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cmd/compile: improve FP FMA performance on riscv64

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FMADD/FMSUB/FNSUB are an efficient FP FMA instructions, which can
be used by the compiler to improve FP performance.

Erf               188.0n ± 2%   139.5n ± 2%  -25.82% (p=0.000 n=10)
Erfc              193.6n ± 1%   143.2n ± 1%  -26.01% (p=0.000 n=10)
Erfinv            244.4n ± 2%   172.6n ± 0%  -29.40% (p=0.000 n=10)
Erfcinv           244.7n ± 2%   173.0n ± 1%  -29.31% (p=0.000 n=10)
geomean           216.0n        156.3n       -27.65%

Ref: The RISC-V Instruction Set Manual Volume I: Unprivileged ISA
11.6 Single-Precision Floating-Point Computational Instructions

Change-Id: I89aa3a4df7576fdd47f4a6ee608ac16feafd093c
Reviewed-on: https://go-review.googlesource.com/c/go/+/506036
Reviewed-by: Joel Sing <joel@sing.id.au>
Run-TryBot: M Zhuo <mzh@golangcn.org>
Reviewed-by: David Chase <drchase@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
This commit is contained in:
Meng Zhuo 2023-06-26 20:46:49 +08:00 committed by M Zhuo
parent e7e99a8e02
commit 05f9511582
6 changed files with 112 additions and 3 deletions
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3
src/cmd/compile/internal/riscv64/ssa.go
View file

@ -694,6 +694,9 @@ func ssaGenValue(s *ssagen.State, v *ssa.Value) {
p.To.Sym = ir.Syms.Duffcopy
p.To.Offset = v.AuxInt
case ssa.OpRISCV64LoweredRound32F, ssa.OpRISCV64LoweredRound64F:
// input is already rounded
case ssa.OpClobber, ssa.OpClobberReg:
// TODO: implement for clobberdead experiment. Nop is ok for now.

5
src/cmd/compile/internal/ssa/_gen/RISCV64.rules
View file

@ -103,7 +103,7 @@
(CvtBoolToUint8 ...) => (Copy ...)
(Round(64|32)F ...) => (Copy ...)
(Round(32|64)F ...) => (LoweredRound(32|64)F ...)
(Slicemask <t> x) => (SRAI [63] (NEG <t> x))
@ -780,6 +780,9 @@
(Select0 m:(LoweredMuluhilo x y)) && m.Uses == 1 => (MULHU x y)
(Select1 m:(LoweredMuluhilo x y)) && m.Uses == 1 => (MUL x y)
(FADDD a (FMULD x y)) && a.Block.Func.useFMA(v) => (FMADDD x y a)
(FSUBD a (FMULD x y)) && a.Block.Func.useFMA(v) => (FNMSUBD x y a)
(FSUBD (FMULD x y) a) && a.Block.Func.useFMA(v) => (FMSUBD x y a)
// Merge negation into fused multiply-add and multiply-subtract.
//
// Key:

4
src/cmd/compile/internal/ssa/_gen/RISCV64Ops.go
View file

@ -237,6 +237,10 @@ func init() {
// gets correctly ordered with respect to GC safepoints.
{name: "MOVconvert", argLength: 2, reg: gp11, asm: "MOV"}, // arg0, but converted to int/ptr as appropriate; arg1=mem
// Round ops to block fused-multiply-add extraction.
{name: "LoweredRound32F", argLength: 1, reg: fp11, resultInArg0: true},
{name: "LoweredRound64F", argLength: 1, reg: fp11, resultInArg0: true},
// Calls
{name: "CALLstatic", argLength: -1, reg: call, aux: "CallOff", call: true}, // call static function aux.(*gc.Sym). last arg=mem, auxint=argsize, returns mem
{name: "CALLtail", argLength: -1, reg: call, aux: "CallOff", call: true, tailCall: true}, // tail call static function aux.(*gc.Sym). last arg=mem, auxint=argsize, returns mem

28
src/cmd/compile/internal/ssa/opGen.go
View file

@ -2400,6 +2400,8 @@ const (
OpRISCV64SLTU
OpRISCV64SLTIU
OpRISCV64MOVconvert
OpRISCV64LoweredRound32F
OpRISCV64LoweredRound64F
OpRISCV64CALLstatic
OpRISCV64CALLtail
OpRISCV64CALLclosure
@ -32198,6 +32200,32 @@ var opcodeTable = [...]opInfo{
},
},
},
{
name: "LoweredRound32F",
argLen: 1,
resultInArg0: true,
reg: regInfo{
inputs: []inputInfo{
{0, 9223372034707292160}, // F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31
},
outputs: []outputInfo{
{0, 9223372034707292160}, // F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31
},
},
},
{
name: "LoweredRound64F",
argLen: 1,
resultInArg0: true,
reg: regInfo{
inputs: []inputInfo{
{0, 9223372034707292160}, // F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31
},
outputs: []outputInfo{
{0, 9223372034707292160}, // F0 F1 F2 F3 F4 F5 F6 F7 F8 F9 F10 F11 F12 F13 F14 F15 F16 F17 F18 F19 F20 F21 F22 F23 F24 F25 F26 F27 F28 F29 F30 F31
},
},
},
{
name: "CALLstatic",
auxType: auxCallOff,

