rs6000.c (ALWAYS_RESTORE_ALTIVEC_BEFORE_POP): Define.

	* config/rs6000/rs6000.c (ALWAYS_RESTORE_ALTIVEC_BEFORE_POP): Define.
	(rs6000_emit_epilogue): Use backchain to restore only when we
	have a large frame.  Make use of frame pointer to restore if we
	have one.  Handle ALWAYS_RESTORE_ALTIVEC_BEFORE_POP.

From-SVN: r134816

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 2e29305b423f341640f51131d297496f414e19cb..e62a91a69fae26fe5c6846538c54a79a39f77889 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,10 @@
+2008-04-30  Alan Modra  <amodra@bigpond.net.au>
+
+       * config/rs6000/rs6000.c (ALWAYS_RESTORE_ALTIVEC_BEFORE_POP): Define.
+       (rs6000_emit_epilogue): Use backchain to restore only when we
+       have a large frame.  Make use of frame pointer to restore if we
+       have one.  Handle ALWAYS_RESTORE_ALTIVEC_BEFORE_POP.
+
 2008-04-29  Paolo Bonzini  <bonzini@gnu.org>
 
        * config/avr/avr.md (*sbrx_branch, *sbix_branch, *sbix_branch_tmp):

diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c
index ec9f83173d43934b7d354dc53c7307318a04f59a..20cfe95b95d00326ba8ba4427dc7ffa0542208b5 100644 (file)
--- a/gcc/config/rs6000/rs6000.c
+++ b/gcc/config/rs6000/rs6000.c
@@ -1,6 +1,6 @@
 /* Subroutines used for code generation on IBM RS/6000.
    Copyright (C) 1991, 1993, 1994, 1995, 1996, 1997, 1998, 1999,
-   2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007
+   2000, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008
    Free Software Foundation, Inc.
    Contributed by Richard Kenner (kenner@vlsi1.ultra.nyu.edu)
 
@@ -16244,6 +16244,10 @@ rs6000_output_function_prologue (FILE *file,
   rs6000_pic_labelno++;
 }
 
+/* Non-zero if vmx regs are restored before the frame pop, zero if
+   we restore after the pop when possible.  */
+#define ALWAYS_RESTORE_ALTIVEC_BEFORE_POP 0
+
 /* Emit function epilogue as insns.
 
    At present, dwarf2out_frame_debug_expr doesn't understand
@@ -16283,13 +16287,18 @@ rs6000_emit_epilogue (int sibcall)
                           || crtl->calls_eh_return
                           || info->first_fp_reg_save == 64
                           || FP_SAVE_INLINE (info->first_fp_reg_save));
-  use_backchain_to_restore_sp = (frame_pointer_needed
-                                || cfun->calls_alloca
-                                || info->total_size > 32767);
   using_mtcr_multiple = (rs6000_cpu == PROCESSOR_PPC601
                         || rs6000_cpu == PROCESSOR_PPC603
                         || rs6000_cpu == PROCESSOR_PPC750
                         || optimize_size);
+  /* Restore via the backchain when we have a large frame, since this
+     is more efficient than an addis, addi pair.  The second condition
+     here will not trigger at the moment;  We don't actually need a
+     frame pointer for alloca, but the generic parts of the compiler
+     give us one anyway.  */
+  use_backchain_to_restore_sp = (info->total_size > 32767
+                                || (cfun->calls_alloca
+                                    && !frame_pointer_needed));
 
   if (WORLD_SAVE_P (info))
     {
@@ -16390,8 +16399,9 @@ rs6000_emit_epilogue (int sibcall)
      stack.  */
   if (TARGET_ALTIVEC_ABI
       && info->altivec_size != 0
-      && DEFAULT_ABI != ABI_V4
-      && info->altivec_save_offset < (TARGET_32BIT ? -220 : -288))
+      && (ALWAYS_RESTORE_ALTIVEC_BEFORE_POP
+         || (DEFAULT_ABI != ABI_V4
+             && info->altivec_save_offset < (TARGET_32BIT ? -220 : -288))))
     {
       int i;
 
@@ -16402,6 +16412,8 @@ rs6000_emit_epilogue (int sibcall)
                          gen_rtx_MEM (Pmode, sp_reg_rtx));
          sp_offset = 0;
        }
+      else if (frame_pointer_needed)
+       frame_reg_rtx = hard_frame_pointer_rtx;
 
       for (i = info->first_altivec_reg_save; i <= LAST_ALTIVEC_REGNO; ++i)
        if (info->vrsave_mask & ALTIVEC_REG_BIT (i))
@@ -16426,18 +16438,23 @@ rs6000_emit_epilogue (int sibcall)
   if (TARGET_ALTIVEC
       && TARGET_ALTIVEC_VRSAVE
       && info->vrsave_mask != 0
-      && DEFAULT_ABI != ABI_V4
-      && info->vrsave_save_offset < (TARGET_32BIT ? -220 : -288))
+      && (ALWAYS_RESTORE_ALTIVEC_BEFORE_POP
+         || (DEFAULT_ABI != ABI_V4
+             && info->vrsave_save_offset < (TARGET_32BIT ? -220 : -288))))
     {
       rtx addr, mem, reg;
 
