Hello,
this patch adds some basic folding capabilities to fold-const for
equal and none-equal comparisons
on integer typed argument.
ChangeLog
2012-04-05 Kai Tietz <kti...@redhat.com>
* fold-const.c (fold_comparison_1): New
function.
(fold_comparison): Use fold_comparison_1.
2012-04-05 Kai Tietz <kti...@redhat.com>
* gcc.dg/fold-compare-1.c: Adjust matching rule
for a == b without argument swap.
* gcc.dg/fold-compare-7.c: New test.
Regession tested for x86_64-unknown-linux-gnu for all languages
(including Ada and Obj-C++). Ok for apply?
Regards,
Kai
Index: gcc/gcc/fold-const.c
===================================================================
--- gcc.orig/gcc/fold-const.c
+++ gcc/gcc/fold-const.c
@@ -8739,6 +8739,241 @@ pointer_may_wrap_p (tree base, tree offs
return total_low > (unsigned HOST_WIDE_INT) size;
}
+/* Sub-routine of fold_comparison. Folding of EQ_EXPR/NE_EXPR
+ comparisons with integral typed arguments. */
+
+static tree
+fold_comparison_1 (location_t loc, enum tree_code code, tree type,
+ tree arg0, tree arg1)
+{
+ enum tree_code c1, c2;
+ tree optype, op0, op1, opr0, opr1, tem;
+
+ if (code != NE_EXPR && code != EQ_EXPR)
+ return NULL_TREE;
+
+ optype = TREE_TYPE (arg0);
+ if (!INTEGRAL_TYPE_P (optype))
+ return NULL_TREE;
+
+ c1 = TREE_CODE (arg0);
+ c2 = TREE_CODE (arg1);
+
+ /* Integer constant is on right-hand side. */
+ if (c1 == INTEGER_CST
+ && c2 != c1)
+ return fold_build2_loc (loc, code, type, arg1, arg0);
+
+ if (!TREE_SIDE_EFFECTS (arg0)
+ && operand_equal_p (arg0, arg1, 0))
+ {
+ if (code == EQ_EXPR)
+ return build_one_cst (type);
+ return build_zero_cst (type);
+ }
+
+
+ if (c1 == NEGATE_EXPR)
+ {
+ op0 = TREE_OPERAND (arg0, 0);
+ /* -X ==/!= -Y -> X ==/!= Y. */
+ if (c2 == c1)
+ return fold_build2_loc (loc, code, type,
+ op0,
+ TREE_OPERAND (arg1, 0));
+ /* -X ==/!= CST -> X ==/!= CST' with CST'= -CST. */
+ else if (c2 == INTEGER_CST)
+ return fold_build2_loc (loc, code, type, op0,
+ fold_build1_loc (loc, NEGATE_EXPR,
+ optype, arg1));
+ }
+ else if (c1 == BIT_NOT_EXPR)
+ {
+ op0 = TREE_OPERAND (arg0, 0);
+ /* ~X ==/!= ~Y -> X ==/!= Y. */
+ if (c2 == c1)
+ return fold_build2_loc (loc, code, type, op0,
+ TREE_OPERAND (arg1, 0));
+ /* ~X ==/!= CST -> X ==/!= CST' with CST'= ~CST. */
+ else if (c2 == INTEGER_CST)
+ return fold_build2_loc (loc, code, type, op0,
+ fold_build1_loc (loc, BIT_NOT_EXPR,
+ optype, arg1));
+ }
+
+ /* See if we can simplify case X == (Y +|-|^ Z). */
+ if (c1 != PLUS_EXPR && c1 != MINUS_EXPR && c1 != BIT_XOR_EXPR)
