[llvm-commits] [llvm] r169796 - in /llvm/trunk: include/llvm/CodeGen/FastISel.h lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp lib/Target/ARM/ARMFastISel.cpp lib/Target/X86/X86FastISel.cpp test/CodeGen/X86/tailcall-fastisel.ll
Chad Rosier
mcrosier at apple.com
Mon Dec 10 16:18:03 PST 2012
Author: mcrosier
Date: Mon Dec 10 18:18:02 2012
New Revision: 169796
URL: http://llvm.org/viewvc/llvm-project?rev=169796&view=rev
Log:
Fall back to the selection dag isel to select tail calls.
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
Modified:
llvm/trunk/include/llvm/CodeGen/FastISel.h
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
llvm/trunk/lib/Target/ARM/ARMFastISel.cpp
llvm/trunk/lib/Target/X86/X86FastISel.cpp
llvm/trunk/test/CodeGen/X86/tailcall-fastisel.ll
Modified: llvm/trunk/include/llvm/CodeGen/FastISel.h
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/include/llvm/CodeGen/FastISel.h?rev=169796&r1=169795&r2=169796&view=diff
==============================================================================
--- llvm/trunk/include/llvm/CodeGen/FastISel.h (original)
+++ llvm/trunk/include/llvm/CodeGen/FastISel.h Mon Dec 10 18:18:02 2012
@@ -131,6 +131,10 @@
/// 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;
@@ -395,10 +399,6 @@
/// 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);
};
}
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp?rev=169796&r1=169795&r2=169796&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp Mon Dec 10 18:18:02 2012
@@ -5273,11 +5273,6 @@
!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);
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp?rev=169796&r1=169795&r2=169796&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp Mon Dec 10 18:18:02 2012
@@ -1113,19 +1113,21 @@
}
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;
}
Modified: llvm/trunk/lib/Target/ARM/ARMFastISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/ARM/ARMFastISel.cpp?rev=169796&r1=169795&r2=169796&view=diff
==============================================================================
--- llvm/trunk/lib/Target/ARM/ARMFastISel.cpp (original)
+++ llvm/trunk/lib/Target/ARM/ARMFastISel.cpp Mon Dec 10 18:18:02 2012
@@ -2284,6 +2284,9 @@
// 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();
Modified: llvm/trunk/lib/Target/X86/X86FastISel.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Target/X86/X86FastISel.cpp?rev=169796&r1=169795&r2=169796&view=diff
==============================================================================
--- llvm/trunk/lib/Target/X86/X86FastISel.cpp (original)
+++ llvm/trunk/lib/Target/X86/X86FastISel.cpp Mon Dec 10 18:18:02 2012
@@ -1529,6 +1529,10 @@
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);
}
Modified: llvm/trunk/test/CodeGen/X86/tailcall-fastisel.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/X86/tailcall-fastisel.ll?rev=169796&r1=169795&r2=169796&view=diff
==============================================================================
--- llvm/trunk/test/CodeGen/X86/tailcall-fastisel.ll (original)
+++ llvm/trunk/test/CodeGen/X86/tailcall-fastisel.ll Mon Dec 10 18:18:02 2012
@@ -1,12 +1,11 @@
-; 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
}
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