Generalize -(-X) a little

2017-11-03  Marc Glisse  <marc.glisse@inria.fr>

gcc/
	* 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.

From-SVN: r254382

gcc/ChangeLog

+2017-11-03  Marc Glisse  <marc.glisse@inria.fr>
+
+	* match.pd (-(-A)): Rewrite.
+
 2017-11-03  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	* config/rs6000/rs60000-protos.h (rs6000_emit_sISEL): Delete.

gcc/match.pd

@@ -1503,12 +1503,31 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT)
        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.  */

gcc/testsuite/ChangeLog

+2017-11-03  Marc Glisse  <marc.glisse@inria.fr>
+
+	* 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.
+
 2017-11-03  Jan Hubicka  <hubicka@ucw.cz>
 
 	* gcc.dg/no-strict-overflow-3.c (foo): Update magic

gcc/testsuite/gcc.dg/tree-ssa/negneg-1.c

+/* { 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"} } */

gcc/testsuite/gcc.dg/tree-ssa/negneg-2.c

+/* { 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"} } */

gcc/testsuite/gcc.dg/tree-ssa/negneg-3.c

+/* { 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"} } */

gcc/testsuite/gcc.dg/tree-ssa/negneg-4.c

+/* { 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();
+}