[PATCH] [OPENMP] Fix use of unsigned counters in loops with zero trip count.
Alexey Bataev
a.bataev at hotmail.com
Mon Apr 20 02:05:24 PDT 2015
Hi rjmccall, hfinkel, fraggamuffin, ejstotzer,
Patch fixes bugs in codegen for loops with unsigned counters and zero trip count. Previously preconditions for all loops were built using logic (Upper - Lower) > 0. But if the loop is a loop with zero trip count, then Upper - Lower is < 0 only for signed integer, for unsigned we're running into an underflow situation.
In this patch we're using original Lower<Upper condition to check that loop body can be executed at least once. Also this allows to skip code generation for loops, if it is known that preconditions for the loop are always false.
http://reviews.llvm.org/D9103
Files:
lib/CodeGen/CGStmtOpenMP.cpp
lib/Sema/SemaOpenMP.cpp
test/OpenMP/for_codegen.cpp
test/OpenMP/for_firstprivate_codegen.cpp
test/OpenMP/for_lastprivate_codegen.cpp
test/OpenMP/parallel_for_codegen.cpp
test/OpenMP/simd_codegen.cpp
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