https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79480
Bug ID: 79480
Summary: -O3 and -mfpu=neon produces crashing code on ARM
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: ---
The gl-117 binary (source link attached) compiled with:
-mcpu=cortex-a5 -O3 -marm -fomit-frame-pointer -mfpu=neon -ftree-vectorize
crashes with a SIGBUS plus this kernel info:
Alignment trap: not handling instruction f4620adf at [<00067c8c>]
Unhandled fault: alignment exception (0x001) at 0x0048fcb1
Moreover, using LTO prints a warning about undefined behaviour:
main.cpp: In function ‘_ZL11myTimerFunci.isra.26’:
main.cpp:4762:29: warning: iteration 256 invokes undefined behavior
[-Waggressive-loop-optimizations]
int h = heat [yind] [i2];
^
main.cpp:4757:5: note: containing loop
for (i2 = 0; i2 < maxfx + 1; i2 ++)
^
The code is rather old C++ (g++ warns: ISO C++ forbids converting a string
constant to ‘char*’) but as long as -mfpu=neon is not used it doesn't crash,
even with the above warning. Reporting just in case.
