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When searching for non-null, check the dominator tree.

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The non-null bitmap only indicates which blocks non-null setting occurs.
Generalized queries need to search the dom tree, whereas propagation
engines only need to know the current block.  Add a flag for this purpose.

	* gimple-range-cache.cc (non_null_ref::non_null_deref_p): Search
	dominator tree is available and requested.
	(ranger_cache::ssa_range_in_bb): Don't search dom tree here.
	(ranger_cache::fill_block_cache): Don't search dom tree here either.
	* gimple-range-cache.h (non_null_deref_p): Add dom_search param.
This commit is contained in:
Andrew MacLeod 2021-04-27 08:44:46 -04:00
parent d942d7332d
commit a7943ea96d
2 changed files with 24 additions and 5 deletions
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27
gcc/gimple-range-cache.cc
View file

@ -48,9 +48,10 @@ non_null_ref::~non_null_ref ()
// Return true if NAME has a non-null dereference in block bb. If this is the
// first query for NAME, calculate the summary first.
// If SEARCH_DOM is true, the search the dominator tree as well.
bool
non_null_ref::non_null_deref_p (tree name, basic_block bb)
non_null_ref::non_null_deref_p (tree name, basic_block bb, bool search_dom)
{
if (!POINTER_TYPE_P (TREE_TYPE (name)))
return false;
@ -59,7 +60,24 @@ non_null_ref::non_null_deref_p (tree name, basic_block bb)
if (!m_nn[v])
process_name (name);
return bitmap_bit_p (m_nn[v], bb->index);
if (bitmap_bit_p (m_nn[v], bb->index))
return true;
// See if any dominator has set non-zero.
if (search_dom && dom_info_available_p (CDI_DOMINATORS))
{
// Search back to the Def block, or the top, whichever is closer.
basic_block def_bb = gimple_bb (SSA_NAME_DEF_STMT (name));
basic_block def_dom = def_bb
? get_immediate_dominator (CDI_DOMINATORS, def_bb)
: NULL;
for ( ;
bb && bb != def_dom;
bb = get_immediate_dominator (CDI_DOMINATORS, bb))
if (bitmap_bit_p (m_nn[v], bb->index))
return true;
}
return false;
}
// Allocate an populate the bitmap for NAME. An ON bit for a block
@ -800,7 +818,7 @@ ranger_cache::ssa_range_in_bb (irange &r, tree name, basic_block bb)
// Check if pointers have any non-null dereferences. Non-call
// exceptions mean we could throw in the middle of the block, so just
// punt for now on those.
if (r.varying_p () && m_non_null.non_null_deref_p (name, bb) &&
if (r.varying_p () && m_non_null.non_null_deref_p (name, bb, false) &&
!cfun->can_throw_non_call_exceptions)
r = range_nonzero (TREE_TYPE (name));
}
@ -1066,7 +1084,8 @@ ranger_cache::fill_block_cache (tree name, basic_block bb, basic_block def_bb)
// Regardless of whether we have visited pred or not, if the
// pred has a non-null reference, revisit this block.
if (m_non_null.non_null_deref_p (name, pred))
// Don't search the DOM tree.
if (m_non_null.non_null_deref_p (name, pred, false))
{
if (DEBUG_RANGE_CACHE)
fprintf (dump_file, "nonnull: update ");

2
gcc/gimple-range-cache.h
View file

@ -33,7 +33,7 @@ class non_null_ref
public:
non_null_ref ();
~non_null_ref ();
bool non_null_deref_p (tree name, basic_block bb);
bool non_null_deref_p (tree name, basic_block bb, bool search_dom = true);
private:
vec <bitmap> m_nn;
void process_name (tree name);