Re: [PATCH] Support multiple registers for the frame pointer

[Kwok Cheung Yeung]

On 04/11/2019 08:02 pm, Dimitar Dimitrov wrote:
On Sat, 2 Nov 2019, 19:28:38 EET Kwok Cheung Yeung wrote:
diff --git a/gcc/ira.c b/gcc/ira.c
index 9f8da67..25e9359 100644
--- a/gcc/ira.c
+++ b/gcc/ira.c
@@ -515,7 +515,13 @@ setup_alloc_regs (bool use_hard_frame_p)
   #endif
     no_unit_alloc_regs = fixed_nonglobal_reg_set;
     if (! use_hard_frame_p)
-    SET_HARD_REG_BIT (no_unit_alloc_regs, HARD_FRAME_POINTER_REGNUM);
+    {
+      int fp_reg_count = hard_regno_nregs (HARD_FRAME_POINTER_REGNUM,
Pmode);
+      for (int reg = HARD_FRAME_POINTER_REGNUM;
+          reg < HARD_FRAME_POINTER_REGNUM + fp_reg_count;
+          reg++)
+       SET_HARD_REG_BIT (no_unit_alloc_regs, reg);
+    }
Please consider using the existing helper function instead:
    add_to_hard_reg_set (&no_unit_alloc_regs, Pmode, reg);

Thank you for the suggestion - I have applied the change. As Vladimir 
has already given his approval for the patch, I will commit it later 
today if there are no objections.

Best regards

Kwok Yeung


    Add support for using multiple registers to hold the frame pointer

    2019-11-06  Kwok Cheung Yeung  <k...@codesourcery.com>

        gcc/
        * ira.c (setup_alloc_regs): Setup no_unit_alloc_regs for
        frame pointer in multiple registers.
        (ira_setup_eliminable_regset): Setup eliminable_regset,
        ira_no_alloc_regs and regs_ever_live for frame pointer in
        multiple registers.

diff --git a/gcc/ira.c b/gcc/ira.c
index 9f8da67..5df9953 100644
--- a/gcc/ira.c
+++ b/gcc/ira.c
@@ -515,7 +515,8 @@ setup_alloc_regs (bool use_hard_frame_p)
 #endif
   no_unit_alloc_regs = fixed_nonglobal_reg_set;
   if (! use_hard_frame_p)
-    SET_HARD_REG_BIT (no_unit_alloc_regs, HARD_FRAME_POINTER_REGNUM);
+    add_to_hard_reg_set (&no_unit_alloc_regs, Pmode,
+                        HARD_FRAME_POINTER_REGNUM);
   setup_class_hard_regs ();
 }

@@ -2248,6 +2249,7 @@ ira_setup_eliminable_regset (void)
 {
   int i;
   static const struct {const int from, to; } eliminables[] = 
ELIMINABLE_REGS;
+  int fp_reg_count = hard_regno_nregs (HARD_FRAME_POINTER_REGNUM, Pmode);

   /* Setup is_leaf as frame_pointer_required may use it.  This function
      is called by sched_init before ira if scheduling is enabled.  */
@@ -2276,7 +2278,8 @@ ira_setup_eliminable_regset (void)
        frame pointer in LRA.  */

   if (frame_pointer_needed)
-    df_set_regs_ever_live (HARD_FRAME_POINTER_REGNUM, true);
+    for (i = 0; i < fp_reg_count; i++)
+      df_set_regs_ever_live (HARD_FRAME_POINTER_REGNUM + i, true);

   ira_no_alloc_regs = no_unit_alloc_regs;
   CLEAR_HARD_REG_SET (eliminable_regset);
@@ -2306,17 +2309,21 @@ ira_setup_eliminable_regset (void)
     }
   if (!HARD_FRAME_POINTER_IS_FRAME_POINTER)
     {
-      if (!TEST_HARD_REG_BIT (crtl->asm_clobbers, 
HARD_FRAME_POINTER_REGNUM))
-       {
-         SET_HARD_REG_BIT (eliminable_regset, HARD_FRAME_POINTER_REGNUM);
-         if (frame_pointer_needed)
-           SET_HARD_REG_BIT (ira_no_alloc_regs, HARD_FRAME_POINTER_REGNUM);
-       }
-      else if (frame_pointer_needed)
-       error ("%s cannot be used in %<asm%> here",
-              reg_names[HARD_FRAME_POINTER_REGNUM]);
-      else
-       df_set_regs_ever_live (HARD_FRAME_POINTER_REGNUM, true);
+      for (i = 0; i < fp_reg_count; i++)
+       if (!TEST_HARD_REG_BIT (crtl->asm_clobbers,
+                               HARD_FRAME_POINTER_REGNUM + i))
+         {
+           SET_HARD_REG_BIT (eliminable_regset,
+                             HARD_FRAME_POINTER_REGNUM + i);
+           if (frame_pointer_needed)
+             SET_HARD_REG_BIT (ira_no_alloc_regs,
+                               HARD_FRAME_POINTER_REGNUM + i);
+         }
+       else if (frame_pointer_needed)
+         error ("%s cannot be used in %<asm%> here",
+                reg_names[HARD_FRAME_POINTER_REGNUM + i]);
+       else
+         df_set_regs_ever_live (HARD_FRAME_POINTER_REGNUM + i, true);
     }
 }