+ {
+ if ((c2 != PLUS_EXPR && c2 != MINUS_EXPR
+ && c2 != BIT_XOR_EXPR)
+ || TREE_SIDE_EFFECTS (arg0))
+ return NULL_TREE;
+
+ op0 = TREE_OPERAND (arg1, 0);
+ op1 = TREE_OPERAND (arg1, 1);
+
+ /* Convert temporary X - Y to X + (-Y). */
+ if (c2 == MINUS_EXPR)
+ op1 = fold_build1_loc (loc, NEGATE_EXPR, optype, op1);
+
+ /* Check if we can simplify X ==/!= (X ^ Y) to Y ==/!= 0,
+ or X ==/!= (X +|- Y) to Y ==/!= 0. */
+ tem = fold_build2_loc (loc, (c2 == BIT_XOR_EXPR ? c2 : MINUS_EXPR),
+ optype, arg0, op0);
+ if (TREE_CODE (tem) == INTEGER_CST
+ && (integer_zerop (tem) || TYPE_UNSIGNED (optype)
+ || c2 == BIT_XOR_EXPR))
+ return fold_build2_loc (loc, code, type, op1, tem);
+
+ /* Check if we can simplify X ==/!= (Y ^ X) to Y ==/!= 0,
+ or X ==/!= (Y + X) to Y ==/!= 0. */
+ tem = fold_build2_loc (loc, (c2 == BIT_XOR_EXPR ? c2 : MINUS_EXPR),
+ optype, arg0, op1);
+ if (TREE_CODE (tem) == INTEGER_CST
+ && (integer_zerop (tem) || TYPE_UNSIGNED (optype)
+ || c2 == BIT_XOR_EXPR))
+ return fold_build2_loc (loc, code, type, op0, tem);
+ }
+ else if (c2 != PLUS_EXPR && c2 != MINUS_EXPR && c2 != BIT_XOR_EXPR)
+ {
+ if ((c1 != PLUS_EXPR && c1 != MINUS_EXPR
+ && c1 != BIT_XOR_EXPR)
+ || TREE_SIDE_EFFECTS (arg1))
+ return NULL_TREE;
+
+ op0 = TREE_OPERAND (arg0, 0);
+ op1 = TREE_OPERAND (arg0, 1);
+
+ /* Convert temporary X - Y to X + (-Y). */
+ if (c1 == MINUS_EXPR)
+ op1 = fold_build1_loc (loc, NEGATE_EXPR, optype, op1);
+
+ /* Check if we can simplify X ==/!= (X ^ Y) to Y ==/!= 0,
+ or X ==/!= (X +|- Y) to Y ==/!= 0. */
+ tem = fold_build2_loc (loc, (c1 == BIT_XOR_EXPR ? c1 : MINUS_EXPR),
+ optype, arg1, op0);
+ if (TREE_CODE (tem) == INTEGER_CST
+ && (integer_zerop (tem) || TYPE_UNSIGNED (optype)
+ || c1 == BIT_XOR_EXPR))
+ return fold_build2_loc (loc, code, type, op1, tem);
+
+ /* Check if we can simplify X ==/!= (Y ^ X) to Y ==/!= 0,
+ or X ==/!= (Y + X) to Y ==/!= 0. */
+ tem = fold_build2_loc (loc, (c1 == BIT_XOR_EXPR ? c1 : MINUS_EXPR),
+ optype, arg1, op1);
+ if (TREE_CODE (tem) == INTEGER_CST
+ && (integer_zerop (tem) || TYPE_UNSIGNED (optype)
+ || c1 == BIT_XOR_EXPR))
+ return fold_build2_loc (loc, code, type, op0, tem);
+ }
+
+ /* We check if arg1 and arg2 are matching one of the patterns
+ (V + W) ==/!= (X + Y), (V + W) ==/!= (X - Y), (V - W) ==/!= (X + Y),
+ (V - W) ==/!= (X - Y), or (V ^ W) ==/!= (X ^ Y). */
+
+ if ((c1 != PLUS_EXPR && c1 != MINUS_EXPR && c1 != BIT_XOR_EXPR)
+ || (c2 != PLUS_EXPR && c2 != MINUS_EXPR && c2 != BIT_XOR_EXPR))
