Re: [PATCH] libgccjit: Add support for creating temporary variables

[Antoni Boucher <bouanto@zoho.com>]

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Hi and thanks for the review!
Here's the updated patch.

Le 2024-01-24 à 09 h 54, David Malcolm a écrit :
> On Fri, 2024-01-19 at 16:54 -0500, Antoni Boucher wrote:
>> Hi.
>> This patch adds a new way to create local variable that won't
>> generate
>> debug info: it is to be used for compiler-generated variables.
>> Thanks for the review.
> 
> Thanks for the patch.
> 
>> diff --git a/gcc/jit/docs/topics/compatibility.rst b/gcc/jit/docs/topics/compatibility.rst
>> index cbf5b414d8c..5d62e264a00 100644
>> --- a/gcc/jit/docs/topics/compatibility.rst
>> +++ b/gcc/jit/docs/topics/compatibility.rst
>> @@ -390,3 +390,12 @@ on functions and variables:
>>     * :func:`gcc_jit_function_add_string_attribute`
>>     * :func:`gcc_jit_function_add_integer_array_attribute`
>>     * :func:`gcc_jit_lvalue_add_string_attribute`
>> +
>> +.. _LIBGCCJIT_ABI_27:
>> +
>> +``LIBGCCJIT_ABI_27``
>> +--------------------
>> +``LIBGCCJIT_ABI_27`` covers the addition of a functions to create a new
> 
> "functions" -> "function"
> 
>> +temporary variable:
>> +
>> +  * :func:`gcc_jit_function_new_temp`
>> diff --git a/gcc/jit/docs/topics/functions.rst b/gcc/jit/docs/topics/functions.rst
>> index 804605ea939..230caf42466 100644
>> --- a/gcc/jit/docs/topics/functions.rst
>> +++ b/gcc/jit/docs/topics/functions.rst
>> @@ -171,6 +171,26 @@ Functions
>>      underlying string, so it is valid to pass in a pointer to an on-stack
>>      buffer.
>>   
>> +.. function:: gcc_jit_lvalue *\
>> +              gcc_jit_function_new_temp (gcc_jit_function *func,\
>> +                                         gcc_jit_location *loc,\
>> +                                         gcc_jit_type *type)
>> +
>> +   Create a new local variable within the function, of the given type.
>> +   This function is similar to :func:`gcc_jit_function_new_local`, but
>> +   it is to be used for compiler-generated variables (as opposed to
>> +   user-defined variables in the language to be compiled) and these
>> +   variables won't show up in the debug info.
>> +
>> +   The parameter ``type`` must be non-`void`.
>> +
>> +   This entrypoint was added in :ref:`LIBGCCJIT_ABI_26`; you can test
>> +   for its presence using
> 
> The ABI number is inconsistent here (it's 27 above and in the .map
> file), but obviously you can fix this when you eventually commit this
> based on what the ABI number actually is.
> 
> [...snip...]
> 
>> diff --git a/gcc/jit/jit-playback.cc b/gcc/jit/jit-playback.cc
>> index 84df6c100e6..cb6b2f66276 100644
>> --- a/gcc/jit/jit-playback.cc
>> +++ b/gcc/jit/jit-playback.cc
>> @@ -31,6 +31,7 @@ along with GCC; see the file COPYING3.  If not see
>>   #include "toplev.h"
>>   #include "tree-cfg.h"
>>   #include "convert.h"
>> +#include "gimple-expr.h"
>>   #include "stor-layout.h"
>>   #include "print-tree.h"
>>   #include "gimplify.h"
>> @@ -1950,13 +1951,27 @@ new_local (location *loc,
>>   	   type *type,
>>   	   const char *name,
>>   	   const std::vector<std::pair<gcc_jit_variable_attribute,
>> -				       std::string>> &attributes)
>> +				       std::string>> &attributes,
>> +	   bool is_temp)
>>   {
>>     gcc_assert (type);
>> -  gcc_assert (name);
>> -  tree inner = build_decl (UNKNOWN_LOCATION, VAR_DECL,
>> +  tree inner;
>> +  if (is_temp)
>> +  {
>> +    inner = build_decl (UNKNOWN_LOCATION, VAR_DECL,
>> +			create_tmp_var_name ("JITTMP"),
>> +			type->as_tree ());
>> +    DECL_ARTIFICIAL (inner) = 1;
>> +    DECL_IGNORED_P (inner) = 1;
>> +    DECL_NAMELESS (inner) = 1;
> 
> We could assert that "name" is null in the is_temp branch.
> 
> An alternative approach might be to drop "is_temp", and instead make
> "name" being null signify that it's a temporary, if you prefer that
> approach.  Would client code ever want to specify a name prefix for a
> temporary?

