On Nov 23, 2013, at 11:21 AM, Mike Stump <mikest...@comcast.net> wrote:
> Richi has asked the we break the wide-int patch so that the individual port
> and front end maintainers can review their parts without have to go through
> the entire patch. This patch covers the documentation.
>
> Ok?
Ping?
* doc/generic.texi
(Constant expressions): Use wide-int interfaces.
* doc/rtl.texi
(const_double): Use wide-int interfaces.
(const_wide_int, CONST_WIDE_INT, CONST_WIDE_INT_VEC): New.
(CONST_WIDE_INT_NUNITS, CONST_WIDE_INT_ELT): New.
* doc/tm.texi.in
(REAL_VALUE_TO_INT): Remove.
(REAL_VALUE_FROM_INT): Remove.
(TARGET_SUPPORTS_WIDE_INT): New.
* doc/tm.texi: Regenerate.
diff --git a/gcc/doc/generic.texi b/gcc/doc/generic.texi
index f2dd0ff..534018e 100644
--- a/gcc/doc/generic.texi
+++ b/gcc/doc/generic.texi
@@ -1022,10 +1022,15 @@ As this example indicates, the operands are
zero-indexed.
@node Constant expressions
@subsection Constant expressions
@tindex INTEGER_CST
-@findex TREE_INT_CST_HIGH
-@findex TREE_INT_CST_LOW
@findex tree_int_cst_lt
@findex tree_int_cst_equal
+@tindex tree_fits_uhwi_p
+@tindex tree_fits_shwi_p
+@tindex tree_to_uhwi
+@tindex tree_to_shwi
+@tindex TREE_INT_CST_NUNITS
+@tindex TREE_INT_CST_ELT
+@tindex TREE_INT_CST_LOW
@tindex REAL_CST
@tindex FIXED_CST
@tindex COMPLEX_CST
@@ -1044,36 +1049,18 @@ These nodes represent integer constants. Note that the
type of these
constants is obtained with @code{TREE_TYPE}; they are not always of type
@code{int}. In particular, @code{char} constants are represented with
@code{INTEGER_CST} nodes. The value of the integer constant @code{e} is
-given by
-@smallexample
-((TREE_INT_CST_HIGH (e) << HOST_BITS_PER_WIDE_INT)
-+ TREE_INST_CST_LOW (e))
-@end smallexample
-@noindent
-HOST_BITS_PER_WIDE_INT is at least thirty-two on all platforms. Both
-@code{TREE_INT_CST_HIGH} and @code{TREE_INT_CST_LOW} return a
-@code{HOST_WIDE_INT}. The value of an @code{INTEGER_CST} is interpreted
-as a signed or unsigned quantity depending on the type of the constant.
-In general, the expression given above will overflow, so it should not
-be used to calculate the value of the constant.
-
-The variable @code{integer_zero_node} is an integer constant with value
-zero. Similarly, @code{integer_one_node} is an integer constant with
-value one. The @code{size_zero_node} and @code{size_one_node} variables
-are analogous, but have type @code{size_t} rather than @code{int}.
-
-The function @code{tree_int_cst_lt} is a predicate which holds if its
-first argument is less than its second. Both constants are assumed to
-have the same signedness (i.e., either both should be signed or both
-should be unsigned.) The full width of the constant is used when doing
-the comparison; the usual rules about promotions and conversions are
-ignored. Similarly, @code{tree_int_cst_equal} holds if the two
-constants are equal. The @code{tree_int_cst_sgn} function returns the
-sign of a constant. The value is @code{1}, @code{0}, or @code{-1}
-according on whether the constant is greater than, equal to, or less
-than zero. Again, the signedness of the constant's type is taken into
-account; an unsigned constant is never less than zero, no matter what
-its bit-pattern.
+represented in an array of HOST_WIDE_INT. There are enough elements
+in the array to represent the value without taking extra elements for
+redundant 0s or -1. The number of elements used to represent @code{e}
+is available via @code{TREE_INT_CST_NUNITS}. Element @code{i} can be
+extracted by using @code{TREE_INT_CST_ELT (e, i)}.
+@code{TREE_INT_CST_LOW} is a shorthand for @code{TREE_INT_CST_ELT (e, 0)}.
