Re: Add support to trace comparison instructions and switch statements

[Wish Wu <wishwu007 at gmail dot com>]

Hi

In fact, under linux with "return address" and file "/proc/self/maps",
we can give unique id for every comparison.

For fuzzing, we may give 3 bits for every comparison as marker of if
"<", "==" or ">" is showed. :D

With Regards
Wish Wu of Ant-financial Light-Year Security Lab

On Thu, Jul 13, 2017 at 6:04 PM, Wish Wu <wishwu007@gmail.com> wrote:
> Hi
>
> In my perspective:
>
> 1. Do we need to assign unique id for every comparison ?
>     Yes, I suggest to implement it like -fsanitize-coverage=trace-pc-guard .
>     Because some fuzzing targets may invoke dlopen() like functions to
> load libraries(modules) after fork(), while these libraries are
> compiled with trace-cmp as well.
>     With ALSR enabled by linker and/or kernel, return address can't be
> a unique id for every comparison.
>
> 2. Should we merge cmp1(),cmp2(),cmp4(),cmp8(),cmpf(),cmpd() into one cmp() ?
>     No, It may reduce the performance of fuzzing. It may wastes
> registers. But the number "switch" statements are much less than "if",
> I forgive "switch"'s wasting behaviors.
>
> 3.Should we record operands(<,>,==,<= ......) ?
>     Probably no. As comparison,"<" , "==" and ">" all of them are
> meaningful, because programmers must have some reasons to do that. As
> practice , "==" is more meaningful.
>
> 4.Should we record comparisons for counting loop checks ?
>     Not sure.
>
> With Regards
> Wish Wu of Ant-financial Light-Year Security Lab
>
> On Thu, Jul 13, 2017 at 4:09 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
>> On Tue, Jul 11, 2017 at 1:59 PM, Wish Wu <wishwu007@gmail.com> wrote:
>>> Hi
>>>
>>> I wrote a test for "-fsanitize-coverage=trace-cmp" .
>>>
>>> Is there anybody tells me if these codes could be merged into gcc ?
>>
>>
>> Nice!
>>
>> We are currently working on Linux kernel fuzzing that use the
>> comparison tracing. We use clang at the moment, but having this
>> support in gcc would be great for kernel land.
>>
>> One concern I have: do we want to do some final refinements to the API
>> before we implement this in both compilers?
>>
>> 2 things we considered from our perspective:
>>  - communicating to the runtime which operands are constants
>>  - communicating to the runtime which comparisons are counting loop checks
>>
>> First is useful if you do "find one operand in input and replace with
>> the other one" thing. Second is useful because counting loop checks
>> are usually not useful (at least all but one).
>> In the original Go implementation I also conveyed signedness of
>> operands, exact comparison operation (<, >, etc):
>> https://github.com/dvyukov/go-fuzz/blob/master/go-fuzz-defs/defs.go#L13
>> But I did not find any use for that.
>> I also gave all comparisons unique IDs:
>> https://github.com/dvyukov/go-fuzz/blob/master/go-fuzz-dep/sonar.go#L24
>> That turned out to be useful. And there are chances we will want this
>> for C/C++ as well.
>>
>> Kostya, did anything like this pop up in your work on libfuzzer?
>> Can we still change the clang API? At least add an additional argument
>> to the callbacks?
>>
>> At the very least I would suggest that we add an additional arg that
>> contains some flags (1/2 arg is a const, this is counting loop check,
>> etc). If we do that we can also have just 1 callback that accepts
>> uint64's for args because we can pass operand size in the flags:
>>
>> void __sanitizer_cov_trace_cmp(uint64 arg1, uint64 arg2, uint64 flags);
>>
>> But I wonder if 3 uint64 args will be too inefficient for 32 bit archs?...
>>
>> If we create a global per comparison then we could put the flags into
>> the global:
>>
>> void __sanitizer_cov_trace_cmp(uint64 arg1, uint64 arg2, something_t *global);
>>
>> Thoughts?
