http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54136
Bug #: 54136
Summary: Compiling phoronix/dcraw with gcc 4.8 trunk causes
infinite execution.
Classification: Unclassified
Product: gcc
Version: tree-ssa
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: [email protected]
ReportedBy: [email protected]
Attached test case is a extracted from dcraw application.
GCC option used -O2 or -O1 -ftree-vrp.
Target: x86_64-unknown-linux-gnu.
With gcc 4.7 the test case completes.
But for gcc4.8 trunk revision r189951 it results in infinite loop execution.
(-----Snip-----)
for (i=0; i < sizeof table / sizeof *table; i++)
if (!strncmp (name, table[i].prefix, strlen(table[i].prefix))) {
if (table[i].black) black = (unsigned short) table[i].black;
if (table[i].maximum) maximum = (unsigned short) table[i].maximum;
for (j=0; j < 12; j++)
cam_xyz[0][j] = table[i].trans[j] / 10000.0;
printf("reached here exiting out of loop : pointer to array cam_xyz
%x\n", cam_xyz);
break;
}
(-----Snip-----)
----test.c.067t.mergephi2-----
D.2580_12 = table[i_1].maximum;
if (D.2580_12 != 0)
goto <bb 7>;
else
goto <bb 10>;
<bb 7>:
D.2583_13 = (short unsigned int) D.2580_12;
maximum.1_14 = (unsigned int) D.2583_13;
maximum = maximum.1_14;
goto <bb 10>;
<bb 9>:
D.2585_16 = table[i_1].trans[j_2];
D.2586_17 = (double) D.2585_16;
D.2587_18 = D.2586_17 / 1.0e+4;
cam_xyz[0][j_2] = D.2587_18;
j_19 = j_2 + 1;
<bb 10>:
# j_2 = PHI <0(6), j_19(9), 0(7)>
if (j_2 <= 11)
goto <bb 9>;
else
goto <bb 11>;
<bb 11>:
printf ("reached here exiting out of loop : pointer to array cam_xyz
%x\n", &cam_xyz);
goto <bb 14>
After VRP
------test.c.068t.vrp1-----
D.2580_12 = table[i_33].maximum;
if (D.2580_12 != 0)
goto <bb 7>;
else
goto <bb 8>;
<bb 7>:
D.2583_13 = (short unsigned int) D.2580_12;
maximum.1_14 = (unsigned int) D.2583_13;
maximum = maximum.1_14;
<bb 8>:
j_15 = 0;
<bb 9>:
# j_2 = PHI <0(8), j_19(9)>
D.2585_16 = table[i_33].trans[j_2];
D.2586_17 = (double) D.2585_16;
D.2587_18 = D.2586_17 / 1.0e+4;
cam_xyz[0][j_2] = D.2587_18;
j_19 = j_2 + 1;
goto <bb 9>; <== infinite loop is formed
<bb 10>:
i_20 = i_1 + 1;
