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Re: Generalize -(-X) a little
On Thu, 2 Nov 2017, Richard Biener wrote:
You can handle floats as followup but some testcases that shouldn't be
optimized for the INT_MIN / unsigned case would be nice.
New version, that does a bit more.
Bootstrap+regtest on powerpc64le-unknown-linux-gnu.
2017-11-03 Marc Glisse <marc.glisse@inria.fr>
gcc/
* fold-const.c (fold_negate_expr_1): Call generic_simplify. Remove
NEGATE_EXPR handling.
* match.pd (-(-A)): Rewrite.
gcc/testsuite/
* gcc.dg/tree-ssa/negneg-1.c: New file.
* gcc.dg/tree-ssa/negneg-2.c: Likewise.
* gcc.dg/tree-ssa/negneg-3.c: Likewise.
* gcc.dg/tree-ssa/negneg-4.c: Likewise.
--
Marc Glisse
Index: gcc/fold-const.c
===================================================================
--- gcc/fold-const.c (revision 254348)
+++ gcc/fold-const.c (working copy)
@@ -585,25 +585,20 @@ fold_negate_expr_1 (location_t loc, tree
fold_negate_expr (loc, TREE_OPERAND (t, 0)),
fold_negate_expr (loc, TREE_OPERAND (t, 1)));
break;
case CONJ_EXPR:
if (negate_expr_p (t))
return fold_build1_loc (loc, CONJ_EXPR, type,
fold_negate_expr (loc, TREE_OPERAND (t, 0)));
break;
- case NEGATE_EXPR:
- if (!TYPE_OVERFLOW_SANITIZED (type))
- return TREE_OPERAND (t, 0);
- break;
-
case PLUS_EXPR:
if (!HONOR_SIGN_DEPENDENT_ROUNDING (element_mode (type))
&& !HONOR_SIGNED_ZEROS (element_mode (type)))
{
/* -(A + B) -> (-B) - A. */
if (negate_expr_p (TREE_OPERAND (t, 1)))
{
tem = negate_expr (TREE_OPERAND (t, 1));
return fold_build2_loc (loc, MINUS_EXPR, type,
tem, TREE_OPERAND (t, 0));
@@ -706,21 +701,21 @@ fold_negate_expr_1 (location_t loc, tree
temp = fold_build2_loc (loc, RSHIFT_EXPR, ntype, temp, op1);
return fold_convert_loc (loc, type, temp);
}
}
break;
default:
break;
}
- return NULL_TREE;
+ return generic_simplify (loc, NEGATE_EXPR, type, t);
}
/* A wrapper for fold_negate_expr_1. */
static tree
fold_negate_expr (location_t loc, tree t)
{
tree type = TREE_TYPE (t);
STRIP_SIGN_NOPS (t);
tree tem = fold_negate_expr_1 (loc, t);
Index: gcc/match.pd
===================================================================
--- gcc/match.pd (revision 254348)
+++ gcc/match.pd (working copy)
@@ -1496,26 +1496,45 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
(if (tree_nop_conversion_p (type, TREE_TYPE (@1))
&& !TYPE_OVERFLOW_SANITIZED (type))
(with
{
tree t1 = type;
if (INTEGRAL_TYPE_P (type)
&& TYPE_OVERFLOW_WRAPS (type) != TYPE_OVERFLOW_WRAPS (TREE_TYPE (@1)))
t1 = TYPE_OVERFLOW_WRAPS (type) ? type : TREE_TYPE (@1);
}
(convert (plus (convert:t1 @0) (convert:t1 @1))))))
- /* -(-A) -> A */
+ /* -(T)(-A) -> (T)A
+ Sign-extension is ok except for INT_MIN, which thankfully cannot
+ happen without overflow. */
(simplify
- (negate (convert? (negate @1)))
- (if (tree_nop_conversion_p (type, TREE_TYPE (@1))
- && !TYPE_OVERFLOW_SANITIZED (type))
+ (negate (convert (negate @1)))
+ (if (INTEGRAL_TYPE_P (type)
+ && (TYPE_PRECISION (type) <= TYPE_PRECISION (TREE_TYPE (@1))
+ || (!TYPE_UNSIGNED (TREE_TYPE (@1))
+ && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@1))))
+ && !TYPE_OVERFLOW_SANITIZED (type)
+ && !TYPE_OVERFLOW_SANITIZED (TREE_TYPE (@1)))
(convert @1)))
+ (simplify
+ (negate (convert negate_expr_p@1))
+ (if (SCALAR_FLOAT_TYPE_P (type)
+ && ((DECIMAL_FLOAT_TYPE_P (type)
