tsan: properly instrument unaligned accesses

If a memory access is unaligned, emit __tsan_unaligned_read/write
callbacks instead of __tsan_read/write.
Required to change semantics of __tsan_unaligned_read/write to not do the user memory.
But since they were unused (other than through __sanitizer_unaligned_load/store) this is fine.
Fixes long standing issue 17:
https://code.google.com/p/thread-sanitizer/issues/detail?id=17

llvm-svn: 227230

compiler-rt/lib/tsan/rtl/tsan_interface.cc

@@ -38,57 +38,80 @@ void __tsan_write16(void *addr) {
   MemoryWrite(cur_thread(), CALLERPC, (uptr)addr + 8, kSizeLog8);
 }
 
-u16 __tsan_unaligned_read2(const uu16 *addr) {
+// __tsan_unaligned_read/write calls are emitted by compiler.
+
+void __tsan_unaligned_read2(const void *addr) {
   UnalignedMemoryAccess(cur_thread(), CALLERPC, (uptr)addr, 2, false, false);
-  return *addr;
 }
 
-u32 __tsan_unaligned_read4(const uu32 *addr) {
+void __tsan_unaligned_read4(const void *addr) {
   UnalignedMemoryAccess(cur_thread(), CALLERPC, (uptr)addr, 4, false, false);
-  return *addr;
 }
 
-u64 __tsan_unaligned_read8(const uu64 *addr) {
+void __tsan_unaligned_read8(const void *addr) {
   UnalignedMemoryAccess(cur_thread(), CALLERPC, (uptr)addr, 8, false, false);
-  return *addr;
 }
 
-void __tsan_unaligned_write2(uu16 *addr, u16 v) {
+void __tsan_unaligned_read16(const void *addr) {
+  UnalignedMemoryAccess(cur_thread(), CALLERPC, (uptr)addr, 16, false, false);
+}
+
+void __tsan_unaligned_write2(void *addr) {
   UnalignedMemoryAccess(cur_thread(), CALLERPC, (uptr)addr, 2, true, false);
-  *addr = v;
 }
 
-void __tsan_unaligned_write4(uu32 *addr, u32 v) {
+void __tsan_unaligned_write4(void *addr) {
   UnalignedMemoryAccess(cur_thread(), CALLERPC, (uptr)addr, 4, true, false);
-  *addr = v;
 }
 
-void __tsan_unaligned_write8(uu64 *addr, u64 v) {
+void __tsan_unaligned_write8(void *addr) {
   UnalignedMemoryAccess(cur_thread(), CALLERPC, (uptr)addr, 8, true, false);
-  *addr = v;
 }
 
+void __tsan_unaligned_write16(void *addr) {
+  UnalignedMemoryAccess(cur_thread(), CALLERPC, (uptr)addr, 16, true, false);
+}
+
+// __sanitizer_unaligned_load/store are for user instrumentation.
+
 extern "C" {
 SANITIZER_INTERFACE_ATTRIBUTE
-uint16_t __sanitizer_unaligned_load16(void *addr)
-    ALIAS("__tsan_unaligned_read2");
-SANITIZER_INTERFACE_ATTRIBUTE
-uint32_t __sanitizer_unaligned_load32(void *addr)
-    ALIAS("__tsan_unaligned_read4");
-SANITIZER_INTERFACE_ATTRIBUTE
-uint64_t __sanitizer_unaligned_load64(void *addr)
-    ALIAS("__tsan_unaligned_read8");
-SANITIZER_INTERFACE_ATTRIBUTE
-void __sanitizer_unaligned_store16(void *addr, uint16_t v)
-    ALIAS("__tsan_unaligned_write2");
-SANITIZER_INTERFACE_ATTRIBUTE
-void __sanitizer_unaligned_store32(void *addr, uint32_t v)
-    ALIAS("__tsan_unaligned_write4");
-SANITIZER_INTERFACE_ATTRIBUTE
-void __sanitizer_unaligned_store64(void *addr, uint64_t v)
-    ALIAS("__tsan_unaligned_write8");
+u16 __sanitizer_unaligned_load16(const uu16 *addr) {
+  __tsan_unaligned_read2(addr);
+  return *addr;
 }
 
+SANITIZER_INTERFACE_ATTRIBUTE
+u32 __sanitizer_unaligned_load32(const uu32 *addr) {
+  __tsan_unaligned_read4(addr);
+  return *addr;
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE
+u64 __sanitizer_unaligned_load64(const uu64 *addr) {
+  __tsan_unaligned_read8(addr);
+  return *addr;
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE
+void __sanitizer_unaligned_store16(uu16 *addr, u16 v) {
+  __tsan_unaligned_write2(addr);
+  *addr = v;
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE
+void __sanitizer_unaligned_store32(uu32 *addr, u32 v) {
+  __tsan_unaligned_write4(addr);
+  *addr = v;
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE
+void __sanitizer_unaligned_store64(uu64 *addr, u64 v) {
+  __tsan_unaligned_write8(addr);
+  *addr = v;
+}
+}  // extern "C"
+
 void __tsan_acquire(void *addr) {
   Acquire(cur_thread(), CALLERPC, (uptr)addr);
 }

compiler-rt/lib/tsan/rtl/tsan_interface.h

@@ -41,12 +41,15 @@ SANITIZER_INTERFACE_ATTRIBUTE void __tsan_write4(void *addr);
 SANITIZER_INTERFACE_ATTRIBUTE void __tsan_write8(void *addr);
 SANITIZER_INTERFACE_ATTRIBUTE void __tsan_write16(void *addr);
 
