1 files changed, 46 insertions, 11 deletions
diff --git a/gcc/doc/rtl.texi b/gcc/doc/rtl.texi
index 20b7187..605a5a1 100644
--- a/gcc/doc/rtl.texi
+++ b/gcc/doc/rtl.texi
@@ -1540,17 +1540,21 @@ 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 @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
@@ -1565,6 +1569,37 @@ 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_INT}s 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}.