand-scheduled code with an
insn in a "jal _mcount" delayslot. But with -mabicalls, the "jal"
expands into a call via $t9 and the delay-slot is already filled.
See PR#5248.
1. Change linkspec to not pass -nostdlib to binutils ld, since on mips,
ld parses "-nostdlib" as a set of short options which produce
nonworking binaries.
2. Turn off ASM_OUTPUT_DEF definition: the egcs iris6.h says that
our old definition (from gcc 2.7.2.2 iris5.h isnt really whats
wanted here.
3. Turn off SET_ASM_OP (which defaults to .set) to stop
dwarf2out.c from emitting debug(?) info for C++ using ".set",
since both gas and mips as use .set to control assembler
optimizations, not for equating labels. From iris6.h.
and nonzero -G values are incompatible with PIC.
4. Set default GVALUE (for -G) to 0; this target always produces PIC
by default, and on mips, PIC is incompatible with `small' segment.
5. Set TARGET_DEFAULT to enable "-mdebuga" to defeat
GO_IF_LEGITIMATE_ADDRESS "smarts". GO_IF_LEGITIMATE_ADDRESS pretends
that mips supports an address mode of constant + register.
For constants larger than 16 bits, that relies on assembler fixups
via $at. egcs 1.1 (expr.c delta 1.76) may break up those addresses
such that the backend cannot output them as offsets in load or store
instructions anymore; no other patterns match so egcs coredumps.
jonathan