On Mon, 16 May 2016, Jeff Law wrote:
- Now that I think of it, maybe I should check that the variable is not
a pointer before calling set_range_info? Having range [0, 1] makes it
unlikely, but who knows...
Maybe using an assert would be better.
I don't think having a pointer there would be completely wrong, just
unlikely, so I'd rather add a check but not assert.
Index: gcc/tree-vrp.c
===================================================================
--- gcc/tree-vrp.c (revision 236194)
+++ gcc/tree-vrp.c (working copy)
@@ -8933,20 +8933,24 @@ simplify_truth_ops_using_ranges (gimple_
gimple_assign_set_rhs_with_ops (gsi,
need_conversion
? NOP_EXPR : TREE_CODE (op0), op0);
/* For A != B we substitute A ^ B. Either with conversion. */
else if (need_conversion)
{
tree tem = make_ssa_name (TREE_TYPE (op0));
gassign *newop
= gimple_build_assign (tem, BIT_XOR_EXPR, op0, op1);
gsi_insert_before (gsi, newop, GSI_SAME_STMT);
+ if (TYPE_PRECISION (TREE_TYPE (tem)) > 1)
+ set_range_info (tem, VR_RANGE,
+ wi::zero (TYPE_PRECISION (TREE_TYPE (tem))),
+ wi::one (TYPE_PRECISION (TREE_TYPE (tem))));
Is there actually a case where TYPE_PRECISION (TREE_TYPE (tem)) > 1 is ever
false? Would an assert make more sense here?
op0 can have precision 1, so tem can as well. In most cases I would expect
need_conversion to be false in that case though. However, it doesn't seem
impossible to have several types with 1-bit precision that are not
equivalent (different TYPE_SIGN for instance). So again, I don't feel
comfortable adding an assert. But I am open to proofs that those events
cannot happen.
static bool
simplify_conversion_using_ranges (gimple *stmt)
Your ChangeLog mentions simplify_switch_using_ranges, not
simplify_conversion_using_ranges.
Oups, bad copy-paste (I keep too much context in the diff for diff -p to
give useful results), thanks.
This is OK for the trunk -- your call on asserting the variable is not a
pointer before calling set_range_info. Similarly on the check that the
TYPE_PRECISION (TREE_TYPE (tem)) > 1.
--
Marc Glisse
