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cmd/asm, cmd/internal/obj: enable rounding mode suffix for riscv64

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This CL adds rounding modes for riscv64 floating point conversion
instructions by suffix with 5 modes: RNE, RTZ, RDN, RUP and RMM.

For example, for round to nearest (RNE), we can use `FCVTLD.RNE`
According to RISCV manual 8.7 and 9.5, we changed these
conversion instructions:

FCVTWS
FCVTLS
FCVTWUS
FCVTLUS
FCVTWD
FCVTLD
FCVTWUD
FCVTLUD

Note: Round towards zero (RTZ) by default for all these instructions above.

Change-Id: I491e522e14d721e24aa7f528ee0c4640c54c5808
Reviewed-on: https://go-review.googlesource.com/c/go/+/504736
Reviewed-by: Joel Sing <joel@sing.id.au>
Run-TryBot: M Zhuo <mengzhuo1203@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Than McIntosh <thanm@google.com>
This commit is contained in:
Meng Zhuo 2023-06-20 11:16:56 +08:00 committed by M Zhuo
parent d4112310a4
commit 3580c212c2
7 changed files with 130 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
src/cmd/asm/internal/asm/asm.go
View File

@ -16,6 +16,7 @@ import (
"cmd/asm/internal/lex"
"cmd/internal/obj"
"cmd/internal/obj/ppc64"
"cmd/internal/obj/riscv"
"cmd/internal/obj/x86"
"cmd/internal/sys"
)
@ -46,7 +47,11 @@ func (p *Parser) append(prog *obj.Prog, cond string, doLabel bool) {
p.errorf("%v", err)
return
}
case sys.RISCV64:
if err := riscv.ParseSuffix(prog, cond); err != nil {
p.errorf("unrecognized suffix .%q", cond)
return
}
default:
p.errorf("unrecognized suffix .%q", cond)
return

4
src/cmd/asm/internal/asm/parse.go
View File

@ -217,8 +217,8 @@ next:
for {
tok = p.nextToken()
if len(operands) == 0 && len(items) == 0 {
if p.arch.InFamily(sys.ARM, sys.ARM64, sys.AMD64, sys.I386) && tok == '.' {
// Suffixes: ARM conditionals or x86 modifiers.
if p.arch.InFamily(sys.ARM, sys.ARM64, sys.AMD64, sys.I386, sys.RISCV64) && tok == '.' {
// Suffixes: ARM conditionals, RISCV rounding mode or x86 modifiers.
tok = p.nextToken()
str := p.lex.Text()
if tok != scanner.Ident {

40
src/cmd/asm/internal/asm/testdata/riscv64.s vendored
View File

@ -233,11 +233,31 @@ start:
// 11.7: Single-Precision Floating-Point Conversion and Move Instructions
FCVTWS F0, X5 // d31200c0
FCVTWS.RNE F0, X5 // d30200c0
FCVTWS.RTZ F0, X5 // d31200c0
FCVTWS.RDN F0, X5 // d32200c0
FCVTWS.RUP F0, X5 // d33200c0
FCVTWS.RMM F0, X5 // d34200c0
FCVTLS F0, X5 // d31220c0
FCVTLS.RNE F0, X5 // d30220c0
FCVTLS.RTZ F0, X5 // d31220c0
FCVTLS.RDN F0, X5 // d32220c0
FCVTLS.RUP F0, X5 // d33220c0
FCVTLS.RMM F0, X5 // d34220c0
FCVTSW X5, F0 // 538002d0
FCVTSL X5, F0 // 538022d0
FCVTWUS F0, X5 // d31210c0
FCVTWUS.RNE F0, X5 // d30210c0
FCVTWUS.RTZ F0, X5 // d31210c0
FCVTWUS.RDN F0, X5 // d32210c0
FCVTWUS.RUP F0, X5 // d33210c0
FCVTWUS.RMM F0, X5 // d34210c0
FCVTLUS F0, X5 // d31230c0
FCVTLUS.RNE F0, X5 // d30230c0
FCVTLUS.RTZ F0, X5 // d31230c0
FCVTLUS.RDN F0, X5 // d32230c0
FCVTLUS.RUP F0, X5 // d33230c0
FCVTLUS.RMM F0, X5 // d34230c0
FCVTSWU X5, F0 // 538012d0
FCVTSLU X5, F0 // 538032d0
FSGNJS F1, F0, F2 // 53011020
@ -277,11 +297,31 @@ start:
// 12.5: Double-Precision Floating-Point Conversion and Move Instructions
FCVTWD F0, X5 // d31200c2
FCVTWD.RNE F0, X5 // d30200c2
FCVTWD.RTZ F0, X5 // d31200c2
FCVTWD.RDN F0, X5 // d32200c2
FCVTWD.RUP F0, X5 // d33200c2
FCVTWD.RMM F0, X5 // d34200c2
FCVTLD F0, X5 // d31220c2
FCVTLD.RNE F0, X5 // d30220c2
FCVTLD.RTZ F0, X5 // d31220c2
FCVTLD.RDN F0, X5 // d32220c2
FCVTLD.RUP F0, X5 // d33220c2
FCVTLD.RMM F0, X5 // d34220c2
FCVTDW X5, F0 // 538002d2
FCVTDL X5, F0 // 538022d2
FCVTWUD F0, X5 // d31210c2
FCVTWUD.RNE F0, X5 // d30210c2
FCVTWUD.RTZ F0, X5 // d31210c2
FCVTWUD.RDN F0, X5 // d32210c2
FCVTWUD.RUP F0, X5 // d33210c2
FCVTWUD.RMM F0, X5 // d34210c2
FCVTLUD F0, X5 // d31230c2
FCVTLUD.RNE F0, X5 // d30230c2
FCVTLUD.RTZ F0, X5 // d31230c2
FCVTLUD.RDN F0, X5 // d32230c2
FCVTLUD.RUP F0, X5 // d33230c2
FCVTLUD.RMM F0, X5 // d34230c2
FCVTDWU X5, F0 // 538012d2
FCVTDLU X5, F0 // 538032d2
FCVTSD F0, F1 // d3001040

