This reverts the fix for PR67769 and installs an alternate fix
which is more targeted. This helps preserving range info where
important (int this case for emitting a -Wstringop-overflow
warning).
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied.
Richard.
2017-12-07 Richard Biener <rguent...@suse.de>
PR tree-optimization/83296
PR tree-optimization/67769
* tree-ssa-phiopt.c (conditional_replacement): Do not reset
flow sensitive info in an unrelated BB.
(value_replacement): Use reset_flow_sensitive_info.
(minmax_replacement): Reset flow sensitive info on the def
we move. Do not reset flow sensitive info in the whole BB
we move the stmt to.
(abs_replacement): Likewise.
* g++.dg/warn/Wstringop-overflow-1.C: New testcase.
Index: gcc/tree-ssa-phiopt.c
===================================================================
--- gcc/tree-ssa-phiopt.c (revision 255461)
+++ gcc/tree-ssa-phiopt.c (working copy)
@@ -672,7 +672,6 @@ conditional_replacement (basic_block con
}
replace_phi_edge_with_variable (cond_bb, e1, phi, new_var);
- reset_flow_sensitive_info_in_bb (cond_bb);
/* Note that we optimized this PHI. */
return true;
@@ -1138,22 +1137,22 @@ value_replacement (basic_block cond_bb,
cond_rhs, false, rhs2))))))
{
gsi = gsi_for_stmt (cond);
+ /* Moving ASSIGN might change VR of lhs, e.g. when moving u_6
+ def-stmt in:
+ if (n_5 != 0)
+ goto <bb 3>;
+ else
+ goto <bb 4>;
+
+ <bb 3>:
+ # RANGE [0, 4294967294]
+ u_6 = n_5 + 4294967295;
+
+ <bb 4>:
+ # u_3 = PHI <u_6(3), 4294967295(2)> */
+ reset_flow_sensitive_info (lhs);
if (INTEGRAL_TYPE_P (TREE_TYPE (lhs)))
{
- /* Moving ASSIGN might change VR of lhs, e.g. when moving u_6
- def-stmt in:
- if (n_5 != 0)
- goto <bb 3>;
- else
- goto <bb 4>;
-
- <bb 3>:
- # RANGE [0, 4294967294]
- u_6 = n_5 + 4294967295;
-
- <bb 4>:
- # u_3 = PHI <u_6(3), 4294967295(2)> */
- SSA_NAME_RANGE_INFO (lhs) = NULL;
/* If available, we can use VR of phi result at least. */
tree phires = gimple_phi_result (phi);
struct range_info_def *phires_range_info
@@ -1166,7 +1165,7 @@ value_replacement (basic_block cond_bb,
for (int i = prep_cnt - 1; i >= 0; --i)
{
tree plhs = gimple_assign_lhs (prep_stmt[i]);
- SSA_NAME_RANGE_INFO (plhs) = NULL;
+ reset_flow_sensitive_info (plhs);
gsi_from = gsi_for_stmt (prep_stmt[i]);
gsi_move_before (&gsi_from, &gsi);
}
@@ -1490,6 +1489,8 @@ minmax_replacement (basic_block cond_bb,
/* Move the statement from the middle block. */
gsi = gsi_last_bb (cond_bb);
gsi_from = gsi_last_nondebug_bb (middle_bb);
+ reset_flow_sensitive_info (SINGLE_SSA_TREE_OPERAND (gsi_stmt (gsi_from),
+ SSA_OP_DEF));
gsi_move_before (&gsi_from, &gsi);
}
@@ -1508,7 +1509,6 @@ minmax_replacement (basic_block cond_bb,
gsi_insert_before (&gsi, new_stmt, GSI_NEW_STMT);
replace_phi_edge_with_variable (cond_bb, e1, phi, result);
- reset_flow_sensitive_info_in_bb (cond_bb);
return true;
}
@@ -1636,7 +1636,6 @@ abs_replacement (basic_block cond_bb, ba
}
replace_phi_edge_with_variable (cond_bb, e1, phi, result);
- reset_flow_sensitive_info_in_bb (cond_bb);
/* Note that we optimized this PHI. */
return true;
Index: gcc/testsuite/g++.dg/warn/Wstringop-overflow-1.C
===================================================================
--- gcc/testsuite/g++.dg/warn/Wstringop-overflow-1.C (nonexistent)
+++ gcc/testsuite/g++.dg/warn/Wstringop-overflow-1.C (working copy)
@@ -0,0 +1,15 @@
+// { dg-do compile }
+// { dg-additional-options "-O2 -Wstringop-overflow=2" }
+
+struct S {
+ char a[5];
+ void (*pf)(void);
+};
+
+void f (struct S *s, int n)
+{
+ if (n < sizeof s->a + 1)
+ n = sizeof s->a + 1;
+
+ __builtin_strncpy (s->a, "123456", n); // { dg-warning "writing 6" }
+}