>>
>>
>>
>>
>>> Index: gcc/testsuite/gcc.dg/sancov/basic3.c
>>> ===================================================================
>>> --- gcc/testsuite/gcc.dg/sancov/basic3.c (nonexistent)
>>> +++ gcc/testsuite/gcc.dg/sancov/basic3.c (working copy)
>>> @@ -0,0 +1,42 @@
>>> +/* Basic test on number of inserted callbacks.  */
>>> +/* { dg-do compile } */
>>> +/* { dg-options "-fsanitize-coverage=trace-cmp -fdump-tree-optimized" } */
>>> +
>>> +void foo(char *a, short *b, int *c, long long *d, float *e, double *f)
>>> +{
>>> +  if (*a)
>>> +    *a += 1;
>>> +  if (*b)
>>> +    *b = *a;
>>> +  if (*c)
>>> +    *c += 1;
>>> +  if(*d)
>>> +    *d = *c;
>>> +  if(*e == *c)
>>> +    *e = *c;
>>> +  if(*f == *e)
>>> +    *f = *e;
>>> +  switch(*a)
>>> +    {
>>> +    case 2:
>>> +      *b += 2;
>>> +      break;
>>> +    default:
>>> +      break;
>>> +    }
>>> +  switch(*d)
>>> +    {
>>> +    case 3:
>>> +      *d += 3;
>>> +    case -4:
>>> +      *d -= 4;
>>> +    }
>>> +}
>>> +
>>> +/* { dg-final { scan-tree-dump-times
>>> "__builtin___sanitizer_cov_trace_cmp1 \\(" 1 "optimized" } } */
>>> +/* { dg-final { scan-tree-dump-times
>>> "__builtin___sanitizer_cov_trace_cmp2 \\(" 1 "optimized" } } */
>>> +/* { dg-final { scan-tree-dump-times
>>> "__builtin___sanitizer_cov_trace_cmp4 \\(" 1 "optimized" } } */
>>> +/* { dg-final { scan-tree-dump-times
>>> "__builtin___sanitizer_cov_trace_cmp8 \\(" 1 "optimized" } } */
>>> +/* { dg-final { scan-tree-dump-times
>>> "__builtin___sanitizer_cov_trace_cmpf \\(" 1 "optimized" } } */
>>> +/* { dg-final { scan-tree-dump-times
>>> "__builtin___sanitizer_cov_trace_cmpd \\(" 1 "optimized" } } */
>>> +/* { dg-final { scan-tree-dump-times
>>> "__builtin___sanitizer_cov_trace_switch \\(" 2 "optimized" } } */
>>>
>>>
>>> With Regards
>>> Wish Wu
>>>
>>> On Mon, Jul 10, 2017 at 8:07 PM, 吴潍浠(此彼) <weixi.wwx@antfin.com> wrote:
>>>> Hi
>>>>
>>>> I write some codes to make gcc support comparison-guided fuzzing.
>>>> It is very like http://clang.llvm.org/docs/SanitizerCoverage.html#tracing-data-flow .
>>>> With -fsanitize-coverage=trace-cmp the compiler will insert extra instrumentation around comparison instructions and switch statements.
>>>> I think it is useful for fuzzing.  :D
>>>>
>>>> Patch is below, I may supply test cases later.
