https://gcc.gnu.org/bugzilla/show_bug.cgi?id=95429
Bug ID: 95429
Summary: Wrong code generated for -Os with target m68k on
Ubuntu
Product: gcc
Version: 9.3.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
Assignee: unassigned at gcc dot gnu.org
Reporter: i...@abp-labs.com
Target Milestone: ---
Created attachment 48638
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=48638&action=edit
C source file compiled with -E option.
Hello,
I am using m68k-linux-gnu-gcc to compile code for my homebrew computer.
With the version gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04), the assembly
for the following code is correct:
RTC_Msg1.nbBytes = 9;
RTC_buffer[0] = 8;
RTC_buffer[1] = RTC_buffer[5] = (uint8_t)(year_bcd >> 24);
RTC_buffer[2] = RTC_buffer[6] = (uint8_t)(year_bcd >> 16);
RTC_buffer[3] = RTC_buffer[7] = (uint8_t)(year_bcd >> 8);
RTC_buffer[4] = RTC_buffer[8] = (uint8_t)(year_bcd);
gcc version 7.5.0 (Ubuntu 7.5.0-3ubuntu1~18.04)
157c 0009 0001 moveb #9,%a2@(1)
1f7c 0008 0012 moveb #8,%sp@(18)
2002 movel %d2,%d0
4240 clrw %d0
4840 swap %d0
e048 lsrw #8,%d0
1f40 0017 moveb %d0,%sp@(23)
1f40 0013 moveb %d0,%sp@(19)
2002 movel %d2,%d0
4240 clrw %d0
4840 swap %d0
1f40 0018 moveb %d0,%sp@(24)
1f40 0014 moveb %d0,%sp@(20)
2002 movel %d2,%d0
e088 lsrl #8,%d0
1f40 0019 moveb %d0,%sp@(25)
1f40 0015 moveb %d0,%sp@(21)
1f42 001a moveb %d2,%sp@(26)
1f42 0016 moveb %d2,%sp@(22)
With the version 9.3.0 provided in Ubuntu 20.04 packages, the following code is
generated and there is an illegal address trap during execution (write a long
at an odd address in the stack):
gcc version 9.3.0 (Ubuntu 9.3.0-10ubuntu1)
157c 0009 0001 moveb #9,%a2@(1)
1f7c 0008 001c moveb #8,%sp@(28)
2f42 001d movel %d2,%sp@(29) /* long on odd address! */
2f42 0021 movel %d2,%sp@(33) /* long on odd address! */
Options are:
-MMD -Os -m68000 -Wall -mpcrel -fdata-sections -ffunction-sections
-fomit-frame-pointer -fno-builtin -fno-ident -Iarch/m68k/include
If I use -O0 instead of -Os, the assembly is OK:
13fc 0009 0006 moveb #9,639fb
39fb
1ebc 0008 moveb #8,%sp@
202f 000a movel %sp@(10),%d0
4240 clrw %d0
4840 swap %d0
e048 lsrw #8,%d0
2000 movel %d0,%d0
1f40 0005 moveb %d0,%sp@(5)
102f 0005 moveb %sp@(5),%d0
1f40 0001 moveb %d0,%sp@(1)
202f 000a movel %sp@(10),%d0
4240 clrw %d0
4840 swap %d0
2000 movel %d0,%d0
1f40 0006 moveb %d0,%sp@(6)
102f 0006 moveb %sp@(6),%d0
1f40 0002 moveb %d0,%sp@(2)
202f 000a movel %sp@(10),%d0
e088 lsrl #8,%d0
2000 movel %d0,%d0
1f40 0007 moveb %d0,%sp@(7)
102f 0007 moveb %sp@(7),%d0
1f40 0003 moveb %d0,%sp@(3)
202f 000a movel %sp@(10),%d0
1f40 0008 moveb %d0,%sp@(8)
102f 0008 moveb %sp@(8),%d0
1f40 0004 moveb %d0,%sp@(4)
Attached the C source file compiled with -E option.
Thanks in advance for the support!
