From: Dibyendu Majumdar <mobile@majumdar.org.uk>
To: Linux-Sparse <linux-sparse@vger.kernel.org>
Subject: Possible incorrect linearization of code (master branch)
Date: Mon, 6 Mar 2017 15:22:19 +0000 [thread overview]
Message-ID: <CACXZuxeNopu3Syg+TCL3TLnhwmA84qkQ1NsN4hjL-VLPi6ASYA@mail.gmail.com> (raw)
Hi,
I have this test program:
extern char *incr(char *p);
char *incr(char *p) {
char *tmp = p;
tmp += 5;
return tmp;
}
int main(const char *argv[]) {
char *text = "abcde";
char *p = incr(text);
return (*p == 'e') ? 0 : 1;
}
The linearizer outputs following which I think is incorrect as it is
missing a load.
incr:
.L0:
<entry-point>
cast.64 %r3 <- (64) %arg1
add.64 %r4 <- %r3, $5
ptrcast.64 %r5 <- (64) %r4
ret.64 %r5
main:
.L2:
<entry-point>
call.64 %r10 <- incr, "abcde"
setne.32 %r15 <- %r13, $101
ret.32 %r15
If I change the return in main to be a if else block then correct code
is generated.
int main(const char *argv[]) {
char *text = "abcde";
char *p = incr(text);
// return (*p == 'e') ? 0 : 1;
if (*p == 'e')
return 0;
else
return 1;
}
main:
.L2:
<entry-point>
call.64 %r10 <- incr, "abcde"
load.8 %r12 <- 0[%r10]
scast.32 %r13 <- (8) %r12
setne.32 %r15 <- %r13, $101
ret.32 %r15
next reply other threads:[~2017-03-06 15:22 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-06 15:22 Dibyendu Majumdar [this message]
2017-03-06 16:36 ` Possible incorrect linearization of code (master branch) Luc Van Oostenryck
2017-03-06 18:47 ` Dibyendu Majumdar
2017-03-06 19:26 ` Luc Van Oostenryck
2017-03-06 22:39 ` Dibyendu Majumdar
2017-03-07 6:42 ` Luc Van Oostenryck
2017-03-07 15:45 ` Christopher Li
2017-03-07 17:13 ` Dibyendu Majumdar
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