From 8331098d1904538a3a97d22e4d847cf2cc94e57d Mon Sep 17 00:00:00 2001
From: Cliff Click <cliffc@acm.org>
Date: Thu, 17 Sep 2026 15:04:32 -0700
Subject: x86 mul reg reg encoding fix

---
 chapter21/Makefile                                 |  2 +-
 .../com/seaofnodes/simple/X86EncodingTest.java     | 33 ----------------------
 .../seaofnodes/simple/codegen/X86EncodingTest.java | 32 +++++++++++++++++++++
 3 files changed, 33 insertions(+), 34 deletions(-)
 delete mode 100644 chapter21/src/test/java/com/seaofnodes/simple/X86EncodingTest.java
 create mode 100644 chapter21/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java

(limited to 'chapter21')

diff --git a/chapter21/Makefile b/chapter21/Makefile
index 055c632a..429e40df 100644
--- a/chapter21/Makefile
+++ b/chapter21/Makefile
@@ -37,7 +37,7 @@ main_javas   := $(wildcard $(SRC)/$(SIMPLE)/*java $(SRC)/$(SIMPLE)/*/*java $(SRC
 test_javas   := $(wildcard $(TST)/$(SIMPLE)/*java $(TST)/$(SIMPLE)/*/*java)
 main_classes := $(patsubst $(SRC)/%java,$(CLZDIR)/main/%class,$(main_javas))
 test_classes := $(patsubst $(TST)/%java,$(CLZDIR)/test/%class,$(test_javas))
-test_cp      := $(patsubst $(TST)/$(SIMPLE)/%.java,com.seaofnodes.simple.%,$(wildcard $(TST)/$(SIMPLE)/*Test.java))
+test_cp      := $(patsubst $(TST)/$(SIMPLE)/%.java,com.seaofnodes.simple.%,$(wildcard $(TST)/$(SIMPLE)/*Test.java)) com.seaofnodes.simple.codegen.X86EncodingTest
 classes = $(main_classes) $(test_classes)
 # All the libraries
 libs = $(wildcard lib/*jar)
diff --git a/chapter21/src/test/java/com/seaofnodes/simple/X86EncodingTest.java b/chapter21/src/test/java/com/seaofnodes/simple/X86EncodingTest.java
deleted file mode 100644
index 54fa96a8..00000000
--- a/chapter21/src/test/java/com/seaofnodes/simple/X86EncodingTest.java
+++ /dev/null
@@ -1,33 +0,0 @@
-package com.seaofnodes.simple;
-
-import com.seaofnodes.simple.codegen.CodeGen;
-import com.seaofnodes.simple.node.cpus.x86_64_v2.CmpMemX86;
-import org.junit.Test;
-import static org.junit.Assert.*;
-
-public class X86EncodingTest {
-    @Test
-    public void testMemoryCompare64Immediate32() {
-        for (int immediate : new int[]{123456789, -123456789}) {
-            String src = "int[] !a = new int[2]; a[0] = arg; return a[arg & 1] == " + immediate + ";";
-            CodeGen code = new CodeGen(src).driver(CodeGen.Phase.Encoding, "x86_64_v2", "SystemV");
-            var cmp = code._stop.walk(n -> n instanceof CmpMemX86 ? n : null);
-            assertNotNull("Must exercise a memory comparison", cmp);
-            var enc = code._encoding;
-            int start = enc._opStart[cmp._nid];
-
-            // REX.W, 81 /7, SIB with scale 8, disp8, and a sign-extended imm32.
-            assertEquals(0x48, enc.read1(start) & 0xF8);
-            assertEquals(0x81, enc.read1(start + 1));
-            assertEquals(0x7C, enc.read1(start + 2));
-            assertEquals(0xC0, enc.read1(start + 3) & 0xC0);
-            assertEquals(8, enc.read1(start + 4));
-            assertEquals(immediate, enc.read4(start + 5));
-            assertEquals("CMP r/m64 uses four immediate bytes", 9, enc._opLen[cmp._nid]);
-
-            // SETE must immediately follow the CPU's nine-byte CMP instruction.
-            assertEquals(0x0F, enc.read1(start + 9));
-            assertEquals(0x94, enc.read1(start + 10));
-        }
-    }
-}
diff --git a/chapter21/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java b/chapter21/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java
new file mode 100644
index 00000000..03a57675
--- /dev/null
+++ b/chapter21/src/test/java/com/seaofnodes/simple/codegen/X86EncodingTest.java
@@ -0,0 +1,32 @@
+package com.seaofnodes.simple.codegen;
+
+import com.seaofnodes.simple.node.cpus.x86_64_v2.CmpMemX86;
+import org.junit.Test;
+import static org.junit.Assert.*;
+
+public class X86EncodingTest {
+    @Test
+    public void testMemoryCompare64Immediate32() {
+        for (int immediate : new int[]{123456789, -123456789}) {
+            String src = "int[] !a = new int[2]; a[0] = arg; return a[arg & 1] == " + immediate + ";";
+            CodeGen code = new CodeGen(src).driver(CodeGen.Phase.Encoding, "x86_64_v2", "SystemV");
+            var cmp = code._stop.walk(n -> n instanceof CmpMemX86 ? n : null);
+            assertNotNull("Must exercise a memory comparison", cmp);
+            var enc = code._encoding;
+            int start = enc._opStart[cmp._nid];
+
+            // REX.W, 81 /7, SIB with scale 8, disp8, and a sign-extended imm32.
+            assertEquals(0x48, enc.read1(start) & 0xF8);
+            assertEquals(0x81, enc.read1(start + 1));
+            assertEquals(0x7C, enc.read1(start + 2));
+            assertEquals(0xC0, enc.read1(start + 3) & 0xC0);
+            assertEquals(8, enc.read1(start + 4));
+            assertEquals(immediate, enc.read4(start + 5));
+            assertEquals("CMP r/m64 uses four immediate bytes", 9, enc._opLen[cmp._nid]);
+
+            // SETE must immediately follow the CPU's nine-byte CMP instruction.
+            assertEquals(0x0F, enc.read1(start + 9));
+            assertEquals(0x94, enc.read1(start + 10));
+        }
+    }
+}
-- 
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