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Commit 37a185d7 by Richard Henderson Committed by Richard Henderson
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mn10300: Emit retf instruction 

Now that we properly track the life of MDR, we can emit
the RETF instruction if MDR has not been modified.  This
insn is 3-4 cycles faster since the return address is
already loaded.

From-SVN: r169013
parent 040c5757
Showing with 69 additions and 49 deletions
gcc/ChangeLog
2011-01-19 Richard Henderson <rth@redhat.com>
* config/mn10300/mn10300.c (mn10300_can_use_retf_insn): New.
(mn10300_can_use_rets_insn): Rename from mn10300_can_use_return_insn.
(mn10300_expand_epilogue): Use it. Compute REG_SAVE_BYTES once.
* config/mn10300/mn10300-protos.h: Update.
* config/mn10300/mn10300.md (return): Use mn10300_can_use_retf_insn.
(return_ret): Likewise. Rename from return_internal_regs.
(return_internal): Remove.
* config/mn10300/mn10300.c (mn10300_unspec_int_label_counter): Remove.
(mn10300_asm_output_addr_const_extra): Don't handle UNSPEC_INT_LABEL.
(mn10300_legitimate_constant_p): Likewise.
......
gcc/config/mn10300/mn10300-protos.h
......@@ -45,7 +45,8 @@ extern bool mn10300_match_ccmode (rtx, Mmode);
#endif /* RTX_CODE */
extern bool mn10300_regno_in_class_p (unsigned, int, bool);
extern int mn10300_can_use_return_insn (void);
extern bool mn10300_can_use_rets_insn (void);
extern bool mn10300_can_use_retf_insn (void);
extern void mn10300_expand_prologue (void);
extern void mn10300_expand_epilogue (void);
extern int mn10300_initial_offset (int, int);
......
gcc/config/mn10300/mn10300.c
......@@ -623,8 +623,33 @@ mn10300_print_reg_list (FILE *file, int mask)
fputc (']', file);
}
int
mn10300_can_use_return_insn (void)
/* If the MDR register is never clobbered, we can use the RETF instruction
which takes the address from the MDR register. This is 3 cycles faster
than having to load the address from the stack. */
bool
mn10300_can_use_retf_insn (void)
{
/* Don't bother if we're not optimizing. In this case we won't
have proper access to df_regs_ever_live_p. */
if (!optimize)
return false;
/* EH returns alter the saved return address; MDR is not current. */
if (crtl->calls_eh_return)
return false;
/* Obviously not if MDR is ever clobbered. */
if (df_regs_ever_live_p (MDR_REG))
return false;
/* ??? Careful not to use this during expand_epilogue etc. */
gcc_assert (!in_sequence_p ());
return leaf_function_p ();
}
bool
mn10300_can_use_rets_insn (void)
{
return !mn10300_initial_offset (ARG_POINTER_REGNUM, STACK_POINTER_REGNUM);
}
......@@ -995,6 +1020,7 @@ void
mn10300_expand_epilogue (void)
{
HOST_WIDE_INT size = mn10300_frame_size ();
int reg_save_bytes = REG_SAVE_BYTES;
if (TARGET_AM33_2 && fp_regs_to_save ())
{
......@@ -1026,14 +1052,14 @@ mn10300_expand_epilogue (void)
this_strategy_size = SIZE_FMOV_SP (size, num_regs_to_save);
/* If size is too large, we'll have to adjust SP with an
add. */
if (size + 4 * num_regs_to_save + REG_SAVE_BYTES > 255)
if (size + 4 * num_regs_to_save + reg_save_bytes > 255)
{
/* Insn: add size + 4 * num_regs_to_save, sp. */
this_strategy_size += SIZE_ADD_SP (size + 4 * num_regs_to_save);
}
/* If we don't have to restore any non-FP registers,
we'll be able to save one byte by using rets. */
if (! REG_SAVE_BYTES)
if (! reg_save_bytes)
this_strategy_size--;
if (this_strategy_size < strategy_size)
......@@ -1060,14 +1086,14 @@ mn10300_expand_epilogue (void)
When size is close to 32Kb, we may be able to adjust SP
with an imm16 add instruction while still using fmov
(d8,sp). */
if (size + 4 * num_regs_to_save + REG_SAVE_BYTES > 255)
if (size + 4 * num_regs_to_save + reg_save_bytes > 255)
{
/* Insn: add size + 4 * num_regs_to_save
+ REG_SAVE_BYTES - 252,sp. */
+ reg_save_bytes - 252,sp. */
this_strategy_size = SIZE_ADD_SP (size + 4 * num_regs_to_save
+ REG_SAVE_BYTES - 252);
+ reg_save_bytes - 252);
/* Insn: fmov (##,sp),fs#, fo each fs# to be restored. */
this_strategy_size += SIZE_FMOV_SP (252 - REG_SAVE_BYTES
this_strategy_size += SIZE_FMOV_SP (252 - reg_save_bytes
