[ARC] Update EH code.

Our ABI says the blink is pushed first on stack followed by an unknown
number of register saves, and finally by fp.  Hence we cannot use the
EH_RETURN_ADDRESS macro as the stack is not finalized at that moment.
The alternative is to use the eh_return pattern and to initialize all
the bits after register allocation when the stack layout is finalized.

gcc/
xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>

	* config/arc/arc.c (arc_eh_return_address_location): Repurpose it
	to fit the eh_return pattern.
	* config/arc/arc.md (eh_return): Define.
	(VUNSPEC_ARC_EH_RETURN): Likewise.
	* config/arc/arc-protos.h (arc_eh_return_address_location): Match
	new implementation.
	* config/arc/arc.h (EH_RETURN_HANDLER_RTX): Remove it.

testsuite/
xxxx-xx-xx  Claudiu Zissulescu  <claziss@synopsys.com>

	* gcc.target/arc/builtin_eh.c: New test.

From-SVN: r266066

4 files changed, 24 insertions, 8 deletions

diff --git a/gcc/config/arc/arc-protos.h b/gcc/config/arc/arc-protos.h
index e653f7f..a9de6d5 100644
--- a/gcc/config/arc/arc-protos.h
+++ b/gcc/config/arc/arc-protos.h
@@ -109,7 +109,7 @@ extern bool arc_legitimize_reload_address (rtx *, machine_mode, int, int);
 extern void arc_secondary_reload_conv (rtx, rtx, rtx, bool);
 extern void arc_cpu_cpp_builtins (cpp_reader *);
 extern bool arc_store_addr_hazard_p (rtx_insn *, rtx_insn *);
-extern rtx arc_eh_return_address_location (void);
+extern void arc_eh_return_address_location (rtx);
 extern bool arc_is_jli_call_p (rtx);
 extern void arc_file_end (void);
 extern bool arc_is_secure_call_p (rtx);
diff --git a/gcc/config/arc/arc.c b/gcc/config/arc/arc.c
index 75c2384..dbe6ff5 100644
--- a/gcc/config/arc/arc.c
+++ b/gcc/config/arc/arc.c
@@ -3947,10 +3947,13 @@ arc_check_multi (rtx op, bool push_p)
 /* Return rtx for the location of the return address on the stack,
    suitable for use in __builtin_eh_return.  The new return address
    will be written to this location in order to redirect the return to
-   the exception handler.  */
+   the exception handler.  Our ABI says the blink is pushed first on
+   stack followed by an unknown number of register saves, and finally
+   by fp.  Hence we cannot use the EH_RETURN_ADDRESS macro as the
+   stack is not finalized.  */
 
-rtx
-arc_eh_return_address_location (void)
+void
+arc_eh_return_address_location (rtx source)
 {
   rtx mem;
   int offset;
@@ -3978,8 +3981,8 @@ arc_eh_return_address_location (void)
      remove this store seems perfectly sensible.  Marking the memory
      address as volatile obviously has the effect of preventing DSE
      from removing the store.  */
-  MEM_VOLATILE_P (mem) = 1;
-  return mem;
+  MEM_VOLATILE_P (mem) = true;
+  emit_move_insn (mem, source);
 }
 
 /* PIC */
diff --git a/gcc/config/arc/arc.h b/gcc/config/arc/arc.h
index 58d66d7..6e9b1e5 100644
--- a/gcc/config/arc/arc.h
+++ b/gcc/config/arc/arc.h
@@ -1391,8 +1391,6 @@ do { \
 
 #define EH_RETURN_STACKADJ_RTX   gen_rtx_REG (Pmode, 2)
 
-#define EH_RETURN_HANDLER_RTX    arc_eh_return_address_location ()
-
 /* Turn off splitting of long stabs.  */
 #define DBX_CONTIN_LENGTH 0
 
diff --git a/gcc/config/arc/arc.md b/gcc/config/arc/arc.md
index dc0a65c..8302362 100644
--- a/gcc/config/arc/arc.md
+++ b/gcc/config/arc/arc.md
@@ -163,6 +163,7 @@
   VUNSPEC_ARC_SC
   VUNSPEC_ARC_LL
   VUNSPEC_ARC_BLOCKAGE
+  VUNSPEC_ARC_EH_RETURN
   ])
 
 (define_constants
@@ -6608,6 +6609,20 @@ core_3, archs4x, archs4xd, archs4xd_slow"
   [(set_attr "type" "call_no_delay_slot")
    (set_attr "length" "2")])
 
+;; Patterns for exception handling
+(define_insn_and_split "eh_return"
+  [(unspec_volatile [(match_operand:SI 0 "register_operand" "r")]
+		    VUNSPEC_ARC_EH_RETURN)]
+  ""
+  "#"
+  "reload_completed"
+  [(const_int 0)]
+  "
+  {
+    arc_eh_return_address_location (operands[0]);
+    DONE;
+  }"
+)
 ;; include the arc-FPX instructions
 (include "fpx.md")