72
src/cmd/compile/internal/ssa/rewriteRISCV64.go
View file

@ -440,6 +440,8 @@ func rewriteValueRISCV64(v *Value) bool {
return rewriteValueRISCV64_OpRISCV64AND(v)
case OpRISCV64ANDI:
return rewriteValueRISCV64_OpRISCV64ANDI(v)
case OpRISCV64FADDD:
return rewriteValueRISCV64_OpRISCV64FADDD(v)
case OpRISCV64FMADDD:
return rewriteValueRISCV64_OpRISCV64FMADDD(v)
case OpRISCV64FMSUBD:
@ -448,6 +450,8 @@ func rewriteValueRISCV64(v *Value) bool {
return rewriteValueRISCV64_OpRISCV64FNMADDD(v)
case OpRISCV64FNMSUBD:
return rewriteValueRISCV64_OpRISCV64FNMSUBD(v)
case OpRISCV64FSUBD:
return rewriteValueRISCV64_OpRISCV64FSUBD(v)
case OpRISCV64MOVBUload:
return rewriteValueRISCV64_OpRISCV64MOVBUload(v)
case OpRISCV64MOVBUreg:
@ -541,10 +545,10 @@ func rewriteValueRISCV64(v *Value) bool {
case OpRotateLeft8:
return rewriteValueRISCV64_OpRotateLeft8(v)
case OpRound32F:
v.Op = OpCopy
v.Op = OpRISCV64LoweredRound32F
return true
case OpRound64F:
v.Op = OpCopy
v.Op = OpRISCV64LoweredRound64F
return true
case OpRsh16Ux16:
return rewriteValueRISCV64_OpRsh16Ux16(v)
@ -3335,6 +3339,31 @@ func rewriteValueRISCV64_OpRISCV64ANDI(v *Value) bool {
}
return false
}
func rewriteValueRISCV64_OpRISCV64FADDD(v *Value) bool {
v_1 := v.Args[1]
v_0 := v.Args[0]
// match: (FADDD a (FMULD x y))
// cond: a.Block.Func.useFMA(v)
// result: (FMADDD x y a)
for {
for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
a := v_0
if v_1.Op != OpRISCV64FMULD {
continue
}
y := v_1.Args[1]
x := v_1.Args[0]
if !(a.Block.Func.useFMA(v)) {
continue
}
v.reset(OpRISCV64FMADDD)
v.AddArg3(x, y, a)
return true
}
break
}
return false
}
func rewriteValueRISCV64_OpRISCV64FMADDD(v *Value) bool {
v_2 := v.Args[2]
v_1 := v.Args[1]
@ -3515,6 +3544,45 @@ func rewriteValueRISCV64_OpRISCV64FNMSUBD(v *Value) bool {
}
return false
}
func rewriteValueRISCV64_OpRISCV64FSUBD(v *Value) bool {
v_1 := v.Args[1]
v_0 := v.Args[0]
// match: (FSUBD a (FMULD x y))
// cond: a.Block.Func.useFMA(v)
// result: (FNMSUBD x y a)
for {
a := v_0
if v_1.Op != OpRISCV64FMULD {
break
}
y := v_1.Args[1]
x := v_1.Args[0]
if !(a.Block.Func.useFMA(v)) {
break
}
v.reset(OpRISCV64FNMSUBD)
v.AddArg3(x, y, a)
return true
}
// match: (FSUBD (FMULD x y) a)
// cond: a.Block.Func.useFMA(v)
// result: (FMSUBD x y a)
for {
if v_0.Op != OpRISCV64FMULD {
break
}
y := v_0.Args[1]
x := v_0.Args[0]
a := v_1
if !(a.Block.Func.useFMA(v)) {
break
}
v.reset(OpRISCV64FMSUBD)
v.AddArg3(x, y, a)
return true
}
return false
}
func rewriteValueRISCV64_OpRISCV64MOVBUload(v *Value) bool {
v_1 := v.Args[1]
v_0 := v.Args[0]

3
test/codegen/floats.go
View file

@ -88,17 +88,20 @@ func FusedAdd64(x, y, z float64) float64 {
// s390x:"FMADD\t"
// ppc64x:"FMADD\t"
// arm64:"FMADDD"
// riscv64:"FMADDD\t"
return x*y + z
}
func FusedSub64_a(x, y, z float64) float64 {
// s390x:"FMSUB\t"
// ppc64x:"FMSUB\t"
// riscv64:"FMSUBD\t"
return x*y - z
}
func FusedSub64_b(x, y, z float64) float64 {
// arm64:"FMSUBD"
// riscv64:"FNMSUBD\t"
return z - x*y
}