Finish separate compilation snapshot in chapter 28b

10 files changed, 311 insertions, 28 deletions

diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/BoundaryTest.java b/chapter28b/src/test/java/com/seaofnodes/simple/BoundaryTest.java
new file mode 100644
index 00000000..b736ccb3
--- /dev/null
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/BoundaryTest.java
@@ -0,0 +1,86 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.*;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+// The new module boundary must preserve the preceding chapters' examples.
+public class BoundaryTest {
+    @Test public void testLocalConstruction() throws java.io.IOException {
+        String src="struct Counter { int x; int y; int z; new Counter={int n -> while(x<n) { int old=x; y=x+1; x=y+1; z=old; }}; }; val c=new Counter(arg); return c.x*100+c.z;";
+        CodeGen code=new CodeGen(src).driver(CodeGen.Phase.LocalSched);
+        assertEquals("2018",Eval2.eval(code,19));
+        assertEquals("0",Eval2.eval(code,0));
+        code._stop.walk(n -> {
+            if( n instanceof StoreNode st ) assertEquals(0,st.cfg0().loopDepth());
+            return null;
+        });
+        code=new CodeGen("struct Byte { new Byte={int n -> self.x=n; self.x+=3;}; u8 x; }; return new Byte(255).x;").driver(CodeGen.Phase.TypeCheck);
+        assertEquals("2",Eval2.eval(code,0));
+        // data is still unset when the constructor reads and updates x.
+        code=new CodeGen("struct Box { int x=7; int[] data; new Box={ -> self.x++; int n=self.x; data=new int[n]; }; }; return new Box().data#;")
+            .driver(CodeGen.Phase.TypeCheck);
+        assertEquals("8",Eval2.eval(code,0));
+        for( String field : new String[]{"data","self.data"} ) {
+            try {
+                new CodeGen("struct Box { int[] data; new Box={ -> int n="+field+"#; data=new int[n]; }; }; return new Box();")
+                    .driver(CodeGen.Phase.TypeCheck);
+                fail("An uninitialized field must not be read");
+            } catch( Parser.ParseException e ) {
+                assertTrue(e.getMessage(),e.getMessage().contains("might not be initialized"));
+            }
+        }
+        java.nio.file.Path cfile=java.nio.file.Path.of("build/objs/constructionBoundary.c");
+        java.nio.file.Files.createDirectories(cfile.getParent());
+        java.nio.file.Files.writeString(cfile,"""
+            __attribute__((CALL_CONV)) extern long long count(long long);
+            int main(void) { return count(19)!=2018 || count(0)!=0; }
+            """);
+        TestC.run("val count={int arg ->"+src+"};","constructionBoundary",null,TestC.CALL_CONVENTION,
+                  TestC.CALL_CONVENTION.equals("win64") ? "ms_abi" : "sysv_abi",cfile.toString(),"",-1);
+    }
+
+    @Test public void testRecursiveCallback() {
+        String src="""
+            val run={int n ->
+                val power={int base,int exponent -> if(exponent<=0) return 1; return base*power(base,exponent-1);};
+                val sumPowers={int n,{int int -> int} f -> if(n<=0) return 0; return f(2,n)+sumPowers(n-1,f);};
+                return sumPowers(n,power);
+            };
+            return run(arg);
+            """;
+        for( long seed : new long[]{2,13,123} ) {
+            CodeGen code=new CodeGen(src,seed,true).driver(CodeGen.Phase.Opto);
+            ParmNode base=code._start.walk(n -> n instanceof ParmNode p && p._label.equals("base") ? p : null);
+            assertNotNull(base);
+            assertSame(TypeInteger.constant(2),base._type);
+            code.driver(CodeGen.Phase.TypeCheck);
+            assertEquals("14",Eval2.eval(code,3));
+        }
+    }
+
+    @Test public void testNativeExposure() {
+        for( String tail : new String[]{
+            "retain(power); return power(2,n);",
+            "if(n) { retain(power); while(true) {} } return power(2,n);"
+        } ) {
+            String src="val run={int n -> val power={int base,int exponent -> if(exponent<=0) return 1; return base*power(base,exponent-1);}; { {int int -> int} -> int } retain=\"C\";"+tail+"}; return run(arg);";
