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Date: Sun, 17 Jul 2005 20:50:00 -0000
From: "pinskia at gcc dot gnu dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Message-ID: <20050717205007.22532.pinskia@gcc.gnu.org>
Reply-To: gcc-bugzilla@gcc.gnu.org
Subject: [Bug tree-optimization/22532] New: [4.1 Regression] We produce worse code on the mainline for a loop
X-Bugzilla-Reason: CC
X-SW-Source: 2005-07/txt/msg02125.txt.bz2
List-Id: <gcc-bugs.sourceware.org>

Take the following code:
#define NUMPOINTS 20

static float opoints[NUMPOINTS];

double sqrt (double);
double f(double);

void NormalizeVectors1 (void)
{
  int i, r;
  float s, x, y, z;
  static float d = 0.0;
  d += 0.2f;
  s = d;
  for (i=0; i<NUMPOINTS; i++)
    opoints[i] = f(s);
}

Compile at -O2 and -O3 and compare.  See how we load/store now at -O3 to the static variable, d 
inside the loop.

-- 
           Summary: [4.1 Regression] We produce worse code on the mainline
                    for a loop
           Product: gcc
           Version: 4.1.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P2
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org
                CC: gcc-bugs at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=22532