8 files changed, 100 insertions, 5 deletions
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java b/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java
index bfb20705..394ba336 100644
--- a/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java
+++ b/chapter22/src/test/java/com/seaofnodes/simple/Chapter22Test.java
@@ -22,7 +22,7 @@ public class Chapter22Test {
         testCPU(src,"arm"      , "SystemV",-1,null);
     }
 
-    static void testCPU( String src, String cpu, String os, int spills, String stop ) {
+    static CodeGen testCPU( String src, String cpu, String os, int spills, String stop ) {
         CodeGen code = new CodeGen(src).driver(CodeGen.Phase.Encoding,cpu,os);
         int delta = spills>>3;
         if( delta==0 ) delta = 1;
@@ -30,15 +30,86 @@ public class Chapter22Test {
             assertEquals("Expect spills:",spills,code._regAlloc._spillScaled,delta);
         if( stop != null )
             assertEquals(stop, code._stop.toString());
+        return code;
     }
 
 
-    @Test public void testR5Load() throws IOException {
-        EvalRisc5 R5 = TestRisc5.build("riscv_load", 0, 0, false);
+    static int testCPUSize( String src, String cpu, String os, int spills, String stop ) {
+        return testCPU(src,cpu,os,spills,stop)._encoding._bits.size();
+    }
+
+    // Should not fold away
+    @Test public void testSextFail() throws IOException {
+        String src = """
+struct Person { i32 age;};
+Person !p = new Person;
+p.age = (arg<<17)>>17;
+return 0;
+""";
+        assertEquals(46, testCPUSize(src, "x86_64_v2","Win64",2,"return 0;"));
+        assertEquals(60, testCPUSize(src, "riscv","SystemV",4,"return 0;"));
+        assertEquals(56, testCPUSize(src, "arm","SystemV",4,"return 0;"));
+
+        // do assertEquals here
+        EvalRisc5 R5 = TestRisc5.build("sext_str_not_fold_away", 0, 4, false);
         int trap = R5.step(100);
         assertEquals(0,trap);
+
+        EvalArm64 A5 = TestArm64.build("sext_str_not_fold_away", 0, 4, false);
+        trap = A5.step(100);
+        assertEquals(0,trap);
+
+    }
+
+    // Should not fold away
+    @Test public void testSextFail2() throws IOException {
+        String src = """
+
+                struct Person { i32 age;};
+                Person !p = new Person;
+                p.age = (arg<<48)>>48;
+                return 0;
+        """;
+
+        EvalRisc5 R5 = TestRisc5.build("sext_str_not_fold_away_2", 0, 4, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+
+        EvalArm64 A5 = TestArm64.build("sext_str_not_fold_away_2", 0, 4, false);
+        int trap_arm = A5.step(100);
+        assertEquals(0,trap_arm);
+
+        assertEquals(46, testCPUSize(src, "x86_64_v2","Win64",2,"return 0;"));
+        assertEquals(60, testCPUSize(src, "riscv","SystemV",4,"return 0;"));
+        assertEquals(56, testCPUSize(src, "arm","SystemV",4,"return 0;"));
+
+    }
+
+    // Should fold away
+    @Test public void testSextSuccess() throws IOException {
+        String src = """
+// Should fold away sign extend
+struct Person { i8 age;};
+Person !p = new Person;
+p.age = (arg<<48)>>48;
+return 0;
+       """;
+
+        EvalRisc5 R5 = TestRisc5.build("sext_str_fold_away", 0, 5, false);
+        int trap = R5.step(100);
+        assertEquals(0,trap);
+
+        EvalArm64 A5 = TestArm64.build("sext_str_fold_away", 0, 5, false);
+        int trap_arm = A5.step(100);
+        assertEquals(0,trap_arm);
+
+        assertEquals(41, testCPUSize(src, "x86_64_v2","Win64",2,"return 0;"));
+        assertEquals(56, testCPUSize(src, "riscv","SystemV",5,"return 0;"));
+        assertEquals(52, testCPUSize(src, "arm","SystemV",5,"return 0;"));
         // do assertEquals here
     }
+
+
     // Int now is changed to 4 bytes.
     @Test public void testPerson() throws IOException {
         String person = "6\n";
@@ -165,4 +236,5 @@ return sum(is);
         assertEquals(0,arm.regs[0]);
     }
 
+
 }
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/progs/person.smp b/chapter22/src/test/java/com/seaofnodes/simple/progs/person.smp
index 9f0f5bea..507fb83b 100644
--- a/chapter22/src/test/java/com/seaofnodes/simple/progs/person.smp
+++ b/chapter22/src/test/java/com/seaofnodes/simple/progs/person.smp
@@ -1,6 +1,6 @@
 // -*-java-*-
 struct Person {
-    int age;
+    i32 age;
 };
 
 val fcn = { Person?[] ps, int x ->
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/progs/riscv_load.smp b/chapter22/src/test/java/com/seaofnodes/simple/progs/riscv_load.smp
index 2366f354..67369feb 100644
--- a/chapter22/src/test/java/com/seaofnodes/simple/progs/riscv_load.smp
+++ b/chapter22/src/test/java/com/seaofnodes/simple/progs/riscv_load.smp
@@ -1 +1,4 @@
-return 123456789012345;
-\ No newline at end of file
+struct Person { i32 age;};
+Person !p = new Person;
+p.age += arg;
+return p.age;
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_1.smp b/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_1.smp
new file mode 100644
index 00000000..cfb3fbcc
--- /dev/null
+++ b/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_1.smp
@@ -0,0 +1,4 @@
+struct Person {i64 age;}
+Person !p  = new Person;
+p.age += arg;
+return p.age;
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_fold_away.smp b/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_fold_away.smp
new file mode 100644
index 00000000..0cf70392
--- /dev/null
+++ b/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_fold_away.smp
@@ -0,0 +1,5 @@
+// Should fold away sign extend
+struct Person { i8 age;};
+Person !p = new Person;
+p.age = (arg<<48)>>48;
+return 0;
+\ No newline at end of file
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away.smp b/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away.smp
new file mode 100644
index 00000000..48cc6409
--- /dev/null
+++ b/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away.smp
@@ -0,0 +1,4 @@
+struct Person { i32 age;};
+Person !p = new Person;
+p.age = (arg<<17)>>17;
+return 0;
+\ No newline at end of file
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away_2.smp b/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away_2.smp
new file mode 100644
index 00000000..3120429b
--- /dev/null
+++ b/chapter22/src/test/java/com/seaofnodes/simple/progs/sext_str_not_fold_away_2.smp
@@ -0,0 +1,4 @@
+struct Person { i32 age;};
+Person !p = new Person;
+p.age = (arg<<48)>>48;
+return 0;
+\ No newline at end of file
diff --git a/chapter22/src/test/java/com/seaofnodes/simple/progs/store_peep.smp b/chapter22/src/test/java/com/seaofnodes/simple/progs/store_peep.smp
new file mode 100644
index 00000000..c3feddd5
--- /dev/null
+++ b/chapter22/src/test/java/com/seaofnodes/simple/progs/store_peep.smp
@@ -0,0 +1,3 @@
+i64 a = 123456789012345;
+i32 b = a; // truncate high order bits
+return b;
+\ No newline at end of file