https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79370
Bug ID: 79370
Summary: Cortex-A7 hardware division switched on for -mcpu but
not -mtune
Product: gcc
Version: 7.0.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: tulipawn at gmail dot com
Target Milestone: ---
Created attachment 40667
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=40667&action=edit
Preprocessed source
Compiling the attachment (produced from http://pastebin.com/X3ZTp1c0) only
emits sdiv instructions for -mcpu=cortex-a7 but not for the more logical case
of -mtune=cortex-a7
FWIW, running the produced "tuned" code on a Cortex-A53 (32bit mode) incurs a
6x penalty compared with -mcpu which is fully consistent with targeting a
soft-division CPU.
gcc version 7.0.1 20170127, switches used:
-Ofast -mtune=cortex-a7 -marm -mfloat-abi=hard -mfpu=vfpv4
