fix #392 - Usage of labels in asm blocks is not detected

src/analysis/unused_label.d

@@ -89,6 +89,30 @@ class UnusedLabelCheck : BaseAnalyzer
 			labelUsed(gotoStatement.label.text);
 	}
 
+	override void visit(const AsmInstruction instr)
+	{
+		instr.accept(this);
+
+		bool jmp;
+		if (instr.identifierOrIntegerOrOpcode.text.length)
+			jmp = instr.identifierOrIntegerOrOpcode.text[0] == 'j';
+
+		if (!jmp || instr.operands.operands.length != 1)
+			return;
+
+		const AsmExp e = cast(AsmExp) instr.operands.operands[0];
+		if (e.left && cast(const(AsmBrExp)) e.left)
+		{
+			const AsmBrExp b = cast(AsmBrExp) e.left;
+			if (b.asmUnaExp && b.asmUnaExp.asmPrimaryExp)
+			{
+				const AsmPrimaryExp p = b.asmUnaExp.asmPrimaryExp;
+				if (p && p.identifierChain && p.identifierChain.identifiers.length == 1)
+					labelUsed(p.identifierChain.identifiers[0].text);
+			}
+		}
+	}
+
 private:
 
 	static struct Label
@@ -181,5 +205,21 @@ unittest
 		}
 	}c, sac);
 
+	assertAnalyzerWarnings(q{
+		void testAsm()
+		{
+			asm { jmp lbl;}
+			lbl:
+		}
+	}c, sac);
+
+	assertAnalyzerWarnings(q{
+		void testAsm()
+		{
+			asm { mov RAX,1;}
+			lbl: // [warn]: Label "lbl" is not used.
+		}
+	}c, sac);
+
 	stderr.writeln("Unittest for UnusedLabelCheck passed.");
 }