https://gcc.gnu.org/bugzilla/show_bug.cgi?id=108008
Bug ID: 108008
Summary: Compiler mis-optimization with posix_memalign
Product: gcc
Version: 12.2.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c++
Assignee: unassigned at gcc dot gnu.org
Reporter: hahnjo at hahnjo dot de
Target Milestone: ---
Created attachment 54033
--> https://gcc.gnu.org/bugzilla/attachment.cgi?id=54033&action=edit
init.cpp
Consider the attached example, reduced from some real code, and also available
on Compiler Explorer: https://godbolt.org/z/x4Gsjo7rT
The expectation is that sameZ[i] = true if zPlanes[i] == zPlanes[i + 1] which
should be the case for i = 1. However, when compiling the code with GCC 11.2.0
or 12.2.0 and -std=c++17 -O3, the output is sameZ = 0 for all three iterations
of the second loop. The problem disappears when changing anything in the
slightest manner: compiling with -O2, using -std=gnu++17, using a different
allocation function, commenting out one of the other two statements in the
first loop, using the unconditional assignment to sameZ[i], or removing the
exit(1).
Could this be a bug in the optimizer?
