PR c++/91979 - mangling nullptr expression

[gcc.git] / gcc / doc / invoke.texi

diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi
index 234c1b7cadf9838c5b6d186a1a920174b16b4a8a..cf7cf206193d96e3b90b43d42c04a8673c13f987 100644 (file)
--- a/gcc/doc/invoke.texi
+++ b/gcc/doc/invoke.texi
@@ -273,6 +273,7 @@ Objective-C and Objective-C++ Dialects}.
 @gccoptlist{-fmessage-length=@var{n}  @gol
 -fdiagnostics-show-location=@r{[}once@r{|}every-line@r{]}  @gol
 -fdiagnostics-color=@r{[}auto@r{|}never@r{|}always@r{]}  @gol
 @gccoptlist{-fmessage-length=@var{n}  @gol
 -fdiagnostics-show-location=@r{[}once@r{|}every-line@r{]}  @gol
 -fdiagnostics-color=@r{[}auto@r{|}never@r{|}always@r{]}  @gol

+-fdiagnostics-urls=@r{[}auto@r{|}never@r{|}always@r{]}  @gol

 -fdiagnostics-format=@r{[}text@r{|}json@r{]}  @gol
 -fno-diagnostics-show-option  -fno-diagnostics-show-caret @gol
 -fno-diagnostics-show-labels  -fno-diagnostics-show-line-numbers @gol
 -fdiagnostics-format=@r{[}text@r{|}json@r{]}  @gol
 -fno-diagnostics-show-option  -fno-diagnostics-show-caret @gol
 -fno-diagnostics-show-labels  -fno-diagnostics-show-line-numbers @gol


@@ -324,6 +325,7 @@ Objective-C and Objective-C++ Dialects}.
 -Winaccessible-base @gol
 -Winit-self  -Winline  -Wno-int-conversion  -Wint-in-bool-context @gol
 -Wno-int-to-pointer-cast  -Winvalid-memory-model  -Wno-invalid-offsetof @gol
 -Winaccessible-base @gol
 -Winit-self  -Winline  -Wno-int-conversion  -Wint-in-bool-context @gol
 -Wno-int-to-pointer-cast  -Winvalid-memory-model  -Wno-invalid-offsetof @gol

+-Wzero-length-bounds @gol

 -Winvalid-pch  -Wlarger-than=@var{byte-size} @gol
 -Wlogical-op  -Wlogical-not-parentheses  -Wlong-long @gol
 -Wmain  -Wmaybe-uninitialized  -Wmemset-elt-size  -Wmemset-transposed-args @gol
 -Winvalid-pch  -Wlarger-than=@var{byte-size} @gol
 -Wlogical-op  -Wlogical-not-parentheses  -Wlong-long @gol
 -Wmain  -Wmaybe-uninitialized  -Wmemset-elt-size  -Wmemset-transposed-args @gol


@@ -341,7 +343,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wno-pragmas  -Wno-prio-ctor-dtor  -Wredundant-decls @gol
 -Wrestrict  -Wno-return-local-addr @gol
 -Wreturn-type  -Wsequence-point  -Wshadow  -Wno-shadow-ivar @gol
 -Wno-pragmas  -Wno-prio-ctor-dtor  -Wredundant-decls @gol
 -Wrestrict  -Wno-return-local-addr @gol
 -Wreturn-type  -Wsequence-point  -Wshadow  -Wno-shadow-ivar @gol

--Wshadow=global,  -Wshadow=local,  -Wshadow=compatible-local @gol
+-Wshadow=global  -Wshadow=local  -Wshadow=compatible-local @gol

 -Wshift-overflow  -Wshift-overflow=@var{n} @gol
 -Wshift-count-negative  -Wshift-count-overflow  -Wshift-negative-value @gol
 -Wsign-compare  -Wsign-conversion  -Wfloat-conversion @gol
 -Wshift-overflow  -Wshift-overflow=@var{n} @gol
 -Wshift-count-negative  -Wshift-count-overflow  -Wshift-negative-value @gol
 -Wsign-compare  -Wsign-conversion  -Wfloat-conversion @gol


@@ -349,6 +351,7 @@ Objective-C and Objective-C++ Dialects}.
 -Wsizeof-pointer-memaccess  -Wsizeof-array-argument @gol
 -Wstack-protector  -Wstack-usage=@var{byte-size}  -Wstrict-aliasing @gol
 -Wstrict-aliasing=n  -Wstrict-overflow  -Wstrict-overflow=@var{n} @gol
 -Wsizeof-pointer-memaccess  -Wsizeof-array-argument @gol
 -Wstack-protector  -Wstack-usage=@var{byte-size}  -Wstrict-aliasing @gol
 -Wstrict-aliasing=n  -Wstrict-overflow  -Wstrict-overflow=@var{n} @gol

