re PR middle-end/65958 (-fstack-check breaks alloca on architectures using generic stack checking)

	PR middle-end/65958
	* config/arm/linux-elf.h (STACK_CHECK_STATIC_BUILTIN): Define.
	* config/arm/arm-protos.h (output_probe_stack_range): Declare.
	* config/arm/arm.c: Include common/common-target.h.
	(use_return_insn): Return 0 if the static chain register was saved
	above a non-APCS frame.
	(arm_compute_static_chain_stack_bytes): Adjust for stack checking.
	(struct scratch_reg): New.
	(get_scratch_register_on_entry): New function.
	(release_scratch_register_on_entry): Likewise.
	(arm_emit_probe_stack_range): Likewise.
	(output_probe_stack_range): Likewise.
	(arm_expand_prologue): Factor out code dealing with the IP register
	for nested function and adjust it for stack checking.
	Invoke arm_emit_probe_stack_range if static builtin stack checking
	is enabled.
	(thumb1_expand_prologue): Sorry out if static builtin stack checking
	is enabled.
	(arm_expand_epilogue): Add the saved static chain register, if any, to
	the amount of pre-pushed registers to pop.
	(arm_frame_pointer_required): Return true if static stack checking is
	enabled and we want to catch the exception with the EABI unwinder.
	* config/arm/unspecs.md (UNSPEC_PROBE_STACK): New constant.
	(UNSPEC_PROBE_STACK_RANGE): Likewise.
	* config/arm/arm.md (probe_stack): New insn.
	(probe_stack_range): Likewise.

From-SVN: r227860

gcc/ChangeLog

+2015-09-17  Eric Botcazou  <ebotcazou@adacore.com>
+
+	PR middle-end/65958
+	* config/arm/linux-elf.h (STACK_CHECK_STATIC_BUILTIN): Define.
+	* config/arm/arm-protos.h (output_probe_stack_range): Declare.
+	* config/arm/arm.c: Include common/common-target.h.
+	(use_return_insn): Return 0 if the static chain register was saved
+	above a non-APCS frame.
+	(arm_compute_static_chain_stack_bytes): Adjust for stack checking.
+	(struct scratch_reg): New.
+	(get_scratch_register_on_entry): New function.
+	(release_scratch_register_on_entry): Likewise.
+	(arm_emit_probe_stack_range): Likewise.
+	(output_probe_stack_range): Likewise.
+	(arm_expand_prologue): Factor out code dealing with the IP register
+	for nested function and adjust it for stack checking.
+	Invoke arm_emit_probe_stack_range if static builtin stack checking
+	is enabled.
+	(thumb1_expand_prologue): Sorry out if static builtin stack checking
+	is enabled.
+	(arm_expand_epilogue): Add the saved static chain register, if any, to
+	the amount of pre-pushed registers to pop.
+	(arm_frame_pointer_required): Return true if static stack checking is
+	enabled and we want to catch the exception with the EABI unwinder.
+	* config/arm/unspecs.md (UNSPEC_PROBE_STACK): New constant.
+	(UNSPEC_PROBE_STACK_RANGE): Likewise.
+	* config/arm/arm.md (probe_stack): New insn.
+	(probe_stack_range): Likewise.
+
 2015-09-17  Richard Biener  <rguenther@suse.de>
 
 	* genmatch.c (parser::parse_expr): Improve error message

gcc/config/arm/arm-protos.h

@@ -146,6 +146,7 @@ extern const char *output_add_immediate (rtx *);
 extern const char *arithmetic_instr (rtx, int);
 extern void output_ascii_pseudo_op (FILE *, const unsigned char *, int);
 extern const char *output_return_instruction (rtx, bool, bool, bool);
+extern const char *output_probe_stack_range (rtx, rtx);
 extern void arm_poke_function_name (FILE *, const char *);
 extern void arm_final_prescan_insn (rtx_insn *);
 extern int arm_debugger_arg_offset (int, rtx);

gcc/config/arm/arm.md

@@ -8259,6 +8259,30 @@
    (set_attr "type" "block")]
 )
 
+(define_insn "probe_stack"
+  [(set (match_operand 0 "memory_operand" "=m")
+        (unspec [(const_int 0)] UNSPEC_PROBE_STACK))]
+  "TARGET_32BIT"
+{
+  return "str%?\\tr0, %0";
+}
+  [(set_attr "type" "store1")
+   (set_attr "predicable" "yes")]
+)
+
+(define_insn "probe_stack_range"
+  [(set (match_operand:SI 0 "register_operand" "=r")
+	(unspec_volatile:SI [(match_operand:SI 1 "register_operand" "0")
+			     (match_operand:SI 2 "register_operand" "r")]
+			     UNSPEC_PROBE_STACK_RANGE))]
+  "TARGET_32BIT"
+{
+  return output_probe_stack_range (operands[0], operands[2]);
+}
+  [(set_attr "type" "multiple")
+   (set_attr "conds" "clob")]
+)
+
 (define_expand "casesi"
   [(match_operand:SI 0 "s_register_operand" "")	; index to jump on
    (match_operand:SI 1 "const_int_operand" "")	; lower bound

gcc/config/arm/linux-elf.h

@@ -124,3 +124,6 @@
    to COPY relocated symbol in the executable.  See PR65780.  */
 #undef TARGET_BINDS_LOCAL_P
 #define TARGET_BINDS_LOCAL_P default_binds_local_p_2
+
+/* Define this to be nonzero if static stack checking is supported.  */
+#define STACK_CHECK_STATIC_BUILTIN 1

gcc/config/arm/unspecs.md

@@ -83,6 +83,8 @@
                         ; FPSCR rounding mode and signal inexactness.
   UNSPEC_VRINTA         ; Represent a float to integral float rounding
                         ; towards nearest, ties away from zero.
+  UNSPEC_PROBE_STACK    ; Probe stack memory reference
+  UNSPEC_PROBE_STACK_RANGE ; Probe stack range
 ])
 
 (define_c_enum "unspec" [

gcc/testsuite/ChangeLog

+2015-09-17  Eric Botcazou  <ebotcazou@adacore.com>
+
+	* gcc.target/arm/stack-checking.c: New test.
+
 2015-09-17  Paul Thomas  <pault@gcc.gnu.org>
 
 	PR fortran/52846

gcc/testsuite/gcc.target/arm/stack-checking.c

+/* { dg-do run { target { *-*-linux* } } } */
+/* { dg-options "-fstack-check" } */
+
+int main(void)
+{
+  char *p;
+  if (1)
+    {
+      char i[48];
+      p = __builtin_alloca(8);
+      p[0] = 1;
+    }
+
+  if (1)
+    {
+      char i[48], j[64];
+      j[48] = 0;
+    }
+
+  return !p[0];
+}