Add atomics to chibicc

This change also fixes #434 and makes the chibicc assembler better.

third_party/chibicc/test/asm_test.c

@@ -83,6 +83,24 @@ void testFlagOutputs(void) {
   ASSERT(false, sf);
 }
 
+void testAugmentLoByte_onlyModifiesLowerBits(void) {
+  int x, y;
+  x = 0x01020304;
+  y = 0x00000005;
+  asm("sub\t%b1,%b0" : "+q"(x) : "q"(y));
+  ASSERT(0x010203ff, x);
+  ASSERT(0x00000005, y);
+}
+
+void testAugmentHiByte_onlyModifiesHigherBits(void) {
+  int x, y;
+  x = 0x01020304;
+  y = 0x00000400;
+  asm("sub\t%h1,%h0" : "+Q"(x) : "Q"(y));
+  ASSERT(0x0102ff04, x);
+  ASSERT(0x00000400, y);
+}
+
 int main() {
   ASSERT(50, asm_fn1());
   ASSERT(55, asm_fn2());
@@ -135,5 +153,8 @@ int main() {
     ASSERT(1, !strcmp(p, "hello"));
   }
 
+  testAugmentLoByte_onlyModifiesLowerBits();
+  testAugmentHiByte_onlyModifiesHigherBits();
+
   return 0;
 }

third_party/chibicc/test/atomic_test.c

@@ -0,0 +1,41 @@
+#include "third_party/chibicc/test/test.h"
+
+_Atomic(int) lock;
+
+main() {
+  int x;
+
+  ASSERT(0, __atomic_exchange_n(&lock, 1, __ATOMIC_SEQ_CST));
+  __atomic_load(&lock, &x, __ATOMIC_SEQ_CST);
+  ASSERT(1, x);
+  ASSERT(1, __atomic_exchange_n(&lock, 2, __ATOMIC_SEQ_CST));
+  ASSERT(2, __atomic_exchange_n(&lock, 3, __ATOMIC_SEQ_CST));
+  ASSERT(3, __atomic_load_n(&lock, __ATOMIC_SEQ_CST));
+  __atomic_store_n(&lock, 0, __ATOMIC_SEQ_CST);
+  ASSERT(0, __atomic_fetch_xor(&lock, 3, __ATOMIC_SEQ_CST));
+  ASSERT(3, __atomic_fetch_xor(&lock, 1, __ATOMIC_SEQ_CST));
+  ASSERT(2, __atomic_load_n(&lock, __ATOMIC_SEQ_CST));
+
+  // CAS success #1
+  x = 2;
+  ASSERT(1, __atomic_compare_exchange_n(&lock, &x, 3, 0, __ATOMIC_SEQ_CST,
+                                        __ATOMIC_SEQ_CST));
+  ASSERT(2, x);
+  ASSERT(3, lock);
+
+  // CAS success #2
+  x = 3;
+  ASSERT(1, __atomic_compare_exchange_n(&lock, &x, 4, 0, __ATOMIC_SEQ_CST,
+                                        __ATOMIC_SEQ_CST));
+  ASSERT(3, x);
+  ASSERT(4, lock);
+
+  // CAS fail
+  x = 3;
+  ASSERT(0, __atomic_compare_exchange_n(&lock, &x, 7, 0, __ATOMIC_SEQ_CST,
+                                        __ATOMIC_SEQ_CST));
+  ASSERT(4, x);
+  ASSERT(4, lock);
+
+  //
+}