Re: [PATCH][gcc] libgccjit: handle long literals in playback::context::new_string_literal

[Andrea Corallo <Andrea.Corallo@arm.com>]

Andrea Corallo writes:

> Hi all,
> yesterday I've found an interesting bug in libgccjit.
> Seems we have an hard limitation of 200 characters for literal strings.
> Attempting to create longer strings lead to ICE during pass_expand
> while performing a sanity check in get_constant_size.
>
> Tracking down the issue seems the code we have was inspired from
> c-family/c-common.c:c_common_nodes_and_builtins were array_domain_type
> is actually defined with a size of 200.
> The comment that follows that point sounded premonitory :) :)
>
> /* Make a type for arrays of characters.
>    With luck nothing will ever really depend on the length of this
>    array type.  */
>
> At least in the current implementation the type is set by
> fix_string_type were the actual string length is taken in account.
>
> I attach a patch updating the logic accordingly and a new testcase
>  for that.
>
> make check-jit is passing clean.
>
> Best Regards
>   Andrea
>
> gcc/jit/ChangeLog
> 2019-??-??  Andrea Corallo  <andrea.corallo@arm.com>
>
> 	* jit-playback.h
> 	(gcc::jit::recording::context m_recording_ctxt): Remove
> 	m_char_array_type_node field.
> 	* jit-playback.c
> 	(playback::context::context) Remove m_char_array_type_node from member
> 	initializer list.
> 	(playback::context::new_string_literal) Fix logic to handle string
> 	length > 200.
>
> gcc/testsuite/ChangeLog
> 2019-??-??  Andrea Corallo  <andrea.corallo@arm.com>
>
> 	* jit.dg/all-non-failing-tests.h: Add test-long-string-literal.c.
> 	* jit.dg/test-long-string-literal.c: New testcase.
> diff --git a/gcc/jit/jit-playback.c b/gcc/jit/jit-playback.c
> index 9eeb2a7..a26b8d3 100644
> --- a/gcc/jit/jit-playback.c
> +++ b/gcc/jit/jit-playback.c
> @@ -88,7 +88,6 @@ playback::context::context (recording::context *ctxt)
>    : log_user (ctxt->get_logger ()),
>      m_recording_ctxt (ctxt),
>      m_tempdir (NULL),
> -    m_char_array_type_node (NULL),
>      m_const_char_ptr (NULL)
>  {
>    JIT_LOG_SCOPE (get_logger ());
> @@ -670,9 +669,12 @@ playback::rvalue *
>  playback::context::
>  new_string_literal (const char *value)
>  {
> -  tree t_str = build_string (strlen (value), value);
> -  gcc_assert (m_char_array_type_node);
> -  TREE_TYPE (t_str) = m_char_array_type_node;
> +  /* Compare with c-family/c-common.c: fix_string_type.  */
> +  size_t len = strlen (value);
> +  tree i_type = build_index_type (size_int (len));
> +  tree a_type = build_array_type (char_type_node, i_type);
> +  tree t_str = build_string (len, value);
> +  TREE_TYPE (t_str) = a_type;
>
>    /* Convert to (const char*), loosely based on
>       c/c-typeck.c: array_to_pointer_conversion,
> @@ -2703,10 +2705,6 @@ playback::context::
>  replay ()
>  {
>    JIT_LOG_SCOPE (get_logger ());
> -  /* Adapted from c-common.c:c_common_nodes_and_builtins.  */
> -  tree array_domain_type = build_index_type (size_int (200));
> -  m_char_array_type_node
> -    = build_array_type (char_type_node, array_domain_type);
>
>    m_const_char_ptr
>      = build_pointer_type (build_qualified_type (char_type_node,
> diff --git a/gcc/jit/jit-playback.h b/gcc/jit/jit-playback.h
> index d4b148e..801f610 100644
> --- a/gcc/jit/jit-playback.h
> +++ b/gcc/jit/jit-playback.h
> @@ -322,7 +322,6 @@ private:
>
>    auto_vec<function *> m_functions;
>    auto_vec<tree> m_globals;
> -  tree m_char_array_type_node;
>    tree m_const_char_ptr;
>
>    /* Source location handling.  */
> diff --git a/gcc/testsuite/jit.dg/all-non-failing-tests.h b/gcc/testsuite/jit.dg/all-non-failing-tests.h
> index 0272e6f8..1b3d561 100644
> --- a/gcc/testsuite/jit.dg/all-non-failing-tests.h
> +++ b/gcc/testsuite/jit.dg/all-non-failing-tests.h
> @@ -220,6 +220,13 @@
>  #undef create_code
>  #undef verify_code
>
> +/* test-long-string-literal.c */
> +#define create_code create_code_long_string_literal
> +#define verify_code verify_code_long_string_literal
> +#include "test-long-string-literal.c"
> +#undef create_code
> +#undef verify_code
> +
>  /* test-sum-of-squares.c */
>  #define create_code create_code_sum_of_squares
>  #define verify_code verify_code_sum_of_squares
> diff --git a/gcc/testsuite/jit.dg/test-long-string-literal.c b/gcc/testsuite/jit.dg/test-long-string-literal.c
> new file mode 100644
> index 0000000..882567c
> --- /dev/null
> +++ b/gcc/testsuite/jit.dg/test-long-string-literal.c
> @@ -0,0 +1,48 @@
> +#include <stdlib.h>
> +#include <stdio.h>
> +#include <string.h>
> +
> +#include "libgccjit.h"
> +
> +#include "harness.h"
> +
> +const char very_long_string[] =
> +  "abcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabc"
> +  "abcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabc"
> +  "abcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabcabc"
> +  "abcabcabcabcabcabcabcabcabcabca";
> +
> +void
> +create_code (gcc_jit_context *ctxt, void *user_data)
> +{
> +  /* Build the test_fn.  */
> +  gcc_jit_function *f =
> +    gcc_jit_context_new_function (
> +      ctxt, NULL,
> +      GCC_JIT_FUNCTION_EXPORTED,
> +      gcc_jit_context_get_type(ctxt,
> +			       GCC_JIT_TYPE_CONST_CHAR_PTR),
> +				"test_long_string_literal",
> +				0, NULL, 0);
> +  gcc_jit_block *blk =
> +    gcc_jit_function_new_block (f, "init_block");
> +  gcc_jit_rvalue *res =
> +    gcc_jit_context_new_string_literal (ctxt, very_long_string);
> +
> +  gcc_jit_block_end_with_return (blk, NULL, res);
> +}
> +
> +void
> +verify_code (gcc_jit_context *ctxt, gcc_jit_result *result)
> +{
> +  typedef const char *(*fn_type) (void);
> +  CHECK_NON_NULL (result);
> +  fn_type test_long_string_literal =
> +    (fn_type)gcc_jit_result_get_code (result, "test_long_string_literal");
> +  CHECK_NON_NULL (test_long_string_literal);
> +
> +  /* Call the JIT-generated function.  */
> +  const char *str = test_long_string_literal ();
> +  CHECK_NON_NULL (str);
> +  CHECK_VALUE (strcmp (str, very_long_string), 0);
> +}

Kindly pinging

Bests
  Andrea