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From-SVN: r81969
This commit is contained in:
Jeff Law 2004-05-17 20:55:41 -06:00
parent dd7473111a
commit 85b87c94af
1 changed files with 13 additions and 3 deletions
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16
gcc/tree-ssa-copy.c
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@ -272,11 +272,16 @@ cprop_into_stmt (tree stmt, varray_type const_and_copies)
/* CONST_AND_COPIES is a table which maps an SSA_NAME to the current
known value for that SSA_NAME (or NULL if no value is known).
Propagate values from CONST_AND_COPIES into the PHI nodes of the
successors of BB. */
NONZERO_VARS is the set SSA_NAMES known to have a nonzero value,
even if we don't know their precise value.
Propagate values from CONST_AND_COPIES and NONZERO_VARS into the PHI
nodes of the successors of BB. */
void
cprop_into_successor_phis (basic_block bb, varray_type const_and_copies)
cprop_into_successor_phis (basic_block bb,
varray_type const_and_copies,
bitmap nonzero_vars)
{
edge e;
@ -342,6 +347,11 @@ cprop_into_successor_phis (basic_block bb, varray_type const_and_copies)
if (TREE_CODE (*orig_p) != SSA_NAME)
continue;
/* If the alternative is known to have a nonzero value, record
that fact in the PHI node itself for future use. */
if (bitmap_bit_p (nonzero_vars, SSA_NAME_VERSION (*orig_p)))
PHI_ARG_NONZERO (phi, i) = true;
/* If we have *ORIG_P in our constant/copy table, then replace
ORIG_P with its value in our constant/copy table. */
new = VARRAY_TREE (const_and_copies, SSA_NAME_VERSION (*orig_p));