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From: "vries at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug tree-optimization/65458] New: parloops transforms omp-generated functions Date: Wed, 18 Mar 2015 07:45:00 -0000 [thread overview] Message-ID: <bug-65458-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=65458 Bug ID: 65458 Summary: parloops transforms omp-generated functions Product: gcc Version: 5.0 Status: UNCONFIRMED Severity: minor Priority: P3 Component: tree-optimization Assignee: unassigned at gcc dot gnu.org Reporter: vries at gcc dot gnu.org parloops parallelizes loops by: - analyzing dependencies - lowering the loop body - annotating the loop with omp parallel and loop pragmas - omp-expanding the loop into a seperate function - replacing the loop with a call to a runtime function, which will run the split-off function in several threads. Parloops has a mechanism to not process again functions that were created by parloops (parallelized_function_p). However, if a source file contains omp pragmas that cause loops to be transformed and split off into seperate functions, there is nothing stopping parloops from processing those functions again. The result is a thread function that itself again creates threads. Look for instance at: ... gcc -fopenmp -O2 -std=c99 src/gcc/testsuite/gcc.dg/gomp/pr25990.c -S -fdump-tree-all-all -ftree-parallelize-loops=2 ... We can see main._omp_fn.1._loopfn.0 in this list: ... $ grep Function pr25990.c.123t.parloops ;; Function main._omp_fn.0 (main._omp_fn.0, funcdef_no=1, decl_uid=2010, cgraph_uid=1, symbol_order=1) ;; Function main._omp_fn.1 (main._omp_fn.1, funcdef_no=2, decl_uid=2047, cgraph_uid=2, symbol_order=2) ;; Function main (main, funcdef_no=0, decl_uid=1739, cgraph_uid=0, symbol_order=0) (executed once) ;; Function main._omp_fn.1._loopfn.0 (main._omp_fn.1._loopfn.0, funcdef_no=3, decl_uid=2397, cgraph_uid=14, symbol_order=14) ;; Function main._loopfn.1 (main._loopfn.1, funcdef_no=4, decl_uid=2512, cgraph_uid=15, symbol_order=15) ... I think we should handle functions splitt off by omp processing conservatively in parloops.
next reply other threads:[~2015-03-18 7:45 UTC|newest] Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top 2015-03-18 7:45 vries at gcc dot gnu.org [this message] 2015-03-18 11:28 ` [Bug tree-optimization/65458] parloops transforms omp-thread functions rguenth at gcc dot gnu.org 2015-03-19 7:27 ` vries at gcc dot gnu.org 2015-03-21 12:55 ` vries at gcc dot gnu.org 2015-03-21 13:02 ` vries at gcc dot gnu.org 2015-03-22 8:53 ` vries at gcc dot gnu.org
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