http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54932
--- Comment #12 from Dominique d'Humieres <dominiq at lps dot ens.fr>
2013-02-01 13:59:11 UTC ---
(In reply to comment #11)
> > > Thus, I close the bug as INVALID.
> > ... in wich case could you, please, update the testcase to be valid and
> > remove
> > the XFAIL I introduced?
>
> We jump through some hoops in or DO loop code generation to execute
> a loop until HUGE(i) in a way that somebody who did not read the
> standard well might expect, but which is actually invalid.
>
> If we do not do this any more, then we can probably simplify our DO
> loops considerably.
This is probably too late for 4.8.0. The following patch takes advantage of the
new option -fno-aggressive-loop-optimizations to remove the xfail (and the two
XPASS at -O0 and -O1):
--- /opt/gcc/_gcc_clean/gcc/testsuite/gfortran.dg/do_1.f90 2012-10-18
00:34:47.000000000 +0200
+++ /opt/gcc/work/gcc/testsuite/gfortran.dg/do_1.f90 2013-01-31
22:02:16.000000000 +0100
@@ -1,5 +1,5 @@
-! { dg-do run { xfail *-*-* } }
-! XFAIL is tracked in PR 54932
+! { dg-do run }
+! { dg-additional-options "-fno-aggressive-loop-optimizations" }
! Program to check corner cases for DO statements.
program do_1
implicit none
Tested on x86_64-apple-darwin10 and powerpc-apple-darwin9.
> We should also warn about invalid code in the FE.
One example is
program test_real_do
integer n
integer x
n=0
do x=0.0,10.0,0.1
n=n+1
end do
print *, "N is ", n
end program test_real_do
which on x86_64-apple-darwin10 gives
Program received signal SIGFPE: Floating-point exception - erroneous arithmetic
operation.
when executed. This is due to the division by zero in
x = 0;
countm1.0 = 10 / 0;
while (1)
{
{
unsigned int countm1t.1;
n = n + 1;
L.1:;
x = NON_LVALUE_EXPR <x>;
countm1t.1 = countm1.0;
countm1.0 = countm1.0 + 4294967295;
if (countm1t.1 == 0) goto L.2;
}
}
L.2:;
The FE should detect that the stride is zero and output an error.
Note that on powerpc-apple-darwin9, the same test (with the same
dump-tree-original) runs and outputs
N is 1
!?-(
