From 4a60186570defebed7d811b37c46092267407a96 Mon Sep 17 00:00:00 2001
From: Maximilian Downey Twiss <creatorsmithmdt@gmail.com>
Date: Fri, 18 Nov 2022 09:05:50 +1100
Subject: [PATCH 13/56] Re-add flag_evaluation_order, reorder_operands_p, and
add reorder bool argument to tree_swap_operands_p.
gcc/ChangeLog:
* common.opt (flag_evaluation_order): Re-add.
* expr.cc (expand_operands): Re-add code guarded by flag_evaluation_order.
* fold-const.cc (reorder_operands_p): Re-add.
(negate_expr_p): Handle reorder_operands_p.
(fold_negate_expr_1): Likewise.
(tree_swap_operands_p): Re-add reorder argument.
(fold_binary_loc): Likewise.
(fold_ternary_loc): Likewise
* fold-const.h (tree_swap_operands_p): Likewise.
* genmatch.cc (dt_operand::gen_gimple_expr): Likewise.
* gimple-fold.cc (fold_stmt_1): Likewise.
* gimple-match-head.cc (gimple_resimplify2): Likewise.
(gimple_resimplify3): Likewise.
(gimple_resimplify4): Likewise.
(gimple_resimplify5): Likewise.
(gimple_simplify): Likewise.
* match.pd: Likewise.
* tree-ssa-dom.cc (record_equality): Likewise.
* tree-ssa-reassoc.cc (optimize_range_tests_var_bound): Likewise.
* tree-ssa-sccvn.cc (vn_nary_op_compute_hash): Likewise.
* tree-ssa-threadedge.cc: Likewise.
---
gcc/common.opt | 4 +++
gcc/expr.cc | 4 +++
gcc/fold-const.cc | 51 ++++++++++++++++++++++++++++++--------
gcc/fold-const.h | 2 +-
gcc/genmatch.cc | 2 +-
gcc/gimple-fold.cc | 8 +++---
gcc/gimple-match-head.cc | 20 +++++++++------
gcc/match.pd | 2 +-
gcc/tree-ssa-dom.cc | 2 +-
gcc/tree-ssa-reassoc.cc | 2 +-
gcc/tree-ssa-sccvn.cc | 4 +--
gcc/tree-ssa-threadedge.cc | 2 +-
12 files changed, 74 insertions(+), 29 deletions(-)
diff --git a/gcc/common.opt b/gcc/common.opt
index 26e9d1cc4e7..318eafc2e8c 100644
--- a/gcc/common.opt
+++ b/gcc/common.opt
@@ -62,6 +62,10 @@ int flag_complex_method = 1
Variable
int flag_default_complex_method = 1
+; Nonzero if subexpressions must be evaluated from left-to-right.
+Variable
+int flag_evaluation_order = 0
+
; Language specific warning pass for unused results.
Variable
bool flag_warn_unused_result = false
diff --git a/gcc/expr.cc b/gcc/expr.cc
index d9407432ea5..2e770ab090d 100644
--- a/gcc/expr.cc
+++ b/gcc/expr.cc
@@ -8576,6 +8576,10 @@ expand_operands (tree exp0, tree exp1, rtx target, rtx *op0, rtx *op1,
}
else
{
+ /* If we need to preserve evaluation order, copy exp0 into its own
+ temporary variable so that it can't be clobbered by exp1. */
+ if (flag_evaluation_order && TREE_SIDE_EFFECTS (exp1))
+ exp0 = save_expr (exp0);
*op0 = expand_expr (exp0, target, VOIDmode, modifier);
*op1 = expand_expr (exp1, NULL_RTX, VOIDmode, modifier);
}
diff --git a/gcc/fold-const.cc b/gcc/fold-const.cc
index b89cac91cae..374878b31a4 100644
--- a/gcc/fold-const.cc
+++ b/gcc/fold-const.cc
@@ -139,6 +139,7 @@ static tree fold_cond_expr_with_comparison (location_t, tree, enum tree_code,
static tree unextend (tree, int, int, tree);
static tree extract_muldiv (tree, tree, enum tree_code, tree, bool *);
static tree extract_muldiv_1 (tree, tree, enum tree_code, tree, bool *);
+static bool reorder_operands_p (const_tree, const_tree);
static tree fold_binary_op_with_conditional_arg (location_t,
enum tree_code, tree,
tree, tree,
@@ -472,7 +473,9 @@ negate_expr_p (tree t)
&& ! TYPE_OVERFLOW_WRAPS (type)))
return false;
