re PR target/42895 (Low registers are preferred than register ip in thumb2 mode)

	PR target/42895
	* doc/tm.texi (ADJUST_REG_ALLOC_ORDER): Renamed from
	ORDER_REGS_FOR_LOCAL_ALLOC.  All instances of this macro changed.
	(HONOR_REG_ALLOC_ORDER): Describe new macro.
	* ira.c (setup_alloc_regs): Use ADJUST_REG_ALLOC_ORDER if defined.
	* ira-color.c (assign_hard_reg): Take prologue/epilogue costs into
	account only if HONOR_REG_ALLOC_ORDER is not defined.
	* config/arm/arm.h (HONOR_REG_ALLOC_ORDER): Define.
	* system.h (ORDER_REGS_FOR_LOCAL_ALLOC): Poison.

From-SVN: r158911

gcc/ChangeLog

+2010-04-29  Bernd Schmidt  <bernds@codesourcery.com>
+
+	PR target/42895
+	* doc/tm.texi (ADJUST_REG_ALLOC_ORDER): Renamed from
+	ORDER_REGS_FOR_LOCAL_ALLOC.  All instances of this macro changed.
+	(HONOR_REG_ALLOC_ORDER): Describe new macro.
+	* ira.c (setup_alloc_regs): Use ADJUST_REG_ALLOC_ORDER if defined.
+	* ira-color.c (assign_hard_reg): Take prologue/epilogue costs into
+	account only if HONOR_REG_ALLOC_ORDER is not defined.
+	* config/arm/arm.h (HONOR_REG_ALLOC_ORDER): Define.
+	* system.h (ORDER_REGS_FOR_LOCAL_ALLOC): Poison.
+	
 2010-04-29  Jon Grant <04@jguk.org>
 	
 	* collect2.c (vflag): Change type from int to bool.

gcc/config/arm/arm.h

@@ -1121,7 +1121,11 @@ extern int arm_structure_size_boundary;
 }
 
 /* Use different register alloc ordering for Thumb.  */
-#define ORDER_REGS_FOR_LOCAL_ALLOC arm_order_regs_for_local_alloc ()
+#define ADJUST_REG_ALLOC_ORDER arm_order_regs_for_local_alloc ()
+
+/* Tell IRA to use the order we define rather than messing it up with its
+   own cost calculations.  */
+#define HONOR_REG_ALLOC_ORDER
 
 /* Interrupt functions can only use registers that have already been
    saved by the prologue, even if they would normally be

gcc/config/avr/avr.h

@@ -232,7 +232,7 @@ extern GTY(()) section *progmem_section;
     32,33,34,35					\
     }
 
-#define ORDER_REGS_FOR_LOCAL_ALLOC order_regs_for_local_alloc ()
+#define ADJUST_REG_ALLOC_ORDER order_regs_for_local_alloc ()
 
 
 #define HARD_REGNO_NREGS(REGNO, MODE) ((GET_MODE_SIZE (MODE) + UNITS_PER_WORD - 1) / UNITS_PER_WORD)

gcc/config/i386/i386.h

@@ -955,7 +955,7 @@ enum target_cpu_default
    registers listed in CALL_USED_REGISTERS, keeping the others
    available for storage of persistent values.
 
-   The ORDER_REGS_FOR_LOCAL_ALLOC actually overwrite the order,
+   The ADJUST_REG_ALLOC_ORDER actually overwrite the order,
    so this is just empty initializer for array.  */
 
 #define REG_ALLOC_ORDER 					\
@@ -964,11 +964,11 @@ enum target_cpu_default
    33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47,  \
    48, 49, 50, 51, 52 }
 
-/* ORDER_REGS_FOR_LOCAL_ALLOC is a macro which permits reg_alloc_order
+/* ADJUST_REG_ALLOC_ORDER is a macro which permits reg_alloc_order
    to be rearranged based on a particular function.  When using sse math,
    we want to allocate SSE before x87 registers and vice versa.  */
 
-#define ORDER_REGS_FOR_LOCAL_ALLOC x86_order_regs_for_local_alloc ()
+#define ADJUST_REG_ALLOC_ORDER x86_order_regs_for_local_alloc ()
 
 
 #define OVERRIDE_ABI_FORMAT(FNDECL) ix86_call_abi_override (FNDECL)

gcc/config/mips/mips.h

@@ -2059,12 +2059,12 @@ enum reg_class
   182,183,184,185,186,187						\
 }
 
-/* ORDER_REGS_FOR_LOCAL_ALLOC is a macro which permits reg_alloc_order
+/* ADJUST_REG_ALLOC_ORDER is a macro which permits reg_alloc_order
    to be rearranged based on a particular function.  On the mips16, we
    want to allocate $24 (T_REG) before other registers for
    instructions for which it is possible.  */
 
-#define ORDER_REGS_FOR_LOCAL_ALLOC mips_order_regs_for_local_alloc ()
+#define ADJUST_REG_ALLOC_ORDER mips_order_regs_for_local_alloc ()
 
 /* True if VALUE is an unsigned 6-bit number.  */
 

gcc/config/picochip/picochip.h

@@ -261,7 +261,7 @@ extern enum picochip_dfa_type picochip_schedule_type;
 /* We can dynamically change the REG_ALLOC_ORDER using the following hook.
    It would be desirable to change it for leaf functions so we can put
    r12 at the end of this list.*/
-#define ORDER_REGS_FOR_LOCAL_ALLOC picochip_order_regs_for_local_alloc ()
+#define ADJUST_REG_ALLOC_ORDER picochip_order_regs_for_local_alloc ()
 
