| Message ID | 20170419135519.GG1809@tucnak |
|---|---|
| State | New |
| Headers | show |
On 04/19/2017 07:55 AM, Jakub Jelinek wrote: > Hi! > > -fcompare-debug fails on the following testcase, because during loop > splitting we attempt to switch into loop closed SSA form and use > also debug stmt uses in those decisions, which is wrong. > Looking at the rest of tree-ssa-loop-manip.c, both find_uses_to_rename_stmt > and check_loop_closed_ssa_stmt ignore debug stmts, this patch just adds > that to another spot. Without it a new SSA_NAME is created (only with -g) > and then soon (in the next pass) removed again because DCE sees it as > dead (it has no non-debug uses) and is replaced by the definition from the > loop again. > > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk? > > 2017-04-19 Jakub Jelinek <jakub@redhat.com> > > PR debug/80436 > * tree-ssa-loop-manip.c (find_uses_to_rename_def): Ignore debug uses. > > * g++.dg/opt/pr80436.C: New test. OK. jeff
--- gcc/tree-ssa-loop-manip.c.jj 2017-02-27 15:19:12.000000000 +0100 +++ gcc/tree-ssa-loop-manip.c 2017-04-19 09:47:30.768610273 +0200 @@ -494,6 +494,9 @@ find_uses_to_rename_def (tree def, bitma FOR_EACH_IMM_USE_STMT (use_stmt, imm_iter, def) { + if (is_gimple_debug (use_stmt)) + continue; + basic_block use_bb = gimple_bb (use_stmt); use_operand_p use_p; --- gcc/testsuite/g++.dg/opt/pr80436.C.jj 2017-04-19 09:54:59.370714079 +0200 +++ gcc/testsuite/g++.dg/opt/pr80436.C 2017-04-19 09:56:28.003549930 +0200 @@ -0,0 +1,42 @@ +// PR debug/80436 +// { dg-do compile { target c++11 } } +// { dg-options "-O3 -fcompare-debug" } + +void fn (...); +void foo (int, int, int); +struct { int elt1; int bits; } *a; +int b, d; + +int +bar (unsigned *x) +{ + if (0) + next_bit: + return 1; + while (1) + { + if (b) + if (a->bits) + goto next_bit; + *x = b; + if (a->elt1) + return 0; + a = 0; + } +} + +enum { C0, C1 } *c; + +void +baz () +{ + int e, m = d; + for (; e < m; e++) + { + if (e < 0) + foo (0, 0, c[e]); + unsigned f; + for (; bar (&f);) + fn (f); + } +}