/* -(A + B) -> (-B) - A. */
- if (negate_expr_p (TREE_OPERAND (t, 1)))
+ if (negate_expr_p (TREE_OPERAND (t, 1))
+ && reorder_operands_p (TREE_OPERAND (t, 0),
+ TREE_OPERAND (t, 1)))
return true;
/* -(A + B) -> (-A) - B. */
return negate_expr_p (TREE_OPERAND (t, 0));
@@ -482,7 +485,9 @@ negate_expr_p (tree t)
return !HONOR_SIGN_DEPENDENT_ROUNDING (type)
&& !HONOR_SIGNED_ZEROS (type)
&& (! ANY_INTEGRAL_TYPE_P (type)
- || TYPE_OVERFLOW_WRAPS (type));
+ || TYPE_OVERFLOW_WRAPS (type))
+ && reorder_operands_p (TREE_OPERAND (t, 0),
+ TREE_OPERAND (t, 1));
case MULT_EXPR:
if (TYPE_UNSIGNED (type))
@@ -643,7 +648,9 @@ fold_negate_expr_1 (location_t loc, tree t)
&& !HONOR_SIGNED_ZEROS (type))
{
/* -(A + B) -> (-B) - A. */
- if (negate_expr_p (TREE_OPERAND (t, 1)))
+ if (negate_expr_p (TREE_OPERAND (t, 1))
+ && reorder_operands_p (TREE_OPERAND (t, 0),
+ TREE_OPERAND (t, 1)))
{
tem = negate_expr (TREE_OPERAND (t, 1));
return fold_build2_loc (loc, MINUS_EXPR, type,
@@ -663,7 +670,8 @@ fold_negate_expr_1 (location_t loc, tree t)
case MINUS_EXPR:
/* - (A - B) -> B - A */
if (!HONOR_SIGN_DEPENDENT_ROUNDING (type)
- && !HONOR_SIGNED_ZEROS (type))
+ && !HONOR_SIGNED_ZEROS (element_mode (type))
+ && reorder_operands_p (TREE_OPERAND (t, 0), TREE_OPERAND (t, 1)))
return fold_build2_loc (loc, MINUS_EXPR, type,
TREE_OPERAND (t, 1), TREE_OPERAND (t, 0));
break;
@@ -7492,12 +7500,27 @@ fold_single_bit_test (location_t loc, enum tree_code code,
return NULL_TREE;
}
+/* Check whether we are allowed to reorder operands arg0 and arg1,
+ such that the evaluation of arg1 occurs before arg0. */
+
+static bool
+reorder_operands_p (const_tree arg0, const_tree arg1)
+{
+ if (! flag_evaluation_order)
+ return true;
+ if (TREE_CONSTANT (arg0) || TREE_CONSTANT (arg1))
+ return true;
+ return ! TREE_SIDE_EFFECTS (arg0)
+ && ! TREE_SIDE_EFFECTS (arg1);
+}
+
/* Test whether it is preferable to swap two operands, ARG0 and
ARG1, for example because ARG0 is an integer constant and ARG1
- isn't. */
+ isn't. If REORDER is true, only recommend swapping if we can
+ evaluate the operands in reverse order. */
bool
-tree_swap_operands_p (const_tree arg0, const_tree arg1)
+tree_swap_operands_p (const_tree arg0, const_tree arg1, bool reorder)
{
if (CONSTANT_CLASS_P (arg1))
return 0;
@@ -7512,6 +7535,10 @@ tree_swap_operands_p (const_tree arg0, const_tree arg1)
if (TREE_CONSTANT (arg0))
return 1;
+ if (reorder && flag_evaluation_order
+ && (TREE_SIDE_EFFECTS (arg0) || TREE_SIDE_EFFECTS (arg1)))
+ return 0;
+
/* It is preferable to swap two SSA_NAME to ensure a canonical form
for commutative and comparison operators. Ensuring a canonical
form allows the optimizers to find additional redundancies without
@@ -10904,13 +10931,13 @@ fold_binary_loc (location_t loc, enum tree_code code, tree type,
/* If this is a commutative operation, and ARG0 is a constant, move it
to ARG1 to reduce the number of tests below. */
if (commutative_tree_code (code)
- && tree_swap_operands_p (arg0, arg1))
+ && tree_swap_operands_p (arg0, arg1, true))
return fold_build2_loc (loc, code, type, op1, op0);
/* Likewise if this is a comparison, and ARG0 is a constant, move it
to ARG1 to reduce the number of tests below. */
if (kind == tcc_comparison
- && tree_swap_operands_p (arg0, arg1))
+ && tree_swap_operands_p (arg0, arg1, true))
