https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103278
Bug ID: 103278
Summary: [12 Regression] Recent change to cddce inhibits switch
optimization
Product: gcc
Version: 12.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: law at gcc dot gnu.org
Target Milestone: ---
On iq2000-elf this change:
commit 045206450386bcd774db3bde0c696828402361c6
Author: Richard Biener <rguent...@suse.de>
Date: Fri Nov 12 10:21:22 2021 +0100
tree-optimization/102880 - improve CD-DCE
[ ... ]
Is inhibiting switch optimization for tree-ssa/if-to-switch-3.c from converting
an if statement into a switch statement:
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-iftoswitch-optimized" } */
int IsMySuperRandomChar(int aChar)
{
return aChar == 0x0009 || aChar == 0x000A ||
aChar == 0x000C || aChar == 0x000D ||
aChar == 0x0020 || aChar == 0x0030;
}
/* { dg-final { scan-tree-dump "Condition chain with \[^\n\r]\* BBs transformed
into a switch statement." "iftoswitch" } } */
After today's cd-dce change we no longer turn that into a switch:
Before:
;; Canonical GIMPLE case clusters: 9-10 12 13 32 48
;; JT can be built: JT(values:6 comparisons:10 range:40 density: 25.00%):9-48
j.c:8:26: optimized: Condition chain with 3 BBs transformed into a switch
statement.
After:
;; Canonical GIMPLE case clusters: 9-10 12-13 32 48
