[Qemu-devel] [PATCH v2 0/3] decodetree improvements

[Qemu-devel] [PATCH v2 0/3] decodetree improvements

[Richard Henderson]

Changes from v1:
  * Drop unintended hunk from MultiField constructor.
  * Typo fixed in ParameterField documentation.

Blurb from v1:
  These are split out from my decodetree coversion of the AArch32
  base instruction sets.

  The first patch has been tidied per review from Peter.  I now
  diagnose nonsense fields containing no bits.  I eliminated the
  unused integer argument passed to the named function.  I improved
  the documentation.

  The second patch is new, a suggestion from Phillipe.  This then
  enables the third patch, tidying up the existing usage in riscv.


r~


Richard Henderson (3):
  decodetree: Allow !function with no input bits
  decodetree: Suppress redundant declaration warnings
  target/riscv: Remove redundant declaration pragmas

 target/riscv/translate.c          | 19 +--------
 docs/devel/decodetree.rst         |  8 +++-
 scripts/decodetree.py             | 71 ++++++++++++++++++++++++++-----
 tests/decode/err_field6.decode    |  5 +++
 tests/decode/succ_function.decode |  6 +++
 5 files changed, 79 insertions(+), 30 deletions(-)
 create mode 100644 tests/decode/err_field6.decode
 create mode 100644 tests/decode/succ_function.decode

-- 
2.17.1

[Qemu-devel] [PATCH v2 1/3] decodetree: Allow !function with no input bits

[Richard Henderson]

Call this form a "parameter", returning a value extracted
from the DisasContext.

Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 docs/devel/decodetree.rst         |  8 ++++-
 scripts/decodetree.py             | 49 ++++++++++++++++++++++++-------
 tests/decode/err_field6.decode    |  5 ++++
 tests/decode/succ_function.decode |  6 ++++
 4 files changed, 56 insertions(+), 12 deletions(-)
 create mode 100644 tests/decode/err_field6.decode
 create mode 100644 tests/decode/succ_function.decode

diff --git a/docs/devel/decodetree.rst b/docs/devel/decodetree.rst
index 44ac621ea8..ce7f52308f 100644
--- a/docs/devel/decodetree.rst
+++ b/docs/devel/decodetree.rst
@@ -23,7 +23,7 @@ Fields
 
 Syntax::
 
-  field_def     := '%' identifier ( unnamed_field )+ ( !function=identifier )?
+  field_def     := '%' identifier ( unnamed_field )* ( !function=identifier )?
   unnamed_field := number ':' ( 's' ) number
 
 For *unnamed_field*, the first number is the least-significant bit position
@@ -34,6 +34,12 @@ present, they are concatenated.  In this way one can define disjoint fields.
 If ``!function`` is specified, the concatenated result is passed through the
 named function, taking and returning an integral value.
 
+One may use ``!function`` with zero ``unnamed_fields``.  This case is called
+a *parameter*, and the named function is only passed the ``DisasContext``
+and returns an integral value extracted from there.
+
+A field with no ``unnamed_fields`` and no ``!function`` is in error.
+
 FIXME: the fields of the structure into which this result will be stored
 is restricted to ``int``.  Which means that we cannot expand 64-bit items.
 
diff --git a/scripts/decodetree.py b/scripts/decodetree.py
index d7a59d63ac..31e2f04ecb 100755
--- a/scripts/decodetree.py
+++ b/scripts/decodetree.py
@@ -245,7 +245,7 @@ class ConstField:
 
 
 class FunctionField:
-    """Class representing a field passed through an expander"""
+    """Class representing a field passed through a function"""
     def __init__(self, func, base):
         self.mask = base.mask
         self.sign = base.sign
@@ -266,6 +266,27 @@ class FunctionField:
 # end FunctionField
 
