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Posted to dev@stdcxx.apache.org by "Colin Lee (JIRA)" <ji...@apache.org> on 2006/07/31 22:26:13 UTC
[jira] Created: (STDCXX-264) LIMITS.cpp WCHAR test causes infinite
loop with IPA, nonstandard code
LIMITS.cpp WCHAR test causes infinite loop with IPA, nonstandard code
---------------------------------------------------------------------
Key: STDCXX-264
URL: http://issues.apache.org/jira/browse/STDCXX-264
Project: C++ Standard Library
Issue Type: Bug
Components: Configuration
Affects Versions: 4.1.3
Environment: > uname -a && CC -V
UNICOS/mp sn702 3.0.62 07230830 crayx1
Cray C++ : Version 5.6.0.0.57 Mon Jul 31, 2006 14:38:56
Reporter: Colin Lee
Priority: Minor
With any compiler that uses interprocedural analysis including leaf node inlining, this WCHAR test in etc/config/src/LIMITS.cpp invokes undefined behavior from signed integer overflow and can result in an infinite loop. Our compiler inlines the greater() function and invokes undefined behavior, so the loop never exits. One workaround is to disable optimization and run the code by hand, but since this code is hidden within the build process, a portable solution is needed. Here's a code snippet:
template <class T>
T greater (T lhs, T rhs)
{
// prevents overzealous gcc optimizer from invoking
// undefined behavior on signed integer over/underflow
return lhs > rhs;
}
template <class T>
T compute_limits (T, const char *pfx, const char *sfx, const char *type)
{
T max = T (1);
T one = T (1);
for (; T (max * 2) > max; max *= 2);
for (T n = max / 4; n; ) {
if (T (max + n) < max) {
if (n > 2)
n /= 2;
else if (greater (T (max + one), max))
n = 1;
else
break;
}
else
max += n;
}
return max;
}
int main(void) {
compute_limits ((wchar_t)0, "WCHAR_T", suffix, "wchar_t");
return 0;
}
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[jira] Commented: (STDCXX-264) LIMITS.cpp WCHAR test causes
infinite loop with IPA, nonstandard code
Posted by "Colin Lee (JIRA)" <ji...@apache.org>.
[ http://issues.apache.org/jira/browse/STDCXX-264?page=comments#action_12424686 ]
Colin Lee commented on STDCXX-264:
----------------------------------
It seems the volatiles fixed the problem. Thanks again.
> LIMITS.cpp WCHAR test causes infinite loop with IPA, nonstandard code
> ---------------------------------------------------------------------
>
> Key: STDCXX-264
> URL: http://issues.apache.org/jira/browse/STDCXX-264
> Project: C++ Standard Library
> Issue Type: Bug
> Components: Configuration
> Affects Versions: 4.1.3
> Environment: > uname -a && CC -V
> UNICOS/mp sn702 3.0.62 07230830 crayx1
> Cray C++ : Version 5.6.0.0.57 Mon Jul 31, 2006 14:38:56
> Reporter: Colin Lee
> Assigned To: Martin Sebor
> Priority: Minor
> Fix For: 4.2
>
>
> With any compiler that uses interprocedural analysis including leaf node inlining, this WCHAR test in etc/config/src/LIMITS.cpp invokes undefined behavior from signed integer overflow and can result in an infinite loop. Our compiler inlines the greater() function and invokes undefined behavior, so the loop never exits. One workaround is to disable optimization and run the code by hand, but since this code is hidden within the build process, a portable solution is needed. Here's a code snippet:
> template <class T>
> T greater (T lhs, T rhs)
> {
> // prevents overzealous gcc optimizer from invoking
> // undefined behavior on signed integer over/underflow
> return lhs > rhs;
> }
> template <class T>
> T compute_limits (T, const char *pfx, const char *sfx, const char *type)
> {
> T max = T (1);
> T one = T (1);
> for (; T (max * 2) > max; max *= 2);
> for (T n = max / 4; n; ) {
> if (T (max + n) < max) {
> if (n > 2)
> n /= 2;
> else if (greater (T (max + one), max))
> n = 1;
> else
> break;
> }
> else
> max += n;
> }
> return max;
> }
> int main(void) {
> compute_limits ((wchar_t)0, "WCHAR_T", suffix, "wchar_t");
> return 0;
> }
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[jira] Commented: (STDCXX-264) LIMITS.cpp WCHAR test causes
infinite loop with IPA, nonstandard code
Posted by "Colin Lee (JIRA)" <ji...@apache.org>.
