[llvm-branch-commits] [llvm-branch] r128200 - in /llvm/branches/release_29: ./ include/llvm/Target/TargetLowering.h lib/Target/ARM/ARMISelLowering.cpp lib/Target/ARM/ARMISelLowering.h lib/Target/X86/X86ISelLowering.cpp lib/Target/X86/X86ISelLowering.h lib/Transforms/Scalar/CodeGenPrepare.cpp test/CodeGen/X86/tailcall-returndup-void.ll
Bill Wendling
isanbard at gmail.com
Wed Mar 23 23:00:53 PDT 2011
Author: void
Date: Thu Mar 24 01:00:53 2011
New Revision: 128200
URL: http://llvm.org/viewvc/llvm-project?rev=128200&view=rev
Log:
--- Merging r127981 into '.':
U include/llvm/Target/TargetLowering.h
U lib/Target/X86/X86ISelLowering.cpp
U lib/Target/X86/X86ISelLowering.h
U lib/Target/ARM/ARMISelLowering.h
U lib/Target/ARM/ARMISelLowering.cpp
U lib/Transforms/Scalar/CodeGenPrepare.cpp
--- Merging r128194 into '.':
G lib/Transforms/Scalar/CodeGenPrepare.cpp
--- Merging r128196 into '.':
G lib/Transforms/Scalar/CodeGenPrepare.cpp
--- Merging r128197 into '.':
A test/CodeGen/X86/tailcall-returndup-void.ll
G lib/Transforms/Scalar/CodeGenPrepare.cpp
Added:
llvm/branches/release_29/test/CodeGen/X86/tailcall-returndup-void.ll
- copied unchanged from r128197, llvm/trunk/test/CodeGen/X86/tailcall-returndup-void.ll
Modified:
llvm/branches/release_29/ (props changed)
llvm/branches/release_29/include/llvm/Target/TargetLowering.h
llvm/branches/release_29/lib/Target/ARM/ARMISelLowering.cpp
llvm/branches/release_29/lib/Target/ARM/ARMISelLowering.h
llvm/branches/release_29/lib/Target/X86/X86ISelLowering.cpp
llvm/branches/release_29/lib/Target/X86/X86ISelLowering.h
llvm/branches/release_29/lib/Transforms/Scalar/CodeGenPrepare.cpp
Propchange: llvm/branches/release_29/
------------------------------------------------------------------------------
--- svn:mergeinfo (original)
+++ svn:mergeinfo Thu Mar 24 01:00:53 2011
@@ -1,2 +1,2 @@
/llvm/branches/Apple/Pertwee:110850,110961
-/llvm/trunk:127241,127263-127264,127298,127325,127328,127350-127351,127441,127464,127780,127871,128041,128100
+/llvm/trunk:127241,127263-127264,127298,127325,127328,127350-127351,127441,127464,127780,127871,127981,128041,128100,128194-128197
Modified: llvm/branches/release_29/include/llvm/Target/TargetLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_29/include/llvm/Target/TargetLowering.h?rev=128200&r1=128199&r2=128200&view=diff
==============================================================================
--- llvm/branches/release_29/include/llvm/Target/TargetLowering.h (original)
+++ llvm/branches/release_29/include/llvm/Target/TargetLowering.h Thu Mar 24 01:00:53 2011
@@ -1287,6 +1287,14 @@
return false;
}
+ /// mayBeEmittedAsTailCall - Return true if the target may be able emit the
+ /// call instruction as a tail call. This is used by optimization passes to
+ /// determine if it's profitable to duplicate return instructions to enable
+ /// tailcall optimization.
+ virtual bool mayBeEmittedAsTailCall(CallInst *CI) const {
+ return false;
+ }
+
/// LowerOperationWrapper - This callback is invoked by the type legalizer
/// to legalize nodes with an illegal operand type but legal result types.
/// It replaces the LowerOperation callback in the type Legalizer.