+            CodeGen code=new CodeGen(src).driver(CodeGen.Phase.Opto);
+            ParmNode base=code._start.walk(n -> n instanceof ParmNode p && p._label.equals("base") ? p : null);
+            assertNotNull(base);
+            assertSame(TypeInteger.BOT,base._type);
+            code.driver(CodeGen.Phase.TypeCheck);
+        }
+    }
+
+    @Test public void testLazyTables() {
+        for( long seed : new long[]{1,123,987654321} ) {
+            CodeGen code=new CodeGen("src/test/smp/lazy","build/objs",null,"App/Main",null,seed,true,TypeInteger.BOT)
+                .driver(CodeGen.Phase.TypeCheck);
+            assertEquals("0",Eval2.eval(code,0));
+            assertEquals("125",Eval2.eval(code,1));
+        }
+    }
+}
diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/ChainedComparisonTest.java b/chapter28b/src/test/java/com/seaofnodes/simple/ChainedComparisonTest.java
new file mode 100644
index 00000000..8db9c024
--- /dev/null
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/ChainedComparisonTest.java
@@ -0,0 +1,37 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.type.TypeInteger;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class ChainedComparisonTest {
+    @Test public void testAdjacentOperandsAndOperators() {
+        String[] expressions = {"10 < arg < 20", "0 < arg <= 3", "3 >= arg > 0",
+                                "0 <= arg < 3", "0 < arg <= 3 < 4"};
+        String[][] expected = {{"0","0","1","0"}, {"0","1","0","0"},
+                               {"0","1","0","0"}, {"1","0","0","0"},
+                               {"0","1","0","0"}};
+        int[] args = {0,3,15,30};
+        for(int i=0;i<expressions.length;i++) {
+            CodeGen code = new CodeGen("return "+expressions[i]+";").driver(CodeGen.Phase.TypeCheck);
+            for(int j=0;j<args.length;j++) assertEquals(expressions[i],expected[i][j],Eval2.eval(code,args[j]));
+        }
+    }
+
+    @Test public void testSingleEvaluationAndShortCircuit() {
+        for(int seed:new int[]{2,13,123}) {
+            CodeGen code = new CodeGen("int x=arg; int y=0; val b=0 < x++ <= (y+=3) < (y+=1); return x*100+y*10+b;",seed,true)
+                .driver(CodeGen.Phase.TypeCheck);
+            assertEquals("100",Eval2.eval(code,0));
+            assertEquals("441",Eval2.eval(code,3));
+            assertEquals("530",Eval2.eval(code,4));
+        }
+        try {
+            new CodeGen("return 0 < arg > 1;").parse();
+            fail("mixed directions");
+        } catch(RuntimeException e) {
+            assertEquals("Mixing relational directions in a chained relational test",e.getMessage());
+        }
+    }
+}
diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/Chapter17bTest.java b/chapter28b/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
index 08029c4b..4019fd38 100644
--- a/chapter28b/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/Chapter17bTest.java
@@ -300,7 +300,7 @@ A x = new A;
         for( String fields : new String[] {
             "!B !b; new A = { -> if (arg) b = new B; };",
             "!B !b; new A = { -> if (arg) return 0; b = new B; };",
-            "!B !b; new A = { !B b -> b = new B; };", // Argument shadows field
+            "!B !b; new A = { !B !b -> b = new B; };", // Argument shadows field
             "new A = { -> }; !B !b;",              // Field declared later
         } ) {
             CodeGen code = new CodeGen("struct B {}; struct A { "+fields+" }; return 0;");
diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/Chapter18Test.java b/chapter28b/src/test/java/com/seaofnodes/simple/Chapter18Test.java
index ae1dca5f..632b9539 100644
--- a/chapter28b/src/test/java/com/seaofnodes/simple/Chapter18Test.java
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/Chapter18Test.java
@@ -436,7 +436,7 @@ return s.x;
         catch( Exception e ) { assertEquals("Accessing unknown field 'x' from '*Test.S'",e.getMessage()); }
     }
 
