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path: root/packages/gcc/gcc-3.3.3/arm-ldm.dpatch
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#! /bin/sh -e

src=gcc
if [ $# -eq 3 -a "$2" = '-d' ]; then
    pdir="-d $3"
    src=$3/gcc
elif [ $# -ne 1 ]; then
    echo >&2 "`basename $0`: script expects -patch|-unpatch as argument"
    exit 1
fi
case "$1" in
    -patch)
        patch $pdir -f --no-backup-if-mismatch -p0 --fuzz 10 < $0
        ;;
    -unpatch)
        patch $pdir -f --no-backup-if-mismatch -R -p0 --fuzz 10 < $0
        ;;
    *)
        echo >&2 "`basename $0`: script expects -patch|-unpatch as argument"
        exit 1
esac
exit 0

# DP: try harder to avoid ldm in function epilogues

--- gcc/config/arm/arm.c	Fri Mar  5 18:49:42 2004
+++ gcc/config/arm/arm.c	Fri Mar  5 16:00:21 2004
@@ -7598,6 +7629,26 @@
   return_used_this_function = 0;  
 }
 
+/* Return the number (counting from 0) of
+   the least significant set bit in MASK.  */
+
+#ifdef __GNUC__
+inline
+#endif
+static int
+number_of_first_bit_set (mask)
+     int mask;
+{
+  int bit;
+
+  for (bit = 0;
+       (mask & (1 << bit)) == 0;
+       ++bit)
+    continue;
+
+  return bit;
+}
+
 const char *
 arm_output_epilogue (really_return)
      int really_return;
@@ -7788,27 +7839,47 @@
 	  saved_regs_mask |=   (1 << PC_REGNUM);
 	}
 
-      /* Load the registers off the stack.  If we only have one register
-	 to load use the LDR instruction - it is faster.  */
-      if (saved_regs_mask == (1 << LR_REGNUM))
-	{
-	  /* The exception handler ignores the LR, so we do
-	     not really need to load it off the stack.  */
-	  if (eh_ofs)
-	    asm_fprintf (f, "\tadd\t%r, %r, #4\n", SP_REGNUM, SP_REGNUM);
-	  else
-	    asm_fprintf (f, "\tldr\t%r, [%r], #4\n", LR_REGNUM, SP_REGNUM);
-	}
-      else if (saved_regs_mask)
+      if (saved_regs_mask)
 	{
-	  if (saved_regs_mask & (1 << SP_REGNUM))
-	    /* Note - write back to the stack register is not enabled
-	       (ie "ldmfd sp!...").  We know that the stack pointer is
-	       in the list of registers and if we add writeback the
-	       instruction becomes UNPREDICTABLE.  */
-	    print_multi_reg (f, "ldmfd\t%r", SP_REGNUM, saved_regs_mask);
+	  /* Load the registers off the stack.  If we only have one register
+	     to load use the LDR instruction - it is faster.  */
+	  if (bit_count (saved_regs_mask) == 1)
+	    {
+	      int reg = number_of_first_bit_set (saved_regs_mask);
+
+	      switch (reg)
+		{
+		case SP_REGNUM:
+		  /* Mustn't use base writeback when loading SP.  */
+		  asm_fprintf (f, "\tldr\t%r, [%r]\n", SP_REGNUM, SP_REGNUM);
+		  break;
+		  
+		case LR_REGNUM:
+		  if (eh_ofs)
+		    {
+		      /* The exception handler ignores the LR, so we do
+			 not really need to load it off the stack.  */
+		      asm_fprintf (f, "\tadd\t%r, %r, #4\n", SP_REGNUM, SP_REGNUM);
+		      break;
+		    }
+		  /* else fall through */
+		  
+		default:
+		  asm_fprintf (f, "\tldr\t%r, [%r], #4\n", reg, SP_REGNUM);
+		  break;
+		}
+	    }
 	  else
-	    print_multi_reg (f, "ldmfd\t%r!", SP_REGNUM, saved_regs_mask);
+	    {
+	      if (saved_regs_mask & (1 << SP_REGNUM))
+		/* Note - write back to the stack register is not enabled
+		   (ie "ldmfd sp!...").  We know that the stack pointer is
+		   in the list of registers and if we add writeback the
+		   instruction becomes UNPREDICTABLE.  */
+		print_multi_reg (f, "ldmfd\t%r", SP_REGNUM, saved_regs_mask);
+	      else
+		print_multi_reg (f, "ldmfd\t%r!", SP_REGNUM, saved_regs_mask);
+	    }
 	}
 
       if (current_function_pretend_args_size)
@@ -9610,26 +9677,6 @@
     }
 }
 
-/* Return the number (counting from 0) of
-   the least significant set bit in MASK.  */
-
-#ifdef __GNUC__
-inline
-#endif
-static int
-number_of_first_bit_set (mask)
-     int mask;
-{
-  int bit;
-
-  for (bit = 0;
-       (mask & (1 << bit)) == 0;
-       ++bit)
-    continue;
-
-  return bit;
-}
-
 /* Generate code to return from a thumb function.
    If 'reg_containing_return_addr' is -1, then the return address is
    actually on the stack, at the stack pointer.  */