Added pedantic_min_int to gfc_integer_info

Added ARITH_ASYMMETRIC to arith
Added support for an "asymmetric integer" warning when compiling with pedantic
Set minimum integer values to reflect realities of two's complement signed integers


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@89785 138bc75d-0d04-0410-961f-82ee72b054a4

2 files changed, 74 insertions, 11 deletions

diff --git a/gcc/fortran/arith.c b/gcc/fortran/arith.c
index 519c7e39486..cc6f3ebd1e1 100644
--- a/gcc/fortran/arith.c
+++ b/gcc/fortran/arith.c
@@ -27,6 +27,7 @@ Software Foundation, 59 Temple Place - Suite 330, Boston, MA
 
 #include "config.h"
 #include "system.h"
+#include "flags.h"
 #include "gfortran.h"
 #include "arith.h"
 
@@ -157,6 +158,9 @@ gfc_arith_error (arith code)
     case ARITH_INCOMMENSURATE:
       p = "Array operands are incommensurate";
       break;
+    case ARITH_ASYMMETRIC:
+      p = "Integer outside symmetric range implied by Standard Fortran";
+      break;
     default:
       gfc_internal_error ("gfc_arith_error(): Bad error code");
     }
@@ -194,11 +198,20 @@ gfc_arith_init_1 (void)
       /* These are the numbers that are actually representable by the
          target.  For bases other than two, this needs to be changed.  */
       if (int_info->radix != 2)
-	gfc_internal_error ("Fix min_int, max_int calculation");
+        gfc_internal_error ("Fix min_int, max_int calculation");
+
+      /* See PRs 13490 and 17912, related to integer ranges.
+         The pedantic_min_int exists for range checking when a program
+         is compiled with -pedantic, and reflects the belief that
+         Standard Fortran requires integers to be symmetrical, i.e.
+         every negative integer must have a representable positive
+         absolute value, and vice versa. */
+         
+      mpz_init (int_info->pedantic_min_int);
+      mpz_neg (int_info->pedantic_min_int, int_info->huge);
 
       mpz_init (int_info->min_int);
-      mpz_neg (int_info->min_int, int_info->huge);
-      /* No -1 here, because the representation is symmetric.  */
+      mpz_sub_ui(int_info->min_int, int_info->pedantic_min_int, 1);
 
       mpz_init (int_info->max_int);
       mpz_add (int_info->max_int, int_info->huge, int_info->huge);
@@ -317,7 +330,8 @@ gfc_arith_done_1 (void)
 
 
 /* Given an integer and a kind, make sure that the integer lies within
-   the range of the kind.  Returns ARITH_OK or ARITH_OVERFLOW.  */
+   the range of the kind.  Returns ARITH_OK, ARITH_ASYMMETRIC or 
+   ARITH_OVERFLOW.  */
 
 static arith
 gfc_check_integer_range (mpz_t p, int kind)
@@ -328,6 +342,12 @@ gfc_check_integer_range (mpz_t p, int kind)
   i = gfc_validate_kind (BT_INTEGER, kind, false);
   result = ARITH_OK;
 
+  if (pedantic)
+    {
+      if (mpz_cmp (p, gfc_integer_kinds[i].pedantic_min_int) < 0)
+        result = ARITH_ASYMMETRIC;
+    }
+
   if (mpz_cmp (p, gfc_integer_kinds[i].min_int) < 0
       || mpz_cmp (p, gfc_integer_kinds[i].max_int) > 0)
     result = ARITH_OVERFLOW;
@@ -529,7 +549,7 @@ gfc_range_check (gfc_expr * e)
     default:
       gfc_internal_error ("gfc_range_check(): Bad type");
     }
-
+    
   return rc;
 }
 