-SANITIZER_INTERFACE_ATTRIBUTE u16 __tsan_unaligned_read2(const uu16 *addr);
-SANITIZER_INTERFACE_ATTRIBUTE u32 __tsan_unaligned_read4(const uu32 *addr);
-SANITIZER_INTERFACE_ATTRIBUTE u64 __tsan_unaligned_read8(const uu64 *addr);
-SANITIZER_INTERFACE_ATTRIBUTE void __tsan_unaligned_write2(uu16 *addr, u16 v);
-SANITIZER_INTERFACE_ATTRIBUTE void __tsan_unaligned_write4(uu32 *addr, u32 v);
-SANITIZER_INTERFACE_ATTRIBUTE void __tsan_unaligned_write8(uu64 *addr, u64 v);
+SANITIZER_INTERFACE_ATTRIBUTE void __tsan_unaligned_read2(const void *addr);
+SANITIZER_INTERFACE_ATTRIBUTE void __tsan_unaligned_read4(const void *addr);
+SANITIZER_INTERFACE_ATTRIBUTE void __tsan_unaligned_read8(const void *addr);
+SANITIZER_INTERFACE_ATTRIBUTE void __tsan_unaligned_read16(const void *addr);
+
+SANITIZER_INTERFACE_ATTRIBUTE void __tsan_unaligned_write2(void *addr);
+SANITIZER_INTERFACE_ATTRIBUTE void __tsan_unaligned_write4(void *addr);
+SANITIZER_INTERFACE_ATTRIBUTE void __tsan_unaligned_write8(void *addr);
+SANITIZER_INTERFACE_ATTRIBUTE void __tsan_unaligned_write16(void *addr);
 
 SANITIZER_INTERFACE_ATTRIBUTE void __tsan_vptr_read(void **vptr_p);
 SANITIZER_INTERFACE_ATTRIBUTE

compiler-rt/test/tsan/aligned_vs_unaligned_race.cc

@@ -1,34 +1,35 @@
-// RUN: %clangxx_tsan -O1 %s -o %t && %run %t 2>&1 | FileCheck %s
+// RUN: %clangxx_tsan -O1 %s -o %t && %deflake %run %t | FileCheck %s
 // Race between an aligned access and an unaligned access, which
 // touches the same memory region.
-// This is a real race which is not detected by tsan.
-// https://code.google.com/p/thread-sanitizer/issues/detail?id=17
-#include <pthread.h>
-#include <stdio.h>
+#include "test.h"
 #include <stdint.h>
 
 uint64_t Global[2];
 
 void *Thread1(void *x) {
   Global[1]++;
+  barrier_wait(&barrier);
   return NULL;
 }
 
 void *Thread2(void *x) {
+  barrier_wait(&barrier);
   char *p1 = reinterpret_cast<char *>(&Global[0]);
-  uint64_t *p4 = reinterpret_cast<uint64_t *>(p1 + 1);
-  (*p4)++;
+  struct __attribute__((packed, aligned(1))) u_uint64_t { uint64_t val; };
+  u_uint64_t *p4 = reinterpret_cast<u_uint64_t *>(p1 + 1);
+  (*p4).val++;
   return NULL;
 }
 
 int main() {
+  barrier_init(&barrier, 2);
   pthread_t t[2];
   pthread_create(&t[0], NULL, Thread1, NULL);
   pthread_create(&t[1], NULL, Thread2, NULL);
   pthread_join(t[0], NULL);
   pthread_join(t[1], NULL);
   printf("Pass\n");
-  // CHECK-NOT: ThreadSanitizer: data race
+  // CHECK: ThreadSanitizer: data race
   // CHECK: Pass
   return 0;
 }

compiler-rt/test/tsan/unaligned_norace.cc

@@ -7,20 +7,20 @@
 uint64_t objs[8*3*3*2][3];
 
 extern "C" {
-uint16_t __tsan_unaligned_read2(void *addr);
-uint32_t __tsan_unaligned_read4(void *addr);
-uint64_t __tsan_unaligned_read8(void *addr);
-void __tsan_unaligned_write2(void *addr, uint16_t v);
-void __tsan_unaligned_write4(void *addr, uint32_t v);
-void __tsan_unaligned_write8(void *addr, uint64_t v);
+void __tsan_unaligned_read2(void *addr);
+void __tsan_unaligned_read4(void *addr);
+void __tsan_unaligned_read8(void *addr);
+void __tsan_unaligned_write2(void *addr);
+void __tsan_unaligned_write4(void *addr);
+void __tsan_unaligned_write8(void *addr);
 }
 
 static void access(char *p, int sz, int rw) {
   if (rw) {
     switch (sz) {
-    case 0: __tsan_unaligned_write2(p, 0); break;
-    case 1: __tsan_unaligned_write4(p, 0); break;
-    case 2: __tsan_unaligned_write8(p, 0); break;
+    case 0: __tsan_unaligned_write2(p); break;
+    case 1: __tsan_unaligned_write4(p); break;
+    case 2: __tsan_unaligned_write8(p); break;
     default: exit(1);
     }
   } else {