return fold_build2_loc (loc, swap_tree_comparison (code), type, op1, op0);
tem = generic_simplify (loc, code, type, op0, op1);
@@ -10969,7 +10996,8 @@ fold_binary_loc (location_t loc, enum tree_code code, tree type,
return build2_loc (loc, COMPOUND_EXPR, type, TREE_OPERAND (arg0, 0),
tem);
}
- if (TREE_CODE (arg1) == COMPOUND_EXPR)
+ if (TREE_CODE (arg1) == COMPOUND_EXPR
+ && reorder_operands_p (arg0, TREE_OPERAND (arg1, 0)))
{
tem = fold_build2_loc (loc, code, type, op0,
fold_convert_loc (loc, TREE_TYPE (op1),
@@ -11519,6 +11547,7 @@ fold_binary_loc (location_t loc, enum tree_code code, tree type,
/* (-A) - B -> (-B) - A where B is easily negated and we can swap. */
if (TREE_CODE (arg0) == NEGATE_EXPR
&& negate_expr_p (op1)
+ && reorder_operands_p (arg0, arg1)
/* If arg0 is e.g. unsigned int and type is int, then this could
introduce UB, because if A is INT_MIN at runtime, the original
expression can be well defined while the latter is not.
@@ -12798,7 +12827,7 @@ fold_ternary_loc (location_t loc, enum tree_code code, tree type,
/* If this is a commutative operation, and OP0 is a constant, move it
to OP1 to reduce the number of tests below. */
if (commutative_ternary_tree_code (code)
- && tree_swap_operands_p (op0, op1))
+ && tree_swap_operands_p (op0, op1, true))
return fold_build3_loc (loc, code, type, op1, op0, op2);
tem = generic_simplify (loc, code, type, op0, op1, op2);
@@ -12931,7 +12960,7 @@ fold_ternary_loc (location_t loc, enum tree_code code, tree type,
/* If the second operand is simpler than the third, swap them
since that produces better jump optimization results. */
if (truth_value_p (TREE_CODE (arg0))
- && tree_swap_operands_p (op1, op2))
+ && tree_swap_operands_p (op1, op2, false))
{
location_t loc0 = expr_location_or (arg0, loc);
/* See if this can be inverted. If it can't, possibly because
diff --git a/gcc/fold-const.h b/gcc/fold-const.h
index fa284c712bf..486dad8d252 100644
--- a/gcc/fold-const.h
+++ b/gcc/fold-const.h
@@ -149,7 +149,7 @@ extern tree build_invariant_address (tree, tree, poly_int64);
extern tree constant_boolean_node (bool, tree);
extern tree div_if_zero_remainder (const_tree, const_tree);
-extern bool tree_swap_operands_p (const_tree, const_tree);
+extern bool tree_swap_operands_p (const_tree, const_tree, bool);
extern enum tree_code swap_tree_comparison (enum tree_code);
extern bool ptr_difference_const (tree, tree, poly_int64_pod *);
diff --git a/gcc/genmatch.cc b/gcc/genmatch.cc
index 4a8802469cd..6b2be7da519 100644
--- a/gcc/genmatch.cc
+++ b/gcc/genmatch.cc
@@ -2873,7 +2873,7 @@ dt_operand::gen_gimple_expr (FILE *f, int indent, int depth)
gen_opname (child_opname0, opno);
gen_opname (child_opname1, opno + 1);
fprintf_indent (f, indent,
- "if (tree_swap_operands_p (%s, %s))\n",
+ "if (tree_swap_operands_p (%s, %s, false))\n",
child_opname0, child_opname1);
fprintf_indent (f, indent,
" std::swap (%s, %s);\n",
diff --git a/gcc/gimple-fold.cc b/gcc/gimple-fold.cc
index c2d9c806aee..efc0354566e 100644
--- a/gcc/gimple-fold.cc
+++ b/gcc/gimple-fold.cc
@@ -6142,7 +6142,7 @@ fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace, tree (*valueize) (tree))
{
tree rhs1 = gimple_assign_rhs1 (stmt);
tree rhs2 = gimple_assign_rhs2 (stmt);
- if (tree_swap_operands_p (rhs1, rhs2))
