* builtins.def: Change SANITIZE_FLOAT_DIVIDE to SANITIZE_NONDEFAULT.

	* gcc.c (sanitize_spec_function): Likewise.
	* convert.c (convert_to_integer): Include "ubsan.h".  Add
	floating-point to integer instrumentation.
	* doc/invoke.texi: Document -fsanitize=float-cast-overflow.
	* flag-types.h (enum sanitize_code): Add SANITIZE_FLOAT_CAST and
	SANITIZE_NONDEFAULT.
	* opts.c (common_handle_option): Handle -fsanitize=float-cast-overflow.
	* sanitizer.def (BUILT_IN_UBSAN_HANDLE_FLOAT_CAST_OVERFLOW,
	BUILT_IN_UBSAN_HANDLE_FLOAT_CAST_OVERFLOW_ABORT): Add.
	* ubsan.c: Include "realmpfr.h" and "dfp.h".
	(get_ubsan_type_info_for_type): Handle REAL_TYPEs.
	(ubsan_type_descriptor): Set tkind to 0xffff for types other than
	float/double/long double.
	(ubsan_instrument_float_cast): New function.
	* ubsan.h (ubsan_instrument_float_cast): Declare.
testsuite/
	* c-c++-common/ubsan/float-cast-overflow-1.c: New test.
	* c-c++-common/ubsan/float-cast-overflow-10.c: New test.
	* c-c++-common/ubsan/float-cast-overflow-2.c: New test.
	* c-c++-common/ubsan/float-cast-overflow-3.c: New test.
	* c-c++-common/ubsan/float-cast-overflow-4.c: New test.
	* c-c++-common/ubsan/float-cast-overflow-5.c: New test.
	* c-c++-common/ubsan/float-cast-overflow-6.c: New test.
	* c-c++-common/ubsan/float-cast-overflow-7.c: New test.
	* c-c++-common/ubsan/float-cast-overflow-7.h: New file.
	* c-c++-common/ubsan/float-cast-overflow-8.c: New test.
	* c-c++-common/ubsan/float-cast-overflow-9.c: New test.
	* c-c++-common/ubsan/float-cast.h: New file.
	* g++.dg/ubsan/float-cast-overflow-bf.C: New test.
	* gcc.dg/ubsan/float-cast-overflow-bf.c: New test.
libsanitizer/
	* ubsan/ubsan_value.cc (getFloatValue): Handle 96-bit
	floating-point types.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@210862 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 142 insertions, 4 deletions

diff --git a/gcc/ubsan.c b/gcc/ubsan.c
index 585569c5810..4de6d6e8ae3 100644
--- a/gcc/ubsan.c
+++ b/gcc/ubsan.c
@@ -47,6 +47,8 @@ along with GCC; see the file COPYING3.  If not see
 #include "asan.h"
 #include "gimplify-me.h"
 #include "intl.h"
+#include "realmpfr.h"
+#include "dfp.h"
 
 /* Map from a tree to a VAR_DECL tree.  */
 
@@ -267,9 +269,14 @@ static unsigned short
 get_ubsan_type_info_for_type (tree type)
 {
   gcc_assert (TYPE_SIZE (type) && tree_fits_uhwi_p (TYPE_SIZE (type)));
-  int prec = exact_log2 (tree_to_uhwi (TYPE_SIZE (type)));
-  gcc_assert (prec != -1);
-  return (prec << 1) | !TYPE_UNSIGNED (type);
+  if (TREE_CODE (type) == REAL_TYPE)
+    return tree_to_uhwi (TYPE_SIZE (type));
+  else
+    {
+      int prec = exact_log2 (tree_to_uhwi (TYPE_SIZE (type)));
+      gcc_assert (prec != -1);
+      return (prec << 1) | !TYPE_UNSIGNED (type);
+    }
 }
 
 /* Helper routine that returns ADDR_EXPR of a VAR_DECL of a type
@@ -359,7 +366,14 @@ ubsan_type_descriptor (tree type, bool want_pointer_type_p)
       tkind = 0x0000;
       break;
     case REAL_TYPE:
-      tkind = 0x0001;
+      /* FIXME: libubsan right now only supports float, double and
+	 long double type formats.  */
+      if (TYPE_MODE (type) == TYPE_MODE (float_type_node)
+	  || TYPE_MODE (type) == TYPE_MODE (double_type_node)
+	  || TYPE_MODE (type) == TYPE_MODE (long_double_type_node))
+	tkind = 0x0001;
+      else
+	tkind = 0xffff;
       break;
     default:
       tkind = 0xffff;
@@ -891,6 +905,130 @@ instrument_bool_enum_load (gimple_stmt_iterator *gsi)
   gsi_insert_before (&gsi2, g, GSI_SAME_STMT);
 }
 
