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Diffstat (limited to 'gcc/doc/tm.texi')
| -rw-r--r-- | gcc/doc/tm.texi | 49 |
1 files changed, 32 insertions, 17 deletions
diff --git a/gcc/doc/tm.texi b/gcc/doc/tm.texi index 5decc331bd4..9b4a921883f 100644 --- a/gcc/doc/tm.texi +++ b/gcc/doc/tm.texi @@ -3376,38 +3376,49 @@ linkage is necessary. The default is @code{0}. @node Stack Checking @subsection Specifying How Stack Checking is Done -GCC will check that stack references are within the boundaries of -the stack, if the @option{-fstack-check} is specified, in one of three ways: +GCC will check that stack references are within the boundaries of the +stack, if the option @option{-fstack-check} is specified, in one of +three ways: @enumerate @item If the value of the @code{STACK_CHECK_BUILTIN} macro is nonzero, GCC -will assume that you have arranged for stack checking to be done at -appropriate places in the configuration files, e.g., in -@code{TARGET_ASM_FUNCTION_PROLOGUE}. GCC will do not other special -processing. +will assume that you have arranged for full stack checking to be done +at appropriate places in the configuration files. GCC will not do +other special processing. @item -If @code{STACK_CHECK_BUILTIN} is zero and you defined a named pattern -called @code{check_stack} in your @file{md} file, GCC will call that -pattern with one argument which is the address to compare the stack -value against. You must arrange for this pattern to report an error if -the stack pointer is out of range. +If @code{STACK_CHECK_BUILTIN} is zero and the value of the +@code{STACK_CHECK_STATIC_BUILTIN} macro is nonzero, GCC will assume +that you have arranged for static stack checking (checking of the +static stack frame of functions) to be done at appropriate places +in the configuration files. GCC will only emit code to do dynamic +stack checking (checking on dynamic stack allocations) using the third +approach below. @item If neither of the above are true, GCC will generate code to periodically ``probe'' the stack pointer using the values of the macros defined below. @end enumerate -Normally, you will use the default values of these macros, so GCC -will use the third approach. +If neither STACK_CHECK_BUILTIN nor STACK_CHECK_STATIC_BUILTIN is defined, +GCC will change its allocation strategy for large objects if the option +@option{-fstack-check} is specified: they will always be allocated +dynamically if their size exceeds @code{STACK_CHECK_MAX_VAR_SIZE} bytes. @defmac STACK_CHECK_BUILTIN A nonzero value if stack checking is done by the configuration files in a machine-dependent manner. You should define this macro if stack checking -is require by the ABI of your machine or if you would like to have to stack -checking in some more efficient way than GCC's portable approach. -The default value of this macro is zero. +is require by the ABI of your machine or if you would like to do stack +checking in some more efficient way than the generic approach. The default +value of this macro is zero. +@end defmac + +@defmac STACK_CHECK_STATIC_BUILTIN +A nonzero value if static stack checking is done by the configuration files +in a machine-dependent manner. You should define this macro if you would +like to do static stack checking in some more efficient way than the generic +approach. The default value of this macro is zero. @end defmac @defmac STACK_CHECK_PROBE_INTERVAL @@ -3418,7 +3429,7 @@ default value of 4096 is suitable for most systems. @end defmac @defmac STACK_CHECK_PROBE_LOAD -A integer which is nonzero if GCC should perform the stack probe +An integer which is nonzero if GCC should perform the stack probe as a load instruction and zero if GCC should use a store instruction. The default is zero, which is the most efficient choice on most systems. @end defmac @@ -3429,6 +3440,10 @@ for languages where such a recovery is supported. The default value of 75 words should be adequate for most machines. @end defmac +The following macros are relevant only if neither STACK_CHECK_BUILTIN +nor STACK_CHECK_STATIC_BUILTIN is defined; you can omit them altogether +in the opposite case. + @defmac STACK_CHECK_MAX_FRAME_SIZE The maximum size of a stack frame, in bytes. GCC will generate probe instructions in non-leaf functions to ensure at least this many bytes of |