* c-common.c (declare_function_name): Declare predefinied variable

        `__func__'.
        * c-decl.c (flag_isoc9x): Set to 1 by default.
        (c_decode_option): Handle -std= option.  Remove -flang-isoc9x.
        (grokdeclarator): Always emit warning about implicit int for ISO C 9x.
        * c-parse.in: Allow constructors in ISO C 9x.
        Rewrite designator list handling.
        Allow [*] parameters.
        Don't warn about comma at end of enum definition for ISO C 9x.
        * cccp.c (c9x): New variable.
        (rest_extension): New variable.
        (print_help): Document new -std= option.
        (main): Recognize -std= option.  Set c9x appropriately.
        (create_definition): Recognize ISO C 9x vararg macros.
        * gcc.c (default_compilers): Adjust specs for -std options.
        (option_map): Add --std.
        (display_help): Document -std.
        * toplev.c (documented_lang_options): Add -std and remove
        -flang-isoc9x.
        * c-lex.c (yylex): Recognize hex FP constants and call REAL_VALUE_ATOF
        or REAL_VALUE_HTOF based on base of the constants.
        * fold-const.c (real_hex_to_f): New function.  Replacement function
        for hex FP conversion if REAL_ARITHMETIC is not defined.
        * real.c (asctoeg): Add handling of hex FP constants.
        * real.h: Define REAL_VALUE_HTOF if necessary using ereal_atof or
        real_hex_to_f.


git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@24049 138bc75d-0d04-0410-961f-82ee72b054a4

1 files changed, 18 insertions, 0 deletions

diff --git a/gcc/extend.texi b/gcc/extend.texi
index dac40359303..c1cd7889db5 100644
--- a/gcc/extend.texi
+++ b/gcc/extend.texi
@@ -33,6 +33,7 @@ C++ Language}, for extensions that apply @emph{only} to C++.
 * Conditionals::        Omitting the middle operand of a @samp{?:} expression.
 * Long Long::		Double-word integers---@code{long long int}.
 * Complex::             Data types for complex numbers.
+* Hex Floats::          Hexadecimal floating-point constants.
 * Zero Length::         Zero-length arrays.
 * Variable Length::     Arrays whose length is computed at run time.
 * Macro Varargs::	Macros with variable number of arguments.
@@ -78,6 +79,7 @@ C++ Language}, for extensions that apply @emph{only} to C++.
 * Conditionals::        Omitting the middle operand of a @samp{?:} expression.
 * Long Long::		Double-word integers---@code{long long int}.
 * Complex::             Data types for complex numbers.
+* Hex Floats::          Hexadecimal floating-point constants.
 * Zero Length::         Zero-length arrays.
 * Variable Length::     Arrays whose length is computed at run time.
 * Macro Varargs::	Macros with variable number of arguments.
@@ -791,6 +793,22 @@ examine and set these two fictitious variables with your debugger.
 A future version of GDB will know how to recognize such pairs and treat
 them as a single variable with a complex type.
 
+@node Hex Floats
+GNU CC recognizes floating-point numbers written not only in the usual
+decimal notation, such as @code{1.55e1}, but also numbers such as
+@code{0x1.fp3} written in hexadecimal format.  In that format the
+@code{0x} hex introducer and the @code{p} or @code{P} exponent field are
+mandatory.  The exponent is a decimal number that indicates the power of
+2 by which the significand part will be multiplied.  Thus @code{0x1.f} is
+1 15/16, @code{p3} multiplies it by 8, and the value of @code{0x1.fp3}
+is the same as @code{1.55e1}.
+
+Unlike for floating-point numbers in the decimal notation the exponent
+is always required in the hexadecimal notation.  Otherwise the compiler
+would not be able to resolve the ambiguity of, e.g., @code{0x1.f}.  This
+could mean @code{1.0f} or @code{1.9375} since @code{f} is also the
+extension for floating-point constants of type @code{float}.
+
 @node Zero Length
 @section Arrays of Length Zero
 @cindex arrays of length zero