From 5b50850c3c6f2eceb8012dcc8d3cd5ddd94fac6c Mon Sep 17 00:00:00 2001 From: Richard Biener Date: Thu, 1 Dec 2022 16:14:14 +0100 Subject: [PATCH] Add --param max-unswitch-depth The following adds a --param to limit the depth of unswitched loop nests. One can use --param max-unswitch-depth=1 to disable unswitching of outer loops (the innermost loop will then be unswitched). PR tree-optimization/107946 * params.opt (-param=max-unswitch-depth=): New. * doc/invoke.texi (--param=max-unswitch-depth): Document. * tree-ssa-loop-unswitch.cc (init_loop_unswitch_info): Honor --param=max-unswitch-depth --- gcc/doc/invoke.texi | 3 +++ gcc/params.opt | 4 ++++ gcc/tree-ssa-loop-unswitch.cc | 4 +++- 3 files changed, 10 insertions(+), 1 deletion(-) diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi index 56e5e87..277ac35 100644 --- a/gcc/doc/invoke.texi +++ b/gcc/doc/invoke.texi @@ -14963,6 +14963,9 @@ The maximum depth of a loop nest suitable for complete peeling. @item max-unswitch-insns The maximum number of insns of an unswitched loop. +@item max-unswitch-depth +The maximum depth of a loop nest to be unswitched. + @item lim-expensive The minimum cost of an expensive expression in the loop invariant motion. diff --git a/gcc/params.opt b/gcc/params.opt index c1dcb7e..397ec0b 100644 --- a/gcc/params.opt +++ b/gcc/params.opt @@ -726,6 +726,10 @@ The maximum number of instructions to consider to unroll in a loop. Common Joined UInteger Var(param_max_unswitch_insns) Init(50) Param Optimization The maximum number of insns of an unswitched loop. +-param=max-unswitch-depth= +Common Joined UInteger Var(param_max_unswitch_depth) Init(50) IntegerRange(1, 50) Param Optimization +The maximum depth of a loop nest to be unswitched. + -param=max-variable-expansions-in-unroller= Common Joined UInteger Var(param_max_variable_expansions) Init(1) Param Optimization If -fvariable-expansion-in-unroller is used, the maximum number of times that an individual variable will be expanded during loop unrolling. diff --git a/gcc/tree-ssa-loop-unswitch.cc b/gcc/tree-ssa-loop-unswitch.cc index e8c9bd6..df7a201 100644 --- a/gcc/tree-ssa-loop-unswitch.cc +++ b/gcc/tree-ssa-loop-unswitch.cc @@ -263,8 +263,10 @@ init_loop_unswitch_info (class loop *&loop, unswitch_predicate *&hottest, /* Unswitch only nests with no sibling loops. */ class loop *outer_loop = loop; + unsigned max_depth = param_max_unswitch_depth; while (loop_outer (outer_loop)->num != 0 - && !loop_outer (outer_loop)->inner->next) + && !loop_outer (outer_loop)->inner->next + && --max_depth != 0) outer_loop = loop_outer (outer_loop); hottest = NULL; hottest_bb = NULL; -- 2.7.4