Modified: llvm/branches/release_29/lib/Target/ARM/ARMISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_29/lib/Target/ARM/ARMISelLowering.cpp?rev=128200&r1=128199&r2=128200&view=diff
==============================================================================
--- llvm/branches/release_29/lib/Target/ARM/ARMISelLowering.cpp (original)
+++ llvm/branches/release_29/lib/Target/ARM/ARMISelLowering.cpp Thu Mar 24 01:00:53 2011
@@ -1803,6 +1803,16 @@
return HasRet;
}
+bool ARMTargetLowering::mayBeEmittedAsTailCall(CallInst *CI) const {
+ if (!EnableARMTailCalls)
+ return false;
+
+ if (!CI->isTailCall())
+ return false;
+
+ return !Subtarget->isThumb1Only();
+}
+
// ConstantPool, JumpTable, GlobalAddress, and ExternalSymbol are lowered as
// their target counterpart wrapped in the ARMISD::Wrapper node. Suppose N is
// one of the above mentioned nodes. It has to be wrapped because otherwise
Modified: llvm/branches/release_29/lib/Target/ARM/ARMISelLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_29/lib/Target/ARM/ARMISelLowering.h?rev=128200&r1=128199&r2=128200&view=diff
==============================================================================
--- llvm/branches/release_29/lib/Target/ARM/ARMISelLowering.h (original)
+++ llvm/branches/release_29/lib/Target/ARM/ARMISelLowering.h Thu Mar 24 01:00:53 2011
@@ -455,6 +455,8 @@
virtual bool isUsedByReturnOnly(SDNode *N) const;
+ virtual bool mayBeEmittedAsTailCall(CallInst *CI) const;
+
SDValue getARMCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC,
SDValue &ARMcc, SelectionDAG &DAG, DebugLoc dl) const;
SDValue getVFPCmp(SDValue LHS, SDValue RHS,
Modified: llvm/branches/release_29/lib/Target/X86/X86ISelLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_29/lib/Target/X86/X86ISelLowering.cpp?rev=128200&r1=128199&r2=128200&view=diff
==============================================================================
--- llvm/branches/release_29/lib/Target/X86/X86ISelLowering.cpp (original)
+++ llvm/branches/release_29/lib/Target/X86/X86ISelLowering.cpp Thu Mar 24 01:00:53 2011
@@ -45,6 +45,7 @@
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/ADT/VectorExtras.h"
+#include "llvm/Support/CallSite.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/Dwarf.h"
#include "llvm/Support/ErrorHandling.h"
@@ -1580,6 +1581,18 @@
return (CC == CallingConv::Fast || CC == CallingConv::GHC);
}
+bool X86TargetLowering::mayBeEmittedAsTailCall(CallInst *CI) const {
+ if (!CI->isTailCall())
+ return false;
+
+ CallSite CS(CI);
+ CallingConv::ID CalleeCC = CS.getCallingConv();
+ if (!IsTailCallConvention(CalleeCC) && CalleeCC != CallingConv::C)
+ return false;
+
+ return true;
+}
+
/// FuncIsMadeTailCallSafe - Return true if the function is being made into
/// a tailcall target by changing its ABI.
static bool FuncIsMadeTailCallSafe(CallingConv::ID CC) {
Modified: llvm/branches/release_29/lib/Target/X86/X86ISelLowering.h
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_29/lib/Target/X86/X86ISelLowering.h?rev=128200&r1=128199&r2=128200&view=diff
==============================================================================
--- llvm/branches/release_29/lib/Target/X86/X86ISelLowering.h (original)
+++ llvm/branches/release_29/lib/Target/X86/X86ISelLowering.h Thu Mar 24 01:00:53 2011
@@ -843,6 +843,8 @@
virtual bool isUsedByReturnOnly(SDNode *N) const;
+ virtual bool mayBeEmittedAsTailCall(CallInst *CI) const;
+
virtual bool
CanLowerReturn(CallingConv::ID CallConv, bool isVarArg,
const SmallVectorImpl<ISD::OutputArg> &Outs,
Modified: llvm/branches/release_29/lib/Transforms/Scalar/CodeGenPrepare.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/branches/release_29/lib/Transforms/Scalar/CodeGenPrepare.cpp?rev=128200&r1=128199&r2=128200&view=diff
==============================================================================
--- llvm/branches/release_29/lib/Transforms/Scalar/CodeGenPrepare.cpp (original)
+++ llvm/branches/release_29/lib/Transforms/Scalar/CodeGenPrepare.cpp Thu Mar 24 01:00:53 2011
@@ -47,16 +47,17 @@
using namespace llvm::PatternMatch;
STATISTIC(NumBlocksElim, "Number of blocks eliminated");
-STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated");
-STATISTIC(NumGEPsElim, "Number of GEPs converted to casts");
+STATISTIC(NumPHIsElim, "Number of trivial PHIs eliminated");
+STATISTIC(NumGEPsElim, "Number of GEPs converted to casts");
STATISTIC(NumCmpUses, "Number of uses of Cmp expressions replaced with uses of "
"sunken Cmps");
STATISTIC(NumCastUses, "Number of uses of Cast expressions replaced with uses "
"of sunken Casts");
STATISTIC(NumMemoryInsts, "Number of memory instructions whose address "
"computations were sunk");
-STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads");
-STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized");
+STATISTIC(NumExtsMoved, "Number of [s|z]ext instructions combined with loads");
+STATISTIC(NumExtUses, "Number of uses of [s|z]ext instructions optimized");
+STATISTIC(NumRetsDup, "Number of return instructions duplicated");
namespace {
class CodeGenPrepare : public FunctionPass {
@@ -71,11 +72,15 @@
/// update it.