No, I don't think anyone would want a different prefix.

> 
> 
>> +  }
>> +  else
>> +  {
>> +    gcc_assert (name);
>> +    inner = build_decl (UNKNOWN_LOCATION, VAR_DECL,
>>   			   get_identifier (name),
>>   			   type->as_tree ());
>> +  }
>>     DECL_CONTEXT (inner) = this->m_inner_fndecl;
>>   
>>     /* Prepend to BIND_EXPR_VARS: */
> 
> [...snip...]
> 
> Thanks again for the patch.  Looks good to me as-is (apart from the
> grammar and ABI number nits), but what do you think of eliminating
> "is_temp" in favor of the "name" ptr being null?  I think it's your
> call.
> 
> Dave
> 

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From 80ea12ce227b2ac5d5dcd99374532e30a775ecbd Mon Sep 17 00:00:00 2001
From: Antoni Boucher <bouanto@zoho.com>
Date: Thu, 18 Jan 2024 16:54:59 -0500
Subject: [PATCH] libgccjit: Add support for creating temporary variables

gcc/jit/ChangeLog:

	* docs/topics/compatibility.rst (LIBGCCJIT_ABI_28): New ABI tag.
	* docs/topics/functions.rst: Document gcc_jit_function_new_temp.
	* jit-playback.cc (new_local): Add support for temporary
	variables.
	* jit-recording.cc (recording::function::new_temp): New method.
	(recording::local::write_reproducer): Support temporary
	variables.
	* jit-recording.h (new_temp): New method.
	* libgccjit.cc (gcc_jit_function_new_temp): New function.
	* libgccjit.h (gcc_jit_function_new_temp): New function.
	* libgccjit.map: New function.

gcc/testsuite/ChangeLog:

	* jit.dg/all-non-failing-tests.h: Mention test-temp.c.
	* jit.dg/test-temp.c: New test.
---
 gcc/jit/docs/topics/compatibility.rst        |  9 ++++
 gcc/jit/docs/topics/functions.rst            | 20 +++++++
 gcc/jit/jit-playback.cc                      | 15 +++++-
 gcc/jit/jit-recording.cc                     | 47 ++++++++++++----
 gcc/jit/jit-recording.h                      | 11 +++-
 gcc/jit/libgccjit.cc                         | 31 +++++++++++
 gcc/jit/libgccjit.h                          |  7 +++
 gcc/jit/libgccjit.map                        |  5 ++
 gcc/testsuite/jit.dg/all-non-failing-tests.h |  3 ++
 gcc/testsuite/jit.dg/test-temp.c             | 56 ++++++++++++++++++++
 10 files changed, 191 insertions(+), 13 deletions(-)
 create mode 100644 gcc/testsuite/jit.dg/test-temp.c

diff --git a/gcc/jit/docs/topics/compatibility.rst b/gcc/jit/docs/topics/compatibility.rst
index 9cfb054f653..ecd65010b5e 100644
--- a/gcc/jit/docs/topics/compatibility.rst
+++ b/gcc/jit/docs/topics/compatibility.rst
@@ -397,3 +397,12 @@ on functions and variables:
 --------------------
 ``LIBGCCJIT_ABI_27`` covers the addition of
 :func:`gcc_jit_context_new_sizeof`
+
+.. _LIBGCCJIT_ABI_28:
+
+``LIBGCCJIT_ABI_28``
+--------------------
+``LIBGCCJIT_ABI_28`` covers the addition of a function to create a new
+temporary variable:
+
+  * :func:`gcc_jit_function_new_temp`
diff --git a/gcc/jit/docs/topics/functions.rst b/gcc/jit/docs/topics/functions.rst
index 804605ea939..17eab55ee3f 100644
--- a/gcc/jit/docs/topics/functions.rst
+++ b/gcc/jit/docs/topics/functions.rst
@@ -171,6 +171,26 @@ Functions
    underlying string, so it is valid to pass in a pointer to an on-stack
    buffer.
 
