https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114243
Bug ID: 114243
Summary: -fsplit-wide-types bloats code by more than 50%
Product: gcc
Version: 14.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: gjl at gcc dot gnu.org
Target Milestone: ---
Created attachment 57616
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=57616&action=edit
pi-sigma.c: C99 test case
Compile the attached test case with:
$ avr-gcc pi-sigma.c -c -Os -mmcu=atmega8 -fstack-usage && avr-size pi-sigma.o
Then the code sizes are for respective versions of the compiler:
avr-gcc-v8: 624
avr-gcc-v14: 1008
which is an increase of code size of more than 60% !
The stack usage also increases by a lot. According to pi-sigma.su:
avr-gcc-v8:
-----------
pi-sigma.c:80:7:sigma 30 static
pi-sigma.c:86:7:pi_n 14 static
avr-gcc-v14:
------------
pi-sigma.c:80:7:sigma 86 static
pi-sigma.c:86:7:pi_n 36 static
That is for the 1st function the stack use almost triples!
With -fno-split-wide-types the performace of v14 code is similar to v8.
Target: avr
Configured with: ../../source/gcc-master/configure --target=avr --disable-nls
--with-dwarf2 --with-gnu-as --with-gnu-ld --disable-shared
--enable-languages=c,c++
Thread model: single
Supported LTO compression algorithms: zlib
gcc version 14.0.1 20240303 (experimental) (GCC)
