[arch] arm64/instgen: allow only certain AClasses in gen

[Junyang Shao (Gerrit)]

Junyang Shao has uploaded the change for review

Commit message

arm64/instgen: allow only certain AClasses in gen

This CL adds logic to allow only certain AClasses to be generated.

It is useful for partial code gen for assembler without all AClasses
support.

Change-Id: Icea821e8ae366edbcc3922e3f8411fe6054f446e

Change diff

diff --git a/arm64/instgen/xmlspec/generator.go b/arm64/instgen/xmlspec/generator.go
index f81584f..e37a93f 100644
--- a/arm64/instgen/xmlspec/generator.go
+++ b/arm64/instgen/xmlspec/generator.go
@@ -125,11 +125,11 @@
 
 const (
 {{- range $i, $e := .NewGoOps}}
-	{{if eq $i 0}}
+	{{- if eq $i 0}}
 	{{$e}} obj.As = obj.ABaseARM64 + obj.A_ARCHSPECIFIC + 1000 + iota
-	{{else}}
+	{{- else}}
 	{{$e}}
-	{{end}}
+	{{- end}}
 {{- end}}
 )
 `
@@ -182,6 +182,16 @@
 	newGoOps := make(map[string]bool)
 	existingGoOps := readExistingGoOps(filepath.Join(outputDir, "a.out.go"))
 
+	allowedOperandTypes := map[string]bool{
+		"AC_ARNG":  true,
+		"AC_PREG":  true,
+		"AC_PREGZ": true,
+		"AC_PREGM": true,
+		"AC_ZREG":  true,
+	}
+
+	usedFuncIndices := make(map[int]bool)
+
 	for _, inst := range insts {
 		for _, iclass := range inst.Classes.Iclass {
 			if !iclass.Regdiagram.parsed {
@@ -192,6 +202,26 @@
 				if !encoding.parsed {
 					continue
 				}
+
+				// Filtering logic:
+				// 1. If 0 operands (len <= 1), keep with warning.
+				// 2. If > 0 operands, ALL must be in allowedOperandTypes.
+				keep := true
+				if len(encoding.operands) <= 1 {
+					log.Printf("Warning: instruction with 0 operands kept: %s", encoding.asm)
+				} else {
+					for _, op := range encoding.operands[1:] {
+						if !allowedOperandTypes[op.typ] {
+							keep = false
+							break
+						}
+					}
+				}
+
+				if !keep {
+					continue
+				}
+
 				if _, ok := goOps[encoding.goOp]; !ok {
 					goOps[encoding.goOp] = struct{}{}
 				}
@@ -224,6 +254,7 @@
 								Index:     j,
 								FuncIndex: idx,
 							})
+							usedFuncIndices[idx] = true
 						}
 					}
 					instData.Args = append(instData.Args, arg)
@@ -241,6 +272,8 @@
 	// Collect constants
 	encodedInMap := make(map[string]string) // raw string -> constant name
 	var uniqueEncodedIn []string
+
+	// Collect ALL constants from global map to ensure invariant names (ENC_X)
 	for _, v := range encodingDescsToEncodedIn {
 		if v == "" || v == "nil" {
 			continue
@@ -252,17 +285,33 @@
 	}
 	sort.Strings(uniqueEncodedIn)
 
+	// Identify used constants
+	neededEncodedIn := make(map[string]bool)
+	for k, idx := range encodingFuncs {
+		if usedFuncIndices[idx] {
+			if v := encodingDescsToEncodedIn[k]; v != "" && v != "nil" {
+				neededEncodedIn[v] = true
+			}
+		}
+	}
+
 	var constants []constantData
 	for i, v := range uniqueEncodedIn {
 		name := fmt.Sprintf("ENC_%d", i)
 		encodedInMap[v] = name
-		constants = append(constants, constantData{
-			ConstName: name,
-			BinName:   v,
-		})
+		// Only add to output if used
+		if neededEncodedIn[v] {
+			constants = append(constants, constantData{
+				ConstName: name,
+				BinName:   v,
+			})
+		}
 	}
 
 	for i, k := range sortedEncodings {
+		if !usedFuncIndices[i+1] {
+			continue
+		}
 		sym := encodingDescsToEncodedIn[k]
 		if name, ok := encodedInMap[sym]; ok {
 			sym = name

Change information

Files:

• M arm64/instgen/xmlspec/generator.go

Change size: M

Delta: 1 file changed, 56 insertions(+), 7 deletions(-)

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Gerrit

Gerrit-MessageType: newchange

Gerrit-Project: arch

Gerrit-Branch: master

Gerrit-Change-Id: Icea821e8ae366edbcc3922e3f8411fe6054f446e

Gerrit-Change-Number: 749940

Gerrit-PatchSet: 1

Gerrit-Owner: Junyang Shao <shaoj...@google.com>