+.. function:: gcc_jit_lvalue *\
+              gcc_jit_function_new_temp (gcc_jit_function *func,\
+                                         gcc_jit_location *loc,\
+                                         gcc_jit_type *type)
+
+   Create a new local variable within the function, of the given type.
+   This function is similar to :func:`gcc_jit_function_new_local`, but
+   it is to be used for compiler-generated variables (as opposed to
+   user-defined variables in the language to be compiled) and these
+   variables won't show up in the debug info.
+
+   The parameter ``type`` must be non-`void`.
+
+   This entrypoint was added in :ref:`LIBGCCJIT_ABI_28`; you can test
+   for its presence using
+
+   .. code-block:: c
+
+      #ifdef LIBGCCJIT_HAVE_gcc_jit_function_new_temp
+
 .. function::  size_t \
                gcc_jit_function_get_param_count (gcc_jit_function *func)
 
diff --git a/gcc/jit/jit-playback.cc b/gcc/jit/jit-playback.cc
index 6baa838af10..e454a64eb11 100644
--- a/gcc/jit/jit-playback.cc
+++ b/gcc/jit/jit-playback.cc
@@ -31,6 +31,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "toplev.h"
 #include "tree-cfg.h"
 #include "convert.h"
+#include "gimple-expr.h"
 #include "stor-layout.h"
 #include "print-tree.h"
 #include "gimplify.h"
@@ -1963,10 +1964,20 @@ new_local (location *loc,
 				       std::string>> &attributes)
 {
   gcc_assert (type);
-  gcc_assert (name);
-  tree inner = build_decl (UNKNOWN_LOCATION, VAR_DECL,
+  tree inner;
+  if (name)
+    inner = build_decl (UNKNOWN_LOCATION, VAR_DECL,
 			   get_identifier (name),
 			   type->as_tree ());
+  else
+  {
+    inner = build_decl (UNKNOWN_LOCATION, VAR_DECL,
+			create_tmp_var_name ("JITTMP"),
+			type->as_tree ());
+    DECL_ARTIFICIAL (inner) = 1;
+    DECL_IGNORED_P (inner) = 1;
+    DECL_NAMELESS (inner) = 1;
+  }
   DECL_CONTEXT (inner) = this->m_inner_fndecl;
 
   /* Prepend to BIND_EXPR_VARS: */
diff --git a/gcc/jit/jit-recording.cc b/gcc/jit/jit-recording.cc
index 68a2e860c1f..bd741a388db 100644
--- a/gcc/jit/jit-recording.cc
+++ b/gcc/jit/jit-recording.cc
@@ -4211,6 +4211,23 @@ recording::function::new_local (recording::location *loc,
   return result;
 }
 
