On 10/24/23 04:50, Richard Sandiford wrote:
The exit block can have multiple predecessors, for example if the function calls __builtin_eh_return. We might then need PHI nodes for values that are live on exit. RTL-SSA uses the normal dominance frontiers approach for calculating where PHI nodes are needed. However, dominannce.cc only calculates dominators for normal blocks, not the exit block. calculate_dominance_frontiers likewise only calculates dominance frontiers for normal blocks. This patch fills in the “missing” frontiers manually. gcc/ * rtl-ssa/internals.h (build_info::exit_block_dominator): New member variable. * rtl-ssa/blocks.cc (build_info::build_info): Initialize it. (bb_walker::bb_walker): Use it, moving the computation of the dominator to... (function_info::process_all_blocks): ...here. (function_info::place_phis): Add dominance frontiers for the exit block.
OK jeff