On Sun, Aug 14, 2016 at 01:23:16AM -0500, Daniel Santos wrote: > I'm experimenting with ways to optimize wine (x86 target only) and I believe > I can shrink wine's total text size by around 7% by outlining the lengthy > pro- and epilogues required for ms_abi functions making sysv_abi calls. > Theoretically, fewer instruction cache misses will offset the extra 4 > instructions per function and result in a net performance gain. However, I'm > new to the gcc project and a novice x86 assembly programmer as well (have > been wanting to work on gcc for a while now!) In short, I want to: > > 1. Replace the prologue that pushes di, sp and xmm6-15 with a single call to > a global "ms_abi_push_regs" routine > 2. Replace the epilogue that pops these regs with a jmp to a global > "ms_abi_pop_regs" routine > 3. Add the two routines somewhere so that they are linked into the output.
I think you want to put those into libgcc then. > > I have this working in a small-scale experiment (writing the ms_abi function > in assembly), but I'm not certain how I would add these routines. Should I > make them built-ins? > > I have found the code that adds the clobber RTL instructions in > ix86_expand_call() (gcc/config/i386/i386.c:25832), and I see that > thread_prologue_and_epilogue_insns() (gcc/function.c) is where these > clobbers are expanded into the prologue and epilogue, but I'm not sure what > the cleanest way to convert this is. My thought was to replace the > clobber_reg() calls with one that would add an insn_call, or would it be > better to do this in thread_prologue_and_epilogue_insns() where prologue and > epilogue generation belongs? But that function is for all targets. Any > pointers greatly appreciated! I think you probably want to look at ix86_expand_prologue. Hope that helps, but I'm no expert, so take it with some salt. Trev