+/* Create a recording::local instance and add it to
+   the functions's context's list of mementos, and to the function's
+   list of locals.
+
+   Implements the post-error-checking part of
+   gcc_jit_function_new_temp.  */
+
+recording::lvalue *
+recording::function::new_temp (recording::location *loc,
+			       type *type)
+{
+  local *result = new local (this, loc, type, NULL);
+  m_ctxt->record (result);
+  m_locals.safe_push (result);
+  return result;
+}
+
 /* Create a recording::block instance and add it to
    the functions's context's list of mementos, and to the function's
    list of blocks.
@@ -6853,16 +6870,26 @@ void
 recording::local::write_reproducer (reproducer &r)
 {
   const char *id = r.make_identifier (this, "local");
-  r.write ("  gcc_jit_lvalue *%s =\n"
-	   "    gcc_jit_function_new_local (%s, /* gcc_jit_function *func */\n"
-	   "                                %s, /* gcc_jit_location *loc */\n"
-	   "                                %s, /* gcc_jit_type *type */\n"
-	   "                                %s); /* const char *name */\n",
-	   id,
-	   r.get_identifier (m_func),
-	   r.get_identifier (m_loc),
-	   r.get_identifier_as_type (m_type),
-	   m_name->get_debug_string ());
+  if (m_name)
+    r.write ("  gcc_jit_lvalue *%s =\n"
+	     "    gcc_jit_function_new_local (%s, /* gcc_jit_function *func */\n"
+	     "                                %s, /* gcc_jit_location *loc */\n"
+	     "                                %s, /* gcc_jit_type *type */\n"
+	     "                                %s); /* const char *name */\n",
+	     id,
+	     r.get_identifier (m_func),
+	     r.get_identifier (m_loc),
+	     r.get_identifier_as_type (m_type),
+	     m_name->get_debug_string ());
+  else
+    r.write ("  gcc_jit_lvalue *%s =\n"
+	     "    gcc_jit_function_new_temp (%s, /* gcc_jit_function *func */\n"
+	     "                               %s, /* gcc_jit_location *loc */\n"
+	     "                               %s); /* gcc_jit_type *type */\n",
+	     id,
+	     r.get_identifier (m_func),
+	     r.get_identifier (m_loc),
+	     r.get_identifier_as_type (m_type));
 }
 
 /* The implementation of class gcc::jit::recording::statement.  */
diff --git a/gcc/jit/jit-recording.h b/gcc/jit/jit-recording.h
index d8d16f4fe29..e49d54c5dd3 100644
--- a/gcc/jit/jit-recording.h
+++ b/gcc/jit/jit-recording.h
@@ -1345,6 +1345,10 @@ public:
 	     type *type,
 	     const char *name);
 
+  lvalue *
+  new_temp (location *loc,
+	    type *type);
+
   block*
   new_block (const char *name);
 
@@ -2149,7 +2153,12 @@ public:
   void write_to_dump (dump &d) final override;
 
 private:
-  string * make_debug_string () final override { return m_name; }
+  string * make_debug_string () final override {
+    if (m_name)
+      return m_name;
+    else
+      return m_ctxt->new_string ("temp");
+  }
   void write_reproducer (reproducer &r) final override;
   enum precedence get_precedence () const final override
   {
diff --git a/gcc/jit/libgccjit.cc b/gcc/jit/libgccjit.cc
index f40a9781405..9d902115b5b 100644
--- a/gcc/jit/libgccjit.cc
+++ b/gcc/jit/libgccjit.cc
@@ -2808,6 +2808,37 @@ gcc_jit_function_new_local (gcc_jit_function *func,
   return (gcc_jit_lvalue *)func->new_local (loc, type, name);
 }
 
+/* Public entrypoint.  See description in libgccjit.h.
+
+   After error-checking, the real work is done by the
+   gcc::jit::recording::function::new_temp method in jit-recording.cc.  */
+
+gcc_jit_lvalue *
+gcc_jit_function_new_temp (gcc_jit_function *func,
+			   gcc_jit_location *loc,
+			   gcc_jit_type *type)
+{
+  RETURN_NULL_IF_FAIL (func, NULL, loc, "NULL function");
+  gcc::jit::recording::context *ctxt = func->m_ctxt;
+  JIT_LOG_FUNC (ctxt->get_logger ());
+  /* LOC can be NULL.  */
+  RETURN_NULL_IF_FAIL (func->get_kind () != GCC_JIT_FUNCTION_IMPORTED,
+		       ctxt, loc,
+		       "Cannot add temps to an imported function");
+  RETURN_NULL_IF_FAIL (type, ctxt, loc, "NULL type");
+  RETURN_NULL_IF_FAIL_PRINTF1 (
+    type->has_known_size (),
+    ctxt, loc,
+    "unknown size for temp (type: %s)",
+    type->get_debug_string ());
+  RETURN_NULL_IF_FAIL (
+    !type->is_void (),
+    ctxt, loc,
+    "void type for temp");
+
+  return (gcc_jit_lvalue *)func->new_temp (loc, type);
+}
+
 /* Public entrypoint.  See description in libgccjit.h.
 
