116 lines
3.2 KiB
Diff
116 lines
3.2 KiB
Diff
Index: gcc/tree-ssa-tail-merge.c
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===================================================================
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--- a/gcc/tree-ssa-tail-merge.c (revision 185028)
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+++ b/gcc/tree-ssa-tail-merge.c (working copy)
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@@ -1123,18 +1123,31 @@ gimple_equal_p (same_succ same_succ, gim
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}
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}
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-/* Let GSI skip backwards over local defs. */
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+/* Let GSI skip backwards over local defs. Return the earliest vuse in VUSE.
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+ Return true in VUSE_ESCAPED if the vuse influenced a SSA_OP_DEF of one of the
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+ processed statements. */
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static void
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-gsi_advance_bw_nondebug_nonlocal (gimple_stmt_iterator *gsi)
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+gsi_advance_bw_nondebug_nonlocal (gimple_stmt_iterator *gsi, tree *vuse,
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+ bool *vuse_escaped)
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{
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gimple stmt;
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+ tree lvuse;
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while (true)
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{
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if (gsi_end_p (*gsi))
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return;
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stmt = gsi_stmt (*gsi);
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+
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+ lvuse = gimple_vuse (stmt);
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+ if (lvuse != NULL_TREE)
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+ {
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+ *vuse = lvuse;
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+ if (!ZERO_SSA_OPERANDS (stmt, SSA_OP_DEF))
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+ *vuse_escaped = true;
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+ }
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+
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if (!(is_gimple_assign (stmt) && local_def (gimple_get_lhs (stmt))
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&& !gimple_has_side_effects (stmt)))
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return;
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@@ -1150,9 +1163,11 @@ find_duplicate (same_succ same_succ, bas
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{
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gimple_stmt_iterator gsi1 = gsi_last_nondebug_bb (bb1);
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gimple_stmt_iterator gsi2 = gsi_last_nondebug_bb (bb2);
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+ tree vuse1 = NULL_TREE, vuse2 = NULL_TREE;
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+ bool vuse_escaped = false;
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- gsi_advance_bw_nondebug_nonlocal (&gsi1);
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- gsi_advance_bw_nondebug_nonlocal (&gsi2);
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+ gsi_advance_bw_nondebug_nonlocal (&gsi1, &vuse1, &vuse_escaped);
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+ gsi_advance_bw_nondebug_nonlocal (&gsi2, &vuse2, &vuse_escaped);
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while (!gsi_end_p (gsi1) && !gsi_end_p (gsi2))
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{
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@@ -1161,13 +1176,20 @@ find_duplicate (same_succ same_succ, bas
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gsi_prev_nondebug (&gsi1);
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gsi_prev_nondebug (&gsi2);
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- gsi_advance_bw_nondebug_nonlocal (&gsi1);
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- gsi_advance_bw_nondebug_nonlocal (&gsi2);
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+ gsi_advance_bw_nondebug_nonlocal (&gsi1, &vuse1, &vuse_escaped);
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+ gsi_advance_bw_nondebug_nonlocal (&gsi2, &vuse2, &vuse_escaped);
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}
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if (!(gsi_end_p (gsi1) && gsi_end_p (gsi2)))
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return;
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+ /* If the incoming vuses are not the same, and the vuse escaped into an
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+ SSA_OP_DEF, then merging the 2 blocks will change the value of the def,
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+ which potentially means the semantics of one of the blocks will be changed.
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+ TODO: make this check more precise. */
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+ if (vuse_escaped && vuse1 != vuse2)
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+ return;
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+
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if (dump_file)
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fprintf (dump_file, "find_duplicates: <bb %d> duplicate of <bb %d>\n",
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bb1->index, bb2->index);
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Index: gcc/testsuite/gcc.dg/pr52734.c
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===================================================================
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--- a/dev/null (new file)
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+++ b/gcc/testsuite/gcc.dg/pr52734.c (revision 0)
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@@ -0,0 +1,35 @@
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+/* { dg-do run } */
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+/* { dg-options "-O2" } */
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+
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+int bbb = 0;
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+
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+int __attribute__((noinline,noclone)) aaa(void)
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+{
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+ ++bbb;
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+ return 0;
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+}
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+
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+int __attribute__((noinline,noclone)) ccc(void)
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+{
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+ int ddd;
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+ /* bbb == 0 */
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+ if (aaa())
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+ return bbb;
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+
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+ /* bbb == 1 */
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+ ddd = bbb;
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+ /* bbb == ddd == 1 */
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+ if (aaa ())
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+ return 0;
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+ /* bbb == 2, ddd == 1 */
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+
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+ return ddd;
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+}
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+
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+int main(void)
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+{
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+ if (ccc() != 1)
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+ __builtin_abort();
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+ return 0;
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+}
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+
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