"The problem is that egcs/gcc-2.95's reorganisation of the prologue and
epilogue code to use rtl instead of output_asm_insn() completely broke our
hooks. rtl is emitted in a different order, only after optimisation, while
output_asm_insn() is emitted immediately. rtl is presumably used so that
the prologue and epilogue can be optimised.
I couldn't find any good examples to copy. gcc's own
FUNCTION_BLOCK_PROFILER still uses output_asm_insn() and seems to be
completely broken. One of the XXX comments points to this.
IIRC, the hacks here basically arrange to emit magic label names; then when
the magic names are output, they are transformed into prologue and epilogue
code."
Submitted by: bde
6995e4285b