    After error-checking, the real work is done by the
diff --git a/gcc/jit/libgccjit.h b/gcc/jit/libgccjit.h
index 74e847b2dec..07f2e50112f 100644
--- a/gcc/jit/libgccjit.h
+++ b/gcc/jit/libgccjit.h
@@ -1396,6 +1396,13 @@ gcc_jit_function_new_local (gcc_jit_function *func,
 			    gcc_jit_type *type,
 			    const char *name);
 
+extern gcc_jit_lvalue *
+gcc_jit_function_new_temp (gcc_jit_function *func,
+			   gcc_jit_location *loc,
+			   gcc_jit_type *type);
+
+#define LIBGCCJIT_HAVE_gcc_jit_function_new_temp
+
 /**********************************************************************
  Statement-creation.
  **********************************************************************/
diff --git a/gcc/jit/libgccjit.map b/gcc/jit/libgccjit.map
index 99aa5970be1..45a7f45bf43 100644
--- a/gcc/jit/libgccjit.map
+++ b/gcc/jit/libgccjit.map
@@ -289,3 +289,8 @@ LIBGCCJIT_ABI_27 {
   global:
     gcc_jit_context_new_sizeof;
 } LIBGCCJIT_ABI_26;
+
+LIBGCCJIT_ABI_28 {
+  global:
+    gcc_jit_function_new_temp;
+} LIBGCCJIT_ABI_27;
diff --git a/gcc/testsuite/jit.dg/all-non-failing-tests.h b/gcc/testsuite/jit.dg/all-non-failing-tests.h
index 14a0a321550..fa6b26a66b2 100644
--- a/gcc/testsuite/jit.dg/all-non-failing-tests.h
+++ b/gcc/testsuite/jit.dg/all-non-failing-tests.h
@@ -360,6 +360,9 @@
 #undef create_code
 #undef verify_code
 
+/* test-temp.c: This can't be in the testcases array as it
+   is target-specific.  */
+
 /* test-string-literal.c */
 #define create_code create_code_string_literal
 #define verify_code verify_code_string_literal
diff --git a/gcc/testsuite/jit.dg/test-temp.c b/gcc/testsuite/jit.dg/test-temp.c
new file mode 100644
index 00000000000..9b1ba9b0100
--- /dev/null
+++ b/gcc/testsuite/jit.dg/test-temp.c
@@ -0,0 +1,56 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <stdint.h>
+
+#include "libgccjit.h"
+
+#define TEST_COMPILING_TO_FILE
+#define OUTPUT_KIND      GCC_JIT_OUTPUT_KIND_ASSEMBLER
+#define OUTPUT_FILENAME  "output-of-test-test-temp.c.s"
+#include "harness.h"
+
+void
+create_code (gcc_jit_context *ctxt, void *user_data)
+{
+  /* Let's try to inject the equivalent of:
+int
+func ()
+{
+   int temp = 10;
+   return temp;
+}
+   */
+  gcc_jit_type *int_type =
+    gcc_jit_context_get_type (ctxt, GCC_JIT_TYPE_INT);
+
+  gcc_jit_function *func =
+    gcc_jit_context_new_function (ctxt,
+				  NULL,
+				  GCC_JIT_FUNCTION_EXPORTED,
+				  int_type,
+				  "func",
+				  0, NULL, 0);
+
+  gcc_jit_block *initial =
+    gcc_jit_function_new_block (func, "initial");
+
+  gcc_jit_lvalue *temp =
+    gcc_jit_function_new_temp (func, NULL, int_type);
+
+  gcc_jit_rvalue *ten =
+    gcc_jit_context_new_rvalue_from_int (ctxt, int_type, 10);
+  gcc_jit_block_add_assignment (initial, NULL, temp, ten);
+
+  gcc_jit_block_end_with_return(initial, NULL,
+    gcc_jit_lvalue_as_rvalue (temp));
+}
+
+void
+verify_code (gcc_jit_context *ctxt, gcc_jit_result *result)
+{
+  CHECK_NON_NULL (result);
+}
+
+/* { dg-final { jit-verify-output-file-was-created "" } } */
+/* { dg-final { jit-verify-assembler-output-not "JITTMP" } } */
-- 
2.44.0