>>>>
>>>> With Regards
>>>> Wish Wu
>>>>
>>>> Index: gcc/asan.c
>>>> ===================================================================
>>>> --- gcc/asan.c  (revision 250082)
>>>> +++ gcc/asan.c  (working copy)
>>>> @@ -2705,6 +2705,29 @@ initialize_sanitizer_builtins (void)
>>>>    tree BT_FN_SIZE_CONST_PTR_INT
>>>>      = build_function_type_list (size_type_node, const_ptr_type_node,
>>>>                                 integer_type_node, NULL_TREE);
>>>> +
>>>> +  tree BT_FN_VOID_UINT8_UINT8
>>>> +    = build_function_type_list (void_type_node, unsigned_char_type_node,
>>>> +                               unsigned_char_type_node, NULL_TREE);
>>>> +  tree BT_FN_VOID_UINT16_UINT16
>>>> +    = build_function_type_list (void_type_node, uint16_type_node,
>>>> +                               uint16_type_node, NULL_TREE);
>>>> +  tree BT_FN_VOID_UINT32_UINT32
>>>> +    = build_function_type_list (void_type_node, uint32_type_node,
>>>> +                               uint32_type_node, NULL_TREE);
>>>> +  tree BT_FN_VOID_UINT64_UINT64
>>>> +    = build_function_type_list (void_type_node, uint64_type_node,
>>>> +                               uint64_type_node, NULL_TREE);
>>>> +  tree BT_FN_VOID_FLOAT_FLOAT
>>>> +    = build_function_type_list (void_type_node, float_type_node,
>>>> +                               float_type_node, NULL_TREE);
>>>> +  tree BT_FN_VOID_DOUBLE_DOUBLE
>>>> +    = build_function_type_list (void_type_node, double_type_node,
>>>> +                               double_type_node, NULL_TREE);
>>>> +  tree BT_FN_VOID_UINT64_PTR
>>>> +    = build_function_type_list (void_type_node, uint64_type_node,
>>>> +                               ptr_type_node, NULL_TREE);
>>>> +
>>>>    tree BT_FN_BOOL_VPTR_PTR_IX_INT_INT[5];
>>>>    tree BT_FN_IX_CONST_VPTR_INT[5];
>>>>    tree BT_FN_IX_VPTR_IX_INT[5];
>>>> Index: gcc/builtin-types.def
>>>> ===================================================================
>>>> --- gcc/builtin-types.def       (revision 250082)
>>>> +++ gcc/builtin-types.def       (working copy)
>>>> @@ -338,8 +338,20 @@ DEF_FUNCTION_TYPE_2 (BT_FN_VOID_PTRMODE_PTR,
>>>>                      BT_VOID, BT_PTRMODE, BT_PTR)
>>>>  DEF_FUNCTION_TYPE_2 (BT_FN_VOID_PTR_PTRMODE,
>>>>                      BT_VOID, BT_PTR, BT_PTRMODE)
>>>> +DEF_FUNCTION_TYPE_2 (BT_FN_VOID_UINT8_UINT8,
>>>> +                    BT_VOID, BT_UINT8, BT_UINT8)
>>>> +DEF_FUNCTION_TYPE_2 (BT_FN_VOID_UINT16_UINT16,
>>>> +                    BT_VOID, BT_UINT16, BT_UINT16)
>>>> +DEF_FUNCTION_TYPE_2 (BT_FN_VOID_UINT32_UINT32,
>>>> +                    BT_VOID, BT_UINT32, BT_UINT32)
>>>>  DEF_FUNCTION_TYPE_2 (BT_FN_VOID_UINT64_UINT64,
>>>>                      BT_VOID, BT_UINT64, BT_UINT64)
>>>> +DEF_FUNCTION_TYPE_2 (BT_FN_VOID_FLOAT_FLOAT,
>>>> +                    BT_VOID, BT_FLOAT, BT_FLOAT)
>>>> +DEF_FUNCTION_TYPE_2 (BT_FN_VOID_DOUBLE_DOUBLE,
>>>> +                    BT_VOID, BT_DOUBLE, BT_DOUBLE)
>>>> +DEF_FUNCTION_TYPE_2 (BT_FN_VOID_UINT64_PTR,
>>>> +                    BT_VOID, BT_UINT64, BT_PTR)
>>>>  DEF_FUNCTION_TYPE_2 (BT_FN_VOID_VALIST_REF_VALIST_ARG,
>>>>                      BT_VOID, BT_VALIST_REF, BT_VALIST_ARG)
>>>>  DEF_FUNCTION_TYPE_2 (BT_FN_LONG_LONG_LONG,
>>>> Index: gcc/common.opt
>>>> ===================================================================
>>>> --- gcc/common.opt      (revision 250082)
>>>> +++ gcc/common.opt      (working copy)
>>>> @@ -226,10 +226,9 @@ unsigned int flag_sanitize
>>>>  Variable
>>>>  unsigned int flag_sanitize_recover = (SANITIZE_UNDEFINED | SANITIZE_UNDEFINED_NONDEFAULT | SANITIZE_KERNEL_ADDRESS) & ~(SANITIZE_UNREACHABLE | SANITIZE_RETURN)
>>>>
>>>> -fsanitize-coverage=trace-pc
>>>> -Common Report Var(flag_sanitize_coverage)
>>>> -Enable coverage-guided fuzzing code instrumentation.
>>>> -Inserts call to __sanitizer_cov_trace_pc into every basic block.