+ == DECIMAL_FLOAT_TYPE_P (TREE_TYPE (@1))
+ && TYPE_PRECISION (type) >= TYPE_PRECISION (TREE_TYPE (@1)))
+ || !HONOR_SIGN_DEPENDENT_ROUNDING (type)))
+ (convert (negate @1))))
+ (simplify
+ (negate (nop_convert (negate @1)))
+ (if (!TYPE_OVERFLOW_SANITIZED (type)
+ && !TYPE_OVERFLOW_SANITIZED (TREE_TYPE (@1)))
+ (view_convert @1)))
/* We can't reassociate floating-point unless -fassociative-math
or fixed-point plus or minus because of saturation to +-Inf. */
(if ((!FLOAT_TYPE_P (type) || flag_associative_math)
&& !FIXED_POINT_TYPE_P (type))
/* Match patterns that allow contracting a plus-minus pair
irrespective of overflow issues. */
/* (A +- B) - A -> +- B */
/* (A +- B) -+ B -> A */
Index: gcc/testsuite/gcc.dg/tree-ssa/negneg-1.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/negneg-1.c (nonexistent)
+++ gcc/testsuite/gcc.dg/tree-ssa/negneg-1.c (working copy)
@@ -0,0 +1,24 @@
+/* { dg-do compile } */
+/* { dg-options "-O -frounding-math -fdump-tree-optimized-raw -Wno-psabi" } */
+
+#define DEF(num, T1, T2) T2 f##num(T1 x) { \
+ T1 y = -x; \
+ T2 z = (T2)y; \
+ return -z; \
+}
+DEF(0, int, long long)
+DEF(1, int, unsigned long long)
+DEF(2, long long, int)
+DEF(3, unsigned long long, int)
+DEF(4, long long, unsigned)
+DEF(5, unsigned long long, unsigned)
+DEF(6, float, double)
+
+typedef int vec __attribute__((vector_size(4*sizeof(int))));
+typedef unsigned uvec __attribute__((vector_size(4*sizeof(int))));
+void h(vec*p,uvec*q){
+ vec a = -*p;
+ *q = -(uvec)a;
+}
+
+/* { dg-final { scan-tree-dump-not "negate_expr" "optimized"} } */
Index: gcc/testsuite/gcc.dg/tree-ssa/negneg-2.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/negneg-2.c (nonexistent)
+++ gcc/testsuite/gcc.dg/tree-ssa/negneg-2.c (working copy)
@@ -0,0 +1,11 @@
+/* { dg-do compile } */
+/* { dg-options "-O -fno-rounding-math -fdump-tree-optimized-raw" } */
+
+#define DEF(num, T1, T2) T2 f##num(T1 x) { \
+ T1 y = -x; \
+ T2 z = (T2)y; \
+ return -z; \
+}
+DEF(0, double, float)
+
+/* { dg-final { scan-tree-dump-not "negate_expr" "optimized"} } */
Index: gcc/testsuite/gcc.dg/tree-ssa/negneg-3.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/negneg-3.c (nonexistent)
+++ gcc/testsuite/gcc.dg/tree-ssa/negneg-3.c (working copy)
@@ -0,0 +1,15 @@
+/* { dg-do compile } */
+/* { dg-options "-O -frounding-math -fdump-tree-optimized-raw" } */
+
+// This assumes that long long is strictly larger than int
+
+#define DEF(num, T1, T2) T2 f##num(T1 x) { \
+ T1 y = -x; \
+ T2 z = (T2)y; \
+ return -z; \
+}
+DEF(0, unsigned, long long)
+DEF(1, unsigned, unsigned long long)
+DEF(2, double, float)
+
+/* { dg-final { scan-tree-dump-times "negate_expr" 6 "optimized"} } */
Index: gcc/testsuite/gcc.dg/tree-ssa/negneg-4.c
===================================================================
--- gcc/testsuite/gcc.dg/tree-ssa/negneg-4.c (nonexistent)
+++ gcc/testsuite/gcc.dg/tree-ssa/negneg-4.c (working copy)
@@ -0,0 +1,18 @@
+/* { dg-do run } */
+/* { dg-options "-O -fwrapv" } */
+
+#define DEF(num, T1, T2) T2 f##num(T1 x) { \
+ T1 y = -x; \
+ T2 z = (T2)y; \
+ return -z; \
+}
+DEF(0, int, long long)
+
+int main(){
+ volatile int a = -1 - __INT_MAX__;
+ volatile long long b = f0 (a);
+ volatile long long c = a;
+ volatile long long d = -c;
+ if (b != d)
+ __builtin_abort();
+}