Hi,
insert_debug_temp_for_var_def has some strange code whereby it creates debug
temporaries for SINGLE_RHS (RHS for gimple_assign_single_p) but not for other
RHS in the same situation. Removing it saves 25% of compilation time at -g -O
for a pathological testcase I have.
Bootstrapped/regtested on x86-64/Linux, OK for the mainline?
2023-04-25 Eric Botcazou <ebotca...@adacore.com>
* tree-ssa.cc (insert_debug_temp_for_var_def): Do not create
superfluous debug temporaries for single GIMPLE assignments.
--
Eric Botcazoudiff --git a/gcc/tree-ssa.cc b/gcc/tree-ssa.cc
index a5cad2d344e..4ca1f5f3104 100644
--- a/gcc/tree-ssa.cc
+++ b/gcc/tree-ssa.cc
@@ -412,8 +412,7 @@ insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var)
{
/* If there's a single use of VAR, and VAR is the entire debug
expression (usecount would have been incremented again
- otherwise), and the definition involves only constants and
- SSA names, then we can propagate VALUE into this single use,
+ otherwise), then we can propagate VALUE into this single use,
avoiding the temp.
We can also avoid using a temp if VALUE can be shared and
@@ -424,11 +423,9 @@ insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var)
are deferred to a debug temp, although we could avoid temps
at the expense of duplication of expressions. */
- if (CONSTANT_CLASS_P (value)
+ if (usecount == 1
|| gimple_code (def_stmt) == GIMPLE_PHI
- || (usecount == 1
- && (!gimple_assign_single_p (def_stmt)
- || is_gimple_min_invariant (value)))
+ || CONSTANT_CLASS_P (value)
|| is_gimple_reg (value))
;
else
@@ -466,11 +463,6 @@ insert_debug_temp_for_var_def (gimple_stmt_iterator *gsi, tree var)
if (value)
{
FOR_EACH_IMM_USE_ON_STMT (use_p, imm_iter)
- /* unshare_expr is not needed here. vexpr is either a
- SINGLE_RHS, that can be safely shared, some other RHS
- that was unshared when we found it had a single debug
- use, or a DEBUG_EXPR_DECL, that can be safely
- shared. */
SET_USE (use_p, unshare_expr (value));
/* If we didn't replace uses with a debug decl fold the
resulting expression. Otherwise we end up with invalid IL. */
