https://gcc.gnu.org/bugzilla/show_bug.cgi?id=101226
Bug ID: 101226
Summary: Suboptimal codegen for >>/>>>
Product: gcc
Version: 11.1.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: d
Assignee: ibuclaw at gdcproject dot org
Reporter: maxsamukha at gmail dot com
Target Milestone: ---
Target: AVR
example.d:
void f1()
{
__gshared ubyte value;
value >>>= 5;
}
void f2()
{
__gshared ubyte value;
value = value >>> 5;
}
----
avr-gcc -fno-druntime -O3 example.d:
example.f1():
lds r24,example.f1().value
swap r24
lsr r24
andi r24,lo8(7)
sts example.f1().value,r24
ret
example.f2():
lds r24,example.f2().value
ldi r25,0
ldi r27,0
ldi r26,0
ldi r18,5
1:
lsr r27
ror r26
ror r25
ror r24
dec r18
brne 1b
sts example.f2().value,r24
ret
The compiler apparently fails to optimize out the integer promotion for >>> in
f2 and produces inefficient machine code.
