Revert "[ObjC][ARC] Use operand bundle 'clang.arc.attachedcall' instead of explicitly emitting retainRV or claimRV calls in the IR"

This caused miscompiles of Chromium tests for iOS due clobbering of live
registers. See discussion on the code review for details.

> Background:
>
> This fixes a longstanding problem where llvm breaks ARC's autorelease
> optimization (see the link below) by separating calls from the marker
> instructions or retainRV/claimRV calls. The backend changes are in
> https://reviews.llvm.org/D92569.
>
> https://clang.llvm.org/docs/AutomaticReferenceCounting.html#arc-runtime-objc-autoreleasereturnvalue
>
> What this patch does to fix the problem:
>
> - The front-end adds operand bundle "clang.arc.attachedcall" to calls,
>   which indicates the call is implicitly followed by a marker
>   instruction and an implicit retainRV/claimRV call that consumes the
>   call result. In addition, it emits a call to
>   @llvm.objc.clang.arc.noop.use, which consumes the call result, to
>   prevent the middle-end passes from changing the return type of the
>   called function. This is currently done only when the target is arm64
>   and the optimization level is higher than -O0.
>
> - ARC optimizer temporarily emits retainRV/claimRV calls after the calls
>   with the operand bundle in the IR and removes the inserted calls after
>   processing the function.
>
> - ARC contract pass emits retainRV/claimRV calls after the call with the
>   operand bundle. It doesn't remove the operand bundle on the call since
>   the backend needs it to emit the marker instruction. The retainRV and
>   claimRV calls are emitted late in the pipeline to prevent optimization
>   passes from transforming the IR in a way that makes it harder for the
>   ARC middle-end passes to figure out the def-use relationship between
>   the call and the retainRV/claimRV calls (which is the cause of
>   PR31925).
>
> - The function inliner removes an autoreleaseRV call in the callee if
>   nothing in the callee prevents it from being paired up with the
>   retainRV/claimRV call in the caller. It then inserts a release call if
>   claimRV is attached to the call since autoreleaseRV+claimRV is
>   equivalent to a release. If it cannot find an autoreleaseRV call, it
>   tries to transfer the operand bundle to a function call in the callee.
>   This is important since the ARC optimizer can remove the autoreleaseRV
>   returning the callee result, which makes it impossible to pair it up
>   with the retainRV/claimRV call in the caller. If that fails, it simply
>   emits a retain call in the IR if retainRV is attached to the call and
>   does nothing if claimRV is attached to it.
>
> - SCCP refrains from replacing the return value of a call with a
>   constant value if the call has the operand bundle. This ensures the
>   call always has at least one user (the call to
>   @llvm.objc.clang.arc.noop.use).
>
> - This patch also fixes a bug in replaceUsesOfNonProtoConstant where
>   multiple operand bundles of the same kind were being added to a call.
>
> Future work:
>
> - Use the operand bundle on x86-64.
>
> - Fix the auto upgrader to convert call+retainRV/claimRV pairs into
>   calls with the operand bundles.
>
> rdar://71443534
>
> Differential Revision: https://reviews.llvm.org/D92808

This reverts commit ed4718eccb12bd42214ca4fb17d196d49561c0c7.

1 files changed, 1 insertions, 102 deletions

diff --git a/llvm/lib/Transforms/Utils/InlineFunction.cpp b/llvm/lib/Transforms/Utils/InlineFunction.cpp
index 5f75ead..3026342 100644
--- a/llvm/lib/Transforms/Utils/InlineFunction.cpp
+++ b/llvm/lib/Transforms/Utils/InlineFunction.cpp
@@ -27,9 +27,8 @@
 #include "llvm/Analysis/CaptureTracking.h"
 #include "llvm/Analysis/EHPersonalities.h"
 #include "llvm/Analysis/InstructionSimplify.h"
-#include "llvm/Analysis/ObjCARCAnalysisUtils.h"
-#include "llvm/Analysis/ObjCARCUtil.h"
 #include "llvm/Analysis/ProfileSummaryInfo.h"
+#include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Analysis/ValueTracking.h"
 #include "llvm/Analysis/VectorUtils.h"
 #include "llvm/IR/Argument.h"
@@ -62,7 +61,6 @@
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Transforms/Utils/AssumeBundleBuilder.h"
 #include "llvm/Transforms/Utils/Cloning.h"
-#include "llvm/Transforms/Utils/Local.h"
 #include "llvm/Transforms/Utils/ValueMapper.h"
 #include <algorithm>
 #include <cassert>
@@ -1652,99 +1650,6 @@ void llvm::updateProfileCallee(
   }
 }
 