@@ -582,6 +602,12 @@ gfc_arith_uminus (gfc_expr * op1, gfc_expr ** resultp)
       rc = ARITH_OK;
       *resultp = result;
     }
+  else if (rc == ARITH_ASYMMETRIC)
+    {
+      gfc_warning ("%s at %L", gfc_arith_error (rc), &op1->where);
+      rc = ARITH_OK;
+      *resultp = result;
+    }
   else if (rc != ARITH_OK)
     gfc_free_expr (result);
   else
@@ -631,6 +657,12 @@ gfc_arith_plus (gfc_expr * op1, gfc_expr * op2, gfc_expr ** resultp)
       rc = ARITH_OK;
       *resultp = result;
     }
+  else if (rc == ARITH_ASYMMETRIC)
+    {
+      gfc_warning ("%s at %L", gfc_arith_error (rc), &op1->where);
+      rc = ARITH_OK;
+      *resultp = result;
+    }
   else if (rc != ARITH_OK)
     gfc_free_expr (result);
   else
@@ -680,6 +712,12 @@ gfc_arith_minus (gfc_expr * op1, gfc_expr * op2, gfc_expr ** resultp)
       rc = ARITH_OK;
       *resultp = result;
     }
+  else if (rc == ARITH_ASYMMETRIC)
+    {
+      gfc_warning ("%s at %L", gfc_arith_error (rc), &op1->where);
+      rc = ARITH_OK;
+      *resultp = result;
+    }
   else if (rc != ARITH_OK)
     gfc_free_expr (result);
   else
@@ -743,6 +781,12 @@ gfc_arith_times (gfc_expr * op1, gfc_expr * op2, gfc_expr ** resultp)
       rc = ARITH_OK;
       *resultp = result;
     }
+  else if (rc == ARITH_ASYMMETRIC)
+    {
+      gfc_warning ("%s at %L", gfc_arith_error (rc), &op1->where);
+      rc = ARITH_OK;
+      *resultp = result;
+    }
   else if (rc != ARITH_OK)
     gfc_free_expr (result);
   else
@@ -839,6 +883,12 @@ gfc_arith_divide (gfc_expr * op1, gfc_expr * op2, gfc_expr ** resultp)
       rc = ARITH_OK;
       *resultp = result;
     }
+  else if (rc == ARITH_ASYMMETRIC)
+    {
+      gfc_warning ("%s at %L", gfc_arith_error (rc), &op1->where);
+      rc = ARITH_OK;
+      *resultp = result;
+    }
   else if (rc != ARITH_OK)
     gfc_free_expr (result);
   else
@@ -1029,11 +1079,17 @@ gfc_arith_power (gfc_expr * op1, gfc_expr * op2, gfc_expr ** resultp)
       rc = ARITH_OK;
       *resultp = result;
     }
+  else if (rc == ARITH_ASYMMETRIC)
+    {
+      gfc_warning ("%s at %L", gfc_arith_error (rc), &op1->where);
+      rc = ARITH_OK;
+      *resultp = result;
+    }
   else if (rc != ARITH_OK)
     gfc_free_expr (result);
   else
     *resultp = result;
-
+  
   return rc;
 }
 
@@ -1932,9 +1988,16 @@ gfc_int2int (gfc_expr * src, int kind)
   if ((rc = gfc_check_integer_range (result->value.integer, kind))
       != ARITH_OK)
     {
-      arith_error (rc, &src->ts, &result->ts, &src->where);
-      gfc_free_expr (result);
-      return NULL;
+      if (rc == ARITH_ASYMMETRIC)
+        {
+          gfc_warning ("%s at %L", gfc_arith_error (rc), &src->where);
+        }
+      else
+        {
+          arith_error (rc, &src->ts, &result->ts, &src->where);
+          gfc_free_expr (result);
+          return NULL;
+        }
     }
 
   return result;
diff --git a/gcc/fortran/gfortran.h b/gcc/fortran/gfortran.h
index 25b7192ba71..85485612d0f 100644
--- a/gcc/fortran/gfortran.h
+++ b/gcc/fortran/gfortran.h
@@ -185,7 +185,7 @@ extern mstring intrinsic_operators[];
 /* Arithmetic results.  */
 typedef enum
 { ARITH_OK = 1, ARITH_OVERFLOW, ARITH_UNDERFLOW, ARITH_NAN,
-  ARITH_DIV0, ARITH_0TO0, ARITH_INCOMMENSURATE
+  ARITH_DIV0, ARITH_0TO0, ARITH_INCOMMENSURATE, ARITH_ASYMMETRIC
 }
 arith;
 
@@ -1100,7 +1100,7 @@ gfc_expr;
 typedef struct
 {
   /* Values really representable by the target.  */
-  mpz_t huge, min_int, max_int;
+  mpz_t huge, pedantic_min_int, min_int, max_int;
 
   int kind, radix, digits, bit_size, range;