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tree-optimization/97897 - complex lowering on abnormal edges

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This fixes complex lowering to not put constants into abnormal
edge PHI values by making sure abnormally used SSA names are
VARYING in its propagation lattice.

2020-11-19  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/97897
	* tree-complex.c (complex_propagate::visit_stmt): Make sure
	abnormally used SSA names are VARYING.
	(complex_propagate::visit_phi): Likewise.
	* tree-ssa.c (verify_phi_args): Verify PHI arguments on abnormal
	edges are SSA names.

	* gcc.dg/pr97897.c: New testcase.
This commit is contained in:
Richard Biener 2020-11-19 09:06:50 +01:00
parent 50134189a4
commit 0d8290959e
3 changed files with 23 additions and 1 deletions
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13
gcc/testsuite/gcc.dg/pr97897.c Normal file
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@ -0,0 +1,13 @@
/* { dg-do compile } */
void h ();
void f () __attribute__ ((returns_twice));
void g (_Complex int a)
{
f ();
if (a != 0)
{
a = 0;
h ();
}
}

5
gcc/tree-complex.c
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@ -318,7 +318,7 @@ complex_propagate::visit_stmt (gimple *stmt, edge *taken_edge_p ATTRIBUTE_UNUSED
lhs = gimple_get_lhs (stmt);
/* Skip anything but GIMPLE_ASSIGN and GIMPLE_CALL with a lhs. */
if (!lhs)
if (!lhs || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
return SSA_PROP_VARYING;
/* These conditions should be satisfied due to the initial filter
@ -417,6 +417,9 @@ complex_propagate::visit_phi (gphi *phi)
set up in init_dont_simulate_again. */
gcc_assert (TREE_CODE (TREE_TYPE (lhs)) == COMPLEX_TYPE);
if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs))
return SSA_PROP_VARYING;
/* We've set up the lattice values such that IOR neatly models PHI meet. */
new_l = UNINITIALIZED;
for (i = gimple_phi_num_args (phi) - 1; i >= 0; --i)

6
gcc/tree-ssa.c
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@ -987,6 +987,12 @@ verify_phi_args (gphi *phi, basic_block bb, basic_block *definition_block)
err = true;
}
if ((e->flags & EDGE_ABNORMAL) && TREE_CODE (op) != SSA_NAME)
{
error ("PHI argument on abnormal edge is not SSA_NAME");
err = true;
}
if (TREE_CODE (op) == SSA_NAME)
{
err = verify_ssa_name (op, virtual_operand_p (gimple_phi_result (phi)));