+-Wstring-compare @gol

 -Wstringop-overflow=@var{n}  -Wstringop-truncation  -Wsubobject-linkage @gol
 -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{|}malloc@r{]} @gol
 -Wsuggest-final-types @gol  -Wsuggest-final-methods  -Wsuggest-override @gol
 -Wstringop-overflow=@var{n}  -Wstringop-truncation  -Wsubobject-linkage @gol
 -Wsuggest-attribute=@r{[}pure@r{|}const@r{|}noreturn@r{|}format@r{|}malloc@r{]} @gol
 -Wsuggest-final-types @gol  -Wsuggest-final-methods  -Wsuggest-override @gol


@@ -404,6 +407,7 @@ Objective-C and Objective-C++ Dialects}.
 -falign-jumps[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
 -falign-labels[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
 -falign-loops[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
 -falign-jumps[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
 -falign-labels[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol
 -falign-loops[=@var{n}[:@var{m}:[@var{n2}[:@var{m2}]]]] @gol

+-fallow-store-data-races @gol

 -fassociative-math  -fauto-profile  -fauto-profile[=@var{path}] @gol
 -fauto-inc-dec  -fbranch-probabilities @gol
 -fcaller-saves @gol
 -fassociative-math  -fauto-profile  -fauto-profile[=@var{path}] @gol
 -fauto-inc-dec  -fbranch-probabilities @gol
 -fcaller-saves @gol


@@ -643,7 +647,8 @@ Objective-C and Objective-C++ Dialects}.
 -march=@var{name}  -mcpu=@var{name}  -mtune=@var{name}  @gol
 -moverride=@var{string}  -mverbose-cost-dump @gol
 -mstack-protector-guard=@var{guard} -mstack-protector-guard-reg=@var{sysreg} @gol
 -march=@var{name}  -mcpu=@var{name}  -mtune=@var{name}  @gol
 -moverride=@var{string}  -mverbose-cost-dump @gol
 -mstack-protector-guard=@var{guard} -mstack-protector-guard-reg=@var{sysreg} @gol

--mstack-protector-guard-offset=@var{offset} -mtrack-speculation }
+-mstack-protector-guard-offset=@var{offset} -mtrack-speculation @gol
+-moutline-atomics }

 
 @emph{Adapteva Epiphany Options}
 @gccoptlist{-mhalf-reg-file  -mprefer-short-insn-regs @gol
 
 @emph{Adapteva Epiphany Options}
 @gccoptlist{-mhalf-reg-file  -mprefer-short-insn-regs @gol


@@ -1005,7 +1010,7 @@ Objective-C and Objective-C++ Dialects}.
 -mwarn-mcu @gol
 -mcode-region=  -mdata-region= @gol
 -msilicon-errata=  -msilicon-errata-warn= @gol
 -mwarn-mcu @gol
 -mcode-region=  -mdata-region= @gol
 -msilicon-errata=  -msilicon-errata-warn= @gol

--mhwmult=  -minrt}
+-mhwmult=  -minrt  -mtiny-printf}

 
 @emph{NDS32 Options}
 @gccoptlist{-mbig-endian  -mlittle-endian @gol
 
 @emph{NDS32 Options}
 @gccoptlist{-mbig-endian  -mlittle-endian @gol


@@ -2408,6 +2413,9 @@ trivial move constructor.
 Version 13, which first appeared in G++ 8.2, fixes the accidental
 change in version 12.
 
 Version 13, which first appeared in G++ 8.2, fixes the accidental
 change in version 12.
 

+Version 14, which first appeared in G++ 10, corrects the mangling of
+the nullptr expression.
+

 See also @option{-Wabi}.
 
 @item -fabi-compat-version=@var{n}
 See also @option{-Wabi}.
 
 @item -fabi-compat-version=@var{n}


@@ -2511,14 +2519,17 @@ exhaustion is signalled by throwing @code{std::bad_alloc}.  See also
 @samp{new (nothrow)}.
 
 @item -fconcepts
 @samp{new (nothrow)}.
 
 @item -fconcepts

+@itemx -fconcepts-ts

 @opindex fconcepts
 @opindex fconcepts

-Enable support for the C++ Extensions for Concepts Technical
-Specification, ISO 19217 (2015), which allows code like
+@opindex fconcepts-ts
+Below @option{-std=c++2a}, @option{-fconcepts} enables support for the
+C++ Extensions for Concepts Technical Specification, ISO 19217 (2015).

 
 

-@smallexample
-template <class T> concept bool Addable = requires (T t) @{ t + t; @};
-template <Addable T> T add (T a, T b) @{ return a + b; @}
-@end smallexample
+With @option{-std=c++2a} and above, Concepts are part of the language
+standard, so @option{-fconcepts} defaults to on.  But the standard
+specification of Concepts differs significantly from the TS, so some
+constructs that were allowed in the TS but didn't make it into the
+standard can still be enabled by @option{-fconcepts-ts}.

