Hi Uros,
Many thanks for the review. As requested here is a revised version of the
patch that's slightly more aggressive in its clean-ups (duplicating 6 lines
of code allowed me to eliminate 9 lines of code), but most significantly
also includes support for the andn for TARGET_BMI, and allows the NOT
operand of andn/pandn to appear as either the first or second operand
(combine/reload/output will swap them as appropriate).
Once again this patch has been tested on x86_64-pc-linux-gnu with
make bootstrap and make -k check, with and without -m32, with no
new failures. Ok for mainline?
2022-05-20 Roger Sayle <ro...@nextmovesoftware.com>
gcc/ChangeLog
* config/i386/i386.cc (ix86_rtx_costs): Split AND from XOR/IOR.
Multi-word binary logic operations require two instructions.
For vector integer modes, AND with a NOT operand requires only
a single instruction (pandn). Likewise, integer andn with -mbmi.
[NOT]: Vector integer NOT requires more than 1 instruction (pxor).
[NEG]: Multi-word negation requires 3 instructions.
Thanks in advance,
Roger
> -----Original Message-----
> From: Uros Bizjak <ubiz...@gmail.com>
> Sent: 19 May 2022 07:29
> To: Roger Sayle <ro...@nextmovesoftware.com>
> Cc: gcc-patches@gcc.gnu.org
> Subject: Re: [x86 PATCH] Some additional ix86_rtx_costs clean-ups: NEG, AND
> and pandn.
>
> On Wed, May 18, 2022 at 7:30 PM Roger Sayle
> <ro...@nextmovesoftware.com> wrote:
> >
> >
> > Hi Uros,
> > Very many thanks for the speedy review and approval of my
> > ix86_rtx_costs patch to correct the cost of multi-word
> > multiplications. In the same spirit, this patch tidies up a few additional
> > nits I
> noticed while there:
> > Multi-word NOT requires two operations, but multi-word NEG requires
> > three operations. Using SSE, vector NOT requires a pxor with -1, but
> > AND of NOT is cheap thanks to the existence of pandn. There's also
> > some legacy (aka incorrect) logic explicitly testing for DImode
> > [independently of TARGET_64BIT] in determining the cost of logic
> > operations that's not required.
> >
> > There should be no behavioural changes from this patch (as confirmed
> > by
> > testing) but hopefully vectorization and other middle-end passes can
> > now rely on more sensible "cost" estimates.
> >
> > This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> > and make -k check, both with and without --target_board=unix{-m32},
> > with no new failures. Ok for mainline?
> >
> >
> > 2022-05-18 Roger Sayle <ro...@nextmovesoftware.com>
> >
> > gcc/ChangeLog
> > * config/i386/i386.cc (ix86_rtx_costs): Split AND from XOR/IOR.
> > Multi-word binary logic operations require two instructions.
> > For vector integer modes, AND with a NOT operand requires only
> > a single instruction (pandn).
> > [NOT]: Vector integer NOT requires more than 1 instruction (pxor).
> > [NEG]: Multi-word negation requires 3 instructions.
>
> - case AND:
> case IOR:
> case XOR:
> if (GET_MODE_CLASS (mode) == MODE_INT
> && GET_MODE_SIZE (mode) > UNITS_PER_WORD)
> {
> - *total = (cost->add * 2
> - + (rtx_cost (XEXP (x, 0), mode, outer_code, opno, speed)
> - << (GET_MODE (XEXP (x, 0)) != DImode))
> - + (rtx_cost (XEXP (x, 1), mode, outer_code, opno, speed)
> - << (GET_MODE (XEXP (x, 1)) != DImode)));
> + *total = cost->add * 2
> + + rtx_cost (XEXP (x, 0), mode, outer_code, opno, speed)
> + + rtx_cost (XEXP (x, 1), mode, outer_code, opno, speed);
> + return true;
> + }
> + else if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT)
> + *total = ix86_vec_cost (mode, cost->sse_op);
> + else if (GET_MODE_SIZE (mode) > UNITS_PER_WORD)
> + *total = cost->add * 2;
> + else
> + *total = cost->add;
> + return false;
>
> Shouldn't this be just:
>
> if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT)
> *total = ix86_vec_cost (mode, cost->sse_op); else if (GET_MODE_SIZE (mode)
> > UNITS_PER_WORD)
> *total = cost->add * 2;
> else
> *total = cost->add;
> return false;
>
> When returning false, subexpressions will be scanned automatically.
>
> + else if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT)
> + {
> + /* pandn is a single instruction. */
> + if (GET_CODE (XEXP (x, 0)) == NOT)
>
> pandn is also a single instruction with BMI. IMO, this should be also
> reflected in
> RTX costs.
