[NDS32] Refine prologue and epilogue code generation.

gcc/
	* config/nds32/nds32.c (nds32_compute_stack_frame,
	nds32_emit_stack_push_multiple, nds32_emit_stack_pop_multiple,
	nds32_emit_stack_v3push, nds32_emit_stack_v3pop,
	nds32_emit_adjust_frame, nds32_expand_prologue, nds32_expand_epilogue,
	nds32_expand_prologue_v3push, nds32_expand_epilogue_v3pop): Refine.
	* config/nds32/nds32.h (NDS32_FIRST_CALLEE_SAVE_GPR_REGNUM,
	NDS32_LAST_CALLEE_SAVE_GPR_REGNUM, NDS32_V3PUSH_AVAILABLE_P): New.
	* config/nds32/nds32.md (prologue, epilogue): Use macro
	NDS32_V3PUSH_AVAILABLE_P to do checking.

Co-Authored-By: Chung-Ju Wu <jasonwucj@gmail.com>
Co-Authored-By: Kito Cheng <kito.cheng@gmail.com>

From-SVN: r258442

gcc/ChangeLog

+2018-03-11  Monk Chiang  <sh.chiang04@gmail.com>
+	    Kito Cheng  <kito.cheng@gmail.com>
+	    Chung-Ju Wu  <jasonwucj@gmail.com>
+
+	* config/nds32/nds32.c (nds32_compute_stack_frame,
+	nds32_emit_stack_push_multiple, nds32_emit_stack_pop_multiple,
+	nds32_emit_stack_v3push, nds32_emit_stack_v3pop,
+	nds32_emit_adjust_frame, nds32_expand_prologue, nds32_expand_epilogue,
+	nds32_expand_prologue_v3push, nds32_expand_epilogue_v3pop): Refine.
+	* config/nds32/nds32.h (NDS32_FIRST_CALLEE_SAVE_GPR_REGNUM,
+	NDS32_LAST_CALLEE_SAVE_GPR_REGNUM, NDS32_V3PUSH_AVAILABLE_P): New.
+	* config/nds32/nds32.md (prologue, epilogue): Use macro
+	NDS32_V3PUSH_AVAILABLE_P to do checking.
+
 2018-03-11  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/58150

gcc/config/nds32/nds32.h

@@ -130,6 +130,10 @@ enum nds32_16bit_address_type
 /* Define the last integer register number.  */
 #define NDS32_LAST_GPR_REGNUM 31
 
+#define NDS32_FIRST_CALLEE_SAVE_GPR_REGNUM 6
+#define NDS32_LAST_CALLEE_SAVE_GPR_REGNUM \
+  (TARGET_REDUCED_REGS ? 10 : 14)
+
 /* Define double word alignment bits.  */
 #define NDS32_DOUBLE_WORD_ALIGNMENT 64
 
@@ -196,6 +200,19 @@ enum nds32_16bit_address_type
 #define NDS32_REQUIRED_CALLEE_SAVED_P(regno)                  \
   ((!call_used_regs[regno]) && (df_regs_ever_live_p (regno)))
 
+/* This macro is to check if the push25/pop25 are available to be used
+   for code generation.  Because pop25 also performs return behavior,
+   the instructions may not be available for some cases.
+   If we want to use push25/pop25, all the following conditions must
+   be satisfied:
+     1. TARGET_V3PUSH is set.
+     2. Current function is not an ISR function.
+     3. Current function is not a variadic function.*/
+#define NDS32_V3PUSH_AVAILABLE_P  \
+  (TARGET_V3PUSH \
+   && !nds32_isr_function_p (current_function_decl) \
+   && (cfun->machine->va_args_size == 0))
+
 /* ------------------------------------------------------------------------ */
 
 /* A C structure for machine-specific, per-function data.

gcc/config/nds32/nds32.md

@@ -2093,11 +2093,8 @@ create_template:
   ""
 {
   /* Note that only under V3/V3M ISA, we could use v3push prologue.
-     In addition, we do not want to use v3push for isr function
-     and variadic function.  */
-  if (TARGET_V3PUSH
-      && !nds32_isr_function_p (current_function_decl)
-      && (cfun->machine->va_args_size == 0))
+     In addition, we need to check if v3push is indeed available.  */
+  if (NDS32_V3PUSH_AVAILABLE_P)
     nds32_expand_prologue_v3push ();
   else
     nds32_expand_prologue ();
@@ -2108,11 +2105,8 @@ create_template:
   ""
 {
   /* Note that only under V3/V3M ISA, we could use v3pop epilogue.
-     In addition, we do not want to use v3pop for isr function
-     and variadic function.  */
-  if (TARGET_V3PUSH
-      && !nds32_isr_function_p (current_function_decl)
-      && (cfun->machine->va_args_size == 0))
+     In addition, we need to check if v3push is indeed available.  */
+  if (NDS32_V3PUSH_AVAILABLE_P)
     nds32_expand_epilogue_v3pop (false);
   else
     nds32_expand_epilogue (false);
@@ -2125,10 +2119,7 @@ create_template:
   /* Pass true to indicate that this is sibcall epilogue and
      exit from a function without the final branch back to the
      calling function.  */
-  if (TARGET_V3PUSH && !nds32_isr_function_p (current_function_decl))
-    nds32_expand_epilogue_v3pop (true);
-  else
-    nds32_expand_epilogue (true);
+  nds32_expand_epilogue (true);
 
   DONE;
 })