BasicBlock::iterator CurInstIterator;
- // Keeps track of non-local addresses that have been sunk into a block. This
- // allows us to avoid inserting duplicate code for blocks with multiple
- // load/stores of the same address.
+ /// Keeps track of non-local addresses that have been sunk into a block.
+ /// This allows us to avoid inserting duplicate code for blocks with
+ /// multiple load/stores of the same address.
DenseMap<Value*, Value*> SunkAddrs;
+ /// UpdateDT - If CFG is modified in anyway, dominator tree may need to
+ /// be updated.
+ bool UpdateDT;
+
public:
static char ID; // Pass identification, replacement for typeid
explicit CodeGenPrepare(const TargetLowering *tli = 0)
@@ -100,6 +105,7 @@
bool OptimizeCallInst(CallInst *CI);
bool MoveExtToFormExtLoad(Instruction *I);
bool OptimizeExtUses(Instruction *I);
+ bool DupRetToEnableTailCallOpts(ReturnInst *RI);
};
}
@@ -114,8 +120,10 @@
bool CodeGenPrepare::runOnFunction(Function &F) {
bool EverMadeChange = false;
+ UpdateDT = false;
DT = getAnalysisIfAvailable<DominatorTree>();
PFI = getAnalysisIfAvailable<ProfileInfo>();
+
// First pass, eliminate blocks that contain only PHI nodes and an
// unconditional branch.
EverMadeChange |= EliminateMostlyEmptyBlocks(F);
@@ -123,13 +131,18 @@
bool MadeChange = true;
while (MadeChange) {
MadeChange = false;
- for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
+ for (Function::iterator I = F.begin(), E = F.end(); I != E; ) {
+ BasicBlock *BB = I++;
MadeChange |= OptimizeBlock(*BB);
+ }
EverMadeChange |= MadeChange;
}
SunkAddrs.clear();
+ if (UpdateDT && DT)
+ DT->DT->recalculate(F);
+
return EverMadeChange;
}
@@ -533,6 +546,125 @@
return Simplifier.fold(CI, TD);
}
+/// DupRetToEnableTailCallOpts - Look for opportunities to duplicate return
+/// instructions to the predecessor to enable tail call optimizations. The
+/// case it is currently looking for is:
+/// bb0:
+/// %tmp0 = tail call i32 @f0()
+/// br label %return
+/// bb1:
+/// %tmp1 = tail call i32 @f1()
+/// br label %return
+/// bb2:
+/// %tmp2 = tail call i32 @f2()
+/// br label %return
+/// return:
+/// %retval = phi i32 [ %tmp0, %bb0 ], [ %tmp1, %bb1 ], [ %tmp2, %bb2 ]
+/// ret i32 %retval
+///
+/// =>
+///
+/// bb0:
+/// %tmp0 = tail call i32 @f0()
+/// ret i32 %tmp0
+/// bb1:
+/// %tmp1 = tail call i32 @f1()
+/// ret i32 %tmp1
+/// bb2:
+/// %tmp2 = tail call i32 @f2()
+/// ret i32 %tmp2
+///
+bool CodeGenPrepare::DupRetToEnableTailCallOpts(ReturnInst *RI) {
+ if (!TLI)
+ return false;
+
+ Value *V = RI->getReturnValue();
+ PHINode *PN = V ? dyn_cast<PHINode>(V) : NULL;
+ if (V && !PN)
+ return false;
+
+ BasicBlock *BB = RI->getParent();
+ if (PN && PN->getParent() != BB)
+ return false;
+
+ // It's not safe to eliminate the sign / zero extension of the return value.
