On Thu, Aug 1, 2024 at 11:55 PM Richard Biener
<richard.guent...@gmail.com> wrote:
>
> On Thu, Aug 1, 2024 at 10:40 PM Andrew Pinski <quic_apin...@quicinc.com>
> wrote:
> >
> > The problem here is that when forwprop does a copy prop, into a statement,
> > we mark the uses of that statement as possibly need to be removed. But it
> > just
> > happened that statement was a debug statement, there will be a difference
> > when
> > compiling with debuging info turned on vs off; this is not expected.
> > So the fix is not to add the old use to dce list to process if it was a
> > debug
> > statement.
> >
> > Bootstrapped and tested on x86_64-linux-gnu with no regressions.
>
> OK
Thanks Applied to the trunk and GCC 14 branch (since it is a regression there).
Thanks,
Andrew Pinski
>
> > PR tree-optimization/116156
> >
> > gcc/ChangeLog:
> >
> > * tree-ssa-forwprop.cc (pass_forwprop::execute): Don't add
> > uses if the statement was a debug statement.
> >
> > gcc/testsuite/ChangeLog:
> >
> > * c-c++-common/torture/pr116156-1.c: New test.
> >
> > Signed-off-by: Andrew Pinski <quic_apin...@quicinc.com>
> > ---
> > .../c-c++-common/torture/pr116156-1.c | 30 +++++++++++++++++++
> > gcc/tree-ssa-forwprop.cc | 16 +++++-----
> > 2 files changed, 39 insertions(+), 7 deletions(-)
> > create mode 100644 gcc/testsuite/c-c++-common/torture/pr116156-1.c
> >
> > diff --git a/gcc/testsuite/c-c++-common/torture/pr116156-1.c
> > b/gcc/testsuite/c-c++-common/torture/pr116156-1.c
> > new file mode 100644
> > index 00000000000..10f938ef4e5
> > --- /dev/null
> > +++ b/gcc/testsuite/c-c++-common/torture/pr116156-1.c
> > @@ -0,0 +1,30 @@
> > +/* { dg-additional-options "-fcompare-debug" } */
> > +/* PR tree-optimization/116156 */
> > +
> > +/* Forwprop used to delete an unused statement
> > + but only with debug statements around. */
> > +
> > +struct jpeg_compress_struct {
> > + int X_density;
> > +};
> > +void gg();
> > +int h(const char*,const char*) __attribute((pure));
> > +int h1(const char*) __attribute((pure));
> > +int f1() __attribute__((returns_twice));
> > +void real_save_jpeg(char **keys, char *values) {
> > + struct jpeg_compress_struct cinfo;
> > + int x_density = 0;
> > + while (*keys)
> > + {
> > + if (h1(*keys) == 0)
> > + gg();
> > + if (h1(*keys) == 0) {
> > + if (!*values)
> > + x_density = -1;
> > + if (x_density <= 0)
> > + gg();
> > + }
> > + }
> > + if (f1())
> > + cinfo.X_density = x_density;
> > +}
> > diff --git a/gcc/tree-ssa-forwprop.cc b/gcc/tree-ssa-forwprop.cc
> > index 44a6b5d39aa..2e37642359c 100644
> > --- a/gcc/tree-ssa-forwprop.cc
> > +++ b/gcc/tree-ssa-forwprop.cc
> > @@ -3923,7 +3923,8 @@ pass_forwprop::execute (function *fun)
> > tree val = fwprop_ssa_val (use);
> > if (val && val != use)
> > {
> > - bitmap_set_bit (simple_dce_worklist, SSA_NAME_VERSION
> > (use));
> > + if (!is_gimple_debug (stmt))
> > + bitmap_set_bit (simple_dce_worklist, SSA_NAME_VERSION
> > (use));
> > if (may_propagate_copy (use, val))
> > {
> > propagate_value (usep, val);
> > @@ -3963,12 +3964,13 @@ pass_forwprop::execute (function *fun)
> > if (gimple_cond_true_p (cond)
> > || gimple_cond_false_p (cond))
> > cfg_changed = true;
> > - /* Queue old uses for simple DCE. */
> > - for (tree use : uses)
> > - if (TREE_CODE (use) == SSA_NAME
> > - && !SSA_NAME_IS_DEFAULT_DEF (use))
> > - bitmap_set_bit (simple_dce_worklist,
> > - SSA_NAME_VERSION (use));
> > + /* Queue old uses for simple DCE if not debug statement.
> > */
> > + if (!is_gimple_debug (stmt))
> > + for (tree use : uses)
> > + if (TREE_CODE (use) == SSA_NAME
> > + && !SSA_NAME_IS_DEFAULT_DEF (use))
> > + bitmap_set_bit (simple_dce_worklist,
> > + SSA_NAME_VERSION (use));
> > }
> >
> > if (changed || substituted_p)
> > --
> > 2.43.0
> >
