[CodeGen] Generate llvm.loop.parallel_accesses instead of llvm.mem.parallel_loop_access metadata.

Instead of generating llvm.mem.parallel_loop_access metadata, generate
llvm.access.group on instructions and llvm.loop.parallel_accesses on
loops. There is one access group per generated loop.

This is clang part of D52116/r349725.

Differential Revision: https://reviews.llvm.org/D52117

llvm-svn: 349823
diff --git a/clang/test/CodeGenCXX/pragma-loop-safety-outer.cpp b/clang/test/CodeGenCXX/pragma-loop-safety-outer.cpp
index 83f534e..d99b86f 100644
--- a/clang/test/CodeGenCXX/pragma-loop-safety-outer.cpp
+++ b/clang/test/CodeGenCXX/pragma-loop-safety-outer.cpp
@@ -1,7 +1,7 @@
 // RUN: %clang_cc1 -triple x86_64-apple-darwin -std=c++11 -emit-llvm -o - %s | FileCheck %s
 
-// Verify that the inner access is tagged with a parallel_loop_access
-// for the outer loop.
+// Verify that the outer loop has the inner loop's access in its
+// llvm.loop.parallel_accesses property.
 void vectorize_outer_test(int *List, int Length) {
 #pragma clang loop vectorize(assume_safety) interleave(disable) unroll(disable)
   for (int i = 0; i < Length; i += 2) {
@@ -12,9 +12,11 @@
 }
 
 // CHECK: %[[MUL:.+]] = mul
-// CHECK: store i32 %[[MUL]], i32* %{{.+}}, !llvm.mem.parallel_loop_access ![[OUTER_LOOPID:[0-9]+]]
+// CHECK: store i32 %[[MUL]], i32* %{{.+}}, !llvm.access.group ![[ACCESS_GROUP_2:[0-9]+]]
 // CHECK: br label %{{.+}}, !llvm.loop ![[INNER_LOOPID:[0-9]+]]
-// CHECK: br label %{{.+}}, !llvm.loop ![[OUTER_LOOPID]]
+// CHECK: br label %{{.+}}, !llvm.loop ![[OUTER_LOOPID:[0-9]+]]
 
-// CHECK: ![[OUTER_LOOPID]] = distinct !{![[OUTER_LOOPID]],
+// CHECK: ![[ACCESS_GROUP_2]] = distinct !{}
 // CHECK: ![[INNER_LOOPID]] = distinct !{![[INNER_LOOPID]],
+// CHECK: ![[OUTER_LOOPID]] = distinct !{![[OUTER_LOOPID]], {{.*}} ![[PARALLEL_ACCESSES_9:[0-9]+]]}
+// CHECK: ![[PARALLEL_ACCESSES_9]] = !{!"llvm.loop.parallel_accesses", ![[ACCESS_GROUP_2]]}