[Attributor] Deduce "nosync" function attribute.

Introduce and deduce "nosync" function attribute to indicate that a function
does not synchronize with another thread in a way that other thread might free memory.

Reviewers: jdoerfert, jfb, nhaehnle, arsenm

Subscribers: wdng, hfinkel, nhaenhle, mehdi_amini, steven_wu,
dexonsmith, arsenm, uenoku, hiraditya, jfb, llvm-commits

Differential Revision: https://reviews.llvm.org/D62766

llvm-svn: 365830

1 files changed, 10 insertions, 3 deletions

diff --git a/llvm/test/Bitcode/attributes.ll b/llvm/test/Bitcode/attributes.ll
index 84630cd4bf8..c6e146791d8 100644
--- a/llvm/test/Bitcode/attributes.ll
+++ b/llvm/test/Bitcode/attributes.ll
@@ -203,8 +203,8 @@ declare void @nobuiltin()
 define void @f34()
 ; CHECK: define void @f34()
 {
-        call void @nobuiltin() nobuiltin
-; CHECK: call void @nobuiltin() #38
+  call void @nobuiltin() nobuiltin
+; CHECK: call void @nobuiltin() #39
         ret void;
 }
 
@@ -362,6 +362,12 @@ define void @f61() nofree {
   ret void
 }
 
+; CHECK: define void @f62() #38
+define void @f62() nosync
+{
+  ret void
+}
+
 ; CHECK: attributes #0 = { noreturn }
 ; CHECK: attributes #1 = { nounwind }
 ; CHECK: attributes #2 = { readnone }
@@ -400,4 +406,5 @@ define void @f61() nofree {
 ; CHECK: attributes #35 = { shadowcallstack }
 ; CHECK: attributes #36 = { willreturn }
 ; CHECK: attributes #37 = { nofree }
-; CHECK: attributes #38 = { nobuiltin }
+; CHECK: attributes #38 = { nosync }
+; CHECK: attributes #39 = { nobuiltin }