http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48390
Summary: Multiple setting to restricted pointer variable not
optimized away
Product: gcc
Version: 4.7.0
Status: UNCONFIRMED
Keywords: missed-optimization
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: bur...@gcc.gnu.org
Missed optimization: In the following program, the first "a = 1" line can be
removed - as the setting is not used and the value is latter overridden,
however, the line remains even with -O3.
function foo (a, b, c, ptr)
real :: a, b, c, foo
real, pointer :: ptr
a = 1 ! Can delete
b = ptr + 2
a = 3
foo = a + b
end function
>From the -O3 dump:
foo (real(kind=4) & restrict a, real(kind=4) & restrict b, real(kind=4) &
restrict c, real(kind=4) * & ptr)
{ [...]
*a_1(D) = 1.0e+0; /* Expected: This line is removed. */
[...]
*a_1(D) = 3.0e+0;
The same result is obtained for the equivalent C program:
float
foo (float * restrict a, float * restrict b, float * restrict c, float *ptr)
{
*a = 1; /* Can delete. */
*b = *ptr + 2;
*a = 3;
return *a + *b;
}
Reported in by Daniel Carrera at
http://groups.google.com/group/comp.lang.fortran/browse_thread/thread/ec8641acbcbbed10/fdc9369d5acf53f1#fdc9369d5acf53f1