>>>> +; What the coverage sanitizers should instrument
>>>> +Variable
>>>> +unsigned int flag_sanitize_coverage
>>>>
>>>>  ; Flag whether a prefix has been added to dump_base_name
>>>>  Variable
>>>> @@ -975,6 +974,10 @@ fsanitize=
>>>>  Common Driver Report Joined
>>>>  Select what to sanitize.
>>>>
>>>> +fsanitize-coverage=
>>>> +Common Driver Report Joined
>>>> +Select what to coverage sanitize.
>>>> +
>>>>  fasan-shadow-offset=
>>>>  Common Joined RejectNegative Var(common_deferred_options) Defer
>>>>  -fasan-shadow-offset=<number>  Use custom shadow memory offset.
>>>> Index: gcc/flag-types.h
>>>> ===================================================================
>>>> --- gcc/flag-types.h    (revision 250082)
>>>> +++ gcc/flag-types.h    (working copy)
>>>> @@ -250,6 +250,14 @@ enum sanitize_code {
>>>>                                   | SANITIZE_BOUNDS_STRICT
>>>>  };
>>>>
>>>> +/* Different trace modes */
>>>> +enum sanitize_coverage_code {
>>>> +  /* Trace PC */
>>>> +  SANITIZE_COV_TRACE_PC = 1UL << 0,
>>>> +  /* Trace Compare */
>>>> +  SANITIZE_COV_TRACE_CMP = 1UL << 1
>>>> +};
>>>> +
>>>>  /* flag_vtable_verify initialization levels. */
>>>>  enum vtv_priority {
>>>>    VTV_NO_PRIORITY       = 0,  /* i.E. Do NOT do vtable verification. */
>>>> Index: gcc/opts.c
>>>> ===================================================================
>>>> --- gcc/opts.c  (revision 250082)
>>>> +++ gcc/opts.c  (working copy)
>>>> @@ -1518,6 +1518,17 @@ const struct sanitizer_opts_s sanitizer_opts[] =
>>>>    { NULL, 0U, 0UL, false }
>>>>  };
>>>>
>>>> +/* -f{,no-}sanitize-coverage= suboptions.  */
>>>> +const struct sanitizer_opts_s coverage_sanitizer_opts[] =
>>>> +{
>>>> +#define SANITIZER_OPT(name, flags, recover) \
>>>> +    { #name, flags, sizeof #name - 1, recover }
>>>> +  SANITIZER_OPT (trace-pc, SANITIZE_COV_TRACE_PC, false),
>>>> +  SANITIZER_OPT (trace-cmp, SANITIZE_COV_TRACE_CMP, false),
>>>> +#undef SANITIZER_OPT
>>>> +  { NULL, 0U, 0UL, false }
>>>> +};
>>>> +
>>>>  /* A struct for describing a run of chars within a string.  */
>>>>
>>>>  struct string_fragment
>>>> @@ -1665,6 +1676,85 @@ parse_sanitizer_options (const char *p, location_t
>>>>    return flags;
>>>>  }
>>>>
>>>> +/* Given ARG, an unrecognized coverage sanitizer option, return the best
>>>> +   matching coverage sanitizer option, or NULL if there isn't one.
