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?
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" } } */
