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From: "SztfG at yandex dot ru" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/68027] New: conditional statement and unnecessary register assignment
Date: Tue, 20 Oct 2015 05:24:00 -0000 [thread overview]
Message-ID: <bug-68027-4@http.gcc.gnu.org/bugzilla/> (raw)
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68027
Bug ID: 68027
Summary: conditional statement and unnecessary register
assignment
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: SztfG at yandex dot ru
Target Milestone: ---
C source code:
int a1(int);
int a2(int);
int a3(int);
int test1(int a)
{
if (a > 100) return a1(a);
else if (a < 100) return a2(a);
return a3(a);
}
-----------------------------------
Assembly output:
test1:
.LFB0:
.cfi_startproc
cmpl $100, %edi
jg .L5
jne .L6
movl $100, %edi # no need to do this, eax is equal $100 at this
point
jmp a3
.p2align 4,,10
.p2align 3
.L6:
jmp a2
.p2align 4,,10
.p2align 3
.L5:
jmp a1
.cfi_endproc
-----------------------------------
Tested on http://gcc.godbolt.org/ : gcc versions 4.4.7 - 5.2.0 have this
problem.
next reply other threads:[~2015-10-20 5:24 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-20 5:24 SztfG at yandex dot ru [this message]
2015-10-20 5:30 ` [Bug middle-end/68027] " SztfG at yandex dot ru
2015-10-20 8:00 ` [Bug tree-optimization/68027] " rguenth at gcc dot gnu.org
2015-10-20 8:28 ` SztfG at yandex dot ru
2015-10-20 17:37 ` SztfG at yandex dot ru
2021-08-10 18:20 ` [Bug tree-optimization/68027] uncprop should work on more than PHI nodes pinskia at gcc dot gnu.org
2021-08-10 18:22 ` pinskia at gcc dot gnu.org
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