+ if (tree_swap_operands_p (rhs1, rhs2, false))
{
gimple_assign_set_rhs1 (stmt, rhs2);
gimple_assign_set_rhs2 (stmt, rhs1);
@@ -6178,7 +6178,9 @@ fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace, tree (*valueize) (tree))
{
tree arg1 = gimple_call_arg (call, opno);
tree arg2 = gimple_call_arg (call, opno + 1);
- if (tree_swap_operands_p (arg1, arg2))
+ /* FIXME: Find the correct third value to set for
+ tree_swap_operands_p here. */
+ if (tree_swap_operands_p (arg1, arg2, false))
{
gimple_call_set_arg (call, opno, arg2);
gimple_call_set_arg (call, opno + 1, arg1);
@@ -6226,7 +6228,7 @@ fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace, tree (*valueize) (tree))
/* Canonicalize operand order. */
tree lhs = gimple_cond_lhs (stmt);
tree rhs = gimple_cond_rhs (stmt);
- if (tree_swap_operands_p (lhs, rhs))
+ if (tree_swap_operands_p (lhs, rhs, false))
{
gcond *gc = as_a <gcond *> (stmt);
gimple_cond_set_lhs (gc, rhs);
diff --git a/gcc/gimple-match-head.cc b/gcc/gimple-match-head.cc
index 9986e3479f9..d48a4ca5c86 100644
--- a/gcc/gimple-match-head.cc
+++ b/gcc/gimple-match-head.cc
@@ -300,7 +300,7 @@ gimple_resimplify2 (gimple_seq *seq, gimple_match_op *res_op,
= (res_op->code.is_tree_code ()
&& TREE_CODE_CLASS (tree_code (res_op->code)) == tcc_comparison);
if ((is_comparison || commutative_binary_op_p (res_op->code, res_op->type))
- && tree_swap_operands_p (res_op->ops[0], res_op->ops[1]))
+ && tree_swap_operands_p (res_op->ops[0], res_op->ops[1], false))
{
std::swap (res_op->ops[0], res_op->ops[1]);
if (is_comparison)
@@ -374,11 +374,13 @@ gimple_resimplify3 (gimple_seq *seq, gimple_match_op *res_op,
}
}
- /* Canonicalize operand order. */
+ /* Canonicalize operand order. */
bool canonicalized = false;
int argno = first_commutative_argument (res_op->code, res_op->type);
if (argno >= 0
- && tree_swap_operands_p (res_op->ops[argno], res_op->ops[argno + 1]))
+ /* FIXME: Find the correct third value to set for
+ tree_swap_operands_p here. */
+ && tree_swap_operands_p (res_op->ops[argno], res_op->ops[argno + 1], false))
{
std::swap (res_op->ops[argno], res_op->ops[argno + 1]);
canonicalized = true;
@@ -428,7 +430,9 @@ gimple_resimplify4 (gimple_seq *seq, gimple_match_op *res_op,
bool canonicalized = false;
int argno = first_commutative_argument (res_op->code, res_op->type);
if (argno >= 0
- && tree_swap_operands_p (res_op->ops[argno], res_op->ops[argno + 1]))
+ /* FIXME: Find the correct third value to set for
+ tree_swap_operands_p here. */
+ && tree_swap_operands_p (res_op->ops[argno], res_op->ops[argno + 1], false))
{
std::swap (res_op->ops[argno], res_op->ops[argno + 1]);
canonicalized = true;
@@ -479,7 +483,9 @@ gimple_resimplify5 (gimple_seq *seq, gimple_match_op *res_op,
bool canonicalized = false;
int argno = first_commutative_argument (res_op->code, res_op->type);
if (argno >= 0
- && tree_swap_operands_p (res_op->ops[argno], res_op->ops[argno + 1]))
+ /* FIXME: Find the correct third value to set for
+ tree_swap_operands_p here. */
+ && tree_swap_operands_p (res_op->ops[argno], res_op->ops[argno + 1], false))
{
std::swap (res_op->ops[argno], res_op->ops[argno + 1]);
canonicalized = true;
@@ -732,7 +738,7 @@ gimple_simplify (enum tree_code code, tree type,
generation. */
if ((commutative_tree_code (code)
