cmd/compile: add wasm architecture

This commit adds the wasm architecture to the compile command.
A later commit will contain the corresponding linker changes.

Design doc: https://docs.google.com/document/d/131vjr4DH6JFnb-blm_uRdaC0_Nv3OUwjEY5qVCxCup4

The following files are generated:
- src/cmd/compile/internal/ssa/opGen.go
- src/cmd/compile/internal/ssa/rewriteWasm.go
- src/cmd/internal/obj/wasm/anames.go

Updates #18892

Change-Id: Ifb4a96a3e427aac2362a1c97967d5667450fba3b
Reviewed-on: https://go-review.googlesource.com/103295
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>

2 files changed, 37 insertions, 0 deletions

diff --git a/src/cmd/asm/internal/arch/arch.go b/src/cmd/asm/internal/arch/arch.go
index 357ec757bc..0e4d63744b 100644
--- a/src/cmd/asm/internal/arch/arch.go
+++ b/src/cmd/asm/internal/arch/arch.go
@@ -11,6 +11,7 @@ import (
 	"cmd/internal/obj/mips"
 	"cmd/internal/obj/ppc64"
 	"cmd/internal/obj/s390x"
+	"cmd/internal/obj/wasm"
 	"cmd/internal/obj/x86"
 	"fmt"
 	"strings"
@@ -87,6 +88,8 @@ func Set(GOARCH string) *Arch {
 		a := archS390x()
 		a.LinkArch = &s390x.Links390x
 		return a
+	case "wasm":
+		return archWasm()
 	}
 	return nil
 }
@@ -95,6 +98,10 @@ func jumpX86(word string) bool {
 	return word[0] == 'J' || word == "CALL" || strings.HasPrefix(word, "LOOP") || word == "XBEGIN"
 }
 
+func jumpWasm(word string) bool {
+	return word == "JMP" || word == "CALL" || word == "Call" || word == "Br" || word == "BrIf"
+}
+
 func archX86(linkArch *obj.LinkArch) *Arch {
 	register := make(map[string]int16)
 	// Create maps for easy lookup of instruction names etc.
@@ -577,3 +584,24 @@ func archS390x() *Arch {
 		IsJump:         jumpS390x,
 	}
 }
+
+func archWasm() *Arch {
+	instructions := make(map[string]obj.As)
+	for i, s := range obj.Anames {
+		instructions[s] = obj.As(i)
+	}
+	for i, s := range wasm.Anames {
+		if obj.As(i) >= obj.A_ARCHSPECIFIC {
+			instructions[s] = obj.As(i) + obj.ABaseWasm
+		}
+	}
+
+	return &Arch{
+		LinkArch:       &wasm.Linkwasm,
+		Instructions:   instructions,
+		Register:       wasm.Register,
+		RegisterPrefix: nil,
+		RegisterNumber: nilRegisterNumber,
+		IsJump:         jumpWasm,
+	}
+}
diff --git a/src/cmd/asm/internal/asm/asm.go b/src/cmd/asm/internal/asm/asm.go
index 4c256f62b2..17572e731d 100644
--- a/src/cmd/asm/internal/asm/asm.go
+++ b/src/cmd/asm/internal/asm/asm.go
@@ -343,6 +343,13 @@ func (p *Parser) asmJump(op obj.As, cond string, a []obj.Addr) {
 		As:   op,
 	}
 	switch len(a) {
+	case 0:
+		if p.arch.Family == sys.Wasm {
+			target = &obj.Addr{Type: obj.TYPE_NONE}
+			break
+		}
+		p.errorf("wrong number of arguments to %s instruction", op)
+		return
 	case 1:
 		target = &a[0]
 	case 2:
@@ -445,6 +452,8 @@ func (p *Parser) asmJump(op obj.As, cond string, a []obj.Addr) {
 	case target.Type == obj.TYPE_CONST:
 		// JMP $4
 		prog.To = a[0]
+	case target.Type == obj.TYPE_NONE:
+		// JMP
 	default:
 		p.errorf("cannot assemble jump %+v", target)
 		return