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Fix wrong-code issue in VN

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The following fixes the wrong removed dead store discovered on the
PR108657 testcase when the reported DSE issue is not fixed.
The issue is we were using ssa_undefined_value_p on virtual operands
which returns a result based on the real definition of the definition
statement.  That doesn't make sense so this patch guards the calls
properly and makes sure nobody else does the same mistake.

	* tree-ssa.cc (ssa_undefined_value_p): Assert we are not
	called on virtual operands.
	* tree-ssa-sccvn.cc (vn_phi_lookup): Guard
	ssa_undefined_value_p calls.
	(vn_phi_insert): Likewise.
	(set_ssa_val_to): Likewise.
	(visit_phi): Avoid extra work with equivalences for
	virtual operand PHIs.
This commit is contained in:
Richard Biener
2023-02-17 09:30:49 +01:00
parent f978585c29
commit 417e95263c
2 changed files with 17 additions and 5 deletions
Download Patch File Download Diff File Expand all files Collapse all files
gcc/tree-ssa-sccvn.cc
+15 -5
View File
@@ -4824,7 +4824,8 @@ vn_phi_lookup (gimple *phi, bool backedges_varying_p)
if (TREE_CODE (def) == SSA_NAME
&& (!backedges_varying_p || !(e->flags & EDGE_DFS_BACK)))
{
if (ssa_undefined_value_p (def, false))
if (!virtual_operand_p (def)
&& ssa_undefined_value_p (def, false))
def = VN_TOP;
else
def = SSA_VAL (def);
@@ -4877,7 +4878,8 @@ vn_phi_insert (gimple *phi, tree result, bool backedges_varying_p)
if (TREE_CODE (def) == SSA_NAME
&& (!backedges_varying_p || !(e->flags & EDGE_DFS_BACK)))
{
if (ssa_undefined_value_p (def, false))
if (!virtual_operand_p (def)
&& ssa_undefined_value_p (def, false))
def = VN_TOP;
else
def = SSA_VAL (def);
@@ -5059,6 +5061,7 @@ set_ssa_val_to (tree from, tree to)
}
curr_invariant = is_gimple_min_invariant (currval);
curr_undefined = (TREE_CODE (currval) == SSA_NAME
&& !virtual_operand_p (currval)
&& ssa_undefined_value_p (currval, false));
if (currval != VN_TOP
&& !curr_invariant
@@ -5081,6 +5084,7 @@ set_ssa_val_to (tree from, tree to)
else if (currval != VN_TOP
&& !curr_undefined
&& TREE_CODE (to) == SSA_NAME
&& !virtual_operand_p (to)
&& ssa_undefined_value_p (to, false))
{
if (dump_file && (dump_flags & TDF_DETAILS))
@@ -5116,6 +5120,7 @@ set_and_exit:
PR82320 for a testcase were we'd otherwise not terminate iteration. */
&& !(curr_undefined
&& TREE_CODE (to) == SSA_NAME
&& !virtual_operand_p (to)
&& ssa_undefined_value_p (to, false))
/* ??? For addresses involving volatile objects or types operand_equal_p
does not reliably detect ADDR_EXPRs as equal. We know we are only
@@ -5880,7 +5885,14 @@ visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p)
sameval = def;
sameval_e = e;
}
else if (!expressions_equal_p (def, sameval))
else if (expressions_equal_p (def, sameval))
sameval_e = NULL;
else if (virtual_operand_p (def))
{
sameval = NULL_TREE;
break;
}
else
{
/* We know we're arriving only with invariant addresses here,
try harder comparing them. We can do some caching here
@@ -5957,8 +5969,6 @@ visit_phi (gimple *phi, bool *inserted, bool backedges_varying_p)
sameval = NULL_TREE;
break;
}
else
sameval_e = NULL;
}
/* If the value we want to use is flowing over the backedge and we
gcc/tree-ssa.cc
+2
View File
@@ -1320,6 +1320,8 @@ ssa_undefined_value_p (tree t, bool partial)
{
gimple *def_stmt;
gcc_checking_assert (!virtual_operand_p (t));
if (ssa_defined_default_def_p (t))
return false;