On Fri, 2016-10-28 at 10:38 +0200, Richard Biener wrote:
> On Thu, Oct 27, 2016 at 5:37 PM, Will Schmidt <will_schm...@vnet.ibm.com>
> wrote:
> > Hi,
> >
> > Per PR72747, A statement such as "v = vec_splats (1);" correctly
> > initializes a vector. However, a statement such as "v[1] = v[0] =
> > vec_splats (1);" initializes both v[1] and v[0] to random garbage.
> >
> > It has been determined that this is occurring because we did not emit
> > the actual initialization statement before our final exit from
> > gimplify_init_constructor, at which time we lose the expression when we
> > assign *expr_p to either NULL or object. This problem affected both
> > constant
> > and non-constant initializers. Corrected this by moving the logic to
> > emit the statement up earlier within the if/else logic.
> >
> > Bootstrapped and make check ran without regressions on
> > powerpc64le-unknown-linux-gnu.
> >
> > OK for trunk?
>
> Ok.
>
> RIchard.
Committed revision 241647.
Thanks.
>
> > Thanks,
> > -Will
> >
> > gcc:
> > 2016-10-26 Will Schmidt <will_schm...@vnet.ibm.com>
> >
> > PR middle-end/72747
> > * gimplify.c (gimplify_init_constructor): Move emit of constructor
> > assignment to earlier in the if/else logic.
> >
> > testsuite:
> > 2016-10-26 Will Schmidt <will_schm...@vnet.ibm.com>
> >
> > PR middle-end/72747
> > * c-c++-common/pr72747-1.c: New test.
> > * c-c++-common/pr72747-2.c: Likewise.
> >
> > Index: gcc/gimplify.c
> > ===================================================================
> > --- gcc/gimplify.c (revision 241600)
> > +++ gcc/gimplify.c (working copy)
> > @@ -4730,24 +4730,23 @@
> >
> > if (ret == GS_ERROR)
> > return GS_ERROR;
> > - else if (want_value)
> > + /* If we have gimplified both sides of the initializer but have
> > + not emitted an assignment, do so now. */
> > + if (*expr_p)
> > {
> > + tree lhs = TREE_OPERAND (*expr_p, 0);
> > + tree rhs = TREE_OPERAND (*expr_p, 1);
> > + gassign *init = gimple_build_assign (lhs, rhs);
> > + gimplify_seq_add_stmt (pre_p, init);
> > + }
> > + if (want_value)
> > + {
> > *expr_p = object;
> > return GS_OK;
> > }
> > else
> > {
> > - /* If we have gimplified both sides of the initializer but have
> > - not emitted an assignment, do so now. */
> > - if (*expr_p)
> > - {
> > - tree lhs = TREE_OPERAND (*expr_p, 0);
> > - tree rhs = TREE_OPERAND (*expr_p, 1);
> > - gassign *init = gimple_build_assign (lhs, rhs);
> > - gimplify_seq_add_stmt (pre_p, init);
> > - *expr_p = NULL;
> > - }
> > -
> > + *expr_p = NULL;
> > return GS_ALL_DONE;
> > }
> > }
> > Index: gcc/testsuite/c-c++-common/pr72747-1.c
> > ===================================================================
> > --- gcc/testsuite/c-c++-common/pr72747-1.c (revision 0)
> > +++ gcc/testsuite/c-c++-common/pr72747-1.c (working copy)
> > @@ -0,0 +1,16 @@
> > +/* { dg-do compile } */
> > +/* { dg-require-effective-target powerpc_altivec_ok } */
> > +/* { dg-options "-maltivec -fdump-tree-gimple" } */
> > +
> > +/* PR 72747: Test that cascaded definition is happening for constant
> > vectors. */
> > +
> > +#include <altivec.h>
> > +
> > +int main (int argc, char *argv[])
> > +{
> > + __vector int v1,v2;
> > + v1 = v2 = vec_splats ((int) 42);
> > + return 0;
> > +}
> > +/* { dg-final { scan-tree-dump-times " v2 = { 42, 42, 42, 42 }" 1 "gimple"
> > } } */
> > +
> > Index: gcc/testsuite/c-c++-common/pr72747-2.c
> > ===================================================================
> > --- gcc/testsuite/c-c++-common/pr72747-2.c (revision 0)
> > +++ gcc/testsuite/c-c++-common/pr72747-2.c (working copy)
> > @@ -0,0 +1,18 @@
> > +/* { dg-do compile } */
> > +/* { dg-require-effective-target powerpc_altivec_ok } */
> > +/* { dg-options "-c -maltivec -fdump-tree-gimple" } */
> > +
> > +/* PR 72747: test that cascaded definition is happening for non constants.
> > */
> > +
> > +void foo ()
> > +{
> > + extern int i;
> > + __vector int v,w;
> > + v = w = (vector int) { i };
> > +}
> > +
> > +int main (int argc, char *argv[])
> > +{
> > + return 0;
> > +}
> > +/* { dg-final { scan-tree-dump-times " w = {i.0_1}" 1 "gimple" } } */
> >
> >
>
