https://gcc.gnu.org/bugzilla/show_bug.cgi?id=82246
Bug ID: 82246
Summary: Wrong optimisation of an offset double* attribute
class allocated in stack
Product: gcc
Version: 7.1.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: erwan.adam at cea dot fr
Target Milestone: ---
Created attachment 42204
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=42204&action=edit
Use case for wrong optimisation of an offset double* attribute class allocated
in stack
The code in attachment fails with -O1 :
[adam]$ g++ -O0 -Wall -pedantic -Wextra -fno-strict-aliasing -fwrapv
-fno-aggressive-loop-optimizations main.cxx && ./a.out
0
1 1
2 2
POMOT3 - Convergency ok
[adam]$ g++ -O1 -Wall -pedantic -Wextra -fno-strict-aliasing -fwrapv
-fno-aggressive-loop-optimizations main.cxx && ./a.out
0
1 1
2 1
3 1
4 1
5 1
POMOT3 - Convergency failed
This code is valgrind free errors but works in O1 with -fsanitize=undefined :
[adam]$ g++ -O1 -Wall -pedantic -Wextra -fno-strict-aliasing -fwrapv
-fno-aggressive-loop-optimizations -fsanitize=undefined main.cxx && ./a.out
0
1 1
2 2
POMOT3 - Convergency ok
