commit 3edc5c41bbee7cf608a781e7056599f32ca1949c
author Dimitry Ivanov <dimitry@google.com> Thu Jan 21 10:55:40 2016 -0800
committer Dimitry Ivanov <dimitry@google.com> Thu Jan 21 14:28:33 2016 -0800
tree 88b26c5a450fb4548479c109a68253e7a41c07e8
parent 8d6e19408cfdbd73ba7e5c9e5b8716d9dad8dcf9

linker: align allocated blocks to 16 bytes

C/C++ requires the result of malloc/new to be
aligned for any primitive type.

Change-Id: I715b7679e738f34b3b409993fb3ef242e1321b7f

linker/tests/linker_block_allocator_test.cpp

diff --git a/linker/tests/linker_block_allocator_test.cpp b/linker/tests/linker_block_allocator_test.cpp
index 3ef0f36..5adc425 100644
--- a/linker/tests/linker_block_allocator_test.cpp
+++ b/linker/tests/linker_block_allocator_test.cpp
@@ -53,10 +53,12 @@
 
   test_struct_nominal* ptr1 = allocator.alloc();
   ASSERT_TRUE(ptr1 != nullptr);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr1) % 16);
   test_struct_nominal* ptr2 = allocator.alloc();
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr2) % 16);
   ASSERT_TRUE(ptr2 != nullptr);
   // they should be next to each other.
-  ASSERT_EQ(ptr1+1, ptr2);
+  ASSERT_EQ(reinterpret_cast<uint8_t*>(ptr1)+16, reinterpret_cast<uint8_t*>(ptr2));
 
   ptr1->value = 42;
 
@@ -71,8 +73,10 @@
   char* ptr2 = reinterpret_cast<char*>(allocator.alloc());
 
   ASSERT_TRUE(ptr1 != nullptr);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr1) % 16);
   ASSERT_TRUE(ptr2 != nullptr);
-  ASSERT_EQ(ptr1+2*sizeof(void*), ptr2);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr2) % 16);
+  ASSERT_EQ(ptr1+16, ptr2); // aligned to 16
 }
 
 TEST(linker_allocator, test_larger) {
@@ -82,9 +86,11 @@
   test_struct_larger* ptr2 = allocator.alloc();
 
   ASSERT_TRUE(ptr1 != nullptr);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr1) % 16);
   ASSERT_TRUE(ptr2 != nullptr);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr2) % 16);
 
-  ASSERT_EQ(ptr1+1, ptr2);
+  ASSERT_EQ(reinterpret_cast<uint8_t*>(ptr1) + 1024, reinterpret_cast<uint8_t*>(ptr2));
 
   // lets allocate until we reach next page.
   size_t n = kPageSize/sizeof(test_struct_larger) + 1 - 2;

linker/tests/linker_memory_allocator_test.cpp

diff --git a/linker/tests/linker_memory_allocator_test.cpp b/linker/tests/linker_memory_allocator_test.cpp
index defd4f3..5b85536 100644
--- a/linker/tests/linker_memory_allocator_test.cpp
+++ b/linker/tests/linker_memory_allocator_test.cpp
@@ -96,6 +96,7 @@
 
   ASSERT_TRUE(reallocated_ptr != nullptr);
   ASSERT_TRUE(reallocated_ptr != array);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(reallocated_ptr) % 16);
 
   ASSERT_TRUE(memcmp(reallocated_ptr, model, array_size * 2) == 0);
 
@@ -107,6 +108,7 @@
 
   ASSERT_TRUE(reallocated_ptr != nullptr);
   ASSERT_TRUE(reallocated_ptr != array);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(reallocated_ptr) % 16);
 
   ASSERT_TRUE(memcmp(reallocated_ptr, model, 4000) == 0);
 
@@ -125,7 +127,10 @@
       reinterpret_cast<test_struct_small*>(allocator.alloc(sizeof(test_struct_small)));
 
   ASSERT_TRUE(ptr1 != nullptr);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr1) % 16);
   ASSERT_TRUE(ptr2 != nullptr);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr2) % 16);
+
   ASSERT_EQ(reinterpret_cast<uintptr_t>(ptr1)+16, reinterpret_cast<uintptr_t>(ptr2));
   ASSERT_TRUE(memcmp(ptr1, zeros, 16) == 0);
 
@@ -143,7 +148,9 @@
       reinterpret_cast<test_struct_huge*>(allocator.alloc(sizeof(test_struct_huge)));
 
   ASSERT_TRUE(ptr1 != nullptr);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr1) % 16);
   ASSERT_TRUE(ptr2 != nullptr);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr2) % 16);
 
   ASSERT_TRUE(
       reinterpret_cast<uintptr_t>(ptr1)/kPageSize != reinterpret_cast<uintptr_t>(ptr2)/kPageSize);
@@ -160,7 +167,9 @@
       reinterpret_cast<test_struct_large*>(allocator.alloc(1024));
 
   ASSERT_TRUE(ptr1 != nullptr);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr1) % 16);
   ASSERT_TRUE(ptr2 != nullptr);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr2) % 16);
 
   ASSERT_EQ(reinterpret_cast<uintptr_t>(ptr1) + 1024, reinterpret_cast<uintptr_t>(ptr2));
 
@@ -179,6 +188,7 @@
       reinterpret_cast<test_struct_large*>(allocator.alloc(sizeof(test_struct_large)));
 
   ASSERT_TRUE(ptr_to_free != nullptr);
+  ASSERT_EQ(0U, reinterpret_cast<uintptr_t>(ptr_to_free) % 16);
 
   allocator.free(ptr1);