 
+class ParameterField:
+    """Class representing a pseudo-field read from a function"""
+    def __init__(self, func):
+        self.mask = 0
+        self.sign = 0
+        self.func = func
+
+    def __str__(self):
+        return self.func
+
+    def str_extract(self):
+        return self.func + '(ctx)'
+
+    def __eq__(self, other):
+        return self.func == other.func
+
+    def __ne__(self, other):
+        return not self.__eq__(other)
+# end FunctionField
+
+
 class Arguments:
     """Class representing the extracted fields of a format"""
     def __init__(self, nm, flds, extern):
@@ -433,17 +454,23 @@ def parse_field(lineno, name, toks):
 
     if width > insnwidth:
         error(lineno, 'field too large')
-    if len(subs) == 1:
-        f = subs[0]
+    if len(subs) == 0:
+        if func:
+            f = ParameterField(func)
+        else:
+            error(lineno, 'field with no value')
     else:
-        mask = 0
-        for s in subs:
-            if mask & s.mask:
-                error(lineno, 'field components overlap')
-            mask |= s.mask
-        f = MultiField(subs, mask)
-    if func:
-        f = FunctionField(func, f)
+        if len(subs) == 1:
+            f = subs[0]
+        else:
+            mask = 0
+            for s in subs:
+                if mask & s.mask:
+                    error(lineno, 'field components overlap')
+                mask |= s.mask
+            f = MultiField(subs, mask)
+        if func:
+            f = FunctionField(func, f)
 
     if name in fields:
         error(lineno, 'duplicate field', name)
diff --git a/tests/decode/err_field6.decode b/tests/decode/err_field6.decode
new file mode 100644
index 0000000000..a719884572
--- /dev/null
+++ b/tests/decode/err_field6.decode
@@ -0,0 +1,5 @@
+# This work is licensed under the terms of the GNU LGPL, version 2 or later.
+# See the COPYING.LIB file in the top-level directory.
+
+# Diagnose no bits in field
+%field
diff --git a/tests/decode/succ_function.decode b/tests/decode/succ_function.decode
new file mode 100644
index 0000000000..7751b1784e
--- /dev/null
+++ b/tests/decode/succ_function.decode
@@ -0,0 +1,6 @@
+# This work is licensed under the terms of the GNU LGPL, version 2 or later.
+# See the COPYING.LIB file in the top-level directory.
+
+# "Field" as parameter pulled from DisasContext.
+%foo  !function=foo
+foo   00000000000000000000000000000000 %foo
-- 
2.17.1

Re: [Qemu-devel] [PATCH v2 1/3] decodetree: Allow !function with no input bits

[Philippe Mathieu-Daudé]

On 8/18/19 8:39 AM, Richard Henderson wrote:
> Call this form a "parameter", returning a value extracted
> from the DisasContext.
> 
> Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
> ---
>  docs/devel/decodetree.rst         |  8 ++++-
>  scripts/decodetree.py             | 49 ++++++++++++++++++++++++-------
>  tests/decode/err_field6.decode    |  5 ++++
>  tests/decode/succ_function.decode |  6 ++++
>  4 files changed, 56 insertions(+), 12 deletions(-)
>  create mode 100644 tests/decode/err_field6.decode
>  create mode 100644 tests/decode/succ_function.decode
> 
> diff --git a/docs/devel/decodetree.rst b/docs/devel/decodetree.rst
> index 44ac621ea8..ce7f52308f 100644
> --- a/docs/devel/decodetree.rst
> +++ b/docs/devel/decodetree.rst
> @@ -23,7 +23,7 @@ Fields
>  
>  Syntax::
>  
> -  field_def     := '%' identifier ( unnamed_field )+ ( !function=identifier )?
> +  field_def     := '%' identifier ( unnamed_field )* ( !function=identifier )?
>    unnamed_field := number ':' ( 's' ) number
>  
>  For *unnamed_field*, the first number is the least-significant bit position
> @@ -34,6 +34,12 @@ present, they are concatenated.  In this way one can define disjoint fields.
>  If ``!function`` is specified, the concatenated result is passed through the
>  named function, taking and returning an integral value.
>  
> +One may use ``!function`` with zero ``unnamed_fields``.  This case is called
> +a *parameter*, and the named function is only passed the ``DisasContext``
> +and returns an integral value extracted from there.
> +
> +A field with no ``unnamed_fields`` and no ``!function`` is in error.
> +
>  FIXME: the fields of the structure into which this result will be stored
>  is restricted to ``int``.  Which means that we cannot expand 64-bit items.
>  
> diff --git a/scripts/decodetree.py b/scripts/decodetree.py
> index d7a59d63ac..31e2f04ecb 100755
> --- a/scripts/decodetree.py
> +++ b/scripts/decodetree.py
> @@ -245,7 +245,7 @@ class ConstField:
>  
>  
>  class FunctionField:
> -    """Class representing a field passed through an expander"""
> +    """Class representing a field passed through a function"""
>      def __init__(self, func, base):
>          self.mask = base.mask
>          self.sign = base.sign
> @@ -266,6 +266,27 @@ class FunctionField:
>  # end FunctionField
>  
>  
> +class ParameterField:
> +    """Class representing a pseudo-field read from a function"""
> +    def __init__(self, func):
> +        self.mask = 0
> +        self.sign = 0
> +        self.func = func
> +
> +    def __str__(self):
> +        return self.func
> +
> +    def str_extract(self):
> +        return self.func + '(ctx)'
> +
> +    def __eq__(self, other):
> +        return self.func == other.func
> +
> +    def __ne__(self, other):
> +        return not self.__eq__(other)
> +# end FunctionField

