[Bug fortran/31120] ICE with integer_exponentiation_1.f90 and -ffast-math

[fxcoudert at gcc dot gnu dot org]

--- Comment #9 from fxcoudert at gcc dot gnu dot org  2007-03-17 19:58 
---
Subject: Bug 31120

Author: fxcoudert
Date: Sat Mar 17 19:58:37 2007
New Revision: 123028

URL: http://gcc.gnu.org/viewcvs?root=gccview=revrev=123028
Log:
PR fortran/31120

* trans-expr.c (gfc_conv_powi): Make n argument unsigned hwi.
(gfc_conv_cst_int_power): Handle integer exponent with care,
since it might be too large for us.

* gfortran.dg/integer_exponentiation_2.f90: New test.

Added:
trunk/gcc/testsuite/gfortran.dg/integer_exponentiation_2.f90
Modified:
trunk/gcc/fortran/ChangeLog
trunk/gcc/fortran/trans-expr.c
trunk/gcc/testsuite/ChangeLog


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31120

[Bug fortran/31120] ICE with integer_exponentiation_1.f90 and -ffast-math

[dominiq at lps dot ens dot fr]

--- Comment #7 from dominiq at lps dot ens dot fr  2007-03-15 08:24 ---
 And Dominique, I would appreciate if you could test the patch on ppc-darwin7.

So far all the tests passed. I am doing a full regtesting of gfortran, but I do
not expect any new failure.
Thanks for the fix.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31120

[Bug fortran/31120] ICE with integer_exponentiation_1.f90 and -ffast-math

[dominiq at lps dot ens dot fr]

--- Comment #8 from dominiq at lps dot ens dot fr  2007-03-15 08:52 ---
regtest results:

...
Running /Users/dominiq/test/gcc-4.3-20070309/gcc/testsuite/gfortran.dg/dg.exp
...
FAIL: gfortran.dg/large_real_kind_2.F90  -O0  execution test
...
FAIL: gfortran.dg/large_real_kind_2.F90  -Os  execution test
FAIL: gfortran.dg/large_real_kind_form_io_2.f90  -O0  execution test
...
FAIL: gfortran.dg/large_real_kind_form_io_2.f90  -Os  execution test
FAIL: gfortran.dg/secnds-1.f  -Os  execution test
Running
/Users/dominiq/test/gcc-4.3-20070309/gcc/testsuite/gfortran.dg/gomp/gomp.exp
...
...

=== gfortran Summary ===

# of expected passes16445
# of unexpected failures17
# of expected failures  7
# of unsupported tests  58
/sw/lib/gcc4/bin/gfortran  version 4.3.0 20070309 (experimental)


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31120

[Bug fortran/31120] ICE with integer_exponentiation_1.f90 and -ffast-math

[fxcoudert at gcc dot gnu dot org]

--- Comment #3 from fxcoudert at gcc dot gnu dot org  2007-03-14 12:31 
---
Here's a patch that should make the code in gfc_conv_cst_int_power() work in
all cases:

Index: trans-expr.c
===
--- trans-expr.c(revision 122912)
+++ trans-expr.c(working copy)
@@ -634,7 +634,7 @@
 /* Recursive function to expand the power operator. The temporary 
values are put in tmpvar. The function returns tmpvar[1] ** n.  */
 static tree
-gfc_conv_powi (gfc_se * se, int n, tree * tmpvar)
+gfc_conv_powi (gfc_se * se, unsigned HOST_WIDE_INT n, tree * tmpvar)
 {
   tree op0;
   tree op1;
@@ -681,15 +681,25 @@
   tree tmp;
   tree type;
   tree vartmp[POWI_TABLE_SIZE];
-  int n;
+  HOST_WIDE_INT m;
+  unsigned HOST_WIDE_INT n;
   int sgn;

+  /* If exponent is too large, we won't expand it anyway, so don't bother
+ with large integer values.  */
+  if (!double_int_fits_in_shwi_p (TREE_INT_CST (rhs)))
+return 0;
+
+  m = double_int_to_shwi (TREE_INT_CST (rhs));
+  /* There's no ABS for HOST_WIDE_INT, so here we go. It also takes care
+ of the asymmetric range of the integer type.  */
+  n = (unsigned HOST_WIDE_INT) (m  0 ? -m : m);
+  
   type = TREE_TYPE (lhs);
-  n = abs (TREE_INT_CST_LOW (rhs));
   sgn = tree_int_cst_sgn (rhs);

-  if (((FLOAT_TYPE_P (type)  !flag_unsafe_math_optimizations) ||
optimize_siz
e)
-   (n  2 || n  -1))
+  if (((FLOAT_TYPE_P (type)  !flag_unsafe_math_optimizations)
+   || optimize_size)  (m  2 || m  -1))
 return 0;

   /* rhs == 0  */
@@ -698,6 +708,7 @@
   se-expr = gfc_build_const (type, integer_one_node);
   return 1;
 }
+
   /* If rhs  0 and lhs is an integer, the result is -1, 0 or 1.  */
   if ((sgn == -1)  (TREE_CODE (type) == INTEGER_TYPE))
 {


It's regtesting right now. The following should now be done:
  * write a testcase, using both kind=4 and 8 integers as exponents, and
testing difficult cases (huge(),-huge(),-huge()-1, etc.); the testcase should
also check constant vs. non-constant results, to make sure the testcase run
isn't rendered useless by constant folding
  * the code generated should be manually checked in the above-mentionned
difficult cases (huge(), -huge(), ...)

