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Retain existing range knowledge when prefilling statements.

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When range_of_stmt was adjusted to avoid large recursion depth, we need to
intersect the calculated range whth the any known range to avoid losing
info.  Range_of_stmt does this, but the new prefill code missed it.

	PR tree-optimization/105276
	gcc/
	* gimple-range.cc (gimple_ranger::prefill_stmt_dependencies): Include
	existing global range with calculated value.

	gcc/testsuite/
	* g++.dg/pr105276.C: New.
This commit is contained in:
Andrew MacLeod 2022-04-25 09:56:35 -04:00
parent 46cd445fc0
commit 362e2a9c62
2 changed files with 22 additions and 0 deletions
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4
gcc/gimple-range.cc
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@ -394,6 +394,10 @@ gimple_ranger::prefill_stmt_dependencies (tree ssa)
// Fold and save the value for NAME.
stmt = SSA_NAME_DEF_STMT (name);
fold_range_internal (r, stmt, name);
// Make sure we don't lose any current global info.
int_range_max tmp;
m_cache.get_global_range (tmp, name);
r.intersect (tmp);
m_cache.set_global_range (name, r);
}
continue;

18
gcc/testsuite/g++.dg/pr105276.C Normal file
View File

@ -0,0 +1,18 @@
/* { dg-do compile } */
/* { dg-options "-O2 -fdump-tree-optimized" } */
bool
foo(unsigned i)
{
bool result = true;
while (i)
{
i = i % 3;
i = i - (i == 2 ? 2 : i ? 1 : 0);
result = !result;
}
return result;
}
/* We should be able to eliminate the i - operation. */
/* { dg-final { scan-tree-dump-not "i_.* - " "optimized" } } */