>>>> +   VALUE is non-zero for the regular form of the option, zero
>>>> +   for the "no-" form (e.g. "-fno-sanitize-coverage=").  */
>>>> +
>>>> +static const char *
>>>> +get_closest_coverage_sanitizer_option (const string_fragment &arg, int value)
>>>> +{
>>>> +  best_match <const string_fragment &, const char*> bm (arg);
>>>> +  for (int i = 0; coverage_sanitizer_opts[i].name != NULL; ++i)
>>>> +    {
>>>> +      bm.consider (coverage_sanitizer_opts[i].name);
>>>> +    }
>>>> +  return bm.get_best_meaningful_candidate ();
>>>> +}
>>>> +
>>>> +/* Parse comma separated sanitizer suboptions from P for option SCODE,
>>>> +   adjust previous FLAGS and return new ones.  If COMPLAIN is false,
>>>> +   don't issue diagnostics.  */
>>>> +
>>>> +unsigned int
>>>> +parse_coverage_sanitizer_options (const char *p, location_t loc,
>>>> +                        unsigned int flags, int value, bool complain)
>>>> +{
>>>> +  while (*p != 0)
>>>> +    {
>>>> +      size_t len, i;
>>>> +      bool found = false;
>>>> +      const char *comma = strchr (p, ',');
>>>> +
>>>> +      if (comma == NULL)
>>>> +       len = strlen (p);
>>>> +      else
>>>> +       len = comma - p;
>>>> +      if (len == 0)
>>>> +       {
>>>> +         p = comma + 1;
>>>> +         continue;
>>>> +       }
>>>> +
>>>> +      /* Check to see if the string matches an option class name.  */
>>>> +      for (i = 0; coverage_sanitizer_opts[i].name != NULL; ++i)
>>>> +       if (len == coverage_sanitizer_opts[i].len
>>>> +           && memcmp (p, coverage_sanitizer_opts[i].name, len) == 0)
>>>> +         {
>>>> +           if (value)
>>>> +             flags |= coverage_sanitizer_opts[i].flag;
>>>> +           else
>>>> +             flags &= ~coverage_sanitizer_opts[i].flag;
>>>> +           found = true;
>>>> +           break;
>>>> +         }
>>>> +
>>>> +      if (! found && complain)
>>>> +       {
>>>> +         const char *hint
>>>> +           = get_closest_coverage_sanitizer_option (string_fragment (p, len),
>>>> +                                                    value);
>>>> +
>>>> +         if (hint)
>>>> +           error_at (loc,
>>>> +                     "unrecognized argument to -f%ssanitize-coverage= option: %q.*s;"
>>>> +                     " did you mean %qs?",
>>>> +                     value ? "" : "no-",
>>>> +                     (int) len, p, hint);
>>>> +         else
>>>> +           error_at (loc,
>>>> +                     "unrecognized argument to -f%ssanitize-coverage= option: %q.*s",
>>>> +                     value ? "" : "no-",
>>>> +                     (int) len, p);
>>>> +       }
>>>> +
>>>> +      if (comma == NULL)
>>>> +       break;
>>>> +      p = comma + 1;
>>>> +    }
>>>> +  return flags;
>>>> +}
>>>> +
>>>>  /* Parse string values of no_sanitize attribute passed in VALUE.
>>>>     Values are separated with comma.  Wrong argument is stored to
>>>>     WRONG_ARGUMENT variable.  */
>>>> @@ -1942,6 +2032,12 @@ common_handle_option (struct gcc_options *opts,
>>>>           &= ~(SANITIZE_UNDEFINED | SANITIZE_UNDEFINED_NONDEFAULT);
>>>>        break;
>>>>
>>>> +    case OPT_fsanitize_coverage_:
>>>> +      opts->x_flag_sanitize_coverage
>>>> +       = parse_coverage_sanitizer_options (arg, loc,
>>>> +                                  opts->x_flag_sanitize_coverage, value, true);
>>>> +      break;
>>>> +
>>>>      case OPT_O:
>>>>      case OPT_Os:
>>>>      case OPT_Ofast:
>>>> Index: gcc/sancov.c
>>>> ===================================================================
>>>> --- gcc/sancov.c        (revision 250082)
>>>> +++ gcc/sancov.c        (working copy)
>>>> @@ -29,31 +29,194 @@ along with GCC; see the file COPYING3.  If not see
>>>>  #include "flags.h"
>>>>  #include "stmt.h"
>>>>  #include "gimple-iterator.h"
>>>> +#include "tree-core.h"
>>>>  #include "tree-cfg.h"
>>>>  #include "tree-pass.h"
>>>>  #include "tree-iterator.h"
>>>> +#include "fold-const.h"
>>>> +#include "stringpool.h"
>>>> +#include "output.h"
>>>> +#include "cgraph.h"
>>>>  #include "asan.h"
>>>>
>>>>  namespace {
>>>>
>>>> +static void
>>>> +instrument_cond (gimple_stmt_iterator *gsi, gimple *stmt)
>>>> +{
>>>> +  tree lhs = gimple_cond_lhs (stmt);
>>>> +  tree rhs = gimple_cond_rhs (stmt);
>>>> +  unsigned int bitno = TYPE_PRECISION (TREE_TYPE (lhs)) > TYPE_PRECISION (TREE_TYPE (rhs)) ?
