On 9/11/19 1:12 PM, Richard Sandiford wrote: > For -fipa-ra, IRA already keeps track of which specific registers > are call-clobbered in a region, rather than using global information. > The patch generalises this so that it tracks which ABIs are used > by calls in the region. > > We can then use the new ABI descriptors to handle partially-clobbered > registers in the same way as fully-clobbered registers, without having > special code for targetm.hard_regno_call_part_clobbered. This in turn > makes -fipa-ra work for partially-clobbered registers too. > > A side-effect of allowing multiple ABIs is that we no longer have > an obvious set of conflicting registers for the self-described > "fragile hack" in ira-constraints.c. This code kicks in for > user-defined registers that aren't live across a call at -O0, > and it tries to avoid allocating a call-clobbered register to them. > Here I've used the set of call-clobbered registers in the current > function's ABI, applying on top of any registers that are clobbered by > called functions. This is enough to keep gcc.dg/debug/dwarf2/pr5948.c > happy. > > The handling of GENERIC_STACK_CHECK in do_reload seemed to have > a reversed condition: > > for (int i = 0; i < FIRST_PSEUDO_REGISTER; i++) > if (df_regs_ever_live_p (i) > && !fixed_regs[i] > && call_used_or_fixed_reg_p (i)) > size += UNITS_PER_WORD; > > The final part of the condition counts registers that don't need to be > saved in the prologue, but I think the opposite was intended. Agreed. Given it's just used to emit a diagnostic and that in reality it's only used for Ada, I'm confident this code isn't getting exercised in any significant way right now.
> > > 2019-09-11 Richard Sandiford <richard.sandif...@arm.com> > > gcc/ > * function-abi.h (call_clobbers_in_region): Declare. > (call_clobbered_in_region_p): New function. > * function-abi.cc (call_clobbers_in_region): Likewise. > * ira-int.h: Include function-abi.h. > (ira_allocno::crossed_calls_abis): New field. > (ALLOCNO_CROSSED_CALLS_ABIS): New macro. > (ira_need_caller_save_regs): New function. > (ira_need_caller_save_p): Likewise. > * ira.c (setup_reg_renumber): Use ira_need_caller_save_p instead > of call_used_or_fixed_regs. > (do_reload): Use crtl->abi to test whether the current function > needs to save a register in the prologue. Count registers that > need to be saved rather than registers that don't. > * ira-build.c (create_cap_allocno): Copy ALLOCNO_CROSSED_CALLS_ABIS. > Remove unnecessary | from ALLOCNO_CROSSED_CALLS_CLOBBERED_REGS. > (propagate_allocno_info): Merge ALLOCNO_CROSSED_CALLS_ABIS too. > (propagate_some_info_from_allocno): Likewise. > (copy_info_to_removed_store_destinations): Likewise. > (ira_flattening): Say that ALLOCNO_CROSSED_CALLS_ABIS and > ALLOCNO_CROSSED_CALLS_CLOBBERED_REGS are handled conservatively. > (ira_build): Use ira_need_caller_save_regs instead of > call_used_or_fixed_regs. > * ira-color.c (calculate_saved_nregs): Use crtl->abi to test > whether the current function would need to save a register > before using it. > (calculate_spill_cost): Likewise. > (allocno_reload_assign): Use ira_need_caller_save_regs and > ira_need_caller_save_p instead of call_used_or_fixed_regs. > * ira-conflicts.c (ira_build_conflicts): Use > ira_need_caller_save_regs rather than call_used_or_fixed_regs > as the set of call-clobbered registers. Remove the > call_used_or_fixed_regs mask from the calculation of > temp_hard_reg_set and mask its use instead. Remove special > handling of partially-clobbered registers. > * ira-costs.c (ira_tune_allocno_costs): Use ira_need_caller_save_p. > * ira-lives.c (process_bb_node_lives): Use mode_clobbers to > calculate the set of conflicting registers for calls that > can throw. Record the ABIs of calls in ALLOCNO_CROSSED_CALLS_ABIS. > Use full_and_partial_reg_clobbers rather than full_reg_clobbers > for the calculation of ALLOCNO_CROSSED_CALLS_CLOBBERED_REGS. > Use eh_edge_abi to calculate the set of registers that could > be clobbered by an EH edge. Include partially-clobbered as > well as fully-clobbered registers. OK jeff