 /* How Values Fit in Registers  */
 

gcc/config/sparc/sparc.h

@@ -1181,7 +1181,7 @@ extern enum reg_class sparc_regno_reg_class[FIRST_PSEUDO_REGISTER];
   96, 97, 98, 99,			/* %fcc0-3 */	\
   100, 0, 14, 30, 31, 101}		/* %icc, %g0, %o6, %i6, %i7, %sfp */
 
-#define ORDER_REGS_FOR_LOCAL_ALLOC order_regs_for_local_alloc ()
+#define ADJUST_REG_ALLOC_ORDER order_regs_for_local_alloc ()
 
 extern char sparc_leaf_regs[];
 #define LEAF_REGISTERS sparc_leaf_regs

gcc/config/xtensa/xtensa.h

@@ -286,7 +286,7 @@ extern unsigned xtensa_current_frame_size;
    incoming argument in a2 is live throughout the function and
    local-alloc decides to use a2, then the incoming argument must
    either be spilled or copied to another register.  To get around
-   this, we define ORDER_REGS_FOR_LOCAL_ALLOC to redefine
+   this, we define ADJUST_REG_ALLOC_ORDER to redefine
    reg_alloc_order for leaf functions such that lowest numbered
    registers are used first with the exception that the incoming
    argument registers are not used until after other register choices
@@ -300,7 +300,7 @@ extern unsigned xtensa_current_frame_size;
   35, \
 }
 
-#define ORDER_REGS_FOR_LOCAL_ALLOC order_regs_for_local_alloc ()
+#define ADJUST_REG_ALLOC_ORDER order_regs_for_local_alloc ()
 
 /* For Xtensa, the only point of this is to prevent GCC from otherwise
    giving preference to call-used registers.  To minimize window

gcc/doc/tm.texi

@@ -2092,7 +2092,7 @@ machines, define @code{REG_ALLOC_ORDER} to be an initializer that lists
 the highest numbered allocable register first.
 @end defmac
 
-@defmac ORDER_REGS_FOR_LOCAL_ALLOC
+@defmac ADJUST_REG_ALLOC_ORDER
 A C statement (sans semicolon) to choose the order in which to allocate
 hard registers for pseudo-registers local to a basic block.
 
@@ -2106,6 +2106,15 @@ The macro body should not assume anything about the contents of
 On most machines, it is not necessary to define this macro.
 @end defmac
 
+@defmac HONOR_REG_ALLOC_ORDER
+Normally, IRA tries to estimate the costs for saving a register in the
+prologue and restoring it in the epilogue.  This discourages it from
+using call-saved registers.  If a machine wants to ensure that IRA
+allocates registers in the order given by REG_ALLOC_ORDER even if some
+call-saved registers appear earlier than call-used ones, this macro
+should be defined.
+@end defmac
+
 @defmac IRA_HARD_REGNO_ADD_COST_MULTIPLIER (@var{regno})
 In some case register allocation order is not enough for the
 Integrated Register Allocator (@acronym{IRA}) to generate a good code.

gcc/ira-color.c

@@ -586,6 +586,7 @@ assign_hard_reg (ira_allocno_t allocno, bool retry_p)
 	continue;
       cost = costs[i];
       full_cost = full_costs[i];
+#ifndef HONOR_REG_ALLOC_ORDER
       if (! allocated_hardreg_p[hard_regno]
 	  && ira_hard_reg_not_in_set_p (hard_regno, mode, call_used_reg_set))
 	/* We need to save/restore the hard register in
@@ -598,6 +599,7 @@ assign_hard_reg (ira_allocno_t allocno, bool retry_p)
 	  cost += add_cost;
 	  full_cost += add_cost;
 	}
+#endif
       if (min_cost > cost)
 	min_cost = cost;
       if (min_full_cost > full_cost)

gcc/ira.c

@@ -431,9 +431,6 @@ setup_class_hard_regs (void)
   HARD_REG_SET processed_hard_reg_set;
 
   ira_assert (SHRT_MAX >= FIRST_PSEUDO_REGISTER);
-  /* We could call ORDER_REGS_FOR_LOCAL_ALLOC here (it is usually
-     putting hard callee-used hard registers first).  But our
-     heuristics work better.  */
   for (cl = (int) N_REG_CLASSES - 1; cl >= 0; cl--)
     {
       COPY_HARD_REG_SET (temp_hard_regset, reg_class_contents[cl]);
@@ -490,6 +487,9 @@ setup_available_class_regs (void)
 static void
 setup_alloc_regs (bool use_hard_frame_p)
 {
+#ifdef ADJUST_REG_ALLOC_ORDER
+  ADJUST_REG_ALLOC_ORDER;
+#endif
   COPY_HARD_REG_SET (no_unit_alloc_regs, fixed_reg_set);
   if (! use_hard_frame_p)
     SET_HARD_REG_BIT (no_unit_alloc_regs, HARD_FRAME_POINTER_REGNUM);

gcc/system.h

@@ -761,7 +761,8 @@ extern void fancy_abort (const char *, int, const char *) ATTRIBUTE_NORETURN;
 	TARGET_ASM_EXCEPTION_SECTION TARGET_ASM_EH_FRAME_SECTION	   \
 	SMALL_ARG_MAX ASM_OUTPUT_SHARED_BSS ASM_OUTPUT_SHARED_COMMON	   \
 	ASM_OUTPUT_SHARED_LOCAL ASM_MAKE_LABEL_LINKONCE			   \
-	STACK_CHECK_PROBE_INTERVAL STACK_CHECK_PROBE_LOAD
+	STACK_CHECK_PROBE_INTERVAL STACK_CHECK_PROBE_LOAD		   \
+	ORDER_REGS_FOR_LOCAL_ALLOC
 
 /* Hooks that are no longer used.  */
  #pragma GCC poison LANG_HOOKS_FUNCTION_MARK LANG_HOOKS_FUNCTION_FREE	\