| Message ID | 56A629CE.1050301@mentor.com |
|---|---|
| State | New |
| Headers | show |
On Mon, 25 Jan 2016, Tom de Vries wrote: > On 27/11/14 15:13, Richard Biener wrote: > > > > Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk. > > > > Richard. > > > > 2014-11-27 Richard Biener <rguenther@suse.de> > > > > PR tree-optimization/64088 > > * tree-ssa-tail-merge.c (update_debug_stmt): After resetting > > the stmt break from the loop over use operands. > > > > * gcc.dg/torture/pr64091.c: New testcase. > > > > Index: gcc/tree-ssa-tail-merge.c > > =================================================================== > > --- gcc/tree-ssa-tail-merge.c (revision 218117) > > +++ gcc/tree-ssa-tail-merge.c (working copy) > > @@ -1606,9 +1613,7 @@ update_debug_stmt (gimple stmt) > > { > > use_operand_p use_p; > > ssa_op_iter oi; > > - basic_block bbdef, bbuse; > > - gimple def_stmt; > > - tree name; > > + basic_block bbuse; > > > > if (!gimple_debug_bind_p (stmt)) > > return; > > @@ -1616,19 +1621,16 @@ update_debug_stmt (gimple stmt) > > bbuse = gimple_bb (stmt); > > FOR_EACH_PHI_OR_STMT_USE (use_p, stmt, oi, SSA_OP_USE) > > { > > - name = USE_FROM_PTR (use_p); > > - gcc_assert (TREE_CODE (name) == SSA_NAME); > > - > > - def_stmt = SSA_NAME_DEF_STMT (name); > > - gcc_assert (def_stmt != NULL); > > - > > - bbdef = gimple_bb (def_stmt); > > + tree name = USE_FROM_PTR (use_p); > > + gimple def_stmt = SSA_NAME_DEF_STMT (name); > > + basic_block bbdef = gimple_bb (def_stmt); > > if (bbdef == NULL || bbuse == bbdef > > || dominated_by_p (CDI_DOMINATORS, bbuse, bbdef)) > > continue; > > > > gimple_debug_bind_reset_value (stmt); > > update_stmt (stmt); > > + break; > > } > > } > > > > Index: gcc/testsuite/gcc.dg/torture/pr64091.c > > =================================================================== > > --- gcc/testsuite/gcc.dg/torture/pr64091.c (revision 0) > > +++ gcc/testsuite/gcc.dg/torture/pr64091.c (working copy) > > @@ -0,0 +1,28 @@ > > +/* { dg-do compile } */ > > +/* { dg-additional-options "-g" } */ > > + > > +extern int foo(void); > > + > > +int main(void) > > +{ > > + int i, a, b; > > + > > + if (foo()) > > + return 0; > > + > > + for (i = 0, a = 0, b = 0; i < 3; i++, a++) > > + { > > + if (foo()) > > + break; > > + > > + if (b += a) > > + a = 0; > > + } > > + > > + if (!a) > > + return 2; > > + > > + b += a; > > + > > + return 0; > > +} > > > > Hi, > > the ICE that the patch above fixes does not reproduce on 4.9. > > One reason is that an edge_flag EDGE_EXECUTABLE happens to be set, which > prevents tail-merge from doing a merge. > > Another reason is that the use that is added to the free_uses freelist during > update_stmt happens to be not immediately reused, so the contents remains the > same. > > Using first attached patch, which: > - clears EDGE_EXECUTABLE in tail-merge, and this shows a latent issue in tail-merging that it doesn't ignore edge flags that are "private" (that is, they have random state upon pass entry). > - clears the contents of a use when adding it to the freelist > we manage to trigger the same problem with 4.9. > > Is seems possible to me that the same problem could trigger on 4.9 for a > different example without the trigger patch. > > The second attached patch is a minimal version of the above fix. > > OK for 4.9? Ok (the minimal fix). Thanks, Richard. > Thanks, > - Tom > > > > > >
Backport "Fix PR64091" 2016-01-25 Tom de Vries <tom@codesourcery.com> backport from trunk: 2014-11-27 Richard Biener <rguenther@suse.de> PR tree-optimization/PR64091 * tree-ssa-tail-merge.c (update_debug_stmt): After resetting the stmt break from the loop over use operands. * gcc.dg/torture/pr64091.c: New testcase. --- gcc/testsuite/gcc.dg/torture/pr64091.c | 28 ++++++++++++++++++++++++++++ gcc/tree-ssa-tail-merge.c | 1 + 2 files changed, 29 insertions(+) diff --git a/gcc/testsuite/gcc.dg/torture/pr64091.c b/gcc/testsuite/gcc.dg/torture/pr64091.c new file mode 100644 index 0000000..0cd994a --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr64091.c @@ -0,0 +1,28 @@ +/* { dg-do compile } */ +/* { dg-additional-options "-g" } */ + +extern int foo(void); + +int main(void) +{ + int i, a, b; + + if (foo()) + return 0; + + for (i = 0, a = 0, b = 0; i < 3; i++, a++) + { + if (foo()) + break; + + if (b += a) + a = 0; + } + + if (!a) + return 2; + + b += a; + + return 0; +} diff --git a/gcc/tree-ssa-tail-merge.c b/gcc/tree-ssa-tail-merge.c index af2641c..b3022ff 100644 --- a/gcc/tree-ssa-tail-merge.c +++ b/gcc/tree-ssa-tail-merge.c @@ -1619,6 +1619,7 @@ update_debug_stmt (gimple stmt) gimple_debug_bind_reset_value (stmt); update_stmt (stmt); + break; } }