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tree-optimization/112767 - spurious diagnostic after sccp/loop-split swap

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We are diagnosing an unreachable loop which we only manage to elide
after the copyprop pass after sccp which leaves the code open for
diagnosing by the intermittent ivcanon pass.  The following makes sure
to clean things up a bit earlier, propagating constant final values
to uses immediately.

	PR tree-optimization/112767
	* tree-scalar-evolution.cc (final_value_replacement_loop):
	Propagate constants to immediate uses immediately.

	* gcc.dg/tree-ssa/pr112767.c: New testcase.
	* gcc.dg/graphite/pr83255.c: Disable SCCP.
This commit is contained in:
Richard Biener 2023-11-30 12:38:53 +01:00
parent 8a6062a47b
commit 2dde9f326d
3 changed files with 29 additions and 2 deletions
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2
gcc/testsuite/gcc.dg/graphite/pr83255.c
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@ -1,5 +1,5 @@
/* { dg-do run } */
/* { dg-options "-O -floop-nest-optimize -fdump-tree-graphite-details" } */
/* { dg-options "-O -floop-nest-optimize -fno-tree-scev-cprop -fdump-tree-graphite-details" } */
int rx, in;

18
gcc/testsuite/gcc.dg/tree-ssa/pr112767.c Normal file
View file

@ -0,0 +1,18 @@
/* { dg-do compile } */
/* { dg-options "-O3" } */
double reg_dict[32];
void foo(int);
void initialize()
{
int i=8;
for (int phi=0; phi<8; ++phi) {
reg_dict[i]=0; /* { dg-bogus "undefined behavior" } */
int sn = 0;
if (i < 16) sn = 20;
foo(sn);
++i;
}
}

11
gcc/tree-scalar-evolution.cc
View file

@ -3841,11 +3841,20 @@ final_value_replacement_loop (class loop *loop)
print_gimple_stmt (dump_file, phi, 0);
fprintf (dump_file, " with expr: ");
print_generic_expr (dump_file, def);
fprintf (dump_file, "\n");
}
any = true;
def = unshare_expr (def);
remove_phi_node (&psi, false);
/* Propagate constants immediately. */
if (CONSTANT_CLASS_P (def))
{
replace_uses_by (rslt, def);
release_ssa_name (rslt);
continue;
}
/* Create the replacement statements. */
gimple_seq stmts;
def = force_gimple_operand (def, &stmts, false, NULL_TREE);
@ -3877,7 +3886,7 @@ final_value_replacement_loop (class loop *loop)
gsi_insert_seq_before (&gsi, stmts, GSI_SAME_STMT);
if (dump_file)
{
fprintf (dump_file, "\n final stmt:\n ");
fprintf (dump_file, " final stmt:\n ");
print_gimple_stmt (dump_file, SSA_NAME_DEF_STMT (rslt), 0);
fprintf (dump_file, "\n");
}