[ http://issues.apache.org/jira/browse/STDCXX-264?page=comments#action_12424681 ]
Colin Lee commented on STDCXX-264:
----------------------------------
Thanks, you have a very fast response rate! I'll look at it soon.
> LIMITS.cpp WCHAR test causes infinite loop with IPA, nonstandard code
> ---------------------------------------------------------------------
>
> Key: STDCXX-264
> URL: http://issues.apache.org/jira/browse/STDCXX-264
> Project: C++ Standard Library
> Issue Type: Bug
> Components: Configuration
> Affects Versions: 4.1.3
> Environment: > uname -a && CC -V
> UNICOS/mp sn702 3.0.62 07230830 crayx1
> Cray C++ : Version 5.6.0.0.57 Mon Jul 31, 2006 14:38:56
> Reporter: Colin Lee
> Assigned To: Martin Sebor
> Priority: Minor
> Fix For: 4.2
>
>
> With any compiler that uses interprocedural analysis including leaf node inlining, this WCHAR test in etc/config/src/LIMITS.cpp invokes undefined behavior from signed integer overflow and can result in an infinite loop. Our compiler inlines the greater() function and invokes undefined behavior, so the loop never exits. One workaround is to disable optimization and run the code by hand, but since this code is hidden within the build process, a portable solution is needed. Here's a code snippet:
> template <class T>
> T greater (T lhs, T rhs)
> {
> // prevents overzealous gcc optimizer from invoking
> // undefined behavior on signed integer over/underflow
> return lhs > rhs;
> }
> template <class T>
> T compute_limits (T, const char *pfx, const char *sfx, const char *type)
> {
> T max = T (1);
> T one = T (1);
> for (; T (max * 2) > max; max *= 2);
> for (T n = max / 4; n; ) {
> if (T (max + n) < max) {
> if (n > 2)
> n /= 2;
> else if (greater (T (max + one), max))
> n = 1;
> else
> break;
> }
> else
> max += n;
> }
> return max;
> }
> int main(void) {
> compute_limits ((wchar_t)0, "WCHAR_T", suffix, "wchar_t");
> return 0;
> }
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[jira] Assigned: (STDCXX-264) LIMITS.cpp WCHAR test causes infinite
loop with IPA, nonstandard code
Posted by "Martin Sebor (JIRA)" <ji...@apache.org>.
[ http://issues.apache.org/jira/browse/STDCXX-264?page=all ]
Martin Sebor reassigned STDCXX-264:
-----------------------------------
Assignee: Martin Sebor
> LIMITS.cpp WCHAR test causes infinite loop with IPA, nonstandard code
> ---------------------------------------------------------------------
>
> Key: STDCXX-264
> URL: http://issues.apache.org/jira/browse/STDCXX-264
> Project: C++ Standard Library
> Issue Type: Bug
> Components: Configuration
> Affects Versions: 4.1.3
> Environment: > uname -a && CC -V
> UNICOS/mp sn702 3.0.62 07230830 crayx1
> Cray C++ : Version 5.6.0.0.57 Mon Jul 31, 2006 14:38:56
> Reporter: Colin Lee
> Assigned To: Martin Sebor
> Priority: Minor
>
> With any compiler that uses interprocedural analysis including leaf node inlining, this WCHAR test in etc/config/src/LIMITS.cpp invokes undefined behavior from signed integer overflow and can result in an infinite loop. Our compiler inlines the greater() function and invokes undefined behavior, so the loop never exits. One workaround is to disable optimization and run the code by hand, but since this code is hidden within the build process, a portable solution is needed. Here's a code snippet:
> template <class T>
> T greater (T lhs, T rhs)
> {
> // prevents overzealous gcc optimizer from invoking
> // undefined behavior on signed integer over/underflow
> return lhs > rhs;
> }
> template <class T>
> T compute_limits (T, const char *pfx, const char *sfx, const char *type)
> {
> T max = T (1);
> T one = T (1);
> for (; T (max * 2) > max; max *= 2);
> for (T n = max / 4; n; ) {
> if (T (max + n) < max) {
> if (n > 2)
> n /= 2;
> else if (greater (T (max + one), max))
> n = 1;
> else
> break;
> }
> else
> max += n;
> }
> return max;
> }
> int main(void) {
> compute_limits ((wchar_t)0, "WCHAR_T", suffix, "wchar_t");
> return 0;
> }
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[jira] Closed: (STDCXX-264) LIMITS.cpp WCHAR test causes infinite
loop with IPA, nonstandard code
Posted by "Martin Sebor (JIRA)" <ji...@apache.org>.