+/* Instrument float point-to-integer conversion.  TYPE is an integer type of
+   destination, EXPR is floating-point expression.  */
+
+tree
+ubsan_instrument_float_cast (location_t loc, tree type, tree expr)
+{
+  tree expr_type = TREE_TYPE (expr);
+  tree t, tt, fn, min, max;
+  enum machine_mode mode = TYPE_MODE (expr_type);
+  int prec = TYPE_PRECISION (type);
+  bool uns_p = TYPE_UNSIGNED (type);
+
+  /* Float to integer conversion first truncates toward zero, so
+     even signed char c = 127.875f; is not problematic.
+     Therefore, we should complain only if EXPR is unordered or smaller
+     or equal than TYPE_MIN_VALUE - 1.0 or greater or equal than
+     TYPE_MAX_VALUE + 1.0.  */
+  if (REAL_MODE_FORMAT (mode)->b == 2)
+    {
+      /* For maximum, TYPE_MAX_VALUE might not be representable
+	 in EXPR_TYPE, e.g. if TYPE is 64-bit long long and
+	 EXPR_TYPE is IEEE single float, but TYPE_MAX_VALUE + 1.0 is
+	 either representable or infinity.  */
+      REAL_VALUE_TYPE maxval = dconst1;
+      SET_REAL_EXP (&maxval, REAL_EXP (&maxval) + prec - !uns_p);
+      real_convert (&maxval, mode, &maxval);
+      max = build_real (expr_type, maxval);
+
+      /* For unsigned, assume -1.0 is always representable.  */
+      if (uns_p)
+	min = build_minus_one_cst (expr_type);
+      else
+	{
+	  /* TYPE_MIN_VALUE is generally representable (or -inf),
+	     but TYPE_MIN_VALUE - 1.0 might not be.  */
+	  REAL_VALUE_TYPE minval = dconstm1, minval2;
+	  SET_REAL_EXP (&minval, REAL_EXP (&minval) + prec - 1);
+	  real_convert (&minval, mode, &minval);
+	  real_arithmetic (&minval2, MINUS_EXPR, &minval, &dconst1);
+	  real_convert (&minval2, mode, &minval2);
+	  if (real_compare (EQ_EXPR, &minval, &minval2)
+	      && !real_isinf (&minval))
+	    {
+	      /* If TYPE_MIN_VALUE - 1.0 is not representable and
+		 rounds to TYPE_MIN_VALUE, we need to subtract
+		 more.  As REAL_MODE_FORMAT (mode)->p is the number
+		 of base digits, we want to subtract a number that
+		 will be 1 << (REAL_MODE_FORMAT (mode)->p - 1)
+		 times smaller than minval.  */
+	      minval2 = dconst1;
+	      gcc_assert (prec > REAL_MODE_FORMAT (mode)->p);
+	      SET_REAL_EXP (&minval2,
+			    REAL_EXP (&minval2) + prec - 1
+			    - REAL_MODE_FORMAT (mode)->p + 1);
+	      real_arithmetic (&minval2, MINUS_EXPR, &minval, &minval2);
+	      real_convert (&minval2, mode, &minval2);
+	    }
+	  min = build_real (expr_type, minval2);
+	}
+    }
+  else if (REAL_MODE_FORMAT (mode)->b == 10)
+    {
+      /* For _Decimal128 up to 34 decimal digits, - sign,
+	 dot, e, exponent.  */
+      char buf[64];
+      mpfr_t m;
+      int p = REAL_MODE_FORMAT (mode)->p;
+      REAL_VALUE_TYPE maxval, minval;
+
+      /* Use mpfr_snprintf rounding to compute the smallest
+	 representable decimal number greater or equal than
+	 1 << (prec - !uns_p).  */
+      mpfr_init2 (m, prec + 2);
+      mpfr_set_ui_2exp (m, 1, prec - !uns_p, GMP_RNDN);
+      mpfr_snprintf (buf, sizeof buf, "%.*RUe", p - 1, m);
+      decimal_real_from_string (&maxval, buf);
+      max = build_real (expr_type, maxval);
+
+      /* For unsigned, assume -1.0 is always representable.  */
+      if (uns_p)
+	min = build_minus_one_cst (expr_type);
+      else
+	{
+	  /* Use mpfr_snprintf rounding to compute the largest
+	     representable decimal number less or equal than
+	     (-1 << (prec - 1)) - 1.  */
+	  mpfr_set_si_2exp (m, -1, prec - 1, GMP_RNDN);
+	  mpfr_sub_ui (m, m, 1, GMP_RNDN);
+	  mpfr_snprintf (buf, sizeof buf, "%.*RDe", p - 1, m);
+	  decimal_real_from_string (&minval, buf);
+	  min = build_real (expr_type, minval);
+	}
+      mpfr_clear (m);
+    }
+  else
+    return NULL_TREE;
+
+  if (flag_sanitize_undefined_trap_on_error)
+    fn = build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_TRAP), 0);
+  else
+    {
+      /* Create the __ubsan_handle_float_cast_overflow fn call.  */
+      tree data = ubsan_create_data ("__ubsan_float_cast_overflow_data", NULL,
+				     NULL,
+				     ubsan_type_descriptor (expr_type, false),
+				     ubsan_type_descriptor (type, false),
+				     NULL_TREE);
+      enum built_in_function bcode
+	= flag_sanitize_recover
+	  ? BUILT_IN_UBSAN_HANDLE_FLOAT_CAST_OVERFLOW
+	  : BUILT_IN_UBSAN_HANDLE_FLOAT_CAST_OVERFLOW_ABORT;
+      fn = builtin_decl_explicit (bcode);
+      fn = build_call_expr_loc (loc, fn, 2,
+				build_fold_addr_expr_loc (loc, data),
+				ubsan_encode_value (expr, false));
+    }
+
+  t = fold_build2 (UNLE_EXPR, boolean_type_node, expr, min);
+  tt = fold_build2 (UNGE_EXPR, boolean_type_node, expr, max);
+  return fold_build3 (COND_EXPR, void_type_node,
+		      fold_build2 (TRUTH_OR_EXPR, boolean_type_node, t, tt),
+		      fn, integer_zero_node);
+}
+
 namespace {
 
 const pass_data pass_data_ubsan =