 
 @item -fconstexpr-depth=@var{n}
 @opindex fconstexpr-depth
 
 @item -fconstexpr-depth=@var{n}
 @opindex fconstexpr-depth


@@ -3903,6 +3914,18 @@ SGR substring for highlighting mismatching types within template
 arguments in the C++ frontend.
 @end table
 
 arguments in the C++ frontend.
 @end table
 

+@item -fdiagnostics-urls[=@var{WHEN}]
+@opindex fdiagnostics-urls
+@cindex urls
+Use escape sequences to embed URLs in diagnostics.  For example, when
+@option{-fdiagnostics-show-option} emits text showing the command-line
+option controlling a diagnostic, embed a URL for documentation of that
+option.
+
+@var{WHEN} is @samp{never}, @samp{always}, or @samp{auto}.
+The default is @samp{auto}, which means to use URL escape sequences only
+when the standard error is a terminal.
+

 @item -fno-diagnostics-show-option
 @opindex fno-diagnostics-show-option
 @opindex fdiagnostics-show-option
 @item -fno-diagnostics-show-option
 @opindex fno-diagnostics-show-option
 @opindex fdiagnostics-show-option


@@ -4098,6 +4121,7 @@ might be printed in JSON form (after formatting) like this:
         ],
         "message": "this \u2018if\u2019 clause does not guard...",
         "option": "-Wmisleading-indentation",
         ],
         "message": "this \u2018if\u2019 clause does not guard...",
         "option": "-Wmisleading-indentation",

+        "option_url": "https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wmisleading-indentation",

         "children": [
             @{
                 "kind": "note",
         "children": [
             @{
                 "kind": "note",


@@ -4418,6 +4442,7 @@ Options} and @ref{Objective-C and Objective-C++ Dialect Options}.
 -Wimplicit-int @r{(C and Objective-C only)} @gol
 -Wimplicit-function-declaration @r{(C and Objective-C only)} @gol
 -Winit-self @r{(only for C++)} @gol
 -Wimplicit-int @r{(C and Objective-C only)} @gol
 -Wimplicit-function-declaration @r{(C and Objective-C only)} @gol
 -Winit-self @r{(only for C++)} @gol

+-Wzero-length-bounds @gol

 -Wlogical-not-parentheses @gol
 -Wmain @r{(only for C/ObjC and unless} @option{-ffreestanding}@r{)}  @gol
 -Wmaybe-uninitialized @gol
 -Wlogical-not-parentheses @gol
 -Wmain @r{(only for C/ObjC and unless} @option{-ffreestanding}@r{)}  @gol
 -Wmaybe-uninitialized @gol


@@ -4481,6 +4506,7 @@ name is still supported, but the newer name is more descriptive.)
 -Wold-style-declaration @r{(C only)}  @gol
 -Woverride-init  @gol
 -Wsign-compare @r{(C only)} @gol
 -Wold-style-declaration @r{(C only)}  @gol
 -Woverride-init  @gol
 -Wsign-compare @r{(C only)} @gol

+-Wstring-compare @gol

 -Wredundant-move @r{(only for C++)}  @gol
 -Wtype-limits  @gol
 -Wuninitialized  @gol
 -Wredundant-move @r{(only for C++)}  @gol
 -Wtype-limits  @gol
 -Wuninitialized  @gol


@@ -5577,21 +5603,20 @@ either specify @option{-Wextra -Wunused} (note that @option{-Wall} implies
 @item -Wuninitialized
 @opindex Wuninitialized
 @opindex Wno-uninitialized
 @item -Wuninitialized
 @opindex Wuninitialized
 @opindex Wno-uninitialized

-Warn if an automatic variable is used without first being initialized
-or if a variable may be clobbered by a @code{setjmp} call. In C++,
-warn if a non-static reference or non-static @code{const} member
-appears in a class without constructors.
+Warn if an automatic variable is used without first being initialized.
+In C++, warn if a non-static reference or non-static @code{const}
+member appears in a class without constructors.

 
 If you want to warn about code that uses the uninitialized value of the
 variable in its own initializer, use the @option{-Winit-self} option.
 
 
 If you want to warn about code that uses the uninitialized value of the
 variable in its own initializer, use the @option{-Winit-self} option.
 

-These warnings occur for individual uninitialized or clobbered
-elements of structure, union or array variables as well as for
-variables that are uninitialized or clobbered as a whole.  They do
-not occur for variables or elements declared @code{volatile}.  Because
-these warnings depend on optimization, the exact variables or elements
-for which there are warnings depends on the precise optimization
-options and version of GCC used.
+These warnings occur for individual uninitialized elements of
+structure, union or array variables as well as for variables that are
+uninitialized as a whole.  They do not occur for variables or elements
+declared @code{volatile}.  Because these warnings depend on
+optimization, the exact variables or elements for which there are
+warnings depend on the precise optimization options and version of GCC
+used.