- 4 * num_regs_to_save,
num_regs_to_save);
/* We're going to use ret to release the FP registers
......@@ -1096,14 +1122,14 @@ mn10300_expand_epilogue (void)
this_strategy_size += 3 * num_regs_to_save;
/* If size is large enough, we may be able to save a
couple of bytes. */
if (size + 4 * num_regs_to_save + REG_SAVE_BYTES > 255)
if (size + 4 * num_regs_to_save + reg_save_bytes > 255)
{
/* Insn: mov a1,sp. */
this_strategy_size += 2;
}
/* If we don't have to restore any non-FP registers,
we'll be able to save one byte by using rets. */
if (! REG_SAVE_BYTES)
if (! reg_save_bytes)
this_strategy_size--;
if (this_strategy_size < strategy_size)
......@@ -1129,8 +1155,8 @@ mn10300_expand_epilogue (void)
emit_insn (gen_addsi3 (stack_pointer_rtx,
stack_pointer_rtx,
GEN_INT (size + 4 * num_regs_to_save
+ REG_SAVE_BYTES - 252)));
size = 252 - REG_SAVE_BYTES - 4 * num_regs_to_save;
+ reg_save_bytes - 252)));
size = 252 - reg_save_bytes - 4 * num_regs_to_save;
break;
case restore_a1:
......@@ -1176,7 +1202,7 @@ mn10300_expand_epilogue (void)
/* If we were using the restore_a1 strategy and the number of
bytes to be released won't fit in the `ret' byte, copy `a1'
to `sp', to avoid having to use `add' to adjust it. */
if (! frame_pointer_needed && reg && size + REG_SAVE_BYTES > 255)
if (! frame_pointer_needed && reg && size + reg_save_bytes > 255)
{
emit_move_insn (stack_pointer_rtx, XEXP (reg, 0));
size = 0;
......@@ -1203,7 +1229,7 @@ mn10300_expand_epilogue (void)
emit_move_insn (stack_pointer_rtx, frame_pointer_rtx);
size = 0;
}
else if (size + REG_SAVE_BYTES > 255)
else if (size + reg_save_bytes > 255)
{
emit_insn (gen_addsi3 (stack_pointer_rtx,
stack_pointer_rtx,
......@@ -1212,15 +1238,10 @@ mn10300_expand_epilogue (void)
}
/* Adjust the stack and restore callee-saved registers, if any. */
if (size || df_regs_ever_live_p (2) || df_regs_ever_live_p (3)
|| df_regs_ever_live_p (6) || df_regs_ever_live_p (7)
|| df_regs_ever_live_p (14) || df_regs_ever_live_p (15)
|| df_regs_ever_live_p (16) || df_regs_ever_live_p (17)
|| frame_pointer_needed)
emit_jump_insn (gen_return_internal_regs
(GEN_INT (size + REG_SAVE_BYTES)));
if (mn10300_can_use_rets_insn ())
emit_jump_insn (gen_rtx_RETURN (VOIDmode));
else
emit_jump_insn (gen_return_internal ());
emit_jump_insn (gen_return_ret (GEN_INT (size + REG_SAVE_BYTES)));
}
/* Recognize the PARALLEL rtx generated by mn10300_gen_multiple_store().
......
gcc/config/mn10300/mn10300.md
......@@ -1607,31 +1607,28 @@
{ mn10300_expand_epilogue (); DONE; }
)
(define_insn "return_internal"
[(const_int 2)
(return)]
""
"rets"
[(set_attr "timings" "66")]
)
(define_insn "return"
[(return)]
"mn10300_can_use_rets_insn ()"
{
/* The RETF insn is 4 cycles faster than RETS, though 1 byte larger. */
if (optimize_insn_for_speed_p () && mn10300_can_use_retf_insn ())
return "retf [],0";
else
return "rets";
})
;; This insn restores the callee saved registers and does a return, it
;; can also deallocate stack space.
(define_insn "return_internal_regs"
[(const_int 0)
(match_operand:SI 0 "const_int_operand" "i")
(return)]
(define_insn "return_ret"
[(return)
(use (match_operand:SI 0 "const_int_operand" ""))]
""
{
fputs ("\tret ", asm_out_file);
/* The RETF insn is up to 3 cycles faster than RET. */
fputs ((mn10300_can_use_retf_insn () ? "\tretf " : "\tret "), asm_out_file);
mn10300_print_reg_list (asm_out_file, mn10300_get_live_callee_saved_regs ());
fprintf (asm_out_file, ",%d\n", (int) INTVAL (operands[0]));
return "";
}
;; Assumes that there will be no more than 8 regs to pop
[(set (attr "timings") (if_then_else (eq_attr "cpu" "am34")
(const_int 1414) (const_int 1313)))]
)
})
;; This instruction matches one generated by mn10300_gen_multiple_store()
(define_insn "store_movm"
......@@ -1651,13 +1648,6 @@
(const_int 99) (const_int 88)))]
)
(define_insn "return"
[(return)]
"mn10300_can_use_return_insn ()"
"rets"
[(set_attr "timings" "66")]
)
(define_expand "load_pic"
[(const_int 0)]
"flag_pic"
......
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