>>>> +                      TYPE_PRECISION (TREE_TYPE (lhs)) : TYPE_PRECISION (TREE_TYPE (rhs));
>>>> +  if (TREE_CODE (TREE_TYPE (lhs)) == INTEGER_TYPE)
>>>> +    {
>>>> +      enum built_in_function fncode;
>>>> +      switch (bitno)
>>>> +       {
>>>> +       case 8:
>>>> +         fncode = BUILT_IN_SANITIZER_COV_TRACE_CMP1;
>>>> +         break;
>>>> +
>>>> +       case 16:
>>>> +         fncode = BUILT_IN_SANITIZER_COV_TRACE_CMP2;
>>>> +         break;
>>>> +
>>>> +       case 32:
>>>> +         fncode = BUILT_IN_SANITIZER_COV_TRACE_CMP4;
>>>> +         break;
>>>> +
>>>> +       case 64:
>>>> +         fncode = BUILT_IN_SANITIZER_COV_TRACE_CMP8;
>>>> +         break;
>>>> +
>>>> +       default:
>>>> +         return;
>>>> +         break;
>>>> +       }
>>>> +      tree fndecl = builtin_decl_implicit (fncode);
>>>> +      gimple *gcall = gimple_build_call (fndecl, 2, lhs, rhs);
>>>> +      gimple_set_location (gcall, gimple_location (stmt));
>>>> +      gsi_insert_before (gsi, gcall, GSI_SAME_STMT);
>>>> +    }
>>>> +  else if (TREE_CODE (TREE_TYPE (lhs)) == REAL_TYPE)
>>>> +    {
>>>> +      enum built_in_function fncode;
>>>> +      switch (bitno)
>>>> +       {
>>>> +       case 32:
>>>> +         fncode = BUILT_IN_SANITIZER_COV_TRACE_CMPF;
>>>> +         break;
>>>> +
>>>> +       case 64:
>>>> +         fncode = BUILT_IN_SANITIZER_COV_TRACE_CMPD;
>>>> +         break;
>>>> +
>>>> +       default:
>>>> +         return;
>>>> +         break;
>>>> +        }
>>>> +      tree fndecl = builtin_decl_implicit (fncode);
>>>> +      gimple *gcall = gimple_build_call (fndecl, 2, lhs, rhs);
>>>> +      gimple_set_location (gcall, gimple_location (stmt));
>>>> +      gsi_insert_before (gsi, gcall, GSI_SAME_STMT);
>>>> +    }
>>>> +}
>>>> +
>>>> +static void
>>>> +instrument_switch (gimple_stmt_iterator *gsi, gimple *stmt, function *fun)
>>>> +{
>>>> +  gswitch *switch_stmt = as_a<gswitch *> (stmt);
>>>> +  tree index = gimple_switch_index (switch_stmt);
>>>> +  unsigned bitno = TYPE_PRECISION (TREE_TYPE (index));
>>>> +  unsigned i, n = gimple_switch_num_labels (switch_stmt), num = 0;
>>>> +  for (i = 0; i < n; ++i)
>>>> +    {
>>>> +      tree label = gimple_switch_label (switch_stmt, i);
>>>> +      tree low_case = CASE_LOW (label);
>>>> +      if (low_case != NULL_TREE)
>>>> +          num++;
>>>> +      tree high_case = CASE_HIGH (label);
>>>> +      if (high_case != NULL_TREE)
>>>> +          num++;
>>>> +    }
>>>> +
>>>> +  tree case_array_elem_type = build_type_variant (uint64_type_node, 1, 0);
>>>> +  tree case_array_type = build_array_type (case_array_elem_type,
>>>> +                                          build_index_type (size_int (num + 2 - 1)));
>>>> +  char name[64];
>>>> +  static size_t case_array_count = 0;
>>>> +  snprintf(name, sizeof(name) - 1, "__sanitizer_cov_trace_switch_array%lu", case_array_count++);
>>>> +  tree case_array_var = build_decl (UNKNOWN_LOCATION, VAR_DECL,
>>>> +                                   get_identifier (name), case_array_type);