If nobody does it before the week-end, I'll do it then (but won't have time
before that). And Dominique, I would appreciate if you could test the patch on
ppc-darwin7.


-- 

fxcoudert at gcc dot gnu dot org changed:

   What|Removed |Added

 AssignedTo|unassigned at gcc dot gnu   |fxcoudert at gcc dot gnu dot
   |dot org |org
 Status|NEW |ASSIGNED
   Keywords||patch
   Last reconfirmed|2007-03-10 12:15:25 |2007-03-14 12:31:35
   date||


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31120

[Bug fortran/31120] ICE with integer_exponentiation_1.f90 and -ffast-math

[dominiq at lps dot ens dot fr]

--- Comment #4 from dominiq at lps dot ens dot fr  2007-03-14 13:58 ---
Subject: Re:  ICE with integer_exponentiation_1.f90 and -ffast-math

 And Dominique, I would appreciate if you could test the patch on ppc-darwin7.

I'll do it tonight, but before could you test the following code:

integer(4)  :: i
integer(8)  :: j
real(4) :: a
real(8) :: b, c, d
a = 1.0 + epsilon(a)
b = 1.0 + epsilon(b)
print *, a**huge(i), a**(-huge(i)), a**(-huge(i)-1)
print '(3(1PG30.17))', b**huge(i), b**(-huge(i)), b**(-huge(i)-1)
c = b**huge(i)
d= b**(-huge(i))
print '(3(1PG30.17))', c*d, d/b, exp(-huge(i)*log(b))
d=1/b
do i = 1, 31
  d = d*d
end do
print '(2(1PG30.17))', d, b*d
!print *, b**huge(j), b**(-huge(j)), b**(-huge(j)-1)
end

If I uncomment the last print, I get:

[karma] f90/bug% gfc test_pow.f90
Out of stack space.
Try running 'limit stacksize unlimited' in the shell to raise its limit.

Is this also fixed by your patch?


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31120

[Bug fortran/31120] ICE with integer_exponentiation_1.f90 and -ffast-math

[fxcoudert at gcc dot gnu dot org]

--- Comment #5 from fxcoudert at gcc dot gnu dot org  2007-03-14 14:02 
---
(In reply to comment #4)
 I'll do it tonight, but before could you test the following code
 [karma] f90/bug% gfc test_pow.f90
 Out of stack space.
 Try running 'limit stacksize unlimited' in the shell to raise its limit.

On i686-linux, the unpatched compiler works OK without -ffast-math and
segfaults with it. With the patch, it runs fine in both cases.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31120

[Bug fortran/31120] ICE with integer_exponentiation_1.f90 and -ffast-math

[dominiq at lps dot ens dot fr]

--- Comment #6 from dominiq at lps dot ens dot fr  2007-03-14 14:27 ---
Subject: Re:  ICE with integer_exponentiation_1.f90 and -ffast-math

 On i686-linux, the unpatched compiler works OK without -ffast-math and
 segfaults with it.

I am a little bit worried about that. As far as I know the stack size on OSX
is limited to 65536 kbytes (at least I don't know how to increase it further
under 10.3). Could you test the code with the last print uncommented and
the stack size limited to 65536 kbytes? TIA


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31120

[Bug fortran/31120] ICE with integer_exponentiation_1.f90 and -ffast-math

[dominiq at lps dot ens dot fr]

--- Comment #1 from dominiq at lps dot ens dot fr  2007-03-10 10:25 ---
FX Coudert reported that compiling the following code

  real :: a, b
  a = 3.0
  b = a**(-4294967296_8)
  print *, b
  end

segfaults on i686-linux (without -ffast-math). On OSX 10.3.9 I get

Out of stack space.
Try running 'limit stacksize unlimited' in the shell to raise its limit.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31120

[Bug fortran/31120] ICE with integer_exponentiation_1.f90 and -ffast-math

[burnus at gcc dot gnu dot org]

-- 

burnus at gcc dot gnu dot org changed:

   What|Removed |Added

 CC||burnus at gcc dot gnu dot
   ||org
 Status|UNCONFIRMED |NEW
 Ever Confirmed|0   |1
 GCC target triplet|powerpc-apple-darwin7   |
   Keywords||ice-on-valid-code
   Last reconfirmed|-00-00 00:00:00 |2007-03-10 12:15:25
   date||


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31120

[Bug fortran/31120] ICE with integer_exponentiation_1.f90 and -ffast-math

[tkoenig at gcc dot gnu dot org]

--- Comment #2 from tkoenig at gcc dot gnu dot org  2007-03-10 12:33 ---
(In reply to comment #1)
 FX Coudert reported that compiling the following code
 
   real :: a, b
   a = 3.0
   b = a**(-4294967296_8)
   print *, b
   end
 
 segfaults on i686-linux (without -ffast-math).

This is closely related to PR 30834.


-- 

tkoenig at gcc dot gnu dot org changed:

   What|Removed |Added

 CC||tkoenig at gcc dot gnu dot
   ||org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=31120