-    @Test @Ignore
+    @Test
     public void testErr5() {
         CodeGen code = new CodeGen(
 """
@@ -450,8 +450,8 @@ return g();
     }
 
 
-    // Mutual recursion.  Fails without SCCP to lift the recursive return types.
-    @Ignore @Test
+    // Mutual recursion: check results, independent of how much gets inlined.
+    @Test
     public void testFcnMutRec() {
         CodeGen code = new CodeGen(
 """
@@ -460,7 +460,6 @@ val is_odd  = { int x -> x ? is_even(x-1) : false; };
 return is_even(arg);
 """);
         code.driver(CodeGen.Phase.TypeCheck);
-        assertEquals("Stop[ return #2; return Phi(Region,0,1,#2); ]", code.print());
         assertEquals("1", Eval2.eval(code, 0));
         assertEquals("0", Eval2.eval(code, 1));
         assertEquals("1", Eval2.eval(code, 2));
diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/Chapter20Test.java b/chapter28b/src/test/java/com/seaofnodes/simple/Chapter20Test.java
index 0458941e..cdfd16a7 100644
--- a/chapter28b/src/test/java/com/seaofnodes/simple/Chapter20Test.java
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/Chapter20Test.java
@@ -202,7 +202,6 @@ flt farg = arg; return _test_sqrt_noInline(farg) + _test_sqrt_noInline(farg+2.0)
     }
 
 
-
     @Test
     public void testArray1() {
         String src =
@@ -257,9 +256,9 @@ val _hashCodeString = { !String self ->
     return hash;
 };
 """;
-        testCPU(src,"x86_64_v2", "SystemV",21,null);
-        testCPU(src,"riscv"    , "SystemV",8,null);
-        testCPU(src,"arm"      , "SystemV",8,null);
+        testCPU(src,"x86_64_v2", "SystemV",12,null);
+        testCPU(src,"riscv"    , "SystemV",6,null);
+        testCPU(src,"arm"      , "SystemV",6,null);
     }
 
     @Test
diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/Chapter21Test.java b/chapter28b/src/test/java/com/seaofnodes/simple/Chapter21Test.java
index 07ae42eb..2fcf65e9 100644
--- a/chapter28b/src/test/java/com/seaofnodes/simple/Chapter21Test.java
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/Chapter21Test.java
@@ -383,9 +383,9 @@ val _hashCodeString = { !String self ->
     return hash;
 };
 """;
-        testCPU(src,"x86_64_v2", "SystemV",21,null);
-        testCPU(src,"riscv"    , "SystemV",8,null);
-        testCPU(src,"arm"      , "SystemV",8,null);
+        testCPU(src,"x86_64_v2", "SystemV",12,null);
+        testCPU(src,"riscv"    , "SystemV",6,null);
+        testCPU(src,"arm"      , "SystemV",6,null);
     }
 
     @Test public void testStringExport() throws IOException {
@@ -422,7 +422,7 @@ val _hashCodeString = { !String self ->
     return hash;
 };
 """;
-        TestC.runC(src, "stringHash", "",21);
+        TestC.runC(src, "stringHash", "",12);
     }
 
