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.
> 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" } } */
>
>
