APAR status
Closed as program error.
Error description
The following test case causes a runtime segfault: ===== COMPILE COMMAND: xlC -g -O0 -std=c++11 test.cc -DFAILPATH ===== TESTCASE: $ cat test.cc #include <vector> #include <map> #include <functional> #include <stdio.h> std::map< int,double> MassOfMaterial( const std::vector<double>& RegionVolumes ) { std::map< int,double> MaterialMass; // Table of masses, Captured by reference // Apply functor to every region for( unsigned region=0; region < RegionVolumes.size(); ++region ) { double currentVolume = RegionVolumes[ region ]; // Computes the mass contribution from a single material within a region cell // both variants fail with xlc++ auto massByRegion = [&] ( int ID, double den ) { double mass = den * currentVolume; auto pair = MaterialMass.insert( std::make_pair(ID,mass) ); bool worked = pair.second; auto iterator = pair.first; if( not worked ) { iterator->second += mass; } return mass; }; massByRegion( 1, 10.0 ); } #ifdef FAILPATH // fails with SEG FAULT using XLC without the std::move return MaterialMass; #else return std::move(MaterialMass); #endif } int main(int argc, char** argv) { std::vector<double> volumes = { .9, 9.0, 90.0 }; std::map< int,double> mass_of_each_material = MassOfMaterial( volumes ); // 3 cells each with density 10.0, .9*10 + 9*10 + 90*10 = 99.9*10 = 999 double expected_value = 999.0; double value = mass_of_each_material[1]; if( value < (expected_value-1.0e-14 ) or value > (expected_value+1.0e-14 ) ) { printf("FAILURE: value was %f but should be %f !! \n", value, expected_value ); } else { printf("PASS: value is correct, %f .\n", value ); } return 0; } // END OF testcase.cc $ ===== WORKAROUND: Use std::move ===== ACTUAL OUTPUT: $ ./a.out Memory fault $ ===== EXPECTED OUTPUT: $ ./a.out PASS: value is correct, 999.000000 . $
Local fix
N/A
Problem summary
USERS AFFECTED: Users who do not use the std::move may be affected by this issue. PROBLEM DESCRIPTION: For the reproted test case, clients who do not use the std::move run into a segfault at runtime. An internal runtime optimization was incorrectly checking for an assignment leading to the segfault.
Problem conclusion
The runtime check has been corrected.
Temporary fix
Comments
APAR Information
APAR number
LI80912
Reported component name
XL C/C++ FOR LI
Reported component ID
5725C7300
Reported release
G11
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2019-06-19
Closed date
2019-06-21
Last modified date
2019-06-21
APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:
Fix information
Fixed component name
XL C/C++ LINUX
Fixed component ID
5725C7310
Applicable component levels
[{"Business Unit":{"code":"BU058","label":"IBM Infrastructure w\/TPS"},"Product":{"code":"SSXVZZ","label":"XL C\/C++ for Linux"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"G11","Edition":"","Line of Business":{"code":"LOB57","label":"Power"}}]
Document Information
Modified date:
21 June 2019