Here's the updated patch.

On Fri, 2022-04-08 at 15:22 -0400, David Malcolm wrote:
> On Fri, 2022-01-21 at 18:41 -0500, Antoni Boucher wrote:
> > Hi.
> > Here's the updated patch.
> > 
> 
> Thanks.  Review below:
> 
> [...snip...]
> 
> > diff --git a/gcc/jit/libgccjit.cc b/gcc/jit/libgccjit.cc
> > index 4c352e8c93d..6bf1e1ceee0 100644
> > --- a/gcc/jit/libgccjit.cc
> > +++ b/gcc/jit/libgccjit.cc
> > @@ -2405,6 +2405,34 @@ gcc_jit_context_new_cast (gcc_jit_context
> > *ctxt,
> >    return static_cast <gcc_jit_rvalue *> (ctxt->new_cast (loc,
> > rvalue, type));
> >  }
> >  
> > +/* Public entrypoint.  See description in libgccjit.h.
> > +
> > +   After error-checking, the real work is done by the
> > +   gcc::jit::recording::context::new_bitcast method in jit-
> > recording.c.  */
> > +
> > +gcc_jit_rvalue *
> > +gcc_jit_context_new_bitcast (gcc_jit_context *ctxt,
> > +                            gcc_jit_location *loc,
> > +                            gcc_jit_rvalue *rvalue,
> > +                            gcc_jit_type *type)
> > +{
> > +  RETURN_NULL_IF_FAIL (ctxt, NULL, loc, "NULL context");
> > +  JIT_LOG_FUNC (ctxt->get_logger ());
> > +  /* LOC can be NULL.  */
> > +  RETURN_NULL_IF_FAIL (rvalue, ctxt, loc, "NULL rvalue");
> > +  RETURN_NULL_IF_FAIL (type, ctxt, loc, "NULL type");
> > +  // TODO: check the sizes.
> > +  /*RETURN_NULL_IF_FAIL_PRINTF3 (
> > +    is_valid_cast (rvalue->get_type (), type),
> > +    ctxt, loc,
> > +    "cannot cast %s from type: %s to type: %s",
> > +    rvalue->get_debug_string (),
> > +    rvalue->get_type ()->get_debug_string (),
> > +    type->get_debug_string ());*/
> 
> I think we agreed that we can't check the sizes at this point, so
> this
> commented-out check would be better replaced with a comment
> explaining
> that we have to defer the check to playback time, when we have the
> trees.
> 
> > +
> > +  return static_cast <gcc_jit_rvalue *> (ctxt->new_bitcast (loc,
> > rvalue, type));
> > +}
> > +
> >  /* Public entrypoint.  See description in libgccjit.h.
> >  
> >     After error-checking, the real work is done by the
> 
> [...snip...]
> 
> > diff --git a/gcc/testsuite/jit.dg/test-bitcast.c
> > b/gcc/testsuite/jit.dg/test-bitcast.c
> > new file mode 100644
> > index 00000000000..a092fa117e6
> > --- /dev/null
> > +++ b/gcc/testsuite/jit.dg/test-bitcast.c
> > @@ -0,0 +1,60 @@
> > +#include <stdlib.h>
> > +#include <stdio.h>
> > +#include <string.h>
> > +
> > +#include "libgccjit.h"
> > +
> > +#include "harness.h"
> > +
> > +void
> > +create_code (gcc_jit_context *ctxt, void *user_data)
> > +{
> > +  /* Let's try to inject the equivalent of:
> > +int
> > +my_bitcast (double x)
> > +{
> > +   return bitcast(x, int);
> > +}
> > +   */
> > +  gcc_jit_type *int_type =
> > +    gcc_jit_context_get_int_type (ctxt, 4, 1);
> > +  gcc_jit_type *float_type =
> > +    gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_FLOAT);
> 
> This uses GCC_JIT_TYPE_FLOAT for the param...
> 
> > +
> > +  gcc_jit_param *x =
> > +    gcc_jit_context_new_param (
> > +      ctxt,
> > +      NULL,
> > +      float_type, "x");
> > +  gcc_jit_param *params[1] = {x};
> > +  gcc_jit_function *func =
> > +    gcc_jit_context_new_function (ctxt,
> > +                                 NULL,
> > +                                 GCC_JIT_FUNCTION_EXPORTED,
> > +                                 int_type,
> > +                                 "my_bitcast",
> > +                                 1, params, 0);
> 
> [..snip...]
> 
> > +
> > +void
> > +verify_code (gcc_jit_context *ctxt, gcc_jit_result *result)
> > +{
> > +  typedef int (*my_bitcast_fn_type) (double);
> 
> ...but this uses "double".  Presumably these should agree, and have
> the
> same sizeof as the integer type.
> 
> > +  CHECK_NON_NULL (result);
> > +  my_bitcast_fn_type my_bitcast =
> > +    (my_bitcast_fn_type)gcc_jit_result_get_code (result,
> > "my_bitcast");
> > +  CHECK_NON_NULL (my_bitcast);
> > +  int val = my_bitcast (-5.1298714);
> > +  note ("my_bitcast returned: %d", val);
> > +  CHECK_VALUE (val, 35569201);
> 
> Out of curiosity, is there any particular significance for these
> values?  FWIW I rather like:
>   http://evanw.github.io/float-toy/
> for directly manipulating the bits of floating point numbers.