>>>> +  TREE_STATIC (case_array_var) = 1;
>>>> +  TREE_PUBLIC (case_array_var) = 0;
>>>> +  TREE_CONSTANT (case_array_var) = 1;
>>>> +  TREE_READONLY (case_array_var) = 1;
>>>> +  DECL_EXTERNAL (case_array_var) = 0;
>>>> +  DECL_ARTIFICIAL (case_array_var) = 1;
>>>> +  DECL_IGNORED_P (case_array_var) = 1;
>>>> +
>>>> +  vec <constructor_elt, va_gc> *v = NULL;
>>>> +  vec_alloc (v, num + 2);
>>>> +  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (uint64_type_node, num));
>>>> +  CONSTRUCTOR_APPEND_ELT (v, NULL_TREE, build_int_cst (uint64_type_node, bitno));
>>>> +  for (i = 0; i < n; ++i)
>>>> +    {
>>>> +      tree label = gimple_switch_label (switch_stmt, i);
>>>> +
>>>> +      tree low_case = CASE_LOW (label);
>>>> +      if (low_case != NULL_TREE)
>>>> +        CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
>>>> +                               build_int_cst (uint64_type_node, TREE_INT_CST_LOW (low_case)));
>>>> +
>>>> +      tree high_case = CASE_HIGH (label);
>>>> +      if (high_case != NULL_TREE)
>>>> +        CONSTRUCTOR_APPEND_ELT (v, NULL_TREE,
>>>> +                               build_int_cst (uint64_type_node, TREE_INT_CST_LOW (high_case)));
>>>> +    }
>>>> +  tree ctor = build_constructor (case_array_type, v);
>>>> +  TREE_STATIC (ctor) = 1;
>>>> +  TREE_PUBLIC (ctor) = 0;
>>>> +  TREE_CONSTANT (ctor) = 1;
>>>> +  TREE_READONLY (ctor) = 1;
>>>> +  DECL_EXTERNAL (ctor) = 0;
>>>> +  DECL_INITIAL (case_array_var) = ctor;
>>>> +  varpool_node::finalize_decl (case_array_var);
>>>> +
>>>> +  tree case_array_var_ref = build_fold_addr_expr (case_array_var);
>>>> +  add_local_decl (fun, case_array_var);
>>>> +  tree fndecl = builtin_decl_implicit (BUILT_IN_SANITIZER_COV_TRACE_SWITCH);
>>>> +  gimple *gcall = gimple_build_call (fndecl, 2, index, case_array_var_ref);
>>>> +  gimple_set_location (gcall, gimple_location (stmt));
>>>> +  gsi_insert_before(gsi, gcall, GSI_SAME_STMT);
>>>> +}
>>>> +
>>>>  unsigned
>>>>  sancov_pass (function *fun)
>>>>  {
>>>>    initialize_sanitizer_builtins ();
>>>>
>>>> +  basic_block bb;
>>>> +
>>>>    /* Insert callback into beginning of every BB. */
>>>> -  tree fndecl = builtin_decl_implicit (BUILT_IN_SANITIZER_COV_TRACE_PC);
>>>> -  basic_block bb;
>>>> -  FOR_EACH_BB_FN (bb, fun)
>>>> +  if (flag_sanitize_coverage & SANITIZE_COV_TRACE_PC)
>>>>      {
>>>> -      gimple_stmt_iterator gsi = gsi_start_nondebug_after_labels_bb (bb);
>>>> -      if (gsi_end_p (gsi))
>>>> -       continue;
>>>> -      gimple *stmt = gsi_stmt (gsi);
>>>> -      gimple *gcall = gimple_build_call (fndecl, 0);
>>>> -      gimple_set_location (gcall, gimple_location (stmt));
>>>> -      gsi_insert_before (&gsi, gcall, GSI_SAME_STMT);
>>>> +      tree fndecl = builtin_decl_implicit (BUILT_IN_SANITIZER_COV_TRACE_PC);
>>>> +      FOR_EACH_BB_FN (bb, fun)
>>>> +        {
>>>> +          gimple_stmt_iterator gsi = gsi_start_nondebug_after_labels_bb (bb);
>>>> +          if (gsi_end_p (gsi))
>>>> +           continue;
>>>> +          gimple *stmt = gsi_stmt (gsi);
