This shouldn't affect codegen for -O0 compiles as tail call markers are not
emitted in unoptimized compiles. Testing with the external/internal nightly
test suite reveals no change in compile time performance. Testing with -O1,
-O2 and -O3 with fast-isel enabled did not cause any compile-time or
execution-time failures. All tests were performed on my x86 machine.
I'll monitor our arm testers to ensure no regressions occur there.
In an upcoming clang patch I will be marking the objc_autoreleaseReturnValue
and objc_retainAutoreleaseReturnValue as tail calls unconditionally. While
it's theoretically true that this is just an optimization, it's an
optimization that we very much want to happen even at -O0, or else ARC
applications become substantially harder to debug.
Part of rdar://
12553082
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@169796
91177308-0d34-0410-b5e6-
96231b3b80d8
/// into the current block.
void recomputeInsertPt();
+ /// removeDeadCode - Remove all dead instructions between the I and E.
+ void removeDeadCode(MachineBasicBlock::iterator I,
+ MachineBasicBlock::iterator E);
+
struct SavePoint {
MachineBasicBlock::iterator InsertPt;
DebugLoc DL;
/// hasTrivialKill - Test whether the given value has exactly one use.
bool hasTrivialKill(const Value *V) const;
-
- /// removeDeadCode - Remove all dead instructions between the I and E.
- void removeDeadCode(MachineBasicBlock::iterator I,
- MachineBasicBlock::iterator E);
};
}
!isInTailCallPosition(CS, CS.getAttributes().getRetAttributes(), TLI))
isTailCall = false;
- // If there's a possibility that fast-isel has already selected some amount
- // of the current basic block, don't emit a tail call.
- if (isTailCall && TM.Options.EnableFastISel)
- isTailCall = false;
-
TargetLowering::
CallLoweringInfo CLI(getRoot(), RetTy, FTy, isTailCall, Callee, Args, DAG,
getCurDebugLoc(), CS);
}
bool HadTailCall = false;
+ MachineBasicBlock::iterator SavedInsertPt = FuncInfo->InsertPt;
SelectBasicBlock(Inst, BI, HadTailCall);
- // Recompute NumFastIselRemaining as Selection DAG instruction
- // selection may have handled the call, input args, etc.
- unsigned RemainingNow = std::distance(Begin, BI);
- NumFastIselFailures += NumFastIselRemaining - RemainingNow;
-
// If the call was emitted as a tail call, we're done with the block.
+ // We also need to delete any previously emitted instructions.
if (HadTailCall) {
+ FastIS->removeDeadCode(SavedInsertPt, FuncInfo->MBB->end());
--BI;
break;
}
+ // Recompute NumFastIselRemaining as Selection DAG instruction
+ // selection may have handled the call, input args, etc.
+ unsigned RemainingNow = std::distance(Begin, BI);
+ NumFastIselFailures += NumFastIselRemaining - RemainingNow;
NumFastIselRemaining = RemainingNow;
continue;
}
// Can't handle inline asm.
if (isa<InlineAsm>(Callee)) return false;
+ // Allow SelectionDAG isel to handle tail calls.
+ if (CI->isTailCall()) return false;
+
// Check the calling convention.
ImmutableCallSite CS(CI);
CallingConv::ID CC = CS.getCallingConv();
if (const IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI))
return X86VisitIntrinsicCall(*II);
+ // Allow SelectionDAG isel to handle tail calls.
+ if (cast<CallInst>(I)->isTailCall())
+ return false;
+
return DoSelectCall(I, 0);
}
-; RUN: llc < %s -march=x86-64 -tailcallopt -fast-isel | not grep TAILCALL
-
-; Fast-isel shouldn't attempt to cope with tail calls.
+; RUN: llc < %s -march=x86-64 -tailcallopt -fast-isel -fast-isel-abort | FileCheck %s
%0 = type { i64, i32, i8* }
define fastcc i8* @"visit_array_aux<`Reference>"(%0 %arg, i32 %arg1) nounwind {
fail: ; preds = %entry
%tmp20 = tail call fastcc i8* @"visit_array_aux<`Reference>"(%0 %arg, i32 undef) ; <i8*> [#uses=1]
+; CHECK: jmp "_visit_array_aux<`Reference>" ## TAILCALL
ret i8* %tmp20
}