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Functions
bool	recognize_if_then_else (basic_block, basic_block , basic_block , bool succs_any=false)
bool	tree_ssa_ifcombine_bb (basic_block)

Function Documentation

◆ recognize_if_then_else()

bool recognize_if_then_else	(	basic_block	cond_bb,
		basic_block *	then_bb,
		basic_block *	else_bb,
		bool	succs_any )

Copyright (C) 2026 Free Software Foundation, Inc.

This file is part of GCC.

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This pass combines COND_EXPRs to simplify control flow.  It
currently recognizes bit tests and comparisons in chains that
represent logical and or logical or of two COND_EXPRs.

It does so by walking basic blocks in a approximate reverse
post-dominator order and trying to match CFG patterns that
represent logical and or logical or of two COND_EXPRs.
Transformations are done if the COND_EXPR conditions match
either

  1. two single bit tests X & (1 << Yn) (for logical and)

  2. two bit tests X & Yn (for logical or)

  3. two comparisons X OPn Y (for logical or)

To simplify this pass, removing basic blocks and dead code
is left to CFG cleanup and DCE.

Recognize a if-then-else CFG pattern starting to match with the COND_BB
basic-block containing the COND_EXPR.  If !SUCCS_ANY, the condition must not
resolve to a constant for a match.  Returns true if the pattern matched,
false otherwise.  In case of a !SUCCS_ANY match, the recognized then end
else blocks are stored to *THEN_BB and *ELSE_BB.  If *THEN_BB and/or
*ELSE_BB are already set, they are required to match the then and else
basic-blocks to make the pattern match.  If SUCCS_ANY, *THEN_BB and *ELSE_BB
will not be filled in, and they will be found to match even if reversed.

References EDGE_COUNT, EDGE_SUCC, known_succ_p(), and basic_block_def::succs.

Referenced by apply_clusters(), tree_ssa_ifcombine_bb(), and tree_ssa_ifcombine_bb_1().

◆ tree_ssa_ifcombine_bb()

bool tree_ssa_ifcombine_bb ( basic_block inner_cond_bb )

Recognize a CFG pattern and dispatch to the appropriate
if-conversion helper.  We start with BB as the innermost
worker basic-block.  Returns true if a transformation was done.

References bb_no_side_effects_p(), changed, forwarder_block_to(), known_succ_p(), NULL, recognize_if_then_else(), same_phi_args_p(), single_pred(), single_pred_p(), single_succ_p(), and tree_ssa_ifcombine_bb_1().

Referenced by tail_merge_optimize().

Functions

Function Documentation

◆ recognize_if_then_else()

◆ tree_ssa_ifcombine_bb()