+
+The functions @code{tree_fits_shwi_p} and @code{tree_fits_uhwi_p}
+can be used to tell if the value is small enough to fit in a
+signed HOST_WIDE_INT or an unsigned HOST_WIDE_INT respectively.
+The value can then be extracted using @code{tree_to_shwi} and
+@code{tree_to_uhwi}.
@item REAL_CST
diff --git a/gcc/doc/rtl.texi b/gcc/doc/rtl.texi
index df2bb68..2565995 100644
--- a/gcc/doc/rtl.texi
+++ b/gcc/doc/rtl.texi
@@ -1541,17 +1541,21 @@ Similarly, there is only one object for the integer
whose value is
@findex const_double
@item (const_double:@var{m} @var{i0} @var{i1} @dots{})
-Represents either a floating-point constant of mode @var{m} or an
-integer constant too large to fit into @code{HOST_BITS_PER_WIDE_INT}
-bits but small enough to fit within twice that number of bits (GCC
-does not provide a mechanism to represent even larger constants). In
-the latter case, @var{m} will be @code{VOIDmode}. For integral values
-constants for modes with more bits than twice the number in
-@code{HOST_WIDE_INT} the implied high order bits of that constant are
-copies of the top bit of @code{CONST_DOUBLE_HIGH}. Note however that
-integral values are neither inherently signed nor inherently unsigned;
-where necessary, signedness is determined by the rtl operation
-instead.
+This represents either a floating-point constant of mode @var{m} or
+(on older ports that do not define
+@code{TARGET_SUPPORTS_WIDE_INT}) an integer constant too large to fit
+into @code{HOST_BITS_PER_WIDE_INT} bits but small enough to fit within
+twice that number of bits. In the latter case, @var{m} will be
+@code{VOIDmode}. For integral values constants for modes with more
+bits than twice the number in @code{HOST_WIDE_INT} the implied high
+order bits of that constant are copies of the top bit of
+@code{CONST_DOUBLE_HIGH}. Note however that integral values are
+neither inherently signed nor inherently unsigned; where necessary,
+signedness is determined by the rtl operation instead.
+
+On more modern ports, @code{CONST_DOUBLE} only represents floating
+point values. New ports define to @code{TARGET_SUPPORTS_WIDE_INT} to
+make this designation.
@findex CONST_DOUBLE_LOW
If @var{m} is @code{VOIDmode}, the bits of the value are stored in
@@ -1566,6 +1570,37 @@ machine's or host machine's floating point format. To
convert them to
the precise bit pattern used by the target machine, use the macro
@code{REAL_VALUE_TO_TARGET_DOUBLE} and friends (@pxref{Data Output}).
+@findex CONST_WIDE_INT
+@item (const_wide_int:@var{m} @var{nunits} @var{elt0} @dots{})
+This contains an array of @code{HOST_WIDE_INTS} that is large enough
+to hold any constant that can be represented on the target. This form
+of rtl is only used on targets that define
+@code{TARGET_SUPPORTS_WIDE_INT} to be nonzero and then
+@code{CONST_DOUBLE}s are only used to hold floating-point values. If
+the target leaves @code{TARGET_SUPPORTS_WIDE_INT} defined as 0,
+@code{CONST_WIDE_INT}s are not used and @code{CONST_DOUBLE}s are as
+they were before.
+
+The values are stored in a compressed format. The higher-order
+0s or -1s are not represented if they are just the logical sign
+extension of the number that is represented.
+
+@findex CONST_WIDE_INT_VEC
+@item CONST_WIDE_INT_VEC (@var{code})
+Returns the entire array of @code{HOST_WIDE_INT}s that are used to
+store the value. This macro should be rarely used.
+
+@findex CONST_WIDE_INT_NUNITS
+@item CONST_WIDE_INT_NUNITS (@var{code})
+The number of @code{HOST_WIDE_INT}s used to represent the number.
+Note that this generally is smaller than the number of
+@code{HOST_WIDE_INT}s implied by the mode size.
+
+@findex CONST_WIDE_INT_ELT
+@item CONST_WIDE_INT_NUNITS (@var{code},@var{i})
+Returns the @code{i}th element of the array. Element 0 is contains
+the low order bits of the constant.
+
@findex const_fixed
@item (const_fixed:@var{m} @dots{})
Represents a fixed-point constant of mode @var{m}.