Nit: end ParameterField

> +
> +
>  class Arguments:
>      """Class representing the extracted fields of a format"""
>      def __init__(self, nm, flds, extern):
> @@ -433,17 +454,23 @@ def parse_field(lineno, name, toks):
>  
>      if width > insnwidth:
>          error(lineno, 'field too large')
> -    if len(subs) == 1:
> -        f = subs[0]
> +    if len(subs) == 0:
> +        if func:
> +            f = ParameterField(func)
> +        else:
> +            error(lineno, 'field with no value')
>      else:
> -        mask = 0
> -        for s in subs:
> -            if mask & s.mask:
> -                error(lineno, 'field components overlap')
> -            mask |= s.mask
> -        f = MultiField(subs, mask)
> -    if func:
> -        f = FunctionField(func, f)
> +        if len(subs) == 1:
> +            f = subs[0]
> +        else:
> +            mask = 0
> +            for s in subs:
> +                if mask & s.mask:
> +                    error(lineno, 'field components overlap')
> +                mask |= s.mask
> +            f = MultiField(subs, mask)
> +        if func:
> +            f = FunctionField(func, f)
>  
>      if name in fields:
>          error(lineno, 'duplicate field', name)
> diff --git a/tests/decode/err_field6.decode b/tests/decode/err_field6.decode
> new file mode 100644
> index 0000000000..a719884572
> --- /dev/null
> +++ b/tests/decode/err_field6.decode
> @@ -0,0 +1,5 @@
> +# This work is licensed under the terms of the GNU LGPL, version 2 or later.
> +# See the COPYING.LIB file in the top-level directory.
> +
> +# Diagnose no bits in field
> +%field
> diff --git a/tests/decode/succ_function.decode b/tests/decode/succ_function.decode
> new file mode 100644
> index 0000000000..7751b1784e
> --- /dev/null
> +++ b/tests/decode/succ_function.decode
> @@ -0,0 +1,6 @@
> +# This work is licensed under the terms of the GNU LGPL, version 2 or later.
> +# See the COPYING.LIB file in the top-level directory.
> +
> +# "Field" as parameter pulled from DisasContext.
> +%foo  !function=foo
> +foo   00000000000000000000000000000000 %foo
> 

Reviewed-by: Philippe Mathieu-Daude <philmd@redhat.com>

[Qemu-devel] [PATCH v2 2/3] decodetree: Suppress redundant declaration warnings

[Richard Henderson]

We can tell that a decodetree input file is "secondary" when it
uses an argument set marked "!extern".  This indicates that at
least one of the insn translation functions will have already
been declared by the "primary" input file, but given only the
secondary we cannot tell which.

