From: Michael Beck <beck@ipd.info.uni-karlsruhe.de>
Date: Wed, 21 Nov 2007 16:45:37 +0000 (+0000)
Subject: add Abs(-x) = Abs(x)
X-Git-Url: http://nsz.repo.hu/git/?a=commitdiff_plain;h=86b557b6be3fd996c4043152e79d21bf911c561d;p=libfirm

add Abs(-x) = Abs(x)

[r16816]
---

diff --git a/include/libfirm/firmstat.h b/include/libfirm/firmstat.h
index d7d90c624..e7a7e914f 100644
--- a/include/libfirm/firmstat.h
+++ b/include/libfirm/firmstat.h
@@ -92,6 +92,7 @@ enum firmstat_optimizations_t {
 	FS_OPT_NOT_PLUS_1,                        /**< ~x + 1 = -x */
 	FS_OPT_ADD_X_NOT_X,                       /**< ~x + x = -1 */
 	FS_OPT_FP_INV_MUL,                        /**< x / y = x * (1.0/y) */
+	FS_OPT_ABS_MINUS_X,                       /**< Abs(-x) = Abs(x) */
 	FS_OPT_CONST_PHI,                         /**< Constant evaluation on Phi */
 	FS_OPT_PREDICATE,                         /**< Predicate optimization */
 	FS_OPT_DEMORGAN,                          /**< optimization using DeMorgan's law */
diff --git a/ir/be/test/localopts.c b/ir/be/test/localopts.c
index e690b75cb..c3980a54e 100644
--- a/ir/be/test/localopts.c
+++ b/ir/be/test/localopts.c
@@ -1,5 +1,6 @@
 /*$ -fno-inline $*/
 #include <stdio.h>
+#include <math.h>
 
 #define CONST 42
 
@@ -188,27 +189,31 @@ int conv3(signed char a) {
 }
 
 int phi1(int x) {
-       int a = x ? 23 : 42;
-       int b = x ? 42 : 23;
-       return a + b;
+	int a = x ? 23 : 42;
+	int b = x ? 42 : 23;
+	return a + b;
 }
 
 int phi2(int x) {
-       int a = x ? 16 : 8;
-       int b = x ? 4  : 2;
-       return a / b;
+	int a = x ? 16 : 8;
+	int b = x ? 4  : 2;
+	return a / b;
 }
 
 int phi3(int x) {
-       int a = x ? 5 : 9;
-       int b = x ? 2 : 4;
-       return a % b;
+	int a = x ? 5 : 9;
+	int b = x ? 2 : 4;
+	return a % b;
 }
 
 int phi4(int x) {
-       int a = x ? 5 : 9;
-       int b = x ? 2 : 4;
-       return (a / b) + (a % b);
+	int a = x ? 5 : 9;
+	int b = x ? 2 : 4;
+	return (a / b) + (a % b);
+}
+
+int abs1(int x) {
+	return abs(-x);
 }
 
 int main(void)
@@ -275,4 +280,5 @@ int main(void)
 	TU(phi2, 1, 4);
 	TU(phi3, 1, 1);
 	TU(phi4, 1, 3);
+	TU(abs1, 1, 1);
 }
diff --git a/ir/ir/iropt.c b/ir/ir/iropt.c
index 8488c1a3a..cdab35eb3 100644
--- a/ir/ir/iropt.c
+++ b/ir/ir/iropt.c
@@ -2815,6 +2815,7 @@ static ir_node *transform_node_Quot(ir_node *n) {
 /**
  * Optimize Abs(x) into  x if x is Confirmed >= 0
  * Optimize Abs(x) into -x if x is Confirmed <= 0
+ * Optimize Abs(-x) int Abs(x)
  */
 static ir_node *transform_node_Abs(ir_node *n) {
 	ir_node *c, *oldn = n;
@@ -2835,7 +2836,7 @@ static ir_node *transform_node_Abs(ir_node *n) {
 		 * not run it in the equivalent_node() context.
 		 */
 		n = new_rd_Minus(get_irn_dbg_info(n), current_ir_graph,
-				get_irn_n(n, -1), a, mode);
+				get_nodes_block(n), a, mode);
 
 		DBG_OPT_CONFIRM(oldn, n);
 		return n;
@@ -2846,8 +2847,17 @@ static ir_node *transform_node_Abs(ir_node *n) {
 		DBG_OPT_CONFIRM(oldn, n);
 		return n;
 	default:
+		break;
+	}
+	if (is_Minus(a)) {
+		/* Abs(-x) = Abs(x) */
+		mode = get_irn_mode(n);
+		n = new_rd_Abs(get_irn_dbg_info(n), current_ir_graph,
+				get_nodes_block(n), get_Minus_op(a), mode);
+		DBG_OPT_ALGSIM0(oldn, n, FS_OPT_ABS_MINUS_X);
 		return n;
 	}
+	return n;
 }  /* transform_node_Abs */
 
 /**
diff --git a/ir/stat/stat_dmp.c b/ir/stat/stat_dmp.c
index 42fd8e0d9..ae209e1df 100644
--- a/ir/stat/stat_dmp.c
+++ b/ir/stat/stat_dmp.c
@@ -109,7 +109,8 @@ static const struct {
 	{ FS_OPT_NOT_MINUS_1,    "algebraic simplification: ~(x - 1) = -x" },
 	{ FS_OPT_NOT_PLUS_1,     "algebraic simplification: ~x + 1 = -x" },
 	{ FS_OPT_ADD_X_NOT_X,    "algebraic simplification: ~x + x = -1" },
-	{ FS_OPT_FP_INV_MUL,     "algebraic simplification:  x / y = x * (1.0/y)" },
+	{ FS_OPT_FP_INV_MUL,     "algebraic simplification: x / y = x * (1.0/y)" },
+	{ FS_OPT_ABS_MINUS_X,    "algebraic simplification: Abs(-x) = Abs(x)" },
 	{ FS_OPT_CONST_PHI,      "constant evaluation on Phi node" },
 	{ FS_OPT_PREDICATE,      "predicate optimization" },
 	{ FS_OPT_DEMORGAN,       "optimization using DeMorgan's law" },