-/// An operand bundle "clang.arc.attachedcall" on a call indicates the call
-/// result is implicitly consumed by a call to retainRV or claimRV immediately
-/// after the call. This function inlines the retainRV/claimRV calls.
-///
-/// There are three cases to consider:
-///
-/// 1. If there is a call to autoreleaseRV that takes a pointer to the returned
-///    object in the callee return block, the autoreleaseRV call and the
-///    retainRV/claimRV call in the caller cancel out. If the call in the caller
-///    is a claimRV call, a call to objc_release is emitted.
-///
-/// 2. If there is a call in the callee return block that doesn't have operand
-///    bundle "clang.arc.attachedcall", the operand bundle on the original call
-///    is transferred to the call in the callee.
-///
-/// 3. Otherwise, a call to objc_retain is inserted if the call in the caller is
-///    a retainRV call.
-static void
-inlineRetainOrClaimRVCalls(CallBase &CB,
-                           const SmallVectorImpl<ReturnInst *> &Returns) {
-  Module *Mod = CB.getModule();
-  bool IsRetainRV = objcarc::hasAttachedCallOpBundle(&CB, true),
-       IsClaimRV = !IsRetainRV;
-
-  for (auto *RI : Returns) {
-    Value *RetOpnd = objcarc::GetRCIdentityRoot(RI->getOperand(0));
-    BasicBlock::reverse_iterator I = ++(RI->getIterator().getReverse());
-    BasicBlock::reverse_iterator EI = RI->getParent()->rend();
-    bool InsertRetainCall = IsRetainRV;
-    IRBuilder<> Builder(RI->getContext());
-
-    // Walk backwards through the basic block looking for either a matching
-    // autoreleaseRV call or an unannotated call.
-    for (; I != EI;) {
-      auto CurI = I++;
-
-      // Ignore casts.
-      if (isa<CastInst>(*CurI))
-        continue;
-
-      if (auto *II = dyn_cast<IntrinsicInst>(&*CurI)) {
-        if (II->getIntrinsicID() == Intrinsic::objc_autoreleaseReturnValue &&
-            II->hasNUses(0) &&
-            objcarc::GetRCIdentityRoot(II->getOperand(0)) == RetOpnd) {
-          // If we've found a matching authoreleaseRV call:
-          // - If claimRV is attached to the call, insert a call to objc_release
-          //   and erase the autoreleaseRV call.
-          // - If retainRV is attached to the call, just erase the autoreleaseRV
-          //   call.
-          if (IsClaimRV) {
-            Builder.SetInsertPoint(II);
-            Function *IFn =
-                Intrinsic::getDeclaration(Mod, Intrinsic::objc_release);
-            Value *BC =
-                Builder.CreateBitCast(RetOpnd, IFn->getArg(0)->getType());
-            Builder.CreateCall(IFn, BC, "");
-          }
-          II->eraseFromParent();
-          InsertRetainCall = false;
-        }
-      } else if (auto *CI = dyn_cast<CallInst>(&*CurI)) {
-        if (objcarc::GetRCIdentityRoot(CI) == RetOpnd &&
-            !objcarc::hasAttachedCallOpBundle(CI)) {
-          // If we've found an unannotated call that defines RetOpnd, add a
-          // "clang.arc.attachedcall" operand bundle.
-          Value *BundleArgs[] = {ConstantInt::get(
-              Builder.getInt64Ty(),
-              objcarc::getAttachedCallOperandBundleEnum(IsRetainRV))};
-          OperandBundleDef OB("clang.arc.attachedcall", BundleArgs);
-          auto *NewCall = CallBase::addOperandBundle(
-              CI, LLVMContext::OB_clang_arc_attachedcall, OB, CI);
-          NewCall->copyMetadata(*CI);
-          CI->replaceAllUsesWith(NewCall);
-          CI->eraseFromParent();
-          InsertRetainCall = false;
-        }
-      }
-
-      break;
-    }
-
-    if (InsertRetainCall) {
-      // The retainRV is attached to the call and we've failed to find a
-      // matching autoreleaseRV or an annotated call in the callee. Emit a call
-      // to objc_retain.
-      Builder.SetInsertPoint(RI);
-      Function *IFn = Intrinsic::getDeclaration(Mod, Intrinsic::objc_retain);
-      Value *BC = Builder.CreateBitCast(RetOpnd, IFn->getArg(0)->getType());
-      Builder.CreateCall(IFn, BC, "");
-    }
-  }
-}
-
 /// This function inlines the called function into the basic block of the
 /// caller. This returns false if it is not possible to inline this call.
 /// The program is still in a well defined state if this occurs though.
@@ -1782,8 +1687,6 @@ llvm::InlineResult llvm::InlineFunction(CallBase &CB, InlineFunctionInfo &IFI,
       // ... and "funclet" operand bundles.
       if (Tag == LLVMContext::OB_funclet)
         continue;
-      if (Tag == LLVMContext::OB_clang_arc_attachedcall)
-        continue;
 
       return InlineResult::failure("unsupported operand bundle");
     }
@@ -1950,10 +1853,6 @@ llvm::InlineResult llvm::InlineFunction(CallBase &CB, InlineFunctionInfo &IFI,
     // Remember the first block that is newly cloned over.
     FirstNewBlock = LastBlock; ++FirstNewBlock;
 
-    // Insert retainRV/clainRV runtime calls.
-    if (objcarc::hasAttachedCallOpBundle(&CB))
-      inlineRetainOrClaimRVCalls(CB, Returns);
-
     if (IFI.CallerBFI != nullptr && IFI.CalleeBFI != nullptr)
       // Update the BFI of blocks cloned into the caller.
       updateCallerBFI(OrigBB, VMap, IFI.CallerBFI, IFI.CalleeBFI,