 
 Note that there may be no warning about a variable that is used only
 to compute a value that itself is never used, because such
 
 Note that there may be no warning about a variable that is used only
 to compute a value that itself is never used, because such


@@ -5797,6 +5822,30 @@ comparisons, so this warning level gives a very large number of
 false positives.
 @end table
 
 false positives.
 @end table
 

+@item -Wstring-compare
+@opindex Wstring-compare
+@opindex Wno-string-compare
+Warn for calls to @code{strcmp} and @code{strncmp} whose result is
+determined to be either zero or non-zero in tests for such equality
+owing to the length of one argument being greater than the size of
+the array the other argument is stored in (or the bound in the case
+of @code{strncmp}).  Such calls could be mistakes.  For example,
+the call to @code{strcmp} below is diagnosed because its result is
+necessarily non-zero irrespective of the contents of the array @code{a}.
+
+@smallexample
+extern char a[4];
+void f (char *d)
+@{
+  strcpy (d, "string");
+  @dots{}
+  if (0 == strcmp (a, d))   // cannot be true
+    puts ("a and d are the same");
+@}
+@end smallexample
+
+@option{-Wstring-compare} is enabled by @option{-Wextra}.
+

 @item -Wstringop-overflow
 @itemx -Wstringop-overflow=@var{type}
 @opindex Wstringop-overflow
 @item -Wstringop-overflow
 @itemx -Wstringop-overflow=@var{type}
 @opindex Wstringop-overflow


@@ -6265,7 +6314,7 @@ can be used to suppress such a warning.
 @opindex Wno-discarded-array-qualifiers
 @opindex Wdiscarded-array-qualifiers
 Do not warn if type qualifiers on arrays which are pointer targets
 @opindex Wno-discarded-array-qualifiers
 @opindex Wdiscarded-array-qualifiers
 Do not warn if type qualifiers on arrays which are pointer targets

-are being discarded. Typically, the compiler warns if a
+are being discarded.  Typically, the compiler warns if a

 @code{const int (*)[]} variable is passed to a function that
 takes a @code{int (*)[]} parameter.  This option can be used to
 suppress such a warning.
 @code{const int (*)[]} variable is passed to a function that
 takes a @code{int (*)[]} parameter.  This option can be used to
 suppress such a warning.


@@ -6286,6 +6335,33 @@ conversions.  This warning is about implicit conversions; for explicit
 conversions the warnings @option{-Wno-int-to-pointer-cast} and
 @option{-Wno-pointer-to-int-cast} may be used.
 
 conversions the warnings @option{-Wno-int-to-pointer-cast} and
 @option{-Wno-pointer-to-int-cast} may be used.
 

+@item -Wzero-length-bounds
+@opindex Wzero-length-bounds
+@opindex Wzero-length-bounds
+Warn about accesses to elements of zero-length array members that might
+overlap other members of the same object.  Declaring interior zero-length
+arrays is discouraged because accesses to them are undefined.  See
+@xref{Zero Length}.
+
+For example, the first two stores in function @code{bad} are diagnosed
+because the array elements overlap the subsequent members @code{b} and
+@code{c}.  The third store is diagnosed by @option{-Warray-bounds}
+because it is beyond the bounds of the enclosing object.
+
+@smallexample
+struct X @{ int a[0]; int b, c; @};
+struct X x;
+
+void bad (void)
+@{
+  x.a[0] = 0;   // -Wzero-length-bounds
+  x.a[1] = 1;   // -Wzero-length-bounds
+  x.a[2] = 2;   // -Warray-bounds
+@}
+@end smallexample
+
+Option @option{-Wzero-length-bounds} is enabled by @option{-Warray-bounds}.
+

 @item -Wno-div-by-zero
 @opindex Wno-div-by-zero
 @opindex Wdiv-by-zero
 @item -Wno-div-by-zero
 @opindex Wno-div-by-zero
 @opindex Wdiv-by-zero


@@ -6464,9 +6540,13 @@ allowed in GCC@.  It is not supported by ISO C90.  @xref{Mixed Declarations}.
 @opindex Wno-shadow
 Warn whenever a local variable or type declaration shadows another
 variable, parameter, type, class member (in C++), or instance variable
 @opindex Wno-shadow
 Warn whenever a local variable or type declaration shadows another
 variable, parameter, type, class member (in C++), or instance variable

-(in Objective-C) or whenever a built-in function is shadowed. Note
+(in Objective-C) or whenever a built-in function is shadowed.  Note

 that in C++, the compiler warns if a local variable shadows an
 explicit typedef, but not if it shadows a struct/class/enum.
 that in C++, the compiler warns if a local variable shadows an
 explicit typedef, but not if it shadows a struct/class/enum.

+If this warning is enabled, it includes also all instances of
+local shadowing.  This means that @option{-Wno-shadow=local}
+and @option{-Wno-shadow=compatible-local} are ignored when
+@option{-Wshadow} is used.

 Same as @option{-Wshadow=global}.
 
 @item -Wno-shadow-ivar @r{(Objective-C only)}
 Same as @option{-Wshadow=global}.
 
 @item -Wno-shadow-ivar @r{(Objective-C only)}


@@ -6476,20 +6556,20 @@ Do not warn whenever a local variable shadows an instance variable in an
 Objective-C method.
 
 @item -Wshadow=global
 Objective-C method.
 
 @item -Wshadow=global

-@opindex Wshadow=local
-The default for @option{-Wshadow}. Warns for any (global) shadowing.
+@opindex Wshadow=global
+Warn for any shadowing.
+Same as @option{-Wshadow}.

 
 @item -Wshadow=local
 @opindex Wshadow=local
 Warn when a local variable shadows another local variable or parameter.
 
