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-rw-r--r--lib/CodeGen/Analysis.cpp18
-rw-r--r--lib/CodeGen/SelectionDAG/LegalizeDAG.cpp23
-rw-r--r--lib/Target/ARM/ARMFrameInfo.cpp23
-rw-r--r--lib/Target/ARM/ARMISelLowering.cpp73
-rw-r--r--lib/Target/ARM/ARMISelLowering.h2
-rw-r--r--lib/Target/X86/README.txt18
-rw-r--r--lib/Target/X86/X86FrameInfo.cpp15
-rw-r--r--lib/Target/X86/X86ISelLowering.cpp41
-rw-r--r--lib/Target/X86/X86ISelLowering.h2
9 files changed, 147 insertions, 68 deletions
diff --git a/lib/CodeGen/Analysis.cpp b/lib/CodeGen/Analysis.cpp
index 2cf3c6666c..36638c36de 100644
--- a/lib/CodeGen/Analysis.cpp
+++ b/lib/CodeGen/Analysis.cpp
@@ -19,6 +19,7 @@
#include "llvm/LLVMContext.h"
#include "llvm/Module.h"
#include "llvm/CodeGen/MachineFunction.h"
+#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetOptions.h"
@@ -283,3 +284,20 @@ bool llvm::isInTailCallPosition(ImmutableCallSite CS, Attributes CalleeRetAttr,
return true;
}
+bool llvm::isInTailCallPosition(SelectionDAG &DAG, SDNode *Node,
+ const TargetLowering &TLI) {
+ const Function *F = DAG.getMachineFunction().getFunction();
+
+ // Conservatively require the attributes of the call to match those of
+ // the return. Ignore noalias because it doesn't affect the call sequence.
+ unsigned CallerRetAttr = F->getAttributes().getRetAttributes();
+ if (CallerRetAttr & ~Attribute::NoAlias)
+ return false;
+
+ // It's not safe to eliminate the sign / zero extension of the return value.
+ if ((CallerRetAttr & Attribute::ZExt) || (CallerRetAttr & Attribute::SExt))
+ return false;
+
+ // Check if the only use is a function return node.
+ return TLI.isUsedByReturnOnly(Node);
+}
diff --git a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
index 6f6dcc0b15..4b970e091f 100644
--- a/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ b/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -11,13 +11,14 @@
//
//===----------------------------------------------------------------------===//
-#include "llvm/CodeGen/SelectionDAG.h"
+#include "llvm/Analysis/DebugInfo.h"
+#include "llvm/CodeGen/Analysis.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineJumpTableInfo.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
-#include "llvm/Analysis/DebugInfo.h"
#include "llvm/CodeGen/PseudoSourceValue.h"
+#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetData.h"
@@ -1948,12 +1949,20 @@ SDValue SelectionDAGLegalize::ExpandLibCall(RTLIB::Libcall LC, SDNode *Node,
// Splice the libcall in wherever FindInputOutputChains tells us to.
const Type *RetTy = Node->getValueType(0).getTypeForEVT(*DAG.getContext());
+
+ // isTailCall may be true since the callee does not reference caller stack
+ // frame. Check if it's in the right position.
+ bool isTailCall = isInTailCallPosition(DAG, Node, TLI);
std::pair<SDValue, SDValue> CallInfo =
TLI.LowerCallTo(InChain, RetTy, isSigned, !isSigned, false, false,
- 0, TLI.getLibcallCallingConv(LC), false,
+ 0, TLI.getLibcallCallingConv(LC), isTailCall,
/*isReturnValueUsed=*/true,
Callee, Args, DAG, Node->getDebugLoc());
+ if (!CallInfo.second.getNode())
+ // It's a tailcall, return the chain (which is the DAG root).
+ return DAG.getRoot();
+
// Legalize the call sequence, starting with the chain. This will advance
// the LastCALLSEQ_END to the legalized version of the CALLSEQ_END node that
// was added by LowerCallTo (guaranteeing proper serialization of calls).