     @Test public void testLoop2() {
diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/Chapter25Test.java b/chapter28b/src/test/java/com/seaofnodes/simple/Chapter25Test.java
index 275be96a..31a616b5 100644
--- a/chapter28b/src/test/java/com/seaofnodes/simple/Chapter25Test.java
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/Chapter25Test.java
@@ -412,7 +412,7 @@ public class Chapter25Test {
     @Test
     public void testHelloWorldDriver() throws Exception {
         String out = "build/objs/helloWorldDriver/";
-        Simple.main(new String[]{"-L",SYS_BLDDIR,"-o",out,"--norun","docs/examples/A_helloWorld.smp"});
+        Simple.main(new String[]{"-L",SYS_BLDDIR,"-o",out,"--norun","src/test/smp/examples/A_helloWorld.smp"});
         assertTrue(Files.isRegularFile(Path.of(out,"A_helloWorld.o")));
     }
 
@@ -423,7 +423,7 @@ public class Chapter25Test {
         try( PrintStream capture = new PrintStream(output,true,StandardCharsets.UTF_8) ) {
             System.setOut(capture);
             Simple.main(new String[]{"-L",SYS_FILE.toString(),"-o","build/objs/helloWorldDriverLibFile/",
-                                    "docs/examples/A_helloWorld.smp"});
+                                    "src/test/smp/examples/A_helloWorld.smp"});
         } finally {
             System.setOut(saved);
         }
@@ -471,7 +471,7 @@ return  rez < buf# ? 0 : sys.libc._exit(-2);
 
     @Test
     public void testBubbles() throws IOException {
-        String src = Files.readString( Path.of("docs/examples/BubbleSort.smp"));
+        String src = Files.readString( Path.of("src/test/smp/examples/BubbleSort.smp"));
         String exe = TestC.compile(src,"BubbleSort",new Ary<>(new String[]{SYS_BLDDIR}),
                                    TestC.CALL_CONVENTION,null,null,-1);
         assertEquals("[-17, 2, 3, 999]\n",
@@ -492,7 +492,7 @@ return  rez < buf# ? 0 : sys.libc._exit(-2);
 
     @Test
     public void testCapitalize() throws IOException {
-        String src = Files.readString(Path.of("docs/examples/Capitalize.smp"));
+        String src = Files.readString(Path.of("src/test/smp/examples/Capitalize.smp"));
         String exe = TestC.compile(src,"Capitalize",new Ary<>(new String[]{SYS_BLDDIR}),
                                    TestC.CALL_CONVENTION,null,null,-1);
         assertEquals("Hello world\n",TestC.exec(exe,"hello world"));
@@ -505,7 +505,7 @@ return  rez < buf# ? 0 : sys.libc._exit(-2);
 
     @Test
     public void testDijkstra() throws IOException {
-        String src = Files.readString(Path.of("docs/examples/Dijkstra.smp"));
+        String src = Files.readString(Path.of("src/test/smp/examples/Dijkstra.smp"));
         String matrix = "[0, 2, 0, 6, 0, 2, 0, 3, 8, 5, 0, 3, 0, 0, 7, 6, 8, 0, 0, 9, 0, 5, 7, 9, 0]";
         String exe = TestC.compile(src,"Dijkstra",new Ary<>(new String[]{SYS_BLDDIR}),
                                    TestC.CALL_CONVENTION,null,null,-1);
@@ -520,7 +520,7 @@ return  rez < buf# ? 0 : sys.libc._exit(-2);
 