Avoid redundant declaration warnings by suppressing them with pragmas.

Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Suggested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 scripts/decodetree.py | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/scripts/decodetree.py b/scripts/decodetree.py
index 31e2f04ecb..12c1cd0ddb 100755
--- a/scripts/decodetree.py
+++ b/scripts/decodetree.py
@@ -33,6 +33,7 @@ arguments = {}
 formats = {}
 patterns = []
 allpatterns = []
+anyextern = False
 
 translate_prefix = 'trans'
 translate_scope = 'static '
@@ -482,12 +483,14 @@ def parse_arguments(lineno, name, toks):
     """Parse one argument set from TOKS at LINENO"""
     global arguments
     global re_ident
+    global anyextern
 
     flds = []
     extern = False
     for t in toks:
         if re_fullmatch('!extern', t):
             extern = True
+            anyextern = True
             continue
         if not re_fullmatch(re_ident, t):
             error(lineno, 'invalid argument set token "{0}"'.format(t))
@@ -1188,6 +1191,7 @@ def main():
     global insnmask
     global decode_function
     global variablewidth
+    global anyextern
 
     decode_scope = 'static '
 
@@ -1248,6 +1252,19 @@ def main():
     # A single translate function can be invoked for different patterns.
     # Make sure that the argument sets are the same, and declare the
     # function only once.
+    #
+    # If we're sharing formats, we're likely also sharing trans_* functions,
+    # but we can't tell which ones.  Prevent issues from the compiler by
+    # suppressing redundant declaration warnings.
+    if anyextern:
+        output("#ifdef CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE\n",
+               "# pragma GCC diagnostic push\n",
+               "# pragma GCC diagnostic ignored \"-Wredundant-decls\"\n",
+               "# ifdef __clang__\n"
+               "#  pragma GCC diagnostic ignored \"-Wtypedef-redefinition\"\n",
+               "# endif\n",
+               "#endif\n\n")
+
     out_pats = {}
     for i in allpatterns:
         if i.name in out_pats:
@@ -1259,6 +1276,11 @@ def main():
             out_pats[i.name] = i
     output('\n')
 
+    if anyextern:
+        output("#ifdef CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE\n",
+               "# pragma GCC diagnostic pop\n",
+               "#endif\n\n")
+
     for n in sorted(formats.keys()):
         f = formats[n]
         f.output_extract()
-- 
2.17.1

[Qemu-devel] [PATCH v2 3/3] target/riscv: Remove redundant declaration pragmas

[Richard Henderson]

These are now generated by decodetree itself.

Tested-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Acked-by: Palmer Dabbelt <palmer@sifive.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
---
 target/riscv/translate.c | 19 +------------------
 1 file changed, 1 insertion(+), 18 deletions(-)

diff --git a/target/riscv/translate.c b/target/riscv/translate.c
index 8d6ab73258..adeddb85f6 100644
--- a/target/riscv/translate.c
+++ b/target/riscv/translate.c
@@ -708,26 +708,9 @@ static bool gen_shift(DisasContext *ctx, arg_r *a,
 #include "insn_trans/trans_rvd.inc.c"
 #include "insn_trans/trans_privileged.inc.c"
 
-/*
- * Auto-generated decoder.
- * Note that the 16-bit decoder reuses some of the trans_* functions
- * initially declared by the 32-bit decoder, which results in duplicate
- * declaration warnings.  Suppress them.
- */
-#ifdef CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE
-# pragma GCC diagnostic push
-# pragma GCC diagnostic ignored "-Wredundant-decls"
-# ifdef __clang__
-#  pragma GCC diagnostic ignored "-Wtypedef-redefinition"
-# endif
-#endif
-
+/* Include the auto-generated decoder for 16 bit insn */
 #include "decode_insn16.inc.c"
 
-#ifdef CONFIG_PRAGMA_DIAGNOSTIC_AVAILABLE
-# pragma GCC diagnostic pop
-#endif
-
 static void decode_opc(DisasContext *ctx)
 {
     /* check for compressed insn */
-- 
2.17.1