>>>> +          gimple *gcall = gimple_build_call (fndecl, 0);
>>>> +          gimple_set_location (gcall, gimple_location (stmt));
>>>> +          gsi_insert_before (&gsi, gcall, GSI_SAME_STMT);
>>>> +        }
>>>>      }
>>>> +
>>>> +  /* Insert callback to every compare statments. */
>>>> +  if (flag_sanitize_coverage & SANITIZE_COV_TRACE_CMP)
>>>> +    {
>>>> +      FOR_EACH_BB_FN (bb, fun)
>>>> +       {
>>>> +          gimple_stmt_iterator gsi;
>>>> +          for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
>>>> +           {
>>>> +              gimple *stmt = gsi_stmt (gsi);
>>>> +              switch (gimple_code (stmt))
>>>> +               {
>>>> +                case GIMPLE_COND:
>>>> +                 instrument_cond (&gsi, stmt);
>>>> +                 break;
>>>> +               case GIMPLE_SWITCH:
>>>> +                 instrument_switch (&gsi, stmt, fun);
>>>> +                 break;
>>>> +               default:
>>>> +                 break;
>>>> +               }
>>>> +            }
>>>> +        }
>>>> +    }
>>>>    return 0;
>>>>  }
>>>>
>>>> Index: gcc/sanitizer.def
>>>> ===================================================================
>>>> --- gcc/sanitizer.def   (revision 250082)
>>>> +++ gcc/sanitizer.def   (working copy)
>>>> @@ -529,6 +529,27 @@ DEF_SANITIZER_BUILTIN(BUILT_IN_UBSAN_HANDLE_DYNAMI
>>>>  DEF_SANITIZER_BUILTIN(BUILT_IN_SANITIZER_COV_TRACE_PC,
>>>>                       "__sanitizer_cov_trace_pc",
>>>>                       BT_FN_VOID, ATTR_NOTHROW_LEAF_LIST)
>>>> +DEF_SANITIZER_BUILTIN(BUILT_IN_SANITIZER_COV_TRACE_CMP1,
>>>> +                     "__sanitizer_cov_trace_cmp1",
>>>> +                     BT_FN_VOID_UINT8_UINT8, ATTR_NOTHROW_LEAF_LIST)
>>>> +DEF_SANITIZER_BUILTIN(BUILT_IN_SANITIZER_COV_TRACE_CMP2,
>>>> +                     "__sanitizer_cov_trace_cmp2",
>>>> +                     BT_FN_VOID_UINT16_UINT16, ATTR_NOTHROW_LEAF_LIST)
>>>> +DEF_SANITIZER_BUILTIN(BUILT_IN_SANITIZER_COV_TRACE_CMP4,
>>>> +                     "__sanitizer_cov_trace_cmp4",
>>>> +                     BT_FN_VOID_UINT32_UINT32, ATTR_NOTHROW_LEAF_LIST)
>>>> +DEF_SANITIZER_BUILTIN(BUILT_IN_SANITIZER_COV_TRACE_CMP8,
>>>> +                     "__sanitizer_cov_trace_cmp8",
>>>> +                     BT_FN_VOID_UINT64_UINT64, ATTR_NOTHROW_LEAF_LIST)
>>>> +DEF_SANITIZER_BUILTIN(BUILT_IN_SANITIZER_COV_TRACE_CMPF,
>>>> +                     "__sanitizer_cov_trace_cmpf",
>>>> +                     BT_FN_VOID_FLOAT_FLOAT, ATTR_NOTHROW_LEAF_LIST)
>>>> +DEF_SANITIZER_BUILTIN(BUILT_IN_SANITIZER_COV_TRACE_CMPD,
>>>> +                     "__sanitizer_cov_trace_cmpd",
>>>> +                     BT_FN_VOID_DOUBLE_DOUBLE, ATTR_NOTHROW_LEAF_LIST)
>>>> +DEF_SANITIZER_BUILTIN(BUILT_IN_SANITIZER_COV_TRACE_SWITCH,
>>>> +                     "__sanitizer_cov_trace_switch",
>>>> +                     BT_FN_VOID_UINT64_PTR, ATTR_NOTHROW_LEAF_LIST)
>>>>
>>>>  /* This has to come after all the sanitizer builtins.  */
>>>>  DEF_BUILTIN_STUB(END_SANITIZER_BUILTINS, (const char *)0)