When range_of_stmt was adjusted to avoid large recursion depth, I added
code to precalculate the dependencies without recursion.
This patch adjusted that pre-fill code to intersect the current known
range with the newly calculated one before setting the global range.
this Is what range_of_stmt does, and was missed.
Its running thru testing now, but I expect no issues with either
bootstrap nor testsuite regressions.
Do you want me to check this when testing is complete, or hold off?
Andrew
commit 035a365988628794311c2d706d0e20e39c5fd261
Author: Andrew MacLeod <amacl...@redhat.com>
Date: Thu Apr 21 11:10:30 2022 -0400
Retain existing range knowledge when prefilling statements.
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.
diff --git a/gcc/gimple-range.cc b/gcc/gimple-range.cc
index f41a989d617..f5e9e77bc71 100644
--- a/gcc/gimple-range.cc
+++ b/gcc/gimple-range.cc
@@ -389,6 +389,10 @@ 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;
diff --git a/gcc/testsuite/g++.dg/pr105276.C b/gcc/testsuite/g++.dg/pr105276.C
new file mode 100644
index 00000000000..ad0e9dd7e09
--- /dev/null
+++ b/gcc/testsuite/g++.dg/pr105276.C
@@ -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" } } */