 @item -Wshadow=local
 @opindex Wshadow=local
 Warn when a local variable shadows another local variable or parameter.

-This warning is enabled by @option{-Wshadow=global}.

 
 @item -Wshadow=compatible-local
 @opindex Wshadow=compatible-local
 Warn when a local variable shadows another local variable or parameter
 
 @item -Wshadow=compatible-local
 @opindex Wshadow=compatible-local
 Warn when a local variable shadows another local variable or parameter

-whose type is compatible with that of the shadowing variable. In C++,
+whose type is compatible with that of the shadowing variable.  In C++,

 type compatibility here means the type of the shadowing variable can be
 type compatibility here means the type of the shadowing variable can be

-converted to that of the shadowed variable. The creation of this flag
+converted to that of the shadowed variable.  The creation of this flag

 (in addition to @option{-Wshadow=local}) is based on the idea that when
 a local variable shadows another one of incompatible type, it is most
 likely intentional, not a bug or typo, as shown in the following example:
 (in addition to @option{-Wshadow=local}) is based on the idea that when
 a local variable shadows another one of incompatible type, it is most
 likely intentional, not a bug or typo, as shown in the following example:


@@ -6508,14 +6588,15 @@ for (SomeIterator i = SomeObj.begin(); i != SomeObj.end(); ++i)
 @end smallexample
 
 Since the two variable @code{i} in the example above have incompatible types,
 @end smallexample
 
 Since the two variable @code{i} in the example above have incompatible types,

-enabling only @option{-Wshadow=compatible-local} will not emit a warning.
+enabling only @option{-Wshadow=compatible-local} does not emit a warning.

 Because their types are incompatible, if a programmer accidentally uses one
 Because their types are incompatible, if a programmer accidentally uses one

-in place of the other, type checking will catch that and emit an error or
-warning. So not warning (about shadowing) in this case will not lead to
-undetected bugs. Use of this flag instead of @option{-Wshadow=local} can
+in place of the other, type checking is expected to catch that and emit an
+error or warning.  Use of this flag instead of @option{-Wshadow=local} can

 possibly reduce the number of warnings triggered by intentional shadowing.
 possibly reduce the number of warnings triggered by intentional shadowing.

+Note that this also means that shadowing @code{const char *i} by
+@code{char *i} does not emit a warning.

 
 

-This warning is enabled by @option{-Wshadow=local}.
+This warning is also enabled by @option{-Wshadow=local}.

 
 @item -Wlarger-than=@var{byte-size}
 @opindex Wlarger-than=
 
 @item -Wlarger-than=@var{byte-size}
 @opindex Wlarger-than=


@@ -8345,6 +8426,7 @@ also turns on the following optimization flags:
 -ffinite-loops @gol
 -fgcse  -fgcse-lm  @gol
 -fhoist-adjacent-loads @gol
 -ffinite-loops @gol
 -fgcse  -fgcse-lm  @gol
 -fhoist-adjacent-loads @gol

+-finline-functions @gol

 -finline-small-functions @gol
 -findirect-inlining @gol
 -fipa-bit-cp  -fipa-cp  -fipa-icf @gol
 -finline-small-functions @gol
 -findirect-inlining @gol
 -fipa-bit-cp  -fipa-cp  -fipa-icf @gol


@@ -8378,7 +8460,6 @@ by @option{-O2} and also turns on the following optimization flags:
 
 @c Please keep the following list alphabetized!
 @gccoptlist{-fgcse-after-reload @gol
 
 @c Please keep the following list alphabetized!
 @gccoptlist{-fgcse-after-reload @gol

--finline-functions @gol

 -fipa-cp-clone
 -floop-interchange @gol
 -floop-unroll-and-jam @gol
 -fipa-cp-clone
 -floop-interchange @gol
 -floop-unroll-and-jam @gol


@@ -8417,9 +8498,9 @@ designed to reduce code size.
 Disregard strict standards compliance.  @option{-Ofast} enables all
 @option{-O3} optimizations.  It also enables optimizations that are not
 valid for all standard-compliant programs.
 Disregard strict standards compliance.  @option{-Ofast} enables all
 @option{-O3} optimizations.  It also enables optimizations that are not
 valid for all standard-compliant programs.

-It turns on @option{-ffast-math} and the Fortran-specific
-@option{-fstack-arrays}, unless @option{-fmax-stack-var-size} is
-specified, and @option{-fno-protect-parens}.
+It turns on @option{-ffast-math}, @option{-fallow-store-data-races}
+and the Fortran-specific @option{-fstack-arrays}, unless
+@option{-fmax-stack-var-size} is specified, and @option{-fno-protect-parens}.

 
 @item -Og
 @opindex Og
 
 @item -Og
 @opindex Og


@@ -8558,7 +8639,7 @@ If all calls to a given function are integrated, and the function is
 declared @code{static}, then the function is normally not output as
 assembler code in its own right.
 
 declared @code{static}, then the function is normally not output as
 assembler code in its own right.
 

-Enabled at levels @option{-O3}, @option{-Os}.  Also enabled
+Enabled at levels @option{-O2}, @option{-O3}, @option{-Os}.  Also enabled

 by @option{-fprofile-use} and @option{-fauto-profile}.
 
