[I ran gcov over the DOM pass + scoped tables to see if there was any
low hanging fruit to be removed. This hardly anything, but this fell
out.]
Clean up some places where we're scanning for constants on the LHS of
a binary operation. This never gets tickled as gimple keeps constants
on the RHS. Don't touch the MINUS_EXPR case, as substraction is not
commutative.
Likewise for record_edge_info where we have an arm for a conditional
with the constant on the left, with a comment saying copy propagation
can produce one. However, fold_stmt canonicalizes the operand order
of a GIMPLE_COND, so by the time record_edge_info gets it, the
constant is on the right.
Assembly is identical with and without this change over a corpus of
.ii files from a stage1 bootstrap and over the LAPACK Fortran sources,
and gcov shows the removed code never executes over those files nor
the C, C++ and Fortran testsuites.
OK?
gcc/ChangeLog:
* tree-ssa-dom.cc (edge_info::derive_equivalences): Remove the
constant-first arms of the PLUS_EXPR and EQ_EXPR cases.
(record_edge_info): Remove the arm for a constant first operand.
---
gcc/tree-ssa-dom.cc | 48 +++++++--------------------------------------
1 file changed, 7 insertions(+), 41 deletions(-)
diff --git a/gcc/tree-ssa-dom.cc b/gcc/tree-ssa-dom.cc
index 1470d65f4e3..26c1d8dc120 100644
--- a/gcc/tree-ssa-dom.cc
+++ b/gcc/tree-ssa-dom.cc
@@ -237,16 +237,10 @@ edge_info::derive_equivalences (tree name, tree value,
int recursion_limit)
tree rhs1 = gimple_assign_rhs1 (def_stmt);
tree rhs2 = gimple_assign_rhs2 (def_stmt);
- /* If either argument is a constant, then we can compute
- a constant value for the nonconstant argument. */
- if (TREE_CODE (rhs1) == INTEGER_CST
- && TREE_CODE (rhs2) == SSA_NAME)
- derive_equivalences (rhs2,
- fold_binary (MINUS_EXPR, TREE_TYPE (rhs1),
- value, rhs1),
- recursion_limit - 1);
- else if (TREE_CODE (rhs2) == INTEGER_CST
- && TREE_CODE (rhs1) == SSA_NAME)
+ /* If the second argument is a constant, then we can compute
+ a constant value for the first one. */
+ if (TREE_CODE (rhs2) == INTEGER_CST
+ && TREE_CODE (rhs1) == SSA_NAME)
derive_equivalences (rhs1,
fold_binary (MINUS_EXPR, TREE_TYPE (rhs1),
value, rhs2),
@@ -296,14 +290,12 @@ edge_info::derive_equivalences (tree name, tree value,
int recursion_limit)
tree rhs1 = gimple_assign_rhs1 (def_stmt);
tree rhs2 = gimple_assign_rhs2 (def_stmt);
- /* If either argument is a constant, then record the
- other argument as being the same as that constant.
+ /* If the second argument is a constant, then record the
+ first argument as being the same as that constant.
If neither operand is a constant, then we have a
conditional name == name equivalence. */
- if (TREE_CODE (rhs1) == INTEGER_CST)
- derive_equivalences (rhs2, rhs1, recursion_limit - 1);
- else if (TREE_CODE (rhs2) == INTEGER_CST)
+ if (TREE_CODE (rhs2) == INTEGER_CST)
derive_equivalences (rhs1, rhs2, recursion_limit - 1);
}
else
@@ -538,32 +530,6 @@ record_edge_info (basic_block bb)
? false_val : true_val));
}
}
- /* This can show up in the IL as a result of copy propagation
- it will eventually be canonicalized, but we have to cope
- with this case within the pass. */
- else if (is_gimple_min_invariant (op0)
- && TREE_CODE (op1) == SSA_NAME)
- {
- tree cond = build2 (code, boolean_type_node, op0, op1);
- tree inverted = invert_truthvalue_loc (loc, cond);
- bool can_infer_simple_equiv
- = !(HONOR_SIGNED_ZEROS (op0) && real_maybe_zerop (op0))
- && !DECIMAL_FLOAT_MODE_P (element_mode (TREE_TYPE (op0)));
- class edge_info *edge_info;
-
- edge_info = new class edge_info (true_edge);
- record_conditions (&edge_info->cond_equivalences, cond,
inverted);
-
- if (can_infer_simple_equiv && code == EQ_EXPR)
- edge_info->record_simple_equiv (op1, op0);
-
- edge_info = new class edge_info (false_edge);
- record_conditions (&edge_info->cond_equivalences, inverted,
cond);
-
- if (can_infer_simple_equiv && TREE_CODE (inverted) == EQ_EXPR)
- edge_info->record_simple_equiv (op1, op0);
- }
-
else if (TREE_CODE (op0) == SSA_NAME
&& (TREE_CODE (op1) == SSA_NAME
|| is_gimple_min_invariant (op1)))
--
2.53.0