+ // See llvm::isInTailCallPosition().
+ const Function *F = BB->getParent();
+ unsigned CallerRetAttr = F->getAttributes().getRetAttributes();
+ if ((CallerRetAttr & Attribute::ZExt) || (CallerRetAttr & Attribute::SExt))
+ return false;
+
+ // Make sure there are no instructions between the PHI and return, or that the
+ // return is the first instruction in the block.
+ if (PN) {
+ BasicBlock::iterator BI = BB->begin();
+ do { ++BI; } while (isa<DbgInfoIntrinsic>(BI));
+ if (&*BI != RI)
+ return false;
+ } else {
+ if (&*BB->begin() != RI)
+ return false;
+ }
+
+ /// Only dup the ReturnInst if the CallInst is likely to be emitted as a tail
+ /// call.
+ SmallVector<CallInst*, 4> TailCalls;
+ if (PN) {
+ for (unsigned I = 0, E = PN->getNumIncomingValues(); I != E; ++I) {
+ CallInst *CI = dyn_cast<CallInst>(PN->getIncomingValue(I));
+ // Make sure the phi value is indeed produced by the tail call.
+ if (CI && CI->hasOneUse() && CI->getParent() == PN->getIncomingBlock(I) &&
+ TLI->mayBeEmittedAsTailCall(CI))
+ TailCalls.push_back(CI);
+ }
+ } else {
+ SmallPtrSet<BasicBlock*, 4> VisitedBBs;
+ for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
+ if (!VisitedBBs.insert(*PI))
+ continue;
+
+ BasicBlock::InstListType &InstList = (*PI)->getInstList();
+ BasicBlock::InstListType::reverse_iterator RI = InstList.rbegin();
+ BasicBlock::InstListType::reverse_iterator RE = InstList.rend();
+ if (++RI == RE)
+ continue;
+ CallInst *CI = dyn_cast<CallInst>(&*RI);
+ if (CI && CI->getType()->isVoidTy() && TLI->mayBeEmittedAsTailCall(CI))
+ TailCalls.push_back(CI);
+ }
+ }
+
+ bool Changed = false;
+ for (unsigned i = 0, e = TailCalls.size(); i != e; ++i) {
+ CallInst *CI = TailCalls[i];
+ CallSite CS(CI);
+
+ // Conservatively require the attributes of the call to match those of the
+ // return. Ignore noalias because it doesn't affect the call sequence.
+ unsigned CalleeRetAttr = CS.getAttributes().getRetAttributes();
+ if ((CalleeRetAttr ^ CallerRetAttr) & ~Attribute::NoAlias)
+ continue;
+
+ // Make sure the call instruction is followed by an unconditional branch to
+ // the return block.
+ BasicBlock *CallBB = CI->getParent();
+ BranchInst *BI = dyn_cast<BranchInst>(CallBB->getTerminator());
+ if (!BI || !BI->isUnconditional() || BI->getSuccessor(0) != BB)
+ continue;
+
+ // Duplicate the return into CallBB.
+ (void)FoldReturnIntoUncondBranch(RI, BB, CallBB);
+ UpdateDT = Changed = true;
+ ++NumRetsDup;
+ }
+
+ // If we eliminated all predecessors of the block, delete the block now.
+ if (Changed && pred_begin(BB) == pred_end(BB))
+ BB->eraseFromParent();
+
+ return Changed;
+}
+
//===----------------------------------------------------------------------===//
// Memory Optimization
//===----------------------------------------------------------------------===//
@@ -956,6 +1088,9 @@
if (CallInst *CI = dyn_cast<CallInst>(I))
return OptimizeCallInst(CI);
+ if (ReturnInst *RI = dyn_cast<ReturnInst>(I))
+ return DupRetToEnableTailCallOpts(RI);
+
return false;
}
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