>
> Uros.
diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
index 30a9cd0..daa60ac 100644
--- a/gcc/config/i386/i386.cc
+++ b/gcc/config/i386/i386.cc
@@ -20738,70 +20738,125 @@ ix86_rtx_costs (rtx x, machine_mode mode, int
outer_code_i, int opno,
}
if (SSE_FLOAT_MODE_SSEMATH_OR_HF_P (mode))
- {
- *total = cost->addss;
- return false;
- }
+ *total = cost->addss;
else if (X87_FLOAT_MODE_P (mode))
- {
- *total = cost->fadd;
- return false;
- }
+ *total = cost->fadd;
else if (FLOAT_MODE_P (mode))
- {
- *total = ix86_vec_cost (mode, cost->addss);
- return false;
- }
- /* FALLTHRU */
+ *total = ix86_vec_cost (mode, cost->addss);
+ else if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT)
+ *total = ix86_vec_cost (mode, cost->sse_op);
+ else if (GET_MODE_SIZE (mode) > UNITS_PER_WORD)
+ *total = cost->add * 2;
+ else
+ *total = cost->add;
+ return false;
- case AND:
case IOR:
case XOR:
- if (GET_MODE_CLASS (mode) == MODE_INT
- && GET_MODE_SIZE (mode) > UNITS_PER_WORD)
+ if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT)
+ *total = ix86_vec_cost (mode, cost->sse_op);
+ else if (GET_MODE_SIZE (mode) > UNITS_PER_WORD)
+ *total = cost->add * 2;
+ else
+ *total = cost->add;
+ return false;
+
+ case AND:
+ if (address_no_seg_operand (x, mode))
{
- *total = (cost->add * 2
- + (rtx_cost (XEXP (x, 0), mode, outer_code, opno, speed)
- << (GET_MODE (XEXP (x, 0)) != DImode))
- + (rtx_cost (XEXP (x, 1), mode, outer_code, opno, speed)
- << (GET_MODE (XEXP (x, 1)) != DImode)));
+ *total = cost->lea;
return true;
}
- else if (code == AND
- && address_no_seg_operand (x, mode))
+ else if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT)
{
- *total = cost->lea;
- return true;
+ /* pandn is a single instruction. */
+ if (GET_CODE (XEXP (x, 0)) == NOT)
+ {
+ *total = ix86_vec_cost (mode, cost->sse_op)
+ + rtx_cost (XEXP (XEXP (x, 0), 0), mode,
+ outer_code, opno, speed)
+ + rtx_cost (XEXP (x, 1), mode,
+ outer_code, opno, speed);
+ return true;
+ }
+ else if (GET_CODE (XEXP (x, 1)) == NOT)
+ {
+ *total = ix86_vec_cost (mode, cost->sse_op)
+ + rtx_cost (XEXP (x, 0), mode,
+ outer_code, opno, speed)
+ + rtx_cost (XEXP (XEXP (x, 1), 0), mode,
+ outer_code, opno, speed);
+ return true;
+ }
+ *total = ix86_vec_cost (mode, cost->sse_op);
}
- /* FALLTHRU */
-
- case NEG:
- if (SSE_FLOAT_MODE_SSEMATH_OR_HF_P (mode))
+ else if (GET_MODE_SIZE (mode) > UNITS_PER_WORD)
{
- *total = cost->sse_op;
- return false;
+ if (TARGET_BMI && GET_CODE (XEXP (x,0)) == NOT)
+ {
+ *total = cost->add * 2
+ + rtx_cost (XEXP (XEXP (x, 0), 0), mode,
+ outer_code, opno, speed)
+ + rtx_cost (XEXP (x, 1), mode,
+ outer_code, opno, speed);
+ return true;
+ }
+ else if (TARGET_BMI && GET_CODE (XEXP (x, 1)) == NOT)
+ {
+ *total = cost->add * 2
+ + rtx_cost (XEXP (x, 0), mode,
+ outer_code, opno, speed)
+ + rtx_cost (XEXP (XEXP (x, 1), 0), mode,
+ outer_code, opno, speed);
+ return true;
+ }
+ *total = cost->add * 2;
}
- else if (X87_FLOAT_MODE_P (mode))
+ else if (TARGET_BMI && GET_CODE (XEXP (x,0)) == NOT)
{
- *total = cost->fchs;
- return false;
+ *total = cost->add
+ + rtx_cost (XEXP (XEXP (x, 0), 0), mode,
+ outer_code, opno, speed)
+ + rtx_cost (XEXP (x, 1), mode, outer_code, opno, speed);
+ return true;
}
- else if (FLOAT_MODE_P (mode))
+ else if (TARGET_BMI && GET_CODE (XEXP (x,1)) == NOT)
{
- *total = ix86_vec_cost (mode, cost->sse_op);
- return false;
+ *total = cost->add
+ + rtx_cost (XEXP (x, 0), mode, outer_code, opno, speed)
+ + rtx_cost (XEXP (XEXP (x, 1), 0), mode,
+ outer_code, opno, speed);
+ return true;
}
- /* FALLTHRU */
+ else
+ *total = cost->add;
+ return false;
case NOT:
if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT)
- *total = ix86_vec_cost (mode, cost->sse_op);
+ // vnot is pxor -1.
+ *total = ix86_vec_cost (mode, cost->sse_op) + 1;
else if (GET_MODE_SIZE (mode) > UNITS_PER_WORD)
*total = cost->add * 2;
else
*total = cost->add;
return false;
+ case NEG:
+ if (SSE_FLOAT_MODE_SSEMATH_OR_HF_P (mode))
+ *total = cost->sse_op;
+ else if (X87_FLOAT_MODE_P (mode))
+ *total = cost->fchs;
+ else if (FLOAT_MODE_P (mode))
+ *total = ix86_vec_cost (mode, cost->sse_op);
+ else if (GET_MODE_CLASS (mode) == MODE_VECTOR_INT)
+ *total = ix86_vec_cost (mode, cost->sse_op);
+ else if (GET_MODE_SIZE (mode) > UNITS_PER_WORD)
+ *total = cost->add * 3;
+ else
+ *total = cost->add;
+ return false;
+
case COMPARE:
rtx op0, op1;
op0 = XEXP (x, 0);
