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Avoid creating useless debug temporaries

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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.

gcc/
	* tree-ssa.cc (insert_debug_temp_for_var_def): Do not create
	superfluous debug temporaries for single GIMPLE assignments.
This commit is contained in:
Eric Botcazou 2023-04-25 17:38:31 +02:00
parent e8d0035301
commit e262cdf49c
1 changed files with 3 additions and 11 deletions
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14
gcc/tree-ssa.cc
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@ -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. */