Bug 23941 - compress_float_constant creates denormals
Summary: compress_float_constant creates denormals
Status: RESOLVED FIXED
Alias: None
Product: gcc
Classification: Unclassified
Component: rtl-optimization (show other bugs)
Version: 4.0.1
: P2 normal
Target Milestone: 4.0.2
Assignee: Richard Henderson
URL:
Keywords:
Depends on:
Blocks:
 
Reported: 2005-09-18 07:24 UTC by Richard Henderson
Modified: 2005-09-19 17:10 UTC (History)
1 user (show)

See Also:
Host:
Target: alpha
Build:
Known to work:
Known to fail:
Last reconfirmed: 2005-09-18 07:24:27


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Description Richard Henderson 2005-09-18 07:24:07 UTC
extern void abort (void);
double d = __FLT_MIN__ / 2;
int main()
{
  double x = __FLT_MIN__ / 2;
  if (x != d)
    abort ();
  return 0;
}

This test will SIGFPE on alpha, because we'll emit the constant for X as
a float.  Obviously this cannot be represented as a normalized number.
Comment 1 GCC Commits 2005-09-19 16:56:32 UTC
Subject: Bug 23941

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	gcc-4_0-branch
Changes by:	rth@gcc.gnu.org	2005-09-19 16:56:24

Modified files:
	gcc            : ChangeLog real.c 
Added files:
	gcc/testsuite/gcc.c-torture/execute: pr23941.c 

Log message:
	PR 23941
	* real.c (exact_real_truncate): Return false if the format cannot
	represent the number as a normal.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=2.7592.2.431&r2=2.7592.2.432
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/real.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=1.151&r2=1.151.8.1
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.c-torture/execute/pr23941.c.diff?cvsroot=gcc&only_with_tag=gcc-4_0-branch&r1=NONE&r2=1.1.2.1

Comment 2 GCC Commits 2005-09-19 17:01:53 UTC
Subject: Bug 23941

CVSROOT:	/cvs/gcc
Module name:	gcc
Changes by:	rth@gcc.gnu.org	2005-09-19 17:01:41

Modified files:
	gcc            : ChangeLog real.c 
Added files:
	gcc/testsuite/gcc.c-torture/execute: pr23941.c 

Log message:
	PR 23941
	* real.c (exact_real_truncate): Return false if the format cannot
	represent the number as a normal.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/testsuite/gcc.c-torture/execute/pr23941.c.diff?cvsroot=gcc&r1=1.1&r2=1.2
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.diff?cvsroot=gcc&r1=2.9979&r2=2.9980
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/real.c.diff?cvsroot=gcc&r1=1.157&r2=1.158

Comment 3 Richard Henderson 2005-09-19 17:10:36 UTC
Fixed.