@@ -1988,7 +1997,7 @@ SelectionDAGLegalize::ExpandChainLibCall(RTLIB::Libcall LC,
const Type *RetTy = Node->getValueType(0).getTypeForEVT(*DAG.getContext());
std::pair<SDValue, SDValue> CallInfo =
TLI.LowerCallTo(InChain, RetTy, isSigned, !isSigned, false, false,
- 0, TLI.getLibcallCallingConv(LC), false,
+ 0, TLI.getLibcallCallingConv(LC), /*isTailCall=*/false,
/*isReturnValueUsed=*/true,
Callee, Args, DAG, Node->getDebugLoc());
@@ -2558,7 +2567,8 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node,
TargetLowering::ArgListTy Args;
std::pair<SDValue, SDValue> CallResult =
TLI.LowerCallTo(Node->getOperand(0), Type::getVoidTy(*DAG.getContext()),
- false, false, false, false, 0, CallingConv::C, false,
+ false, false, false, false, 0, CallingConv::C,
+ /*isTailCall=*/false,
/*isReturnValueUsed=*/true,
DAG.getExternalSymbol("__sync_synchronize",
TLI.getPointerTy()),
@@ -2609,7 +2619,8 @@ void SelectionDAGLegalize::ExpandNode(SDNode *Node,
TargetLowering::ArgListTy Args;
std::pair<SDValue, SDValue> CallResult =
TLI.LowerCallTo(Node->getOperand(0), Type::getVoidTy(*DAG.getContext()),
- false, false, false, false, 0, CallingConv::C, false,
+ false, false, false, false, 0, CallingConv::C,
+ /*isTailCall=*/false,
/*isReturnValueUsed=*/true,
DAG.getExternalSymbol("abort", TLI.getPointerTy()),
Args, DAG, dl);
diff --git a/lib/Target/ARM/ARMFrameInfo.cpp b/lib/Target/ARM/ARMFrameInfo.cpp
index e2531d04d0..58a7c61d90 100644
--- a/lib/Target/ARM/ARMFrameInfo.cpp
+++ b/lib/Target/ARM/ARMFrameInfo.cpp
@@ -374,16 +374,19 @@ void ARMFrameInfo::emitEpilogue(MachineFunction &MF,
MachineOperand &JumpTarget = MBBI->getOperand(0);
// Jump to label or value in register.
- if (RetOpcode == ARM::TCRETURNdi) {
- BuildMI(MBB, MBBI, dl,
- TII.get(STI.isThumb() ? ARM::TAILJMPdt : ARM::TAILJMPd)).
- addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
- JumpTarget.getTargetFlags());
- } else if (RetOpcode == ARM::TCRETURNdiND) {
- BuildMI(MBB, MBBI, dl,
- TII.get(STI.isThumb() ? ARM::TAILJMPdNDt : ARM::TAILJMPdND)).
- addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
- JumpTarget.getTargetFlags());
+ if (RetOpcode == ARM::TCRETURNdi || RetOpcode == ARM::TCRETURNdiND) {
+ unsigned TCOpcode = (RetOpcode == ARM::TCRETURNdi)
+ ? (STI.isThumb() ? ARM::TAILJMPdt : ARM::TAILJMPd)
+ : (STI.isThumb() ? ARM::TAILJMPdNDt : ARM::TAILJMPdND);
+ MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(TCOpcode));
+ if (JumpTarget.isGlobal())
+ MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
+ JumpTarget.getTargetFlags());
+ else {
+ assert(JumpTarget.isSymbol());
+ MIB.addExternalSymbol(JumpTarget.getSymbolName(),
+ JumpTarget.getTargetFlags());
+ }
} else if (RetOpcode == ARM::TCRETURNri) {
BuildMI(MBB, MBBI, dl, TII.get(ARM::TAILJMPr)).
addReg(JumpTarget.getReg(), RegState::Kill);
diff --git a/lib/Target/ARM/ARMISelLowering.cpp b/lib/Target/ARM/ARMISelLowering.cpp
index da274de5a0..3c90704b7e 100644
--- a/lib/Target/ARM/ARMISelLowering.cpp
+++ b/lib/Target/ARM/ARMISelLowering.cpp
@@ -1519,30 +1519,13 @@ ARMTargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,
// whether LR is going to be used. Probably the right approach is to
// generate the tail call here and turn it back into CALL/RET in
// emitEpilogue if LR is used.
- if (Subtarget->isThumb1Only())
- return false;
-
- // For the moment, we can only do this to functions defined in this
- // compilation, or to indirect calls. A Thumb B to an ARM function,
- // or vice versa, is not easily fixed up in the linker unlike BL.
- // (We could do this by loading the address of the callee into a register;
- // that is an extra instruction over the direct call and burns a register
- // as well, so