 @item -finline-functions-called-once
 by @option{-fprofile-use} and @option{-fauto-profile}.
 
 @item -finline-functions-called-once


@@ -10181,6 +10262,12 @@ The maximum allowed @var{n} option value is 65536.
 
 Enabled at levels @option{-O2}, @option{-O3}.
 
 
 Enabled at levels @option{-O2}, @option{-O3}.
 

+@item -fallow-store-data-races
+@opindex fallow-store-data-races
+Allow the compiler to introduce new data races on stores.
+
+Enabled at level @option{-Ofast}.
+

 @item -funit-at-a-time
 @opindex funit-at-a-time
 This option is left for compatibility reasons. @option{-funit-at-a-time}
 @item -funit-at-a-time
 @opindex funit-at-a-time
 This option is left for compatibility reasons. @option{-funit-at-a-time}


@@ -10339,6 +10426,14 @@ conflicting translation units.  Specifically
 precedence; and for example @option{-ffp-contract=off} takes precedence
 over @option{-ffp-contract=fast}.  You can override them at link time.
 
 precedence; and for example @option{-ffp-contract=off} takes precedence
 over @option{-ffp-contract=fast}.  You can override them at link time.
 

+To enable debug info generation you need to supply @option{-g} at
+compile-time.  If any of the input files at link time were built
+with debug info generation enabled the link will enable debug info
+generation as well.  Any elaborate debug info settings
+like the dwarf level @option{-gdwarf-5} need to be explicitly repeated
+at the linker command line and mixing different settings in different
+translation units is discouraged.
+

 If LTO encounters objects with C linkage declared with incompatible
 types in separate translation units to be linked together (undefined
 behavior according to ISO C99 6.2.7), a non-fatal diagnostic may be
 If LTO encounters objects with C linkage declared with incompatible
 types in separate translation units to be linked together (undefined
 behavior according to ISO C99 6.2.7), a non-fatal diagnostic may be


@@ -10798,12 +10893,12 @@ Do not allow the built-in functions @code{ceil}, @code{floor},
 double} variants, to generate code that raises the ``inexact''
 floating-point exception for noninteger arguments.  ISO C99 and C11
 allow these functions to raise the ``inexact'' exception, but ISO/IEC
 double} variants, to generate code that raises the ``inexact''
 floating-point exception for noninteger arguments.  ISO C99 and C11
 allow these functions to raise the ``inexact'' exception, but ISO/IEC

-TS 18661-1:2014, the C bindings to IEEE 754-2008, does not allow these
-functions to do so.
+TS 18661-1:2014, the C bindings to IEEE 754-2008, as integrated into
+ISO C2X, does not allow these functions to do so.

 
 The default is @option{-ffp-int-builtin-inexact}, allowing the
 
 The default is @option{-ffp-int-builtin-inexact}, allowing the

-exception to be raised.  This option does nothing unless
-@option{-ftrapping-math} is in effect.
+exception to be raised, unless C2X or a later C standard is selected.
+This option does nothing unless @option{-ftrapping-math} is in effect.

 
 Even if @option{-fno-fp-int-builtin-inexact} is used, if the functions
 generate a call to a library function then the ``inexact'' exception
 
 Even if @option{-fno-fp-int-builtin-inexact} is used, if the functions
 generate a call to a library function then the ``inexact'' exception


@@ -11166,19 +11261,30 @@ when modulo scheduling a loop.  Larger values can exponentially increase
 compilation time.
 
 @item max-inline-insns-single
 compilation time.
 
 @item max-inline-insns-single

-Several parameters control the tree inliner used in GCC@.
-This number sets the maximum number of instructions (counted in GCC's
-internal representation) in a single function that the tree inliner
-considers for inlining.  This only affects functions declared
-inline and methods implemented in a class declaration (C++).
+@item max-inline-insns-single-O2
+Several parameters control the tree inliner used in GCC@.  This number sets the
+maximum number of instructions (counted in GCC's internal representation) in a
+single function that the tree inliner considers for inlining.  This only
+affects functions declared inline and methods implemented in a class
+declaration (C++). 
+
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{max-inline-insns-single} is
+applied. In other cases @option{max-inline-insns-single-O2} is applied.
+

 
 @item max-inline-insns-auto
 
 @item max-inline-insns-auto

+@item max-inline-insns-auto-O2

 When you use @option{-finline-functions} (included in @option{-O3}),
 a lot of functions that would otherwise not be considered for inlining
 by the compiler are investigated.  To those functions, a different
 (more restrictive) limit compared to functions declared inline can
 be applied.
 
 When you use @option{-finline-functions} (included in @option{-O3}),
 a lot of functions that would otherwise not be considered for inlining
 by the compiler are investigated.  To those functions, a different
 (more restrictive) limit compared to functions declared inline can
 be applied.
 

+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{max-inline-insns-auto} is
+applied. In other cases @option{max-inline-insns-auto-O2} is applied.
+

 @item max-inline-insns-small
 This is bound applied to calls which are considered relevant with
 @option{-finline-small-functions}.
 @item max-inline-insns-small
 This is bound applied to calls which are considered relevant with
 @option{-finline-small-functions}.


