feat(asm): add EVEX/AVX-512 encoding and assemble the AVX-512 kernel byte-identically

Assisted-by: Qwen 3.8 Max Preview

asm/assemble.go

@@ -414,18 +414,18 @@ func operandFromAST(op *ast.Operand, size int, fi frameInfo, link *linkInfo) (Op
 			off := fi.spAdjust + a.Sym.Offset
 			return Mem{Base: spReg, Disp: off, HasBase: true, Size: size}, nil
 		}
-		// SB (global symbol): a static (file-local, <>) symbol becomes a
-		// RIP-relative reference resolved by the file-level layout; anything
-		// external needs object-file emission.
+		// SB (global symbol): a symbol defined in the same file (GLOBL) is
+		// encoded RIP-relative and resolved by the file-level layout;
+		// anything not defined here needs object-file emission.
 		if a.Sym != nil && a.Sym.Pseudo == "SB" {
-			if !a.Sym.Static {
-				return nil, fmt.Errorf("external symbol %q needs object-file emission", a.Sym.Name)
-			}
 			if link == nil || link.symbols == nil {
-				return nil, fmt.Errorf("static symbol %q needs file-level assembly (AssembleFile)", a.Sym.Name)
+				return nil, fmt.Errorf("symbol %q needs file-level assembly (AssembleFile)", a.Sym.Name)
 			}
 			if !link.symbols[a.Sym.Name] {
-				return nil, fmt.Errorf("undefined symbol %q", a.Sym.Name)
+				if a.Sym.Static {
+					return nil, fmt.Errorf("undefined symbol %q", a.Sym.Name)
+				}
+				return nil, fmt.Errorf("external symbol %q needs object-file emission", a.Sym.Name)
 			}
 			return sbMem{size: size, name: a.Sym.Name, addend: a.Sym.Offset}, nil
 		}