https://gcc.gnu.org/bugzilla/show_bug.cgi?id=67998
Bug ID: 67998
Summary: redundant test for 0 when also checking inequality
Product: gcc
Version: 5.1.0
Status: UNCONFIRMED
Severity: enhancement
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: rv at rasmusvillemoes dot dk
Target Milestone: ---
int f(unsigned a, unsigned b)
{
if (!a || b >= a)
return 5;
return 2;
}
compiles to
f(unsigned int, unsigned int):
testl %edi, %edi
je .L3
cmpl %esi, %edi
jbe .L3
movl $2, %eax
ret
.L3:
movl $5, %eax
ret
The first test is redundant, since if a is zero, the inequality is guaranteed
to hold.
