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| author | Geoff Keating <geoffk@cygnus.com> | 1999-08-18 10:43:26 +0000 |
|---|---|---|
| committer | Geoffrey Keating <geoffk@gcc.gnu.org> | 1999-08-18 10:43:26 +0000 |
| commit | 312f625598f2eed11718c43a649027bc760ef30a (patch) | |
| tree | 4fb0b080db23c76c2853dadb847aff9aa64d9dc6 /gcc/invoke.texi | |
| parent | 075ff1b238e01efca6c3a0dc6ddd82046fda4c5a (diff) | |
| download | gcc-312f625598f2eed11718c43a649027bc760ef30a.zip gcc-312f625598f2eed11718c43a649027bc760ef30a.tar.gz gcc-312f625598f2eed11718c43a649027bc760ef30a.tar.bz2 | |
cse.c (cse_insn): Call never_reached_warning when a jump is changed to be unconditional.
* cse.c (cse_insn): Call never_reached_warning when a jump is
changed to be unconditional.
* flags.h: Declare warn_notreached.
* flow.c (delete_block): Call never_reached_warning when
a block is deleted.
* jump.c (delete_barrier_successors): Call never_reached_warning
when we delete everything after a BARRIER.
(never_reached_warning): New function.
* rtl.h: Declare never_reached_warning.
* toplev.c (warn_notreached): New variable.
(lang_independent_options): Set warn_notreached
when -Wunreachable-code.
(compile_file): We need line numbers for -Wunreachable-code.
Also modify documentation to suit.
From-SVN: r28747
Diffstat (limited to 'gcc/invoke.texi')
| -rw-r--r-- | gcc/invoke.texi | 25 |
1 files changed, 23 insertions, 2 deletions
diff --git a/gcc/invoke.texi b/gcc/invoke.texi index b707cdb..7dadd3f 100644 --- a/gcc/invoke.texi +++ b/gcc/invoke.texi @@ -132,8 +132,8 @@ in the following sections. -Wparentheses -Wpointer-arith -Wredundant-decls -Wreturn-type -Wshadow -Wsign-compare -Wstrict-prototypes -Wswitch -Wtraditional --Wtrigraphs -Wundef -Wuninitialized -Wunused -Wwrite-strings --Wunknown-pragmas +-Wtrigraphs -Wundef -Wuninitialized -Wunknown-pragmas -Wunreachable-code +-Wunused -Wwrite-strings @end smallexample @item Debugging Options @@ -1766,6 +1766,27 @@ cases where multiple declaration is valid and changes nothing. @item -Wnested-externs Warn if an @code{extern} declaration is encountered within an function. +@item -Wunreachable-code +Warn if the compiler detects that code will never be executed. + +This option is intended to warn when the compiler detects that at +least a whole line of source code will never be executed, because +some condition is never satisfied or because it is after a +procedure that never returns. + +It is possible for this option to produce a warning even though there +are circumstances under which part of the affected line can be executed, +so care should be taken when removing apparently-unreachable code. + +For instance, when a function is inlined, a warning may mean that the +line is unreachable in only one inlined copy of the function. + +This option is not made part of @samp{-Wall} because in a debugging +version of a program there is often substantial code which checks +correct functioning of the program and is, hopefully, unreachable +because the program does work. Another common use of unreachable +code is to provide behaviour which is selectable at compile-time. + @item -Winline Warn if a function can not be inlined, and either it was declared as inline, or else the @samp{-finline-functions} option was given. |