c-common.c (enum attrs): Add A_NO_LIMIT_STACK.

* c-common.c (enum attrs): Add A_NO_LIMIT_STACK.
(init_attributes): Add A_NO_LIMIT_STACK.
(decl_attributes): Handle A_NO_LIMIT_STACK.
* c-decl.c (duplicate_decls): Handle DECL_NO_LIMIT_STACK.
* explow.c (allocate_dynamic_stack_space) [!HAVE_allocate_stack]:
Handle stack bounds checking.
* flags.h (flag_stack_check): Use the word 'probe' rather than
'check', because the flag doesn't actually cause any checking to
be done.
* function.c (expand_function_start): Set
current_function_limit_stack.
* function.h (struct function): Add limit_stack.
(current_function_limit_stack): Define.
* invoke.texi (Code Gen Options): Document new options.
* rtl.h: Declare stack_limit_rtx.
* toplev.c (stack_limit_rtx): New variable.
(decode_f_option): Handle new options -fstack-limit-register=REG,
-fstack-limit-symbol=IDENT, -fno-stack-limit.
(main): Add stack_limit_rtx as GC root.
* tree.h (DECL_NO_LIMIT_STACK): New macro.
(struct tree_decl): New member no_limit_stack.

* config/rs6000/rs6000.c (rs6000_allocate_stack_space): Handle
stack_limit_rtx.
* config/rs6000/rs6000.md (allocate_stack): Handle stack_limit_rtx.
(conditional_trap+1): Get new mnemonic correct.
(conditional_trap+2): New pattern for DImode traps.

* config/m68k/m68k.c (output_function_prologue): Handle
stack_limit_rtx.
* config/m68k/m68k.md (trap): New insn.
(conditional_trap): New insn.
* md.texi (Standard Names): Document `trap' and
`conditional_trap'.
* optabs.c (gen_cond_trap): Use start_sequence()/end_sequence()
so a cc0 setter doesn't get emitted at some random place in the
function.

* config/i960/i960.md (trap): New insn.
(conditional_trap): New expander.
(conditional_trap+1, conditional_trap+2): New insns for signed
and unsigned cases.
* config/i960/i960.c (i960_function_prologue): Use
STARTING_FRAME_OFFSET.  Handle stack_limit_rtx.

Co-Authored-By: Greg McGary <gkm@gnu.org>

From-SVN: r30771

1 files changed, 20 insertions, 0 deletions

diff --git a/gcc/invoke.texi b/gcc/invoke.texi
index ea90467..5e4eb75 100644
--- a/gcc/invoke.texi
+++ b/gcc/invoke.texi
@@ -439,6 +439,7 @@ in the following sections.
 -freg-struct-return  -fshared-data  -fshort-enums
 -fshort-double  -fvolatile  -fvolatile-global -fvolatile-static
 -fverbose-asm -fpack-struct  -fstack-check
+-fstack-limit-register=@var{reg}  -fstack-limit-symbol=@var{sym}
 -fargument-alias  -fargument-noalias
 -fargument-noalias-global
 -fleading-underscore
@@ -7085,6 +7086,25 @@ environment with multiple threads, but only rarely need to specify it in
 a single-threaded environment since stack overflow is automatically
 detected on nearly all systems if there is only one stack.
 
+Note that this switch does not actually cause checking to be done; the
+operating system must do that.  The switch causes generation of code
+to ensure that the operating system sees the stack being extended.
+
+@item -fstack-limit-register=@var{reg}
+@itemx -fstack-limit-symbol=@var{sym}
+@itemx -fno-stack-limit
+Generate code to ensure that the stack does not grow beyond a certain value,
+either the value of a register or the address of a symbol.  If the stack
+would grow beyond the value, a signal is raised.  For most targets,
+the signal is raised before the stack overruns the boundary, so
+it is possible to catch the signal without taking special precautions.
+
+For instance, if the stack starts at address @samp{0x80000000} and grows
+downwards you can use the flags
+@samp{-fstack-limit-symbol=__stack_limit}
+@samp{-Wl,--defsym,__stack_limit=0x7ffe0000} which will enforce a stack
+limit of 128K.
+
 @cindex aliasing of parameters
 @cindex parameters, aliased
 @item -fargument-alias