On Fri, Jul 27, 2012 at 7:16 PM, Uros Bizjak <ubiz...@gmail.com> wrote:
>> Attached patch enables ix86_avoid_lea_for_addr to process
>> zero-extended addresses. This patch should help atom performance,
>> especially in x32 mode.
>>
>> Please note the complication with insn re-recognition in
>> ix86_avoid_lea_for_addr, to solve the problem as described in the
>> comment:
>>
>> /* ix86_avoid_lea_for_addr re-recognizes insn and changes operands[]
>> array behind our backs. To make things worse, zero-extended oeprands
>> (zero_extend:DI (addr:SI)) are re-recognized as (addr:DI), since they
>> also satisfy operand constraints of one of many *lea<mode> insn
>> patterns.
>
> Actually, the instruction gets re-recognized as
> *zero_extendsidi2_rex64, this is the reason why we got DImode
> (addr:DI) operand. This fact further uncovers existing problem with
> ix86_avoid_lea_for_addr. This function should not mark addresses
> having less than two operands for splitting. These patterns are
> re-recognized as MOV (and now as zero-extending MOVL) due to the
> approach, described in the comment above, and due to the fact that we
> define *mov{si,di} and *zero_extendsidi2_rex64 patterns before
> *lea<mode> in the i386.md.
>
> However, here is no point messing with these patterns in splitters,
> they are conditionally converted to LEAs at the insn emission phase
> (see i.e. *zero_extendsidi2_rex64 change in attached patch). The
> attached patch prevents splitting by a simple criteria function.
>
> As a bonus, the patch also includes conditional splitter for
> non-destructive zero-extended adds.
Here is what I have committed to mainline SVN.
2012-07-27 Uros Bizjak <ubiz...@gmail.com>
* config/i386/i386.c (ix86_avoid_lea_for_addr): Handle
zero-extended addresses. Return false if the address has less
than two components.
(ix86_split_lea_for_addr): Unconditionally convert target and
all address operands to requested mode.
* config/i386/i386.md (*lea<mode>): Recover operands from curr_insn.
Pass SImode to ix86_split_lea_for_addr when splitting zero-extended
address.
(zero-extended add splitter): New splitter to conditionally split
non-destructive adds.
(*zero_extendsidi2_rex64): Conditionally emit leal instead of movl.
Uros.
Index: config/i386/i386.c
===================================================================
--- config/i386/i386.c (revision 189915)
+++ config/i386/i386.c (working copy)
@@ -17036,11 +17036,6 @@ ix86_avoid_lea_for_addr (rtx insn, rtx operands[])
struct ix86_address parts;
int ok;
- /* FIXME: Handle zero-extended addresses. */
- if (GET_CODE (operands[1]) == ZERO_EXTEND
- || GET_CODE (operands[1]) == AND)
- return false;
-
/* Check we need to optimize. */
if (!TARGET_OPT_AGU || optimize_function_for_size_p (cfun))
return false;
@@ -17052,6 +17047,11 @@ ix86_avoid_lea_for_addr (rtx insn, rtx operands[])
ok = ix86_decompose_address (operands[1], &parts);
gcc_assert (ok);
+ /* There should be at least two components in the address. */
+ if ((parts.base != NULL_RTX) + (parts.index != NULL_RTX)
+ + (parts.disp != NULL_RTX) + (parts.scale > 1) < 2)
+ return false;
+
/* We should not split into add if non legitimate pic
operand is used as displacement. */
if (parts.disp && flag_pic && !LEGITIMATE_PIC_OPERAND_P (parts.disp))
@@ -17124,7 +17124,7 @@ ix86_emit_binop (enum rtx_code code, enum machine_
It is assumed that it is allowed to clobber flags register
at lea position. */
-extern void
+void
ix86_split_lea_for_addr (rtx operands[], enum machine_mode mode)
{
unsigned int regno0, regno1, regno2;
@@ -17135,7 +17135,7 @@ ix86_split_lea_for_addr (rtx operands[], enum mach
ok = ix86_decompose_address (operands[1], &parts);
gcc_assert (ok);