2
src/cmd/internal/obj/link.go
View File

@ -314,7 +314,7 @@ type Prog struct {
RegTo2 int16 // 2nd destination operand
Mark uint16 // bitmask of arch-specific items
Optab uint16 // arch-specific opcode index
Scond uint8 // bits that describe instruction suffixes (e.g. ARM conditions)
Scond uint8 // bits that describe instruction suffixes (e.g. ARM conditions, RISCV Rounding Mode)
Back uint8 // for x86 back end: backwards branch state
Ft uint8 // for x86 back end: type index of Prog.From
Tt uint8 // for x86 back end: type index of Prog.To

51
src/cmd/internal/obj/riscv/cpu.go
View File

@ -28,7 +28,12 @@
package riscv
import "cmd/internal/obj"
import (
"errors"
"fmt"
"cmd/internal/obj"
)
//go:generate go run ../stringer.go -i $GOFILE -o anames.go -p riscv
@ -607,6 +612,50 @@ const (
ALAST
)
// opSuffix encoding to uint8 which fit into p.Scond
var rmSuffixSet = map[string]uint8{
"RNE": RM_RNE,
"RTZ": RM_RTZ,
"RDN": RM_RDN,
"RUP": RM_RUP,
"RMM": RM_RMM,
}
const rmSuffixBit uint8 = 1 << 7
func rmSuffixEncode(s string) (uint8, error) {
if s == "" {
return 0, errors.New("empty suffix")
}
enc, ok := rmSuffixSet[s]
if !ok {
return 0, fmt.Errorf("invalid encoding for unknown suffix:%q", s)
}
return enc | rmSuffixBit, nil
}
func rmSuffixString(u uint8) (string, error) {
if u&rmSuffixBit == 0 {
return "", fmt.Errorf("invalid suffix, require round mode bit:%x", u)
}
u &^= rmSuffixBit
for k, v := range rmSuffixSet {
if v == u {
return k, nil
}
}
return "", fmt.Errorf("unknown suffix:%x", u)
}
const (
RM_RNE uint8 = iota // Round to Nearest, ties to Even
RM_RTZ // Round towards Zero
RM_RDN // Round Down
RM_RUP // Round Up
RM_RMM // Round to Nearest, ties to Max Magnitude
)
// All unary instructions which write to their arguments (as opposed to reading
// from them) go here. The assembly parser uses this information to populate
// its AST in a semantically reasonable way.

16
src/cmd/internal/obj/riscv/list.go
View File

@ -13,6 +13,7 @@ import (
func init() {
obj.RegisterRegister(obj.RBaseRISCV, REG_END, RegName)
obj.RegisterOpcode(obj.ABaseRISCV, Anames)
obj.RegisterOpSuffix("riscv64", opSuffixString)
}
func RegName(r int) string {
@ -31,3 +32,18 @@ func RegName(r int) string {
return fmt.Sprintf("Rgok(%d)", r-obj.RBaseRISCV)
}
}
func opSuffixString(s uint8) string {
if s&rmSuffixBit == 0 {
return ""
}
ss, err := rmSuffixString(s)
if err != nil {
ss = fmt.Sprintf("<invalid 0x%x>", s)
}
if ss == "" {
return ss
}
return fmt.Sprintf(".%s", ss)
}

17
src/cmd/internal/obj/riscv/obj.go
View File

@ -28,6 +28,7 @@ import (
"internal/abi"
"log"
"math/bits"
"strings"
)
func buildop(ctxt *obj.Link) {}
@ -2273,8 +2274,12 @@ func instructionsForProg(p *obj.Prog) []*instruction {
ins.imm = 0x0ff
case AFCVTWS, AFCVTLS, AFCVTWUS, AFCVTLUS, AFCVTWD, AFCVTLD, AFCVTWUD, AFCVTLUD:
// Set the rounding mode in funct3 to round to zero.
ins.funct3 = 1
// Set the default rounding mode in funct3 to round to zero.
if p.Scond&rmSuffixBit == 0 {
ins.funct3 = uint32(RM_RTZ)
} else {
ins.funct3 = uint32(p.Scond &^ rmSuffixBit)
}
case AFNES, AFNED:
// Replace FNE[SD] with FEQ[SD] and NOT.
@ -2478,6 +2483,14 @@ func isUnsafePoint(p *obj.Prog) bool {
return p.Mark&USES_REG_TMP == USES_REG_TMP || p.From.Reg == REG_TMP || p.To.Reg == REG_TMP || p.Reg == REG_TMP
}
func ParseSuffix(prog *obj.Prog, cond string) (err error) {
switch prog.As {
case AFCVTWS, AFCVTLS, AFCVTWUS, AFCVTLUS, AFCVTWD, AFCVTLD, AFCVTWUD, AFCVTLUD:
prog.Scond, err = rmSuffixEncode(strings.TrimPrefix(cond, "."))
}
return
}
var LinkRISCV64 = obj.LinkArch{
Arch: sys.ArchRISCV64,
Init: buildop,