     @Test
     public void testFileIO() throws IOException {
-        String src = Files.readString(Path.of("docs/examples/FileIO.smp"));
+        String src = Files.readString(Path.of("src/test/smp/examples/FileIO.smp"));
         String exe = TestC.compile(src,"FileIO",new Ary<>(new String[]{SYS_BLDDIR}),
                                    TestC.CALL_CONVENTION,null,null,-1);
         assertEquals("File I/O succeeded\n",TestC.exec(exe));
diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/FinalConstructionTest.java b/chapter28b/src/test/java/com/seaofnodes/simple/FinalConstructionTest.java
new file mode 100644
index 00000000..f583e2d2
--- /dev/null
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/FinalConstructionTest.java
@@ -0,0 +1,65 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.codegen.CodeGen;
+import com.seaofnodes.simple.node.StoreNode;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class FinalConstructionTest {
+    private static final String LOOP = """
+        val step={int x -> x*2+1;};
+        struct C {
+            val x=1;
+            new C={int n ->
+                x=0; x=1;
+                for(int i=0; i<n; i++) x=step(x);
+            };
+            val get={->x;};
+        };
+        return new C(arg).get();
+        """;
+
+    @Test public void testFinalConstructorLocals() throws java.io.IOException {
+        var code=new CodeGen(LOOP).driver(CodeGen.Phase.LocalSched);
+        assertEquals("1",Eval2.eval(code,0));
+        assertEquals("15",Eval2.eval(code,3));
+        assertEquals("63",Eval2.eval(code,5));
+        code._stop.walk(n -> {
+            if( n instanceof StoreNode st && st._name.equals("x") )
+                assertEquals("Final field writes belong after the loop",0,st.cfg0().loopDepth());
+            return null;
+        });
+        String[] sources={
+            "struct C { val x=1; new C={->x=1; x=2;}; }; return new C().x;",
+            "struct C { int ~x; new C={int n -> self.x=1; for(int i=0;i<n;i++) self.x*=2;}; }; return new C(arg).x;",
+            "struct C { val x=1; new C={int n -> for(int i=0;i<n;i++) ++x;}; }; return new C(arg).x;",
+            "struct C { val x=1.5; new C={->x=2.5;}; }; return new C().x;",
+            "struct C { val x=\"a\"; new C={int n -> for(int i=0;i<n;i++) x=\"b\";}; }; return new C(arg).x[0];",
+            "struct C { val x=new int[1]; new C={->x=new int[2]; x=new int[3];}; }; return new C().x#;"
+        };
+        String[] results={"2","8","4","2.5","98","3"};
+        for( int i=0; i<sources.length; i++ )
+            assertEquals(results[i],Eval2.eval(new CodeGen(sources[i]).driver(CodeGen.Phase.TypeCheck),3));
+
+        String[] rejected={
+            "struct C { val x=1; }; val c=new C(); c.x=2; return c.x;",
+            "struct C { new C={->val x=1; x=2;}; }; return new C();",
+            "struct C { val f={->1;}; new C={->f={->2;};}; }; return new C().f();"
+        };
+        for( String src : rejected ) {
+            try { new CodeGen(src).driver(CodeGen.Phase.TypeCheck); fail(src); }
+            catch( Parser.ParseException e ) { assertTrue(e.getMessage(),e.getMessage().startsWith("Cannot")); }
+        }
+
+        var dir=java.nio.file.Path.of("build/objs");
+        java.nio.file.Files.createDirectories(dir);
+        java.nio.file.Files.writeString(dir.resolve("finalConstruction.smp"),"val buildFinal={int arg ->"+LOOP+"};");
+        java.nio.file.Files.writeString(dir.resolve("finalConstruction.c"),"""
+            extern long long buildFinal(long long);
+            int main(void) { return buildFinal(0)!=1 || buildFinal(3)!=15 || buildFinal(5)!=63; }
+            """);
+        TestC.run("val buildFinal={int arg ->"+LOOP+"};","finalConstruction",null,TestC.CALL_CONVENTION,
+                  TestC.CALL_CONVENTION.equals("win64") ? "ms_abi" : "sysv_abi",
+                  dir.resolve("finalConstruction.c").toString(),"",-1);
+    }
+}
diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/SeparateCompilationTest.java b/chapter28b/src/test/java/com/seaofnodes/simple/SeparateCompilationTest.java
new file mode 100644
index 00000000..4576bc94
--- /dev/null
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/SeparateCompilationTest.java
@@ -0,0 +1,90 @@
+package com.seaofnodes.simple;
+
+import com.seaofnodes.simple.codegen.*;
+import com.seaofnodes.simple.node.*;
+import com.seaofnodes.simple.type.TypeInteger;
+import com.seaofnodes.simple.util.Ary;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class SeparateCompilationTest {
+    @Test public void testImportedNativeExposure() throws Exception {
