https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87079
Bug ID: 87079
Summary: nios2 optimization for size - case of regression
relatively to 5.3.0
Product: gcc
Version: 8.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: already5chosen at yahoo dot com
Target Milestone: ---
Created attachment 44586
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=44586&action=edit
5.3->8.3 regression - shifts instead of mulx
The issue was already reported together with another case that proved unrelated
to nios2. The original thread is now dedicated to this more general issue, so I
am repeating the reort of the first issue for convenience of tracking.
A case of significant regression in optimization for size between 5.3.0 (a
version supplied in Altera Nios2 SDK) and 8.2.0.
Compiled with -Wall -Os -ffreestanding -fbuiltin -mhw-div -mhw-mul -mhw-mulx
It looks like -Os flag caused to compiler to forget that hw-mulx is present.
The problem appears unique to nios2 back end. Similar back ends (MIPS32r6 and
RISCV32IM) are not affected.
