From 113dab2b9d511f3aadc30a6a921fc30bd5f93706 Mon Sep 17 00:00:00 2001 From: Aldy Hernandez Date: Thu, 28 Oct 2021 11:44:13 +0200 Subject: [PATCH] Improve backward threading with switches. We've been essentially using find_taken_edge_switch_expr() in the backward threader, but this is suboptimal because said function only works with singletons. VRP has a much smarter find_case_label_range that works with ranges. Tested on x86-64 Linux with: a) Bootstrap & regtests. b) Verifying we get more threads than before. c) Asserting that the new code catches everything the old one code caught (over a set of bootstrap .ii files). gcc/ChangeLog: * tree-ssa-threadbackward.c (back_threader::find_taken_edge_switch): Use find_case_label_range instead of find_taken_edge. gcc/testsuite/ChangeLog: * gcc.dg/tree-ssa/vrp106.c: Adjust for threading. * gcc.dg/tree-ssa/vrp113.c: Same. --- gcc/testsuite/gcc.dg/tree-ssa/vrp106.c | 4 ++-- gcc/testsuite/gcc.dg/tree-ssa/vrp113.c | 2 -- gcc/tree-ssa-threadbackward.c | 8 ++++---- 3 files changed, 6 insertions(+), 8 deletions(-) diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp106.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp106.c index f25ea9c..dc5021a 100644 --- a/gcc/testsuite/gcc.dg/tree-ssa/vrp106.c +++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp106.c @@ -1,6 +1,6 @@ /* PR tree-optimization/18046 */ -/* { dg-options "-O2 -fdump-tree-vrp-thread1-details" } */ -/* { dg-final { scan-tree-dump-times "Threaded jump" 1 "vrp-thread1" } } */ +/* { dg-options "-O2 -fdump-tree-ethread-details" } */ +/* { dg-final { scan-tree-dump-times "Registering jump thread" 1 "ethread" } } */ /* During VRP we expect to thread the true arm of the conditional through the switch and to the BB that corresponds to the 7 ... 9 case label. */ extern void foo (void); diff --git a/gcc/testsuite/gcc.dg/tree-ssa/vrp113.c b/gcc/testsuite/gcc.dg/tree-ssa/vrp113.c index ab8d91e..dfe4989 100644 --- a/gcc/testsuite/gcc.dg/tree-ssa/vrp113.c +++ b/gcc/testsuite/gcc.dg/tree-ssa/vrp113.c @@ -13,5 +13,3 @@ int f(int a) { case 7: return 19; } } - -/* { dg-final { scan-tree-dump "return 3;" "vrp1" { xfail *-*-* } } } */ diff --git a/gcc/tree-ssa-threadbackward.c b/gcc/tree-ssa-threadbackward.c index 6c1b159..456effc 100644 --- a/gcc/tree-ssa-threadbackward.c +++ b/gcc/tree-ssa-threadbackward.c @@ -195,11 +195,11 @@ back_threader::find_taken_edge_switch (const vec &path, if (r.varying_p ()) return NULL; - tree val; - if (r.singleton_p (&val)) - return ::find_taken_edge (gimple_bb (sw), val); + tree label = find_case_label_range (sw, &r); + if (!label) + return NULL; - return NULL; + return find_edge (gimple_bb (sw), label_to_block (cfun, CASE_LABEL (label))); } // Same as find_taken_edge, but for paths ending in a GIMPLE_COND. -- 2.7.4