diff options
Diffstat (limited to 'gcc')
| -rw-r--r-- | gcc/ada/ChangeLog | 48 | ||||
| -rw-r--r-- | gcc/ada/gnat_rm.texi | 13 | ||||
| -rw-r--r-- | gcc/ada/gnat_ugn.texi | 66 |
3 files changed, 103 insertions, 24 deletions
diff --git a/gcc/ada/ChangeLog b/gcc/ada/ChangeLog index eda7458..3d047f0 100644 --- a/gcc/ada/ChangeLog +++ b/gcc/ada/ChangeLog @@ -1,5 +1,53 @@ 2008-08-08 Thomas Quinot <quinot@adacore.com> + * gsocket.h: + On Windows, include <errno.h> and redefine only selected errno values + from their <winsock2.h> definitions. + + * s-osinte-freebsd.ads: Minor reformatting + + * s-osinte-hpux.ads, s-osinte-irix.ads: Minor reformatting + + * g-soccon.ads: New file. + + * g-stheme.adb, g-socthi-vms.adb, g-socthi-vxworks.adb, + g-socthi-mingw.adb, g-sttsne-vxworks.adb, g-socthi.adb, + g-stsifd-sockets.adb, g-socket.adb, g-socket.ads, + g-sothco.adb, g-sothco.ads: Add back GNAT.Sockets.Constants as a child + unit, to allow building software that depends on this internal unit + with both older and newer compilers. + +2008-08-08 Robert Dewar <dewar@adacore.com> + + * s-strxdr.adb: Minor reformatting + +2008-08-08 Bob Duff <duff@adacore.com> + + * gnat_ugn.texi: The "Run-Time Checks" section said "arithmetic overflow + checking for integer operations (including division by zero)", which + is wrong -- divide by zero is not part of overflow checking. + Also added misc clarification about what check-suppression means. + + * gnat_rm.texi: Clarify the meaning of pragma Suppress. + +2008-08-08 Jerome Lambourg <lambourg@adacore.com> + + * g-comlin.adb (Add_Switch): Handle addition of switches at the + begining of the command line. + (Append, Add): Renaming of Append to Add as this now allows addition + at the begining of the list. + + * g-comlin.ads (Add_Switch): Handle addition of switches at the + begining of the command line. + +2008-08-08 Thomas Quinot <quinot@adacore.com> + + * g-sercom.ads: + (Name): Document application scope (only legacy PC serial ports on + Linux and Windows). + +2008-08-08 Thomas Quinot <quinot@adacore.com> + * gcc-interface/Makefile.in, gcc-interface/Make-lang.in: Revert previous change, not needed after all. diff --git a/gcc/ada/gnat_rm.texi b/gcc/ada/gnat_rm.texi index 29c1aec..a768528 100644 --- a/gcc/ada/gnat_rm.texi +++ b/gcc/ada/gnat_rm.texi @@ -3413,7 +3413,7 @@ Syntax: @smallexample @c ada pragma Obsolescent - (Entity => NAME [, static_string_EXPRESSION [,Ada_05]]); + [(Entity => NAME [, static_string_EXPRESSION [,Ada_05]])]; @end smallexample @noindent @@ -4447,6 +4447,17 @@ on addresses used in address clauses. Such checks can also be suppressed by suppressing range checks, but the specific use of @code{Alignment_Check} allows suppression of alignment checks without suppressing other range checks. +Note that pragma Suppress gives the compiler permission to omit +checks, but does not require the compiler to omit checks. The compiler +will generate checks if they are essentially free, even when they are +suppressed. In particular, if the compiler can prove that a certain +check will necessarily fail, it will generate code to do an +unconditional ``raise'', even if checks are suppressed. The compiler +warns in this case. + +Of course, run-time checks are omitted whenever the compiler can prove +that they will not fail, whether or not checks are suppressed. + @node Pragma Suppress_All @unnumberedsec Pragma Suppress_All @findex Suppress_All diff --git a/gcc/ada/gnat_ugn.texi b/gcc/ada/gnat_ugn.texi index 3c5d287..5918edd 100644 --- a/gcc/ada/gnat_ugn.texi +++ b/gcc/ada/gnat_ugn.texi @@ -4022,12 +4022,12 @@ catches that cannot be dealt with in the front-end. @item -gnato @cindex @option{-gnato} (@command{gcc}) Enable numeric overflow checking (which is not normally enabled by -default). Not that division by zero is a separate check that is not +default). Note that division by zero is a separate check that is not controlled by this switch (division by zero checking is on by default). @item -gnatp @cindex @option{-gnatp} (@command{gcc}) -Suppress all checks. +Suppress all checks. See @ref{Run-Time Checks} for details. @item -gnatP @cindex @option{-gnatP} (@command{gcc}) @@ -6222,14 +6222,11 @@ clears any previously set style checks. @cindex Checks, stack overflow checking @noindent -If you compile with the default options, GNAT will insert many run-time -checks into the compiled code, including code that performs range -checking against constraints, but not arithmetic overflow checking for -integer operations (including division by zero), checks for access -before elaboration on subprogram calls, or stack overflow checking. All -other run-time checks, as required by the Ada Reference Manual, are -generated by default. The following @command{gcc} switches refine this -default behavior: +By default, the following checks are suppressed: integer overflow +checks, stack overflow checks, and checks for access before +elaboration on subprogram calls. All other checks, including range +checks and array bounds checks, are turned on by default. The +following @command{gcc} switches refine this default behavior. @table @option @c !sort! @@ -6238,13 +6235,33 @@ default behavior: @cindex Suppressing checks @cindex Checks, suppressing @findex Suppress -Suppress all run-time checks as though @code{pragma Suppress (all_checks}) +Suppress all run-time checks as though @code{pragma Suppress (All_checks)} had been present in the source. Validity checks are also suppressed (in other words @option{-gnatp} also implies @option{-gnatVn}. Use this switch to improve the performance of the code at the expense of safety in the presence of invalid data or program bugs. +Note that when checks are suppressed, the compiler is allowed, but not +required, to omit the checking code. If the run-time cost of the +checking code is zero or near-zero, the compiler will generate it even +if checks are suppressed. In particular, if the compiler can prove +that a certain check will necessarily fail, it will generate code to +do an unconditional ``raise'', even if checks are suppressed. The +compiler warns in this case. + +Of course, run-time checks are omitted whenever the compiler can prove +that they will not fail, whether or not checks are suppressed. + +Note that if you suppress a check that would have failed, program +execution is erroneous, which means the behavior is totally +unpredictable. The program might crash, or print wrong answers, or +do anything else. It might even do exactly what you wanted it to do +(and then it might start failing mysteriously next week or next +year). The compiler will generate code based on the assumption that +the condition being checked is true, which can result in disaster if +that assumption is wrong. + @item -gnato @cindex @option{-gnato} (@command{gcc}) @cindex Overflow checks @@ -6271,22 +6288,23 @@ X4 := Integer (F); @end smallexample @noindent -Note that if explicit values are assigned at compile time, the compiler may -be able to detect overflow at compile time, in which case no run-time check -is required, and the setting of -gnato is irrelevant. That's why the assigned -values in the above fragment are in quotes, the meaning is "assign a value -not known to the compiler that happens to be equal to ...". The remaining -discussion assumes that the compiler cannot detect the values at compile time. +Note that if explicit values are assigned at compile time, the +compiler may be able to detect overflow at compile time, in which case +no actual run-time checking code is required, and Constraint_Error +will be raised unconditionally, with or without +@option{-gnato}. That's why the assigned values in the above fragment +are in quotes, the meaning is "assign a value not known to the +compiler that happens to be equal to ...". The remaining discussion +assumes that the compiler cannot detect the values at compile time. Here the first addition results in a value that is outside the base range of Integer, and hence requires an overflow check for detection of the constraint error. Thus the first assignment to @code{X1} raises a @code{Constraint_Error} exception only if @option{-gnato} is set. -The second increment operation results in a violation -of the explicit range constraint, and such range checks are always -performed (unless specifically suppressed with a pragma @code{suppress} -or the use of @option{-gnatp}). +The second increment operation results in a violation of the explicit +range constraint; such range checks are performed by default, and are +unaffected by @option{-gnato}. The two conversions of @code{F} both result in values that are outside the base range of type @code{Integer} and thus will raise @@ -6342,6 +6360,8 @@ explicitly use the -gnato switch either on the @command{gnatmake} or @cindex Check, elaboration Enables dynamic checks for access-before-elaboration on subprogram calls and generic instantiations. +Note that @option{-gnatE} is not necessary for safety, because in the +default mode, GNAT ensures statically that the checks would not fail. For full details of the effect and use of this switch, @xref{Compiling Using gcc}. @@ -9548,8 +9568,8 @@ some guidelines on debugging optimized code. @subsection Controlling Run-Time Checks @noindent -By default, GNAT generates all run-time checks, except arithmetic overflow -checking for integer operations and checks for access before elaboration on +By default, GNAT generates all run-time checks, except integer overflow +checks, stack overflow checks, and checks for access before elaboration on subprogram calls. The latter are not required in default mode, because all necessary checking is done at compile time. @cindex @option{-gnatp} (@command{gcc}) |