Compile the following with -O1 in 4.0 branch. Don't be in a hurry; I killed it
after 10 minutes, but I'm told it goes for hours.
With -fno-ivopts added it completes almost immediately. The recursion is
in instantiate_parameters_1 called from simple_iv.
/**********************************************************************/
extern int Loop1Max,Loop2Max;
void bar(int a, int b, int c);
void foo(int parm);
/**********************************************************************/
#define x7(x) x;x;x;x;x;x;x
#define REPL(x) x7(x);x7(x);x7(x);x7(x);x7(x);x7(x)
// 6 * 7 = 42 (0.06 seconds compile-time for GCC 3.3, 1 year for GCC
4.0)
// Changing REPL from 42 to 21 will reduce GCC 4.0 compile-time to 20
sec
onds.
/**********************************************************************/
void foo(int parm)
{
register int x,y;
register int a,b,c;
a = b = c = parm;
for (y=0; y<Loop2Max; ++y)
{
for (x=0; x<Loop1Max; ++x)
{
REPL
(
a = c * a;
b = a * b;
c = parm - a;
);
}
}
bar(a,b,c);
return;
}
/**********************************************************************/
--
Summary: Pseudo-infinite recursion in ivopts
Product: gcc
Version: 4.0.0
Status: UNCONFIRMED
Severity: normal
Priority: P2
Component: tree-optimization
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: dalej at gcc dot gnu dot org
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: powerpc-apple-darwin8.0.0
GCC host triplet: powerpc-apple-darwin8.0.0
GCC target triplet: powerpc-apple-darwin8.0.0
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=20803