+        Path build=Path.of("build/objs/separate");
+        Files.createDirectories(build);
+        Path lib=Files.createTempDirectory(build,"callbacks-");
+        String src="""
+            val run={int n ->
+                val power={int base,int exponent ->
+                    if(exponent<=0) return 1;
+                    return base*power(base,exponent-1);
+                };
+                { {int int -> int} -> int } retain="C";
+                retain(power);
+                return power(2,n);
+            };
+            """;
+        new CodeGen(null,lib.toString(),null,"Callbacks",src,123,true,TypeInteger.BOT)
+            .driver(TestC.CPU_PORT,TestC.CALL_CONVENTION,false,false);
+        CodeGen code=new CodeGen(null,null,new Ary<>(new String[]{lib.toString()}),
+            "Client","return Callbacks.run(arg);",123,true,TypeInteger.BOT)
+            .driver(CodeGen.Phase.Opto);
+        assertNull(code._compunits.get("Callbacks")._src);
+        ParmNode base=code._start.walk(n -> n instanceof ParmNode p && p._label.equals("base") ? p : null);
+        assertNotNull(base);
+        assertSame("Native code may call the saved callback with any base",TypeInteger.BOT,base._type);
+        code.driver(CodeGen.Phase.TypeCheck);
+    }
+
+    // The client root contains no library source. The saved constructor must
+    // keep local loop values, and retained calls must use the library's storage.
+    @Test public void testImportedConstructorAndState() throws Exception {
+        Path fixtures=Path.of("src/test/smp/separate");
+        Path build=Path.of("build/objs/separate");
+        Files.createDirectories(build);
+        Path lib=Files.createTempDirectory(build,"library-");
+        Path client=Files.createTempDirectory(build,"client-");
+        new CodeGen(fixtures.resolve("library").toString(),lib.toString(),null,
+            "Counters",null,123,true,TypeInteger.BOT)
+            .driver(TestC.CPU_PORT,TestC.CALL_CONVENTION,false,false);
+        assertTrue(Files.isRegularFile(lib.resolve("Counters.o")));
+        assertFalse(Files.exists(fixtures.resolve("client/Counters.smp")));
+        var paths=new Ary<>(new String[]{lib.toString()});
+        for( long seed : new long[]{2,13,123} ) {
+            CodeGen code=new CodeGen(fixtures.resolve("client").toString(),client.toString(),paths,
+                "Main",null,seed,true,TypeInteger.BOT).driver(CodeGen.Phase.TypeCheck);
+            CompUnit imported=code._compunits.get("Counters");
+            assertNotNull(imported);
+            assertNull("Library source must not be parsed",imported._src);
+            assertEquals(lib.resolve("Counters.o").toRealPath(),imported._obj.toPath().toRealPath());
+            assertEquals("0",Eval2.eval(code,0));
+            assertEquals("107",Eval2.eval(code,3));
+            assertEquals("131",Eval2.eval(code,5));
+        }
+        new CodeGen(fixtures.resolve("client").toString(),client.toString(),paths,
+            "Main",null,123,true,TypeInteger.BOT)
+            .driver(TestC.CPU_PORT,TestC.CALL_CONVENTION,false,false);
+        Path driver=client.resolve("driver.c");
+        Files.writeString(driver,"""
+            #include <stdio.h>
+            __attribute__((CALL_CONV)) extern long long run(long long);
+            int main(void) {
+                long long args[]={0,3,5,0,3}, expected[]={0,107,231,0,307};
+                for(int i=0;i<5;i++) {
+                    long long actual=run(args[i]);
+                    if(actual!=expected[i]) {
+                        printf("call %d: got %lld, expected %lld\\n",i,actual,expected[i]);
+                        return 1;
+                    }
+                }
+                return 0;
+            }
+            """);
+        String exe=client.resolve(TestC.OS.startsWith("Windows")?"test.exe":"test").toString();
+        TestC.linkExe(client.resolve("Main.o").toString(),
+            TestC.CALL_CONVENTION.equals("win64")?"ms_abi":"sysv_abi",driver.toString(),
+            new Ary<>(new String[]{lib.resolve("Counters.o").toString()}),exe);
+        assertEquals("",TestC.exec(TestC.TEST_TIMEOUT_SECONDS,exe));
+    }
+}
diff --git a/chapter28b/src/test/java/com/seaofnodes/simple/Simple.java b/chapter28b/src/test/java/com/seaofnodes/simple/Simple.java
index 2d688bbe..7cfdf57d 100644
--- a/chapter28b/src/test/java/com/seaofnodes/simple/Simple.java
+++ b/chapter28b/src/test/java/com/seaofnodes/simple/Simple.java
@@ -13,7 +13,6 @@ import java.io.InputStreamReader;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.util.ArrayList;
-import java.util.stream.Collectors;
 
