From aecfc21dc36c6705efdfee01ab12edbe03f96ee2 Mon Sep 17 00:00:00 2001
From: rakdver <rakdver@138bc75d-0d04-0410-961f-82ee72b054a4>
Date: Fri, 17 Nov 2006 10:29:07 +0000
Subject: [PATCH] PR tree-optimization/29801 * tree-ssa-ccp.c
(get_symbol_constant_value): New function. (get_default_value): Use
get_symbol_constant_value. (set_lattice_value): ICE when the value of the
constant is changed. (visit_assignment): Ignore VDEFs of read-only
variables.
* gcc.dg/pr29801.c: New test.
git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@118926 138bc75d-0d04-0410-961f-82ee72b054a4
---
gcc/ChangeLog | 9 ++++++++
gcc/testsuite/ChangeLog | 5 ++++
gcc/testsuite/gcc.dg/pr29801.c | 24 +++++++++++++++++++
gcc/tree-ssa-ccp.c | 42 ++++++++++++++++++++++++++--------
4 files changed, 71 insertions(+), 9 deletions(-)
create mode 100644 gcc/testsuite/gcc.dg/pr29801.c
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ebdf75ff2bc5..ab9b5526eec0 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,12 @@
+2006-11-17 Zdenek Dvorak <dvorakz@suse.cz>
+
+ PR tree-optimization/29801
+ * tree-ssa-ccp.c (get_symbol_constant_value): New function.
+ (get_default_value): Use get_symbol_constant_value.
+ (set_lattice_value): ICE when the value of the constant is
+ changed.
+ (visit_assignment): Ignore VDEFs of read-only variables.
+
2006-11-17 Zdenek Dvorak <dvorakz@suse.cz>
* tree-vect-transform.c (vect_create_epilog_for_reduction): Fix
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 6ba65d40a585..84bce0c911e3 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,8 @@
+2006-11-17 Zdenek Dvorak <dvorakz@suse.cz>
+
+ PR tree-optimization/29801
+ * gcc.dg/pr29801.c: New test.
+
2006-11-17 Jakub Jelinek <jakub@redhat.com>
PR middle-end/29584
diff --git a/gcc/testsuite/gcc.dg/pr29801.c b/gcc/testsuite/gcc.dg/pr29801.c
new file mode 100644
index 000000000000..b61ae51425dc
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr29801.c
@@ -0,0 +1,24 @@
+/* We used to crash in ccp here, because the initial constant value of 2
+ was changed to 5. */
+
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-optimized" } */
+
+static const int a = 2;
+
+int test (int param)
+{
+ int *p = (int *) &a;
+
+ if (param)
+ *p = 5;
+
+ return a;
+}
+
+/* Check that we return the correct (unchanged) value. */
+
+/* { dg-final { scan-tree-dump-times "return 2" 1 "optimized" } } */
+/* { dg-final { scan-tree-dump-times "return 5" 0 "optimized" } } */
+
+/* { dg-final { cleanup-tree-dump "optimized" } } */
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 9dd63fe3fd27..2acd62e36915 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -293,6 +293,24 @@ ccp_decl_initial_min_invariant (tree t)
return true;
}
+/* If SYM is a constant variable with known value, return the value.
+ NULL_TREE is returned otherwise. */
+
+static tree
+get_symbol_constant_value (tree sym)
+{
+ if (TREE_STATIC (sym)
+ && TREE_READONLY (sym)
+ && !MTAG_P (sym))
+ {
+ tree val = DECL_INITIAL (sym);
+ if (val
+ && ccp_decl_initial_min_invariant (val))
+ return val;
+ }
+
+ return NULL_TREE;
+}
/* Compute a default value for variable VAR and store it in the
CONST_VAL array. The following rules are used to get default
@@ -320,6 +338,7 @@ get_default_value (tree var)
{
tree sym = SSA_NAME_VAR (var);
prop_value_t val = { UNINITIALIZED, NULL_TREE, NULL_TREE };
+ tree cst_val;
if (!do_store_ccp && !is_gimple_reg (var))
{
@@ -333,16 +352,12 @@ get_default_value (tree var)
val.lattice_val = CONSTANT;
val.value = SSA_NAME_VALUE (var);
}
- else if (TREE_STATIC (sym)
- && TREE_READONLY (sym)
- && !MTAG_P (sym)
- && DECL_INITIAL (sym)
- && ccp_decl_initial_min_invariant (DECL_INITIAL (sym)))
+ else if ((cst_val = get_symbol_constant_value (sym)) != NULL_TREE)
{
/* Globals and static variables declared 'const' take their
initial value. */
val.lattice_val = CONSTANT;
- val.value = DECL_INITIAL (sym);
+ val.value = cst_val;
val.mem_ref = sym;
}
else
@@ -415,9 +430,10 @@ set_lattice_value (tree var, prop_value_t new_val)
value. If *OLD_VAL and NEW_VAL are the same, return false to
inform the caller that this was a non-transition. */
- gcc_assert (old_val->lattice_val <= new_val.lattice_val
+ gcc_assert (old_val->lattice_val < new_val.lattice_val
|| (old_val->lattice_val == new_val.lattice_val
- && old_val->value == new_val.value
+ && ((!old_val->value && !new_val.value)
+ || operand_equal_p (old_val->value, new_val.value, 0))
&& old_val->mem_ref == new_val.mem_ref));
if (old_val->lattice_val != new_val.lattice_val)
@@ -1222,7 +1238,15 @@ visit_assignment (tree stmt, tree *output_p)
/* Set the value of every VDEF to VAL. */
changed = false;
FOR_EACH_SSA_TREE_OPERAND (vdef, stmt, i, SSA_OP_VIRTUAL_DEFS)
- changed |= set_lattice_value (vdef, val);
+ {
+ /* See PR 29801. We may have VDEFs for read-only variables
+ (see the handling of unmodifiable variables in
+ add_virtual_operand); do not attempt to change their value. */
+ if (get_symbol_constant_value (SSA_NAME_VAR (vdef)) != NULL_TREE)
+ continue;
+
+ changed |= set_lattice_value (vdef, val);
+ }
/* Note that for propagation purposes, we are only interested in
visiting statements that load the exact same memory reference
--
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