[llvm] r356707 - Don't add a tail keyword to calls to ObjC runtime functions if the calls

[Akira Hatanaka via llvm-commits]

Author: ahatanak
Date: Thu Mar 21 13:16:09 2019
New Revision: 356707

URL: http://llvm.org/viewvc/llvm-project?rev=356707&view=rev
Log:
Don't add a tail keyword to calls to ObjC runtime functions if the calls
are annotated with notail.

r356705 annotated calls to objc_retainAutoreleasedReturnValue with
notail on x86-64. This commit teaches ARC optimizer to check the notail
marker on the call before turning it into a tail call.

rdar://problem/38675807

Modified:
    llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
    llvm/trunk/test/Transforms/ObjCARC/tail-call-invariant-enforcement.ll

Modified: llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp?rev=356707&r1=356706&r2=356707&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp (original)
+++ llvm/trunk/lib/Transforms/ObjCARC/ObjCARCOpts.cpp Thu Mar 21 13:16:09 2019
@@ -848,7 +848,7 @@ void ObjCARCOpt::OptimizeIndividualCalls
 
     // For functions which can never be passed stack arguments, add
     // a tail keyword.
-    if (IsAlwaysTail(Class)) {
+    if (IsAlwaysTail(Class) && !cast<CallInst>(Inst)->isNoTailCall()) {
       Changed = true;
       LLVM_DEBUG(
           dbgs() << "Adding tail keyword to function since it can never be "

Modified: llvm/trunk/test/Transforms/ObjCARC/tail-call-invariant-enforcement.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/ObjCARC/tail-call-invariant-enforcement.ll?rev=356707&r1=356706&r2=356707&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/ObjCARC/tail-call-invariant-enforcement.ll (original)
+++ llvm/trunk/test/Transforms/ObjCARC/tail-call-invariant-enforcement.ll Thu Mar 21 13:16:09 2019
@@ -48,10 +48,12 @@ entry:
   ret i8* %x
 }
 
-; Always tail call objc_retainAutoreleasedReturnValue.
+; Always tail call objc_retainAutoreleasedReturnValue unless it's annotated with
+; notail.
 ; CHECK: define i8* @test3(i8* %x) [[NUW]] {
 ; CHECK: %tmp0 = tail call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %y) [[NUW]]
 ; CHECK: %tmp1 = tail call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %z) [[NUW]]
+; CHECK: %tmp2 = notail call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %z2) [[NUW]]
 ; CHECK: }
 define i8* @test3(i8* %x) nounwind {
 entry:
@@ -59,6 +61,8 @@ entry:
   %tmp0 = call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %y)
   %z = call i8* @tmp(i8* %x)
   %tmp1 = tail call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %z)
+  %z2 = call i8* @tmp(i8* %x)
+  %tmp2 = notail call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %z2)
   ret i8* %x
 }