[ http://issues.apache.org/jira/browse/STDCXX-264?page=all ]
Martin Sebor closed STDCXX-264.
-------------------------------
Great, thanks for the confirmation (and the report itself)!
> LIMITS.cpp WCHAR test causes infinite loop with IPA, nonstandard code
> ---------------------------------------------------------------------
>
> Key: STDCXX-264
> URL: http://issues.apache.org/jira/browse/STDCXX-264
> Project: C++ Standard Library
> Issue Type: Bug
> Components: Configuration
> Affects Versions: 4.1.3
> Environment: > uname -a && CC -V
> UNICOS/mp sn702 3.0.62 07230830 crayx1
> Cray C++ : Version 5.6.0.0.57 Mon Jul 31, 2006 14:38:56
> Reporter: Colin Lee
> Assigned To: Martin Sebor
> Priority: Minor
> Fix For: 4.2
>
>
> With any compiler that uses interprocedural analysis including leaf node inlining, this WCHAR test in etc/config/src/LIMITS.cpp invokes undefined behavior from signed integer overflow and can result in an infinite loop. Our compiler inlines the greater() function and invokes undefined behavior, so the loop never exits. One workaround is to disable optimization and run the code by hand, but since this code is hidden within the build process, a portable solution is needed. Here's a code snippet:
> template <class T>
> T greater (T lhs, T rhs)
> {
> // prevents overzealous gcc optimizer from invoking
> // undefined behavior on signed integer over/underflow
> return lhs > rhs;
> }
> template <class T>
> T compute_limits (T, const char *pfx, const char *sfx, const char *type)
> {
> T max = T (1);
> T one = T (1);
> for (; T (max * 2) > max; max *= 2);
> for (T n = max / 4; n; ) {
> if (T (max + n) < max) {
> if (n > 2)
> n /= 2;
> else if (greater (T (max + one), max))
> n = 1;
> else
> break;
> }
> else
> max += n;
> }
> return max;
> }
> int main(void) {
> compute_limits ((wchar_t)0, "WCHAR_T", suffix, "wchar_t");
> return 0;
> }
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[jira] Resolved: (STDCXX-264) LIMITS.cpp WCHAR test causes infinite
loop with IPA, nonstandard code
Posted by "Martin Sebor (JIRA)" <ji...@apache.org>.
[ http://issues.apache.org/jira/browse/STDCXX-264?page=all ]
Martin Sebor resolved STDCXX-264.
---------------------------------
Fix Version/s: 4.2
Resolution: Fixed
The referenced patch should fix it. Colin -- please let us know if the problem persists.
> LIMITS.cpp WCHAR test causes infinite loop with IPA, nonstandard code
> ---------------------------------------------------------------------
>
> Key: STDCXX-264
> URL: http://issues.apache.org/jira/browse/STDCXX-264
> Project: C++ Standard Library
> Issue Type: Bug
> Components: Configuration
> Affects Versions: 4.1.3
> Environment: > uname -a && CC -V
> UNICOS/mp sn702 3.0.62 07230830 crayx1
> Cray C++ : Version 5.6.0.0.57 Mon Jul 31, 2006 14:38:56
> Reporter: Colin Lee
> Assigned To: Martin Sebor
> Priority: Minor
> Fix For: 4.2
>
>
> With any compiler that uses interprocedural analysis including leaf node inlining, this WCHAR test in etc/config/src/LIMITS.cpp invokes undefined behavior from signed integer overflow and can result in an infinite loop. Our compiler inlines the greater() function and invokes undefined behavior, so the loop never exits. One workaround is to disable optimization and run the code by hand, but since this code is hidden within the build process, a portable solution is needed. Here's a code snippet:
> template <class T>
> T greater (T lhs, T rhs)
> {
> // prevents overzealous gcc optimizer from invoking
> // undefined behavior on signed integer over/underflow
> return lhs > rhs;
> }
> template <class T>
> T compute_limits (T, const char *pfx, const char *sfx, const char *type)
> {
> T max = T (1);
> T one = T (1);
> for (; T (max * 2) > max; max *= 2);
> for (T n = max / 4; n; ) {
> if (T (max + n) < max) {
> if (n > 2)
> n /= 2;
> else if (greater (T (max + one), max))
> n = 1;
> else
> break;
> }
> else
> max += n;
> }
> return max;
> }
> int main(void) {
> compute_limits ((wchar_t)0, "WCHAR_T", suffix, "wchar_t");
> return 0;
> }
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