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi
index 35cfa99..12b0724 100644
--- a/gcc/doc/tm.texi
+++ b/gcc/doc/tm.texi
@@ -9683,18 +9683,6 @@ Returns the negative of the floating point value @var{x}.
Returns the absolute value of @var{x}.
@end deftypefn
-@deftypefn Macro void REAL_VALUE_TO_INT (HOST_WIDE_INT @var{low},
HOST_WIDE_INT @var{high}, REAL_VALUE_TYPE @var{x})
-Converts a floating point value @var{x} into a double-precision integer
-which is then stored into @var{low} and @var{high}. If the value is not
-integral, it is truncated.
-@end deftypefn
-
-@deftypefn Macro void REAL_VALUE_FROM_INT (REAL_VALUE_TYPE @var{x},
HOST_WIDE_INT @var{low}, HOST_WIDE_INT @var{high}, enum machine_mode @var{mode})
-Converts a double-precision integer found in @var{low} and @var{high},
-into a floating point value which is then stored into @var{x}. The
-value is truncated to fit in mode @var{mode}.
-@end deftypefn
-
@node Mode Switching
@section Mode Switching Instructions
@cindex mode switching
@@ -11091,7 +11079,7 @@ function version at run-time for a given set of
function versions.
body must be generated.
@end deftypefn
-@deftypefn {Target Hook} bool TARGET_CAN_USE_DOLOOP_P (double_int
@var{iterations}, double_int @var{iterations_max}, unsigned int
@var{loop_depth}, bool @var{entered_at_top})
+@deftypefn {Target Hook} bool TARGET_CAN_USE_DOLOOP_P (const widest_int
@var{&iterations}, const widest_int @var{&iterations_max}, unsigned int
@var{loop_depth}, bool @var{entered_at_top})
Return true if it is possible to use low-overhead loops (@code{doloop_end}
and @code{doloop_begin}) for a particular loop. @var{iterations} gives the
exact number of iterations, or 0 if not known. @var{iterations_max} gives
@@ -11503,3 +11491,49 @@ The default value of this hook is based on target's
libc.
@deftypefn {Target Hook} void TARGET_ATOMIC_ASSIGN_EXPAND_FENV (tree
*@var{hold}, tree *@var{clear}, tree *@var{update})
ISO C11 requires atomic compound assignments that may raise floating-point
exceptions to raise exceptions corresponding to the arithmetic operation whose
result was successfully stored in a compare-and-exchange sequence. This
requires code equivalent to calls to @code{feholdexcept}, @code{feclearexcept}
and @code{feupdateenv} to be generated at appropriate points in the
compare-and-exchange sequence. This hook should set @code{*@var{hold}} to an
expression equivalent to the call to @code{feholdexcept}, @code{*@var{clear}}
to an expression equivalent to the call to @code{feclearexcept} and
@code{*@var{update}} to an expression equivalent to the call to
@code{feupdateenv}. The three expressions are @code{NULL_TREE} on entry to the
hook and may be left as @code{NULL_TREE} if no code is required in a particular
place. The default implementation leaves all three expressions as
@code{NULL_TREE}. The @code{__atomic_feraiseexcept} function from
@code{libatomic} may be of use as part of the code generated in
@code{*@var{update}}.
@end deftypefn
+
+@defmac TARGET_SUPPORTS_WIDE_INT
+
+On older ports, large integers are stored in @code{CONST_DOUBLE} rtl
+objects. Newer ports define @code{TARGET_SUPPORTS_WIDE_INT} to be nonzero
+to indicate that large integers are stored in
+@code{CONST_WIDE_INT} rtl objects. The @code{CONST_WIDE_INT} allows
+very large integer constants to be represented. @code{CONST_DOUBLE}
+is limited to twice the size of the host's @code{HOST_WIDE_INT}
+representation.
+
+Converting a port mostly requires looking for the places where
+@code{CONST_DOUBLE}s are used with @code{VOIDmode} and replacing that
+code with code that accesses @code{CONST_WIDE_INT}s. @samp{"grep -i
+const_double"} at the port level gets you to 95% of the changes that
+need to be made. There are a few places that require a deeper look.
+
+@itemize @bullet
+@item
+There is no equivalent to @code{hval} and @code{lval} for
+@code{CONST_WIDE_INT}s. This would be difficult to express in the md
+language since there are a variable number of elements.
