https://gcc.gnu.org/bugzilla/show_bug.cgi?id=87376
Bug ID: 87376
Summary: [avr] Miscompilation with __memx and long long
addition
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: target
Assignee: unassigned at gcc dot gnu.org
Reporter: saaadhu at gcc dot gnu.org
Target Milestone: ---
Attempting to add a __memx long long with a long long in the generic address
space results in wrong code. 2 of the 8 bytes of the variable in __memx do not
get loaded at all.
Compiling the below code with -Os -mmcu=avr51
extern const __memx long long a;
extern const long long b;
long long add (void) { return a + b;}
results in the following assembly output. Note the missing loads for a+3 and
a+4.
<snip>
ldi r24,lo8(a)
ldi r25,hi8(a)
ldi r26,hlo8(a)
movw r30,r24
mov r21,r26
call __xload_1
mov r18,r22
ldi r24,lo8(a+1)
ldi r25,hi8(a+1)
ldi r26,hlo8(a+1)
movw r30,r24
mov r21,r26
call __xload_1
mov r19,r22
ldi r24,lo8(a+2)
ldi r25,hi8(a+2)
ldi r26,hlo8(a+2)
movw r30,r24
mov r21,r26
call __xload_1
mov r20,r22
ldi r24,lo8(a+5)
ldi r25,hi8(a+5)
ldi r26,hlo8(a+5)
movw r30,r24
mov r21,r26
call __xload_1
mov r23,r22
ldi r24,lo8(a+6)
ldi r25,hi8(a+6)
ldi r26,hlo8(a+6)
movw r30,r24
mov r21,r26
call __xload_1
mov r24,r22
ldi r25,lo8(a+7)
mov r12,r25
ldi r25,hi8(a+7)
mov r13,r25
ldi r25,hlo8(a+7)
mov r14,r25
movw r30,r12
mov r21,r14
call __xload_1
mov r25,r22
lds r10,b
lds r11,b+1
lds r12,b+2
lds r13,b+3
lds r14,b+4
lds r15,b+5
lds r16,b+6
lds r17,b+7
call __adddi3
</snip>