+ return NULL_TREE;
+ if (c1 != c2 && (c1 == BIT_XOR_EXPR || c2 == BIT_XOR_EXPR))
+ return NULL_TREE;
+
+ op0 = TREE_OPERAND (arg0, 0);
+ op1 = TREE_OPERAND (arg0, 1);
+ opr0 = TREE_OPERAND (arg1, 0);
+ opr1 = TREE_OPERAND (arg1, 1);
+
+ /* Convert temporary (X - Y) to (X + (-Y)). */
+ if (c1 == MINUS_EXPR)
+ {
+ op1 = fold_build1_loc (loc, NEGATE_EXPR, optype, op1);
+ c1 = PLUS_EXPR;
+ }
+
+ /* Convert temporary (X - Y) to (X + (-Y)). */
+ if (c2 == MINUS_EXPR)
+ {
+ opr1 = fold_build1_loc (loc, NEGATE_EXPR, optype, opr1);
+ c2 = PLUS_EXPR;
+ }
+
+ if (c1 != c2)
+ return NULL_TREE;
+
+ /* If OP0 has no side-effects, we might be able to optimize
+ (OP0 + OP1) ==/!= (OP0 + OPR1) to OP1 ==/!= OPR1,
+ (OP0 + OP1) ==/!= (OPR0 + OP0) to OP1 ==/!= OPR0,
+ (OP0 ^ OP1) ==/!= (OP0 ^ OPR1) to OP1 ==/!= OPR1,
+ or (OP0 ^ OP1) ==/!= (OPR0 ^ OP0) to OP1 ==/!= OPR0.. */
+ if (!TREE_SIDE_EFFECTS (op0))
+ {
+ tem = fold_build2_loc (loc, (c1 == PLUS_EXPR ? MINUS_EXPR : c1),
+ optype, op0, opr0);
+ if (TREE_CODE (tem) == INTEGER_CST
+ && !TREE_SIDE_EFFECTS (opr0)
+ && (integer_zerop (tem) || TYPE_UNSIGNED (optype)
+ || c1 == BIT_XOR_EXPR))
+ {
+ if (!integer_zerop (tem))
+ tem = fold_build2_loc (loc, c1, optype, op1, tem);
+ else
+ tem = op1;
+
+ return fold_build2_loc (loc, code, type, tem, opr1);
+ }
+ tem = fold_build2_loc (loc, (c1 == PLUS_EXPR ? MINUS_EXPR : c1),
+ optype, op0, opr1);
+ if (TREE_CODE (tem) == INTEGER_CST
+ && !TREE_SIDE_EFFECTS (opr1)
+ && (integer_zerop (tem) || TYPE_UNSIGNED (optype)
+ || c1 == BIT_XOR_EXPR))
+ {
+ if (!integer_zerop (tem))
+ tem = fold_build2_loc (loc, c1, optype, op1, tem);
+ else
+ tem = op1;
+ return fold_build2_loc (loc, code, type, tem, opr0);
+ }
+ }
+
+ /* If OP1 has no side-effects, we might be able to optimize
+ (OP0 + OP1) ==/!= (OP1 + OPR1) to OP0 ==/!= OPR1,
+ (OP0 + OP1) ==/!= (OPR0 + OP1) to OP0 ==/!= OPR0,
+ (OP0 ^ OP1) ==/!= (OP1 ^ OPR1) to OP0 ==/!= OPR1,
+ or (OP0 ^ OP1) ==/!= (OPR0 ^ OP1) to OP0 ==/!= OPR0.. */
+ if (!TREE_SIDE_EFFECTS (op1))
+ {
+ tem = fold_build2_loc (loc, (c1 == PLUS_EXPR ? MINUS_EXPR : c1),
+ optype, op1, opr0);
+ if (TREE_CODE (tem) == INTEGER_CST
+ && !TREE_SIDE_EFFECTS (opr0)
+ && (integer_zerop (tem) || TYPE_UNSIGNED (optype)
+ || c1 == BIT_XOR_EXPR))
+ {
+ if (!integer_zerop (tem))
+ tem = fold_build2_loc (loc, c1, optype, op0, tem);
+ else
+ tem = op0;
+ return fold_build2_loc (loc, code, type, tem, opr1);
+ }
+
+ tem = fold_build2_loc (loc, (c1 == PLUS_EXPR ? MINUS_EXPR : c1),
