From 195da47bbbf6402e3147dc1e6be6cacde140f7f3 Mon Sep 17 00:00:00 2001
From: Jeff Law <law@redhat.com>
Date: Tue, 21 Sep 2004 22:07:23 -0600
Subject: [PATCH] tree-ssa-ccp.c (get_default_value): If we have a constant
value recorded for an SSA_NAME...
* tree-ssa-ccp.c (get_default_value): If we have a constant
value recorded for an SSA_NAME, then use that constant as
the initial lattice value.
(substitute_and_fold): Transfer equivalences discovered into
SSA_NAME_EQUIV.
* tree.h (SSA_NAME_EQUIV): Add comments.
(SET_SSA_NAME_EQUIV): Similarly.
From-SVN: r87844
---
gcc/ChangeLog | 11 +++++++++++
gcc/tree-ssa-ccp.c | 29 ++++++++++++++++++++++++++++-
gcc/tree.h | 5 ++++-
3 files changed, 43 insertions(+), 2 deletions(-)
diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 3047ad658471..b6ae90ac7821 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,14 @@
+2004-09-21 Jeff Law <law@redhat.com>
+
+ * tree-ssa-ccp.c (get_default_value): If we have a constant
+ value recorded for an SSA_NAME, then use that constant as
+ the initial lattice value.
+ (substitute_and_fold): Transfer equivalences discovered into
+ SSA_NAME_EQUIV.
+
+ * tree.h (SSA_NAME_EQUIV): Add comments.
+ (SET_SSA_NAME_EQUIV): Similarly.
+
2004-09-21 David Edelsohn <edelsohn@gnu.org>
* config/rs6000/linux64.h (PROCESSOR_DEFAULT64): Default to POWER4.
diff --git a/gcc/tree-ssa-ccp.c b/gcc/tree-ssa-ccp.c
index 81ce67321c57..5fe1e1de66ff 100644
--- a/gcc/tree-ssa-ccp.c
+++ b/gcc/tree-ssa-ccp.c
@@ -135,7 +135,14 @@ get_default_value (tree var)
val.lattice_val = UNDEFINED;
val.const_val = NULL_TREE;
- if (TREE_CODE (sym) == PARM_DECL || TREE_THIS_VOLATILE (sym))
+ if (TREE_CODE (var) == SSA_NAME
+ && SSA_NAME_EQUIV (var)
+ && is_gimple_min_invariant (SSA_NAME_EQUIV (var)))
+ {
+ val.lattice_val = CONSTANT;
+ val.const_val = SSA_NAME_EQUIV (var);
+ }
+ else if (TREE_CODE (sym) == PARM_DECL || TREE_THIS_VOLATILE (sym))
{
/* Function arguments and volatile variables are considered VARYING. */
val.lattice_val = VARYING;
@@ -512,6 +519,7 @@ static void
substitute_and_fold (void)
{
basic_block bb;
+ unsigned int i;
if (dump_file && (dump_flags & TDF_DETAILS))
fprintf (dump_file,
@@ -586,6 +594,25 @@ substitute_and_fold (void)
}
}
}
+
+ /* And transfer what we learned from VALUE_VECTOR into the
+ SSA_NAMEs themselves. This probably isn't terribly important
+ since we probably constant propagated the values to their
+ use sites above. */
+ for (i = 0; i < num_ssa_names; i++)
+ {
+ tree name = ssa_name (i);
+ value *value;
+
+ if (!name)
+ continue;
+
+ value = get_value (name);
+ if (value->lattice_val == CONSTANT
+ && is_gimple_reg (name)
+ && is_gimple_min_invariant (value->const_val))
+ SET_SSA_NAME_EQUIV (name, value->const_val)
+ }
}
diff --git a/gcc/tree.h b/gcc/tree.h
index 0f78e743897b..e2742bc5c684 100644
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -1304,13 +1304,14 @@ struct tree_exp GTY(())
#define SSA_NAME_OCCURS_IN_ABNORMAL_PHI(NODE) \
SSA_NAME_CHECK (NODE)->common.asm_written_flag
-
/* Nonzero if this SSA_NAME expression is currently on the free list of
SSA_NAMES. Using NOTHROW_FLAG seems reasonably safe since throwing
has no meaning for an SSA_NAME. */
#define SSA_NAME_IN_FREE_LIST(NODE) \
SSA_NAME_CHECK (NODE)->common.nothrow_flag
+/* If NAME is equivalent to some other SSA_NAME or an invariant, then
+ return the equivalent SSA_NAME or invariant, else return NULL. */
#define SSA_NAME_EQUIV(NAME) __extension__ \
({ tree equiv = SSA_NAME_CHECK (NAME)->ssa_name.equiv; \
if (equiv && TREE_CODE (equiv) == SSA_NAME) \
@@ -1318,6 +1319,8 @@ struct tree_exp GTY(())
equiv; \
})
+/* Record that NAME (an SSA_NAME) is equivalent to EQUIV. */
+
#define SET_SSA_NAME_EQUIV(NAME, EQUIV)\
SSA_NAME_CHECK (NAME)->ssa_name.equiv = (EQUIV);
--
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