@@ -11195,17 +11301,34 @@ function prologue and epilogue.
 Extra time accounted by inliner for function overhead such as time needed to
 execute function prologue and epilogue
 
 Extra time accounted by inliner for function overhead such as time needed to
 execute function prologue and epilogue
 

+@item inline-heuristics-hint-percent
+@item inline-heuristics-hint-percent-O2
+The scale (in percents) applied to @option{inline-insns-single},
+@option{inline-insns-single-O2}, @option{inline-insns-auto},
+@option{inline-insns-auto-O2} when inline heuristics hints that inlining is
+very profitable (will enable later optimizations).
+
+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter
+@option{inline-heuristics-hint-percent} is applied. In other cases
+@option{inline-heuristics-hint-percent-O2} is applied.
+

 @item uninlined-thunk-insns
 @item uninlined-thunk-time
 Same as @option{--param uninlined-function-insns} and
 @option{--param uninlined-function-time} but applied to function thunks
 
 @item inline-min-speedup
 @item uninlined-thunk-insns
 @item uninlined-thunk-time
 Same as @option{--param uninlined-function-insns} and
 @option{--param uninlined-function-time} but applied to function thunks
 
 @item inline-min-speedup

+@item inline-min-speedup-O2

 When estimated performance improvement of caller + callee runtime exceeds this
 threshold (in percent), the function can be inlined regardless of the limit on
 @option{--param max-inline-insns-single} and @option{--param
 max-inline-insns-auto}.
 
 When estimated performance improvement of caller + callee runtime exceeds this
 threshold (in percent), the function can be inlined regardless of the limit on
 @option{--param max-inline-insns-single} and @option{--param
 max-inline-insns-auto}.
 

+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{inline-min-speedup} is
+applied. In other cases @option{inline-min-speedup-O2} is applied.
+

 @item large-function-insns
 The limit specifying really large functions.  For functions larger than this
 limit after inlining, inlining is constrained by
 @item large-function-insns
 The limit specifying really large functions.  For functions larger than this
 limit after inlining, inlining is constrained by


@@ -11283,9 +11406,14 @@ via a given call expression.  This parameter limits inlining only to call
 expressions whose probability exceeds the given threshold (in percents).
 
 @item early-inlining-insns
 expressions whose probability exceeds the given threshold (in percents).
 
 @item early-inlining-insns

+@item early-inlining-insns-O2

 Specify growth that the early inliner can make.  In effect it increases
 the amount of inlining for code having a large abstraction penalty.
 
 Specify growth that the early inliner can make.  In effect it increases
 the amount of inlining for code having a large abstraction penalty.
 

+For functions compiled with optimization levels
+@option{-O3} and @option{-Ofast} parameter @option{early-inlining-insns} is
+applied. In other cases @option{early-inlining-insns-O2} is applied.
+

 @item max-early-inliner-iterations
 Limit of iterations of the early inliner.  This basically bounds
 the number of nested indirect calls the early inliner can resolve.
 @item max-early-inliner-iterations
 Limit of iterations of the early inliner.  This basically bounds
 the number of nested indirect calls the early inliner can resolve.


@@ -11861,6 +11989,11 @@ parameters only when their cumulative size is less or equal to
 @option{ipa-sra-ptr-growth-factor} times the size of the original
 pointer parameter.
 
 @option{ipa-sra-ptr-growth-factor} times the size of the original
 pointer parameter.
 

+@item ipa-sra-max-replacements
+Maximum pieces of an aggregate that IPA-SRA tracks.  As a
+consequence, it is also the maximum number of replacements of a formal
+parameter.
+

 @item sra-max-scalarization-size-Ospeed
 @itemx sra-max-scalarization-size-Osize
 The two Scalar Reduction of Aggregates passes (SRA and IPA-SRA) aim to
 @item sra-max-scalarization-size-Ospeed
 @itemx sra-max-scalarization-size-Osize
 The two Scalar Reduction of Aggregates passes (SRA and IPA-SRA) aim to


@@ -11929,6 +12062,19 @@ not spend too much time analyzing huge functions, it gives up and
 consider all memory clobbered after examining
 @option{ipa-max-aa-steps} statements modifying memory.
 
 consider all memory clobbered after examining
 @option{ipa-max-aa-steps} statements modifying memory.
 

+@item ipa-max-switch-predicate-bounds
+Maximal number of boundary endpoints of case ranges of switch statement.
+For switch exceeding this limit, IPA-CP will not construct cloning cost
+predicate, which is used to estimate cloning benefit, for default case
+of the switch statement.
+
+@item ipa-max-param-expr-ops
+IPA-CP will analyze conditional statement that references some function
+parameter to estimate benefit for cloning upon certain constant value.
+But if number of operations in a parameter expression exceeds
+@option{ipa-max-param-expr-ops}, the expression is treated as complicated
+one, and is not handled by IPA analysis.
+

 @item lto-partitions
 Specify desired number of partitions produced during WHOPR compilation.
 The number of partitions should exceed the number of CPUs used for compilation.
 @item lto-partitions
 Specify desired number of partitions produced during WHOPR compilation.
 The number of partitions should exceed the number of CPUs used for compilation.