|| TREE_CODE_CLASS (code) == tcc_comparison)
- && tree_swap_operands_p (op0, op1))
+ && tree_swap_operands_p (op0, op1, false))
{
std::swap (op0, op1);
if (TREE_CODE_CLASS (code) == tcc_comparison)
@@ -764,7 +770,7 @@ gimple_simplify (enum tree_code code, tree type,
/* Canonicalize operand order both for matching and fallback stmt
generation. */
if (commutative_ternary_tree_code (code)
- && tree_swap_operands_p (op0, op1))
+ && tree_swap_operands_p (op0, op1, false))
std::swap (op0, op1);
gimple_match_op res_op;
diff --git a/gcc/match.pd b/gcc/match.pd
index a4d1386fd9f..367cd6d8ca6 100644
--- a/gcc/match.pd
+++ b/gcc/match.pd
@@ -7870,7 +7870,7 @@ and,
/* Since the order of @0 and @2 doesn't matter, let tree_swap_operands_p
pick a canonical order. This increases the chances of using the
same pointer_plus in multiple checks. */
- (with { bool swap_p = tree_swap_operands_p (@0, @2);
+ (with { bool swap_p = tree_swap_operands_p (@0, @2, false);
tree rhs_tree = wide_int_to_tree (sizetype, rhs); }
(if (cmp == LT_EXPR)
(gt (convert:sizetype
diff --git a/gcc/tree-ssa-dom.cc b/gcc/tree-ssa-dom.cc
index c7f095d79fc..edcaa71e12e 100644
--- a/gcc/tree-ssa-dom.cc
+++ b/gcc/tree-ssa-dom.cc
@@ -1449,7 +1449,7 @@ record_equality (tree x, tree y, class const_and_copies *const_and_copies)
{
tree prev_x = NULL, prev_y = NULL;
- if (tree_swap_operands_p (x, y))
+ if (tree_swap_operands_p (x, y, false))
std::swap (x, y);
/* Most of the time tree_swap_operands_p does what we want. But there
diff --git a/gcc/tree-ssa-reassoc.cc b/gcc/tree-ssa-reassoc.cc
index b39c3c882c4..d50bece1d38 100644
--- a/gcc/tree-ssa-reassoc.cc
+++ b/gcc/tree-ssa-reassoc.cc
@@ -3987,7 +3987,7 @@ optimize_range_tests_var_bound (enum tree_code opcode, int first, int length,
rhs2 = gimple_assign_lhs (g);
gsi_insert_before (&gsi, g, GSI_SAME_STMT);
}
- if (tree_swap_operands_p (rhs1, rhs2))
+ if (tree_swap_operands_p (rhs1, rhs2, false))
{
std::swap (rhs1, rhs2);
ccode = swap_tree_comparison (ccode);
diff --git a/gcc/tree-ssa-sccvn.cc b/gcc/tree-ssa-sccvn.cc
index 37484403c56..47872db7bcd 100644
--- a/gcc/tree-ssa-sccvn.cc
+++ b/gcc/tree-ssa-sccvn.cc
@@ -4146,10 +4146,10 @@ vn_nary_op_compute_hash (const vn_nary_op_t vno1)
&& commutative_tree_code (vno1->opcode))
|| (vno1->length == 3
&& commutative_ternary_tree_code (vno1->opcode)))
- && tree_swap_operands_p (vno1->op[0], vno1->op[1]))
+ && tree_swap_operands_p (vno1->op[0], vno1->op[1], false))
std::swap (vno1->op[0], vno1->op[1]);
else if (TREE_CODE_CLASS (vno1->opcode) == tcc_comparison
- && tree_swap_operands_p (vno1->op[0], vno1->op[1]))
+ && tree_swap_operands_p (vno1->op[0], vno1->op[1], false))
{
std::swap (vno1->op[0], vno1->op[1]);
vno1->opcode = swap_tree_comparison (vno1->opcode);
diff --git a/gcc/tree-ssa-threadedge.cc b/gcc/tree-ssa-threadedge.cc
index 905a98c8c68..0caef94a62b 100644
--- a/gcc/tree-ssa-threadedge.cc
+++ b/gcc/tree-ssa-threadedge.cc
@@ -490,7 +490,7 @@ jump_threader::simplify_control_stmt_condition_1
example, op0 might be a constant while op1 is an
SSA_NAME. Failure to canonicalize will cause us to
miss threading opportunities. */
- if (tree_swap_operands_p (op0, op1))
+ if (tree_swap_operands_p (op0, op1, false))
{
cond_code = swap_tree_comparison (cond_code);
std::swap (op0, op1);
--
2.38.1
