On Thu, Apr 26, 2012 at 5:34 PM, Uros Bizjak <ubiz...@gmail.com> wrote:
> On Thu, Apr 26, 2012 at 5:28 PM, Jakub Jelinek <ja...@redhat.com> wrote:
>
>>> > We have a splitter for reg1 = reg2 & 0xffffffff, but only if regnums
>>> > are different. But movl %edi, %edi is a cheaper variant of
>>> > andq $0xffffffff, %rdi even with the same register and doesn't clobber
>>> > flags, so this patch attempts to expand it as a zero extension early.
>>> >
>>> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>>> >
>>> > 2012-04-25 Jakub Jelinek <ja...@redhat.com>
>>> >
>>> > PR target/53110
>>> > * config/i386/i386.md (and<mode>3): For andq $0xffffffff, reg
>>> > instead expand it as zero extension.
>>>
>>> Perhaps we can go all the way and also convert ANDs with $0xff and
>>> $0xffff to relevant zero_extend patterns, like in the referred
>>> splitter.
>>
>> I wasn't sure about 0xffff, on which CPUs it would be a win and on which it
>> would not. 0xffffffff is a win always.
It is always a win, especially when loading from memory. In the latter
case, no execution units are used, only load (memory read) unit.
> My recent changes to zero_extend expanders should handle this
> automatically, and will undo generation of zero_extend pattern. Please
> see zero_extend<mode>si2_and expander, and how it handles
> TARGET_ZERO_EXTEND_WITH_AND targets.
Attached patch implements this idea. In addition, it fixes the
splitter to not change output mode of zero_extension from HImode and
QImode from DImode to SImode. Although they generate the same
instruction, I think we should better keep original mode here.
2012-04-30 Uros Bizjak <ubiz...@gmail.com>
* config/i386/i386.md (and<mode>3): Expand masking operations with
0xff, 0xffff or 0xffffffff immediates to corresponding zero_extend RTX.
(and splitter): Split to DImode zero_extend RTX for DImode operand[0].
Patch was bootstrapped and regression tested on x86_64-pc-linux-gnu
{,-m32} and committed to mainline SVN.
Uros.
Index: config/i386/i386.md
===================================================================
--- config/i386/i386.md (revision 186954)
+++ config/i386/i386.md (working copy)
@@ -7695,14 +7695,45 @@
(match_operand:SWIM 2 "<general_szext_operand>")))]
""
{
- if (<MODE>mode == DImode
- && GET_CODE (operands[2]) == CONST_INT
- && INTVAL (operands[2]) == (HOST_WIDE_INT) 0xffffffff
- && REG_P (operands[1]))
- emit_insn (gen_zero_extendsidi2 (operands[0],
- gen_lowpart (SImode, operands[1])));
+ enum machine_mode mode = GET_MODE (operands[1]);
+ rtx (*insn) (rtx, rtx);
+
+ if (CONST_INT_P (operands[2]) && REG_P (operands[0]))
+ {
+ HOST_WIDE_INT ival = INTVAL (operands[2]);
+
+ if (ival == (HOST_WIDE_INT) 0xffffffff)
+ mode = SImode;
+ else if (ival == 0xffff)
+ mode = HImode;
+ else if (ival == 0xff)
+ mode = QImode;
+ }
+
+ if (mode == GET_MODE (operands[1]))
+ {
+ ix86_expand_binary_operator (AND, <MODE>mode, operands);
+ DONE;
+ }
+
+ operands[1] = gen_lowpart (mode, operands[1]);
+
+ if (GET_MODE (operands[0]) == DImode)
+ insn = (mode == SImode)
+ ? gen_zero_extendsidi2
+ : (mode == HImode)
+ ? gen_zero_extendhidi2
+ : gen_zero_extendqidi2;
+ else if (GET_MODE (operands[0]) == SImode)
+ insn = (mode == HImode)
+ ? gen_zero_extendhisi2
+ : gen_zero_extendqisi2;
+ else if (GET_MODE (operands[0]) == HImode)
+ insn = gen_zero_extendqihi2;
else
- ix86_expand_binary_operator (AND, <MODE>mode, operands);
+ gcc_unreachable ();
+
+ emit_insn (insn (operands[0], operands[1]));
DONE;
})
@@ -7839,32 +7870,38 @@
&& true_regnum (operands[0]) != true_regnum (operands[1])"
[(const_int 0)]
{
+ HOST_WIDE_INT ival = INTVAL (operands[2]);
enum machine_mode mode;
+ rtx (*insn) (rtx, rtx);
- if (INTVAL (operands[2]) == (HOST_WIDE_INT) 0xffffffff)
+ if (ival == (HOST_WIDE_INT) 0xffffffff)
mode = SImode;
- else if (INTVAL (operands[2]) == 0xffff)
+ else if (ival == 0xffff)
mode = HImode;
else
{
- gcc_assert (INTVAL (operands[2]) == 0xff);
+ gcc_assert (ival == 0xff);
mode = QImode;
}
operands[1] = gen_lowpart (mode, operands[1]);
- if (mode == SImode)
- emit_insn (gen_zero_extendsidi2 (operands[0], operands[1]));
+ if (GET_MODE (operands[0]) == DImode)
+ insn = (mode == SImode)
+ ? gen_zero_extendsidi2
+ : (mode == HImode)
+ ? gen_zero_extendhidi2
+ : gen_zero_extendqidi2;
else
{
- rtx (*insn) (rtx, rtx);
-
/* Zero extend to SImode to avoid partial register stalls. */
operands[0] = gen_lowpart (SImode, operands[0]);
- insn = (mode == HImode) ? gen_zero_extendhisi2 : gen_zero_extendqisi2;
- emit_insn (insn (operands[0], operands[1]));
+ insn = (mode == HImode)
+ ? gen_zero_extendhisi2
+ : gen_zero_extendqisi2;
}
+ emit_insn (insn (operands[0], operands[1]));
DONE;
})
