[llvm] a9a3781 - [ObjC] Override TailCallKind when lowering objc intrinsics
Francis Visoiu Mistrih via llvm-commits
llvm-commits at lists.llvm.org
Mon Nov 11 08:32:48 PST 2019
Author: Francis Visoiu Mistrih
Date: 2019-11-11T08:30:06-08:00
New Revision: a9a3781df81a8a630e5d233efbc8b15b24ddd1dd
URL: https://github.com/llvm/llvm-project/commit/a9a3781df81a8a630e5d233efbc8b15b24ddd1dd
DIFF: https://github.com/llvm/llvm-project/commit/a9a3781df81a8a630e5d233efbc8b15b24ddd1dd.diff
LOG: [ObjC] Override TailCallKind when lowering objc intrinsics
The tail-call-kind-ness is known by the ObjCARC analysis and can be
enforced while lowering the intrinsics to calls.
This allows us to get the requested tail calls at -O0 without trying to
preserve the attributes throughout passes that change code even at -O0
,like the Always Inliner, where the ObjCOpt pass doesn't run.
Differential Revision: https://reviews.llvm.org/D69980
Added:
Modified:
llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp
llvm/test/Transforms/PreISelIntrinsicLowering/objc-arc.ll
Removed:
################################################################################
diff --git a/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp b/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp
index 0d2f6f99ca96..79d0c80dd35a 100644
--- a/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp
+++ b/llvm/lib/CodeGen/PreISelIntrinsicLowering.cpp
@@ -12,6 +12,7 @@
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/PreISelIntrinsicLowering.h"
+#include "llvm/Analysis/ObjCARCInstKind.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/Intrinsics.h"
@@ -56,6 +57,17 @@ static bool lowerLoadRelative(Function &F) {
return Changed;
}
+// ObjCARC has knowledge about whether an obj-c runtime function needs to be
+// always tail-called or never tail-called.
+static CallInst::TailCallKind getOverridingTailCallKind(const Function &F) {
+ objcarc::ARCInstKind Kind = objcarc::GetFunctionClass(&F);
+ if (objcarc::IsAlwaysTail(Kind))
+ return CallInst::TCK_Tail;
+ else if (objcarc::IsNeverTail(Kind))
+ return CallInst::TCK_NoTail;
+ return CallInst::TCK_None;
+}
+
static bool lowerObjCCall(Function &F, const char *NewFn,
bool setNonLazyBind = false) {
if (F.use_empty())
@@ -75,6 +87,8 @@ static bool lowerObjCCall(Function &F, const char *NewFn,
}
}
+ CallInst::TailCallKind OverridingTCK = getOverridingTailCallKind(F);
+
for (auto I = F.use_begin(), E = F.use_end(); I != E;) {
auto *CI = cast<CallInst>(I->getUser());
assert(CI->getCalledFunction() && "Cannot lower an indirect call!");
@@ -84,7 +98,17 @@ static bool lowerObjCCall(Function &F, const char *NewFn,
SmallVector<Value *, 8> Args(CI->arg_begin(), CI->arg_end());
CallInst *NewCI = Builder.CreateCall(FCache, Args);
NewCI->setName(CI->getName());
- NewCI->setTailCallKind(CI->getTailCallKind());
+
+ // Try to set the most appropriate TailCallKind based on both the current
+ // attributes and the ones that we could get from ObjCARC's special
+ // knowledge of the runtime functions.
+ //
+ // std::max respects both requirements of notail and tail here:
+ // * notail on either the call or from ObjCARC becomes notail
+ // * tail on either side is stronger than none, but not notail
+ CallInst::TailCallKind TCK = CI->getTailCallKind();
+ NewCI->setTailCallKind(std::max(TCK, OverridingTCK));
+
if (!CI->use_empty())
CI->replaceAllUsesWith(NewCI);
CI->eraseFromParent();
diff --git a/llvm/test/Transforms/PreISelIntrinsicLowering/objc-arc.ll b/llvm/test/Transforms/PreISelIntrinsicLowering/objc-arc.ll
index 8b7d11ea75f4..5ff620a71b87 100644
--- a/llvm/test/Transforms/PreISelIntrinsicLowering/objc-arc.ll
+++ b/llvm/test/Transforms/PreISelIntrinsicLowering/objc-arc.ll
@@ -7,7 +7,7 @@
define i8* @test_objc_autorelease(i8* %arg0) {
; CHECK-LABEL: test_objc_autorelease
; CHECK-NEXT: entry
-; CHECK-NEXT: %0 = call i8* @objc_autorelease(i8* %arg0)
+; CHECK-NEXT: %0 = notail call i8* @objc_autorelease(i8* %arg0)
; CHECK-NEXT: ret i8* %0
entry:
%0 = call i8* @llvm.objc.autorelease(i8* %arg0)
@@ -37,7 +37,7 @@ entry:
define i8* @test_objc_autoreleaseReturnValue(i8* %arg0) {
; CHECK-LABEL: test_objc_autoreleaseReturnValue
; CHECK-NEXT: entry
-; CHECK-NEXT: %0 = call i8* @objc_autoreleaseReturnValue(i8* %arg0)
+; CHECK-NEXT: %0 = tail call i8* @objc_autoreleaseReturnValue(i8* %arg0)
; CHECK-NEXT: ret i8* %0
entry:
%0 = call i8* @llvm.objc.autoreleaseReturnValue(i8* %arg0)
@@ -117,7 +117,7 @@ entry:
define i8* @test_objc_retain(i8* %arg0) {
; CHECK-LABEL: test_objc_retain
; CHECK-NEXT: entry
-; CHECK-NEXT: %0 = call i8* @objc_retain(i8* %arg0)
+; CHECK-NEXT: %0 = tail call i8* @objc_retain(i8* %arg0)
; CHECK-NEXT: ret i8* %0
entry:
%0 = call i8* @llvm.objc.retain(i8* %arg0)
@@ -147,7 +147,7 @@ entry:
define i8* @test_objc_retainAutoreleasedReturnValue(i8* %arg0) {
; CHECK-LABEL: test_objc_retainAutoreleasedReturnValue
; CHECK-NEXT: entry
-; CHECK-NEXT: %0 = call i8* @objc_retainAutoreleasedReturnValue(i8* %arg0)
+; CHECK-NEXT: %0 = tail call i8* @objc_retainAutoreleasedReturnValue(i8* %arg0)
; CHECK-NEXT: ret i8* %0
entry:
%0 = call i8* @llvm.objc.retainAutoreleasedReturnValue(i8* %arg0)
@@ -187,7 +187,7 @@ entry:
define i8* @test_objc_unsafeClaimAutoreleasedReturnValue(i8* %arg0) {
; CHECK-LABEL: test_objc_unsafeClaimAutoreleasedReturnValue
; CHECK-NEXT: entry
-; CHECK-NEXT: %0 = call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* %arg0)
+; CHECK-NEXT: %0 = tail call i8* @objc_unsafeClaimAutoreleasedReturnValue(i8* %arg0)
; CHECK-NEXT: ret i8* %0
entry:
%0 = call i8* @llvm.objc.unsafeClaimAutoreleasedReturnValue(i8* %arg0)
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