From c7151283dc747769d4ac4f216d8f519bda2569b5 Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Mon, 19 Feb 2024 11:10:50 +0100 Subject: [PATCH] rtl-optimization/54052 - RTL SSA PHI insertion compile-time hog The following tries to address the PHI insertion compile-time hog in RTL fwprop observed with the PR54052 testcase where the loop computing the "unfiltered" set of variables possibly needing PHI nodes for each block exhibits quadratic compile-time and memory-use. It does so by pruning the local DEFs with LR_OUT of the block, removing regs that can never be LR_IN (defined by this block) in the dominance frontier. PR rtl-optimization/54052 * rtl-ssa/blocks.cc (function_info::place_phis): Filter local defs by LR_OUT. --- gcc/rtl-ssa/blocks.cc | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/gcc/rtl-ssa/blocks.cc b/gcc/rtl-ssa/blocks.cc index 8996443e8d5..cf4224e61ec 100644 --- a/gcc/rtl-ssa/blocks.cc +++ b/gcc/rtl-ssa/blocks.cc @@ -645,7 +645,12 @@ function_info::place_phis (build_info &bi) if (bitmap_empty_p (&frontiers[b1])) continue; - bitmap b1_def = &DF_LR_BB_INFO (BASIC_BLOCK_FOR_FN (m_fn, b1))->def; + // Defs in B1 that are possibly in LR_IN in the dominance frontier + // blocks. + auto_bitmap b1_def; + bitmap_and (b1_def, &DF_LR_BB_INFO (BASIC_BLOCK_FOR_FN (m_fn, b1))->def, + DF_LR_OUT (BASIC_BLOCK_FOR_FN (m_fn, b1))); + bitmap_iterator bmi; unsigned int b2; EXECUTE_IF_SET_IN_BITMAP (&frontiers[b1], 0, b2, bmi)