 public class Simple {
     static void usage() {
@@ -83,7 +82,11 @@ Options:
 
     static String getInput() {
         BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
-        return reader.lines().collect(Collectors.joining("\n"));
+        StringBuilder text=new StringBuilder();
+        try {
+            for( String line; (line=reader.readLine())!=null; ) text.append(line).append('\n');
+        } catch( IOException e ) { throw new RuntimeException(e); }
+        return text.toString();
     }
 
     public static void main(String[] args) throws Exception {
@@ -140,6 +143,9 @@ Options:
             case "-o":                        if (out != null || i + 1 >= args.length || args[i + 1].charAt(0) == '-') bad_usage();
                                               out = args[++i];  do_codegen=true;
                                               break;
+            case "--root":                    if( root!=null || i+1>=args.length ) bad_usage();
+                                              root=args[++i];
+                                              break;
             case "-L":                        if (i + 1 >= args.length || args[i + 1].charAt(0) == '-') bad_usage();
                                               libPaths.add(args[++i]);
                                               break;
@@ -175,7 +181,8 @@ Options:
             if( modPath == null )
                 modPath = Path.of(".");
         } else {
-            throw Utils.TODO();
+            modPath=Path.of(root);
+            inPath=modPath.resolve(inPath);
         }
 
         // Compute the module-relative paths for all sources
@@ -184,7 +191,8 @@ Options:
         Path relPath = n==1 ? null : srcRelPath.subpath(0,n-1);
         // Compute source/class name
         String srcNameExt = srcRelPath.getName(n-1).toString();
-        String srcName = srcNameExt.substring(0,srcNameExt.length()-4);
+        String srcName = srcRelPath.toString().replace('\\','/');
+        srcName=srcName.substring(0,srcName.length()-4);
 
         // Compute the build path.
         Path outPath;
@@ -219,15 +227,14 @@ Options:
         if( simpleHome != null && !simpleHome.isEmpty() )
             libPaths.add(Path.of(simpleHome,cpu+"_"+abi).toString());
 
-        // Read input file
-        try {
-            src = input_filename.isEmpty() ? getInput() : Files.readString(Path.of(input_filename));
-        } catch( IOException e ) { throw bad("Cannot read input file: "+input_filename);  }
+        // Keep file-backed units so discovery sees parents and siblings.
+        src = input_filename.isEmpty() ? getInput() : null;
 
         // Compilation pipeline
         Ary<String> externPaths = libPaths.isEmpty() ? null : new Ary<>(libPaths.toArray(new String[0]));
         CodeGen code = new CodeGen(modPath.toString(), outPath.toString(), externPaths, srcName, src, 456, true, TypeInteger.BOT );
-        code.driver(Phase.LastPhase,cpu,abi, false, emit_main || do_run || do_eval, dump);
+        code.driver(do_eval && !do_codegen ? Phase.TypeCheck : Phase.LastPhase,
+                    cpu,abi, false, emit_main || do_run || do_eval, dump);
 
         if( do_codegen && print_asm )
             System.out.println(code.asm());