Remove unreachable returns

This removes unreachable return statements as diagnosed by
the -Wunreachable-code patch.  Some cases are more obviously
an improvement than others - in fact some may get you the idea
to replace them with gcc_unreachable () instead, leading to
cases of the 'Remove unreachable gcc_unreachable () at the end
of functions' patch.

2021-11-25  Richard Biener  <rguenther@suse.de>

	* vec.c (qsort_chk): Do not return the void return value
	from the noreturn qsort_chk_error.
	* ccmp.c (expand_ccmp_expr_1): Remove unreachable return.
	* df-scan.c (df_ref_equal_p): Likewise.
	* dwarf2out.c (is_base_type): Likewise.
	(add_const_value_attribute): Likewise.
	* fixed-value.c (fixed_arithmetic): Likewise.
	* gimple-fold.c (gimple_fold_builtin_fputs): Likewise.
	* gimple-ssa-strength-reduction.c (stmt_cost): Likewise.
	* graphite-isl-ast-to-gimple.c
	(gcc_expression_from_isl_expr_op): Likewise.
	(gcc_expression_from_isl_expression): Likewise.
	* ipa-fnsummary.c (will_be_nonconstant_expr_predicate):
	Likewise.
	* lto-streamer-in.c (lto_input_mode_table): Likewise.

gcc/c-family/
	* c-opts.c (c_common_post_options): Remove unreachable return.
	* c-pragma.c (handle_pragma_target): Likewise.
	(handle_pragma_optimize): Likewise.

gcc/c/
	* c-typeck.c (c_tree_equal): Remove unreachable return.
	* c-parser.c (get_matching_symbol): Likewise.

libgomp/
	* oacc-plugin.c (GOMP_PLUGIN_acc_default_dim): Remove unreachable
	return.

gcc/c-family/c-opts.c

@@ -1109,10 +1109,7 @@ c_common_post_options (const char **pfilename)
 	out_stream = fopen (out_fname, "w");
 
       if (out_stream == NULL)
-	{
-	  fatal_error (input_location, "opening output file %s: %m", out_fname);
-	  return false;
-	}
+	fatal_error (input_location, "opening output file %s: %m", out_fname);
 
       init_pp_output (out_stream);
     }

gcc/c-family/c-pragma.c

@@ -916,10 +916,7 @@ handle_pragma_target(cpp_reader *ARG_UNUSED(dummy))
     }
 
   if (token != CPP_STRING)
-    {
-      GCC_BAD_AT (loc, "%<#pragma GCC option%> is not a string");
-      return;
-    }
+    GCC_BAD_AT (loc, "%<#pragma GCC option%> is not a string");
 
   /* Strings are user options.  */
   else
@@ -991,10 +988,7 @@ handle_pragma_optimize (cpp_reader *ARG_UNUSED(dummy))
     }
 
   if (token != CPP_STRING && token != CPP_NUMBER)
-    {
-      GCC_BAD ("%<#pragma GCC optimize%> is not a string or number");
-      return;
-    }
+    GCC_BAD ("%<#pragma GCC optimize%> is not a string or number");
 
   /* Strings/numbers are user options.  */
   else

gcc/c/c-parser.c

@@ -1132,7 +1132,6 @@ get_matching_symbol (enum cpp_ttype type)
     {
     default:
       gcc_unreachable ();
-      return "";
     case CPP_CLOSE_PAREN:
       return "(";
     case CPP_CLOSE_BRACE:

gcc/c/c-typeck.c

@@ -15984,8 +15984,6 @@ c_tree_equal (tree t1, tree t2)
     default:
       gcc_unreachable ();
     }
-  /* We can get here with --disable-checking.  */
-  return false;
 }
 
 /* Returns true when the function declaration FNDECL is implicit,

gcc/ccmp.c

@@ -273,8 +273,6 @@ expand_ccmp_expr_1 (gimple *g, rtx_insn **prep_seq, rtx_insn **gen_seq)
 	return NULL_RTX;
       return expand_ccmp_next (op1, code, tmp, prep_seq, gen_seq);
     }
-
-  return NULL_RTX;
 }
 
 /* Main entry to expand conditional compare statement G.

gcc/df-scan.c

@@ -2059,7 +2059,6 @@ df_ref_equal_p (df_ref ref1, df_ref ref2)
     default:
       gcc_unreachable ();
     }
-  return false;
 }
 
 

gcc/dwarf2out.c

@@ -13359,8 +13359,6 @@ is_base_type (tree type)
 	return 0;
       gcc_unreachable ();
     }
-
-  return 0;
 }
 
