Add a mjsunit test to cover more paths in the ia32 code generator.

test/mjsunit/codegen_coverage.js

+// Copyright 2009 the V8 project authors. All rights reserved.
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+
+// Test the paths in the code generator where values in specific
+// registers get moved around so that the shift operation can use
+// register ECX on ia32 for the shift amount.  Other codegen coverage
+// tests should go here too.
+
+
+
+function identity(x) {
+  return x;
+}
+
+function cover_codegen_paths() {
+  var x = 1;
+  var a;  // Register EAX
+  var b;  // Register EBX
+  var c;  // Register ECX
+  var d;  // Register EDX
+  // Register ESI is already used.
+  var di;  // Register EDI
+
+  while (x == 1) {
+    x = identity(1);
+    a = x + 1;
+    c = x + 1;
+    d = x + 1;
+    b = x + 1;
+    di = x + 1;
+    // Locals are in the corresponding registers here.
+    assertEquals(c << a, 8);
+
+    x = identity(1);
+    a = x + 1;
+    c = x + 1;
+    d = x + 1;
+    b = x + 1;
+    di = x + 1;
+    // Locals are in the corresponding registers here.
+    assertEquals(a << c, 8);
+
+    x = identity(1);
+    a = x + 1;
+    c = x + 1;
+    d = x + 1;
+    b = x + 1;
+    di = x + 1;
+    // Locals are in the corresponding registers here.
+    c = 0; // Free register ecx.
+    assertEquals(a << d, 8);
+
+    x = identity(1);
+    a = x + 1;
+    c = x + 1;
+    d = x + 1;
+    b = x + 1;
+    di = x + 1;
+    // Locals are in the corresponding registers here.
+    b = 0; // Free register ebx.
+    assertEquals(a << d, 8);
+
+    x = 3;
+  }
+}
+
+cover_codegen_paths();