+ optype, op1, opr1);
+ if (TREE_CODE (tem) == INTEGER_CST
+ && !TREE_SIDE_EFFECTS (opr1)
+ && (integer_zerop (tem) || TYPE_UNSIGNED (optype)
+ || c1 == BIT_XOR_EXPR))
+ {
+ if (!integer_zerop (tem))
+ tem = fold_build2_loc (loc, c1, optype, op0, tem);
+ else
+ tem = op0;
+ return fold_build2_loc (loc, code, type, tem, opr0);
+ }
+ }
+
+ return NULL_TREE;
+}
+
/* Subroutine of fold_binary. This routine performs all of the
transformations that are common to the equality/inequality
operators (EQ_EXPR and NE_EXPR) and the ordering operators
@@ -8767,6 +9002,10 @@ fold_comparison (location_t loc, enum tr
if (tree_swap_operands_p (arg0, arg1, true))
return fold_build2_loc (loc, swap_tree_comparison (code), type, op1, op0);
+ tem = fold_comparison_1 (loc, code, type, arg0, arg1);
+ if (tem != NULL_TREE)
+ return tem;
+
/* Transform comparisons of the form X +- C1 CMP C2 to X CMP C2 +- C1. */
if ((TREE_CODE (arg0) == PLUS_EXPR || TREE_CODE (arg0) == MINUS_EXPR)
&& (TREE_CODE (TREE_OPERAND (arg0, 1)) == INTEGER_CST
Index: gcc/gcc/testsuite/gcc.dg/fold-compare-1.c
===================================================================
--- gcc.orig/gcc/testsuite/gcc.dg/fold-compare-1.c
+++ gcc/gcc/testsuite/gcc.dg/fold-compare-1.c
@@ -41,7 +41,7 @@ int test8(int l)
return ~l >= 2;
}
-/* { dg-final { scan-tree-dump-times "b == a" 1 "original" } } */
+/* { dg-final { scan-tree-dump-times "b == a|a == b" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "c == d" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "e == -5" 1 "original" } } */
/* { dg-final { scan-tree-dump-times "f == -6" 1 "original" } } */
Index: gcc/gcc/testsuite/gcc.dg/fold-compare-7.c
===================================================================
--- /dev/null
+++ gcc/gcc/testsuite/gcc.dg/fold-compare-7.c
@@ -0,0 +1,36 @@
+/* { dg-do compile } */
+/* { dg-options "-O2 -fdump-tree-original" } */
+
+int test1(int a, int elim)
+{
+ return ~elim == (elim ^ a);
+}
+
+int test2(int elim, int b)
+{
+ return -elim == (b - elim);
+}
+
+int test3(int c, int elim, int d)
+{
+ return (c + elim) != (elim + d);
+}
+
+int test4(int e, int f, int elim)
+{
+ return (e - elim) != (-elim + f);
+}
+
+int test5(int g, int h, int elim)
+{
+ return (elim ^ g) == (h ^ elim);
+}
+
+int test6(int i, int j, int elim)
+{
+ return (elim ^ i) == (j ^ ~elim);
+}
+
+/* { dg-final { scan-tree-dump-times "elim" 0 "original" } } */
+/* { dg-final { cleanup-tree-dump "original" } } */
+
