Richard,
Jakub,
the following patch fixes PR51879.
Consider the following test-case:
...
int bar (int);
void baz (int);
void
foo (int y)
{
int a;
if (y == 6)
a = bar (7);
else
a = bar (7);
baz (a);
}
...
after compiling at -02, the representation looks like this before tail-merging:
...
# BLOCK 3 freq:1991
# PRED: 2 [19.9%] (true,exec)
# .MEMD.1714_7 = VDEF <.MEMD.1714_6(D)>
# USE = nonlocal
# CLB = nonlocal
aD.1709_3 = barD.1703 (7);
goto <bb 5>;
# SUCC: 5 [100.0%] (fallthru,exec)
# BLOCK 4 freq:8009
# PRED: 2 [80.1%] (false,exec)
# .MEMD.1714_8 = VDEF <.MEMD.1714_6(D)>
# USE = nonlocal
# CLB = nonlocal
aD.1709_4 = barD.1703 (7);
# SUCC: 5 [100.0%] (fallthru,exec)
# BLOCK 5 freq:10000
# PRED: 3 [100.0%] (fallthru,exec) 4 [100.0%] (fallthru,exec)
# aD.1709_1 = PHI <aD.1709_3(3), aD.1709_4(4)>
# .MEMD.1714_5 = PHI <.MEMD.1714_7(3), .MEMD.1714_8(4)>
# .MEMD.1714_9 = VDEF <.MEMD.1714_5>
# USE = nonlocal
# CLB = nonlocal
bazD.1705 (aD.1709_1);
# VUSE <.MEMD.1714_9>
return;
...
the patch allows aD.1709_4 to be value numbered to aD.1709_3, and .MEMD.1714_8
to .MEMD.1714_7, which enables tail-merging of blocks 4 and 5.
The patch makes sure non-const/pure call results (gimple_vdef and
gimple_call_lhs) are properly value numbered.
Bootstrapped and reg-tested on x86_64.
ok for stage1?
Thanks,
- Tom
2012-01-23 Tom de Vries <t...@codesourcery.com>
PR tree-optimization/51879
tree-ssa-sccvn.c (visit_reference_op_call): Handle gimple_vdef.
(visit_use): Handle non-pure/const calls using visit_reference_op_call.
gcc.dg/pr51879.c: New test.
gcc.dg/pr51879-2.c: Same.
gcc.dg/pr51879-3.c: Same.
gcc.dg/pr51879-4.c: Same.
Index: gcc/tree-ssa-sccvn.c
===================================================================
--- gcc/tree-ssa-sccvn.c (revision 183325)
+++ gcc/tree-ssa-sccvn.c (working copy)
@@ -2591,6 +2591,7 @@ visit_reference_op_call (tree lhs, gimpl
struct vn_reference_s vr1;
tree result;
tree vuse = gimple_vuse (stmt);
+ tree vdef = gimple_vdef (stmt);
vr1.vuse = vuse ? SSA_VAL (vuse) : NULL_TREE;
vr1.operands = valueize_shared_reference_ops_from_call (stmt);
@@ -2600,7 +2601,11 @@ visit_reference_op_call (tree lhs, gimpl
result = vn_reference_lookup_1 (&vr1, NULL);
if (result)
{
- changed = set_ssa_val_to (lhs, result);
+ tree result_vdef = gimple_vdef (SSA_NAME_DEF_STMT (result));
+ if (vdef)
+ changed |= set_ssa_val_to (vdef, result_vdef);
+ changed |= set_ssa_val_to (lhs, result);
+
if (TREE_CODE (result) == SSA_NAME
&& VN_INFO (result)->has_constants)
VN_INFO (lhs)->has_constants = true;
@@ -2609,7 +2614,9 @@ visit_reference_op_call (tree lhs, gimpl
{
void **slot;
vn_reference_t vr2;
- changed = set_ssa_val_to (lhs, lhs);
+ if (vdef)
+ changed |= set_ssa_val_to (vdef, vdef);
+ changed |= set_ssa_val_to (lhs, lhs);
vr2 = (vn_reference_t) pool_alloc (current_info->references_pool);
vr2->vuse = vr1.vuse;
vr2->operands = valueize_refs (create_reference_ops_from_call (stmt));
@@ -3359,8 +3366,10 @@ visit_use (tree use)
/* ??? We should handle stores from calls. */
else if (TREE_CODE (lhs) == SSA_NAME)
{
+ tree vuse = gimple_vuse (stmt);
if (!gimple_call_internal_p (stmt)
- && gimple_call_flags (stmt) & (ECF_PURE | ECF_CONST))
+ && (gimple_call_flags (stmt) & (ECF_PURE | ECF_CONST)
+ || (vuse && SSA_VAL (vuse) != VN_TOP)))
changed = visit_reference_op_call (lhs, stmt);
else
changed = defs_to_varying (stmt);
Index: gcc/testsuite/gcc.dg/pr51879-2.c
===================================================================
--- /dev/null (new file)
+++ gcc/testsuite/gcc.dg/pr51879-2.c (revision 0)
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-pre" } */
+
+int bar (int);
+void baz (int);
+
+void
+foo (int y)
+{
+ int a;
+ if (y)
+ baz (bar (7) + 6);
+ else
+ baz (bar (7) + 6);
+}
+
+/* { dg-final { scan-tree-dump-times "bar \\(" 1 "pre"} } */
+/* { dg-final { scan-tree-dump-times "baz \\(" 1 "pre"} } */
+/* { dg-final { cleanup-tree-dump "pre" } } */
Index: gcc/testsuite/gcc.dg/pr51879.c
===================================================================
--- /dev/null (new file)
+++ gcc/testsuite/gcc.dg/pr51879.c (revision 0)
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-pre" } */
+
+int bar (int);
+void baz (int);
+
+void
+foo (int y)
+{
+ int a;
+ if (y == 6)
+ a = bar (7);
+ else
+ a = bar (7);
+ baz (a);
+}
+
+/* { dg-final { scan-tree-dump-times "bar \\(" 1 "pre"} } */
+/* { dg-final { cleanup-tree-dump "pre" } } */
Index: gcc/testsuite/gcc.dg/pr51879-3.c
===================================================================
--- /dev/null (new file)
+++ gcc/testsuite/gcc.dg/pr51879-3.c (revision 0)
@@ -0,0 +1,19 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-pre" } */
+
+int bar (int);
+void baz (int);
+
+void
+foo (int y)
+{
+ int a;
+ if (y == 6)
+ a = bar (7) + 6;
+ else
+ a = bar (7) + 6;
+ baz (a);
+}
+
+/* { dg-final { scan-tree-dump-times "bar \\(" 1 "pre"} } */
+/* { dg-final { cleanup-tree-dump "pre" } } */
Index: gcc/testsuite/gcc.dg/pr51879-4.c
===================================================================
--- /dev/null (new file)
+++ gcc/testsuite/gcc.dg/pr51879-4.c (revision 0)
@@ -0,0 +1,16 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-pre" } */
+
+int bar (int);
+void baz (int);
+
+int foo (int y)
+{
+ int a, b;
+ a = bar (7) + 6;
+ b = bar (7) + 6;
+ return a + b;
+}
+
+/* { dg-final { scan-tree-dump-times "bar \\(" 2 "pre"} } */
+/* { dg-final { cleanup-tree-dump "pre" } } */