+
+Most ports only check that @code{hval} is either 0 or -1 to see if the
+value is small. As mentioned above, this will no longer be necessary
+since small constants are always @code{CONST_INT}. Of course there
+are still a few exceptions, the alpha's constraint used by the zap
+instruction certainly requires careful examination by C code.
+However, all the current code does is pass the hval and lval to C
+code, so evolving the c code to look at the @code{CONST_WIDE_INT} is
+not really a large change.
+
+@item
+Because there is no standard template that ports use to materialize
+constants, there is likely to be some futzing that is unique to each
+port in this code.
+
+@item
+The rtx costs may have to be adjusted to properly account for larger
+constants that are represented as @code{CONST_WIDE_INT}.
+@end itemize
+
+All and all it does not take long to convert ports that the
+maintainer is familiar with.
+
+@end defmac
diff --git a/gcc/doc/tm.texi.in b/gcc/doc/tm.texi.in
index b10ecd7..55e96bb 100644
--- a/gcc/doc/tm.texi.in
+++ b/gcc/doc/tm.texi.in
@@ -7345,18 +7345,6 @@ Returns the negative of the floating point value @var{x}.
Returns the absolute value of @var{x}.
@end deftypefn
-@deftypefn Macro void REAL_VALUE_TO_INT (HOST_WIDE_INT @var{low},
HOST_WIDE_INT @var{high}, REAL_VALUE_TYPE @var{x})
-Converts a floating point value @var{x} into a double-precision integer
-which is then stored into @var{low} and @var{high}. If the value is not
-integral, it is truncated.
-@end deftypefn
-
-@deftypefn Macro void REAL_VALUE_FROM_INT (REAL_VALUE_TYPE @var{x},
HOST_WIDE_INT @var{low}, HOST_WIDE_INT @var{high}, enum machine_mode @var{mode})
-Converts a double-precision integer found in @var{low} and @var{high},
-into a floating point value which is then stored into @var{x}. The
-value is truncated to fit in mode @var{mode}.
-@end deftypefn
-
@node Mode Switching
@section Mode Switching Instructions
@cindex mode switching
@@ -8408,3 +8396,49 @@ and the associated definitions of those functions.
@hook TARGET_HAS_IFUNC_P
@hook TARGET_ATOMIC_ASSIGN_EXPAND_FENV
+
+@defmac TARGET_SUPPORTS_WIDE_INT
+
+On older ports, large integers are stored in @code{CONST_DOUBLE} rtl
+objects. Newer ports define @code{TARGET_SUPPORTS_WIDE_INT} to be nonzero
+to indicate that large integers are stored in
+@code{CONST_WIDE_INT} rtl objects. The @code{CONST_WIDE_INT} allows
+very large integer constants to be represented. @code{CONST_DOUBLE}
+is limited to twice the size of the host's @code{HOST_WIDE_INT}
+representation.
+
+Converting a port mostly requires looking for the places where
+@code{CONST_DOUBLE}s are used with @code{VOIDmode} and replacing that
+code with code that accesses @code{CONST_WIDE_INT}s. @samp{"grep -i
+const_double"} at the port level gets you to 95% of the changes that
+need to be made. There are a few places that require a deeper look.
+
+@itemize @bullet
+@item
+There is no equivalent to @code{hval} and @code{lval} for
+@code{CONST_WIDE_INT}s. This would be difficult to express in the md
+language since there are a variable number of elements.
+
+Most ports only check that @code{hval} is either 0 or -1 to see if the
+value is small. As mentioned above, this will no longer be necessary
+since small constants are always @code{CONST_INT}. Of course there
+are still a few exceptions, the alpha's constraint used by the zap
+instruction certainly requires careful examination by C code.
+However, all the current code does is pass the hval and lval to C
+code, so evolving the c code to look at the @code{CONST_WIDE_INT} is
+not really a large change.
+
+@item
+Because there is no standard template that ports use to materialize
+constants, there is likely to be some futzing that is unique to each
+port in this code.
+
+@item
+The rtx costs may have to be adjusted to properly account for larger
+constants that are represented as @code{CONST_WIDE_INT}.
+@end itemize
+
+All and all it does not take long to convert ports that the
+maintainer is familiar with.
+
+@end defmac