The given float values, when bitcast to an int, gives the given int
value.

> 
> 
> [...snip...]
> 
> > diff --git a/gcc/toplev.cc b/gcc/toplev.cc
> > index 534da1462e8..bc4921974eb 100644
> > --- a/gcc/toplev.cc
> > +++ b/gcc/toplev.cc
> > @@ -2368,6 +2368,7 @@ toplev::finalize (void)
> >    gcse_c_finalize ();
> >    ipa_cp_c_finalize ();
> >    ira_costs_c_finalize ();
> > +  tree_cc_finalize ();
> >  
> >    /* save_decoded_options uses opts_obstack, so these must
> >       be cleaned up together.  */
> > diff --git a/gcc/tree.cc b/gcc/tree.cc
> > index ae159ee20ce..fe9d9083026 100644
> > --- a/gcc/tree.cc
> > +++ b/gcc/tree.cc
> > @@ -6963,6 +6963,15 @@ build_reference_type (tree to_type)
> >    (HOST_BITS_PER_WIDE_INT > 64 ? HOST_BITS_PER_WIDE_INT : 64)
> >  static GTY(()) tree nonstandard_integer_type_cache[2 *
> > MAX_INT_CACHED_PREC + 2];
> >  
> > +static void
> > +clear_nonstandard_integer_type_cache (void)
> > +{
> > +  for (size_t i = 0 ; i < 2 * MAX_INT_CACHED_PREC + 2 ; i++)
> > +  {
> > +    nonstandard_integer_type_cache[i] = NULL;
> > +  }
> > +}
> > +
> >  /* Builds a signed or unsigned integer type of precision
> > PRECISION.
> >     Used for C bitfields whose precision does not match that of
> >     built-in target types.  */
> > @@ -14565,6 +14574,12 @@ get_attr_nonstring_decl (tree expr, tree
> > *ref)
> >    return NULL_TREE;
> >  }
> >  
> > +void
> > +tree_cc_finalize (void)
> > +{
> > +  clear_nonstandard_integer_type_cache ();
> > +}
> > +
> >  #if CHECKING_P
> >  
> >  namespace selftest {
> > diff --git a/gcc/tree.h b/gcc/tree.h
> > index 30bc53c2996..bf886fc2472 100644
> > --- a/gcc/tree.h
> > +++ b/gcc/tree.h
> > @@ -5385,6 +5385,7 @@ extern bool real_minus_onep (const_tree);
> >  extern void init_ttree (void);
> >  extern void build_common_tree_nodes (bool);
> >  extern void build_common_builtin_nodes (void);
> > +extern void tree_cc_finalize (void);
> >  extern tree build_nonstandard_integer_type (unsigned
> > HOST_WIDE_INT, int);
> >  extern tree build_nonstandard_boolean_type (unsigned
> > HOST_WIDE_INT);
> >  extern tree build_range_type (tree, tree, tree);
> 
> Looks OK to me, but am not officially a maintainer of these parts.
> 
> LGTM with those nits fixed - for next stage 1, or for trunk now if
> the
> release maintainers are OK with it.
> 
> Thanks again for the patch, and sorry about the belated review.
> 
> Dave
> 
> 
>