unary_uses_operand test case

test_properties.json

@@ -419,6 +419,9 @@
         "chapter_20/int_only/no_coalescing/unary_interference.c": [
             "chapter_20/libraries/util.c"
         ],
+        "chapter_20/int_only/no_coalescing/unary_uses_operand.c": [
+            "chapter_20/libraries/util.c"
+        ],
         "chapter_20/all_types/no_coalescing/track_dbl_arg_registers.c": [
             "chapter_20/libraries/track_dbl_arg_registers_lib.c"
         ],

tests/chapter_20/int_only/no_coalescing/unary_uses_operand.c

@@ -0,0 +1,44 @@
+/* Test that we recognize that a unary instruction uses its operand;
+ * i.e. negl %a makes a live. Don't inspect assembly, just validate behavior.
+ * NOTE: only works as intended after we've implemented register coalescing.
+ * TODO consider using a common template for this and bin_uses_operand
+ * */
+
+#include "util.h"
+
+int glob = 1;
+
+int target(void) {
+    int a = 0;
+
+    // wrap this in an if statement so we can't copy prop temporary result of
+    // id(100) into uses of a below
+    if (id(1)) {
+        a = id(100);
+    }
+
+    // wrap this in if statement so we can't copy prop temporary values
+    // into check_one_int calls below
+    if (id(1)) {
+        // this addition becomes:
+        // movl %a, %tmp
+        // addl %glob, %tmp
+        // movl %tmp, %glob
+        // so we'll coalesce a & tmp unless we recognize that a is still live,
+        // which requires us to realize that neg instruction below doesn't kill
+        // it
+        glob = a + glob;
+
+        // First round of coalescing will coalesce a with temporary
+        // variable holding result of negation, so this will be:
+        // negl %a
+        // so we need to recognize that this negl instruction uses a
+        a = -a;
+    }
+    check_one_int(a, -100);
+    check_one_int(glob, 101);
+}
+
+int main(void) {
+    return target();
+}