https://llvm.org/bugs/show_bug.cgi?id=31260
Bug ID: 31260
Summary: wrong code at -Os and above on x86_64-linux-gnu (in
both 32-bit and 64-bit modes)
Product: clang
Version: trunk
Hardware: PC
OS: All
Status: NEW
Severity: normal
Priority: P
Component: -New Bugs
Assignee: unassignedclangb...@nondot.org
Reporter: s...@cs.ucdavis.edu
CC: llvm-bugs@lists.llvm.org
Classification: Unclassified
This seems to be a recent regression. The test case is difficult to reduce and
still quite large (1285 bytes), but it should be valid.
$ clang -v
clang version 4.0.0 (trunk 288581)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /usr/local/clang-trunk/bin
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/4.9.4
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/i686-linux-gnu/5.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.6.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.7.3
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.8.5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9.4
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/5.3.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.2.0
Selected GCC installation: /usr/lib/gcc/x86_64-linux-gnu/4.9
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Candidate multilib: x32;@mx32
Selected multilib: .;@m64
$
$ clang -O1 -w small.c; ./a.out
4
$
$ clang -Os -w small.c
$ ./a.out
$
$
----------------------------------------------------
int printf (const char *, ...);
unsigned a = 294967288;
int b, e, g, h, i, j, k, l, m, n, o;
char c, d, f;
short p = 5344;
static int fn1 (int r)
{
for (;; 1)
{
int s;
while (0)
for (;; 0)
for (;; 1)
for (;; 1)
while (1)
for (;; j)
for (;; k)
for (;; 1)
while (0)
for (;; e)
for (;; l)
for (;; m)
while (0)
goto L4;
L1:
L2:
L3:
if (c)
for (;; 1)
goto L5;
while (0)
while (0)
for (;; h)
for (;; g)
while (0)
for (;; 0)
while (0)
for (;; j)
for (;; k)
for (;; 0)
for (;; i)
for (;; g)
for (;; 1)
goto L6;
while (!b)
{
for (; 0; 0)
while (0)
for (;; 3)
for (;; c)
for (;; 0)
;
L7:
d = r = 1;
for (; 0; r)
;
}
for (; 1; 1)
{
while (0)
for (;; n)
for (;; o)
for (;; 1)
for (;; e)
for (;; s)
for (;; 1)
for (;; f)
;
for (;; 1)
{
unsigned b = a = p * a;
if (a > 94967288)
{
printf ("%d\n", 4);
goto L6;
}
if (r)
{
if (c < 0)
continue;
break;
}
}
L4:
for (; 0;)
L5:
L6:
return 0;
}
}
}
int main ()
{
b = 1;
fn1 (4);
return 0;
}
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