[Bug tree-optimization/17892] New: gcc-4.0 should not reassociate floating point add or multiplication

[Bug tree-optimization/17892] New: gcc-4.0 should not reassociate floating point add or multiplication

[fjahanian at apple dot com]

In the following code the repeated multiplication is folded into a single operation 
(multiplication by Infinity). 
For different values of "x" this leads to undeserved or absent floating point exceptions, and 
breaks some of the elementary math functions in Libm. Occurs at optimization O1 and higher. 

static const double C = 0x1.0p1023;

double foo(double x)
{
        return ( ( (x * C) * C ) * C );
}

-- 
           Summary: gcc-4.0 should not reassociate floating point add or
                    multiplication
           Product: gcc
           Version: 4.0.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P1
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: fjahanian at apple dot com
                CC: gcc-bugs at gcc dot gnu dot org,roger at eyesopen dot
                    com
 GCC build triplet: powerpc-apple-darwin
  GCC host triplet: powerpc-apple-darwin
GCC target triplet: powerpc-apple-darwin


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17892

[Bug tree-optimization/17892] [4.0 Regression] gcc-4.0 should not reassociate floating point add or multiplication

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-10-08 16:59 -------
Confirmed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |wrong-code
   Last reconfirmed|0000-00-00 00:00:00         |2004-10-08 16:59:47
               date|                            |
            Summary|gcc-4.0 should not          |[4.0 Regression] gcc-4.0
                   |reassociate floating point  |should not reassociate
                   |add or multiplication       |floating point add or
                   |                            |multiplication
   Target Milestone|---                         |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17892

[Bug tree-optimization/17892] [4.0 Regression] gcc-4.0 should not reassociate floating point add or multiplication

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-10-12 20:50 -------
Subject: Bug 17892

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	fjahanian@gcc.gnu.org	2004-10-12 20:50:08

Modified files:
	gcc            : ChangeLog tree-outof-ssa.c tree-ssa-dom.c 
Added files:
	gcc/testsuite/gcc.c-torture/execute/ieee: unsafe-fp-assoc.c 

Log message:
	PR 17892.
	OKed by Roger Sayle.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.5850&r2=2.5851
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/tree-outof-ssa.c.diff?cvsroot=gcc&r1=2.25&r2=2.26
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/tree-ssa-dom.c.diff?cvsroot=gcc&r1=2.58&r2=2.59
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.c-torture/execute/ieee/unsafe-fp-assoc.c.diff?cvsroot=gcc&r1=NONE&r2=1.1



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17892

[Bug tree-optimization/17892] [4.0 Regression] gcc-4.0 should not reassociate floating point add or multiplication

[fjahanian at apple dot com]

------- Additional Comments From fjahanian at apple dot com  2004-10-12 20:57 -------
tree-outof-ssa.c is not part of this patch. I accidentally checked it in. I have since backed it out.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17892

[Bug tree-optimization/17892] [4.0 Regression] gcc-4.0 should not reassociate floating point add or multiplication

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-10-12 22:28 -------
Fixed.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17892

[Bug tree-optimization/17892] [4.0 Regression] gcc-4.0 should not reassociate floating point add or multiplication

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-11-10 17:18 -------
Subject: Bug 17892

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	fjahanian@gcc.gnu.org	2004-11-10 17:18:01

Modified files:
	gcc            : tree-ssa-dom.c ChangeLog 
	gcc/testsuite  : ChangeLog 

Log message:
	Fix for PR tree-optimization/17892.
	OKed by Roger Sayle.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/tree-ssa-dom.c.diff?cvsroot=gcc&r1=2.65&r2=2.66
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.6263&r2=2.6264
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/ChangeLog.diff?cvsroot=gcc&r1=1.4570&r2=1.4571



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17892

[Bug tree-optimization/17892] [4.0 Regression] gcc-4.0 should not reassociate floating point add or multiplication

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-11-10 19:07 -------
Subject: Bug 17892

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	fjahanian@gcc.gnu.org	2004-11-10 19:06:54

Added files:
	gcc/testsuite/gcc.c-torture/execute/ieee: unsafe-fp-assoc-1.c 

Log message:
	Test for PR tree-optimization/17892.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.c-torture/execute/ieee/unsafe-fp-assoc-1.c.diff?cvsroot=gcc&r1=1.1&r2=1.2



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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=17892