@@ -11962,10 +12108,6 @@ The maximum number of conditional store pairs that can be sunk.  Set to 0
 if either vectorization (@option{-ftree-vectorize}) or if-conversion
 (@option{-ftree-loop-if-convert}) is disabled.
 
 if either vectorization (@option{-ftree-vectorize}) or if-conversion
 (@option{-ftree-loop-if-convert}) is disabled.
 

-@item allow-store-data-races
-Allow optimizers to introduce new data races on stores.
-Set to 1 to allow, otherwise to 0.
-

 @item case-values-threshold
 The smallest number of different values for which it is best to use a
 jump-table instead of a tree of conditional branches.  If the value is
 @item case-values-threshold
 The smallest number of different values for which it is best to use a
 jump-table instead of a tree of conditional branches.  If the value is


@@ -15860,6 +16002,19 @@ be used by the compiler when expanding calls to
 @code{__builtin_speculation_safe_copy} to permit a more efficient code
 sequence to be generated.
 
 @code{__builtin_speculation_safe_copy} to permit a more efficient code
 sequence to be generated.
 

+@item -moutline-atomics
+@itemx -mno-outline-atomics
+Enable or disable calls to out-of-line helpers to implement atomic operations.
+These helpers will, at runtime, determine if the LSE instructions from
+ARMv8.1-A can be used; if not, they will use the load/store-exclusive
+instructions that are present in the base ARMv8.0 ISA.
+
+This option is only applicable when compiling for the base ARMv8.0
+instruction set.  If using a later revision, e.g. @option{-march=armv8.1-a}
+or @option{-march=armv8-a+lse}, the ARMv8.1-Atomics instructions will be
+used directly.  The same applies when using @option{-mcpu=} when the
+selected cpu supports the @samp{lse} feature.
+

 @item -march=@var{name}
 @opindex march
 Specify the name of the target architecture and, optionally, one or
 @item -march=@var{name}
 @opindex march
 Specify the name of the target architecture and, optionally, one or


@@ -23079,8 +23234,33 @@ The ISA and hardware multiply supported for the different MCUs is hard-coded
 into GCC.  However, an external @samp{devices.csv} file can be used to
 extend device support beyond those that have been hard-coded.
 
 into GCC.  However, an external @samp{devices.csv} file can be used to
 extend device support beyond those that have been hard-coded.
 

-GCC searches for the @samp{devices.csv} file on the paths specified
-with the @code{-I} and @code{-L} options.
+GCC searches for the @samp{devices.csv} file using the following methods in the
+given precedence order, where the first method takes precendence over the
+second which takes precedence over the third.
+
+@table @asis
+@item Include path specified with @code{-I} and @code{-L}
+@samp{devices.csv} will be searched for in each of the directories specified by
+include paths and linker library search paths.
+@item Path specified by the environment variable @samp{MSP430_GCC_INCLUDE_DIR}
+Define the value of the global environment variable
+@samp{MSP430_GCC_INCLUDE_DIR}
+to the full path to the directory containing devices.csv, and GCC will search
+this directory for devices.csv.  If devices.csv is found, this directory will
+also be registered as an include path, and linker library path.  Header files
+and linker scripts in this directory can therefore be used without manually
+specifying @code{-I} and @code{-L} on the command line.
+@item The @samp{msp430-elf/include/devices} directory
+Finally, GCC will examine @samp{msp430-elf/include/devices} from the
+toolchain root directory.  This directory does not exist in a default
+installation, but if the user has created it and copied @samp{devices.csv}
+there, then the MCU data will be read.  As above, this directory will
+also be registered as an include path, and linker library path.
+
+@end table
+If none of the above search methods find @samp{devices.csv}, then the
+hard-coded MCU data is used.
+

 
 @item -mwarn-mcu
 @itemx -mno-warn-mcu
 
 @item -mwarn-mcu
 @itemx -mno-warn-mcu


@@ -23146,6 +23326,19 @@ initializers or constructors.  This is intended for memory-constrained
 devices.  The compiler includes special symbols in some objects
 that tell the linker and runtime which code fragments are required.
 
 devices.  The compiler includes special symbols in some objects
 that tell the linker and runtime which code fragments are required.
 

+@item -mtiny-printf
+@opindex mtiny-printf
+Enable reduced code size @code{printf} and @code{puts} library functions.
+The @samp{tiny} implementations of these functions are not reentrant, so
+must be used with caution in multi-threaded applications.
+
+Support for streams has been removed and the string to be printed will
+always be sent to stdout via the @code{write} syscall.  The string is not
+buffered before it is sent to write.
+
+This option requires Newlib Nano IO, so GCC must be configured with
+@samp{--enable-newlib-nano-formatted-io}.
+

 @item -mcode-region=
 @itemx -mdata-region=
 @opindex mcode-region
 @item -mcode-region=
 @itemx -mdata-region=
 @opindex mcode-region