-      if (use_backchain_to_restore_sp
-         && frame_reg_rtx == sp_reg_rtx)
+      if (frame_reg_rtx == sp_reg_rtx)
        {
-         frame_reg_rtx = gen_rtx_REG (Pmode, 11);
-         emit_move_insn (frame_reg_rtx,
-                         gen_rtx_MEM (Pmode, sp_reg_rtx));
-         sp_offset = 0;
+         if (use_backchain_to_restore_sp)
+           {
+             frame_reg_rtx = gen_rtx_REG (Pmode, 11);
+             emit_move_insn (frame_reg_rtx,
+                             gen_rtx_MEM (Pmode, sp_reg_rtx));
+             sp_offset = 0;
+           }
+         else if (frame_pointer_needed)
+           frame_reg_rtx = hard_frame_pointer_rtx;
        }
 
       addr = gen_rtx_PLUS (Pmode, frame_reg_rtx,
@@ -16449,17 +16466,11 @@ rs6000_emit_epilogue (int sibcall)
       emit_insn (generate_set_vrsave (reg, info, 1));
     }
 
-  /* If we have a frame pointer, a call to alloca,  or a large stack
-     frame, restore the old stack pointer using the backchain.  Otherwise,
-     we know what size to update it with.  */
+  /* If we have a large stack frame, restore the old stack pointer
+     using the backchain.  */
   if (use_backchain_to_restore_sp)
     {
-      if (frame_reg_rtx != sp_reg_rtx)
-       {
-         emit_move_insn (sp_reg_rtx, frame_reg_rtx);
-         frame_reg_rtx = sp_reg_rtx;
-       }
-      else
+      if (frame_reg_rtx == sp_reg_rtx)
        {
          /* Under V.4, don't reset the stack pointer until after we're done
             loading the saved registers.  */
@@ -16470,6 +16481,30 @@ rs6000_emit_epilogue (int sibcall)
                          gen_rtx_MEM (Pmode, sp_reg_rtx));
          sp_offset = 0;
        }
+      else if (ALWAYS_RESTORE_ALTIVEC_BEFORE_POP
+              && DEFAULT_ABI == ABI_V4)
+       /* frame_reg_rtx has been set up by the altivec restore.  */
+       ;
+      else
+       {
+         emit_move_insn (sp_reg_rtx, frame_reg_rtx);
+         frame_reg_rtx = sp_reg_rtx;
+       }
+    }
+  /* If we have a frame pointer, we can restore the old stack pointer
+     from it.  */
+  else if (frame_pointer_needed)
+    {
+      frame_reg_rtx = sp_reg_rtx;
+      if (DEFAULT_ABI == ABI_V4)
+       frame_reg_rtx = gen_rtx_REG (Pmode, 11);
+
+      emit_insn (TARGET_32BIT
+                ? gen_addsi3 (frame_reg_rtx, hard_frame_pointer_rtx,
+                              GEN_INT (info->total_size))
+                : gen_adddi3 (frame_reg_rtx, hard_frame_pointer_rtx,
+                              GEN_INT (info->total_size)));
+      sp_offset = 0;
     }
   else if (info->push_p
           && DEFAULT_ABI != ABI_V4
@@ -16484,7 +16519,8 @@ rs6000_emit_epilogue (int sibcall)
     }
 
   /* Restore AltiVec registers if we have not done so already.  */
-  if (TARGET_ALTIVEC_ABI
+  if (!ALWAYS_RESTORE_ALTIVEC_BEFORE_POP
+      && TARGET_ALTIVEC_ABI
       && info->altivec_size != 0
       && (DEFAULT_ABI == ABI_V4
          || info->altivec_save_offset >= (TARGET_32BIT ? -220 : -288)))
@@ -16511,7 +16547,8 @@ rs6000_emit_epilogue (int sibcall)
     }
 
   /* Restore VRSAVE if we have not done so already.  */
-  if (TARGET_ALTIVEC
+  if (!ALWAYS_RESTORE_ALTIVEC_BEFORE_POP
+      && TARGET_ALTIVEC
       && TARGET_ALTIVEC_VRSAVE
       && info->vrsave_mask != 0
       && (DEFAULT_ABI == ABI_V4