- target = operands[0];
+ target = gen_lowpart (mode, operands[0]);
regno0 = true_regnum (target);
regno1 = INVALID_REGNUM;
@@ -17143,18 +17143,19 @@ ix86_split_lea_for_addr (rtx operands[], enum mach
if (parts.base)
{
- if (GET_MODE (parts.base) != mode)
- parts.base = gen_lowpart (mode, parts.base);
+ parts.base = gen_lowpart (mode, parts.base);
regno1 = true_regnum (parts.base);
}
if (parts.index)
{
- if (GET_MODE (parts.index) != mode)
- parts.index = gen_lowpart (mode, parts.index);
+ parts.index = gen_lowpart (mode, parts.index);
regno2 = true_regnum (parts.index);
}
+ if (parts.disp)
+ parts.disp = gen_lowpart (mode, parts.disp);
+
if (parts.scale > 1)
{
/* Case r1 = r1 + ... */
Index: config/i386/i386.md
===================================================================
--- config/i386/i386.md (revision 189915)
+++ config/i386/i386.md (working copy)
@@ -3474,13 +3474,28 @@
(match_operand:SI 1 "x86_64_zext_general_operand"
"rmWz,0,r ,m ,r ,m")))]
"TARGET_64BIT"
- "@
- mov{l}\t{%1, %k0|%k0, %1}
- #
- movd\t{%1, %0|%0, %1}
- movd\t{%1, %0|%0, %1}
- %vmovd\t{%1, %0|%0, %1}
- %vmovd\t{%1, %0|%0, %1}"
+{
+ switch (get_attr_type (insn))
+ {
+ case TYPE_IMOVX:
+ if (ix86_use_lea_for_mov (insn, operands))
+ return "lea{l}\t{%E1, %k0|%k0, %E1}";
+ else
+ return "mov{l}\t{%1, %k0|%k0, %1}";
+
+ case TYPE_MULTI:
+ return "#";
+
+ case TYPE_MMXMOV:
+ return "movd\t{%1, %0|%0, %1}";
+
+ case TYPE_SSEMOV:
+ return "%vmovd\t{%1, %0|%0, %1}";
+
+ default:
+ gcc_unreachable ();
+ }
+}
[(set_attr "type" "imovx,multi,mmxmov,mmxmov,ssemov,ssemov")
(set_attr "prefix" "orig,*,orig,orig,maybe_vex,maybe_vex")
(set_attr "prefix_0f" "0,*,*,*,*,*")
@@ -5479,7 +5494,23 @@
"reload_completed && ix86_avoid_lea_for_addr (insn, operands)"
[(const_int 0)]
{
- ix86_split_lea_for_addr (operands, <MODE>mode);
+ enum machine_mode mode = <MODE>mode;
+ rtx pat;
+
+ /* ix86_avoid_lea_for_addr re-recognizes insn and may
+ change operands[] array behind our back. */
+ pat = PATTERN (curr_insn);
+
+ operands[0] = SET_DEST (pat);
+ operands[1] = SET_SRC (pat);
+
+ /* Emit all operations in SImode for zero-extended addresses. Recall
+ that x86_64 inheretly zero-extends SImode operations to DImode. */
+ if (GET_CODE (operands[1]) == ZERO_EXTEND
+ || GET_CODE (operands[1]) == AND)
+ mode = SImode;
+
+ ix86_split_lea_for_addr (operands, mode);
DONE;
}
[(set_attr "type" "lea")
@@ -5807,11 +5838,11 @@
(define_split
[(set (match_operand:SWI48 0 "register_operand")
(plus:SWI48 (match_operand:SWI48 1 "register_operand")
- (match_operand:SWI48 2 "nonmemory_operand")))
+ (match_operand:SWI48 2 "x86_64_nonmemory_operand")))
(clobber (reg:CC FLAGS_REG))]
"reload_completed && ix86_avoid_lea_for_add (insn, operands)"
[(set (match_dup 0) (match_dup 1))
- (parallel [(set (match_dup 0) (plus:<MODE> (match_dup 0) (match_dup 2)))
+ (parallel [(set (match_dup 0) (plus:SWI48 (match_dup 0) (match_dup 2)))
(clobber (reg:CC FLAGS_REG))])])
;; Convert add to the lea pattern to avoid flags dependency.
@@ -5840,6 +5871,21 @@
DONE;
})
+;; Split non destructive adds if we cannot use lea.
+(define_split
+ [(set (match_operand:DI 0 "register_operand")
+ (zero_extend:DI
+ (plus:SI (match_operand:SI 1 "register_operand")
+ (match_operand:SI 2 "x86_64_nonmemory_operand"))))
+ (clobber (reg:CC FLAGS_REG))]
+ "TARGET_64BIT
+ && reload_completed && ix86_avoid_lea_for_add (insn, operands)"
+ [(set (match_dup 3) (match_dup 1))
+ (parallel [(set (match_dup 0)
+ (zero_extend:DI (plus:SI (match_dup 3) (match_dup 2))))
+ (clobber (reg:CC FLAGS_REG))])]
+ "operands[3] = gen_lowpart (SImode, operands[0]);")
+
;; Convert add to the lea pattern to avoid flags dependency.
(define_split
[(set (match_operand:DI 0 "register_operand")