 /* Given a pointer to a tree node, assumed to be some kind of a ..._TYPE
@@ -20240,7 +20238,6 @@ add_const_value_attribute (dw_die_ref die, machine_mode mode, rtx rtl)
       /* No other kinds of rtx should be possible here.  */
       gcc_unreachable ();
     }
-  return false;
 }
 
 /* Determine whether the evaluation of EXPR references any variables

gcc/fixed-value.c

@@ -756,7 +756,6 @@ fixed_arithmetic (FIXED_VALUE_TYPE *f, int icode, const FIXED_VALUE_TYPE *op0,
     default:
       gcc_unreachable ();
     }
-  return false;
 }
 
 /* Compare fixed-point values by tree_code.

gcc/gimple-fold.c

@@ -2993,7 +2993,6 @@ gimple_fold_builtin_fputs (gimple_stmt_iterator *gsi,
     default:
       gcc_unreachable ();
     }
-  return false;
 }
 
 /* Fold a call to the __mem{cpy,pcpy,move,set}_chk builtin.

gcc/gimple-ssa-strength-reduction.c

@@ -763,7 +763,6 @@ stmt_cost (gimple *gs, bool speed)
     }
   
   gcc_unreachable ();
-  return 0;
 }
 
 /* Look up the defining statement for BASE_IN and return a pointer

gcc/graphite-isl-ast-to-gimple.c

@@ -526,8 +526,6 @@ gcc_expression_from_isl_expr_op (tree type, __isl_take isl_ast_expr *expr,
     default:
       gcc_unreachable ();
     }
-
-  return NULL_TREE;
 }
 
 /* Converts an isl AST expression E back to a GCC expression tree of
@@ -557,8 +555,6 @@ gcc_expression_from_isl_expression (tree type, __isl_take isl_ast_expr *expr,
     default:
       gcc_unreachable ();
     }
-
-  return NULL_TREE;
 }
 
 /* Creates a new LOOP corresponding to isl_ast_node_for.  Inserts an

gcc/ipa-fnsummary.c

@@ -2042,7 +2042,6 @@ will_be_nonconstant_expr_predicate (ipa_func_body_info *fbi,
       debug_tree (expr);
       gcc_unreachable ();
     }
-  return false;
 }
 
 

gcc/lto-streamer-in.c

@@ -1963,11 +1963,8 @@ lto_input_mode_table (struct lto_file_decl_data *file_data)
   const char *data
     = lto_get_summary_section_data (file_data, LTO_section_mode_table, &len);
   if (! data)
-    {
-      internal_error ("cannot read LTO mode table from %s",
-		      file_data->file_name);
-      return;
-    }
+    internal_error ("cannot read LTO mode table from %s",
+		    file_data->file_name);
 
   unsigned char *table = ggc_cleared_vec_alloc<unsigned char> (1 << 8);
   file_data->mode_table = table;

gcc/vec.c

@@ -229,23 +229,23 @@ qsort_chk (void *base, size_t n, size_t size, sort_r_cmp_fn *cmp, void *data)
 	if (CMP (i1, i2))
 	  break;
 	else if (CMP (i2, i1))
-	  return ERR2 (i1, i2);
+	  ERR2 (i1, i2);
       size_t lim1 = LIM (i2 - i1), lim2 = LIM (n - i2);
       /* Verify that other pairs within current span compare equal.  */
       for (i = i1 + 1; i + 1 < i2; i++)
 	for (j = i + 1; j < i1 + lim1; j++)
 	  if (CMP (i, j))
-	    return ERR3 (i, i1, j);
+	    ERR3 (i, i1, j);
 	  else if (CMP (j, i))
-	    return ERR2 (i, j);
+	    ERR2 (i, j);
       /* Verify that elements within this span compare less than
          elements beyond the span.  */
       for (i = i1; i < i2; i++)
 	for (j = i2; j < i2 + lim2; j++)
 	  if (CMP (i, j) >= 0)
-	    return ERR3 (i, i1, j);
+	    ERR3 (i, i1, j);
 	  else if (CMP (j, i) <= 0)
-	    return ERR2 (i, j);
+	    ERR2 (i, j);
     }
 #undef ERR3
 #undef ERR2

libgomp/oacc-plugin.c

@@ -62,7 +62,6 @@ GOMP_PLUGIN_acc_default_dim (unsigned int i)
   if (i >= GOMP_DIM_MAX)
     {
       gomp_fatal ("invalid dimension argument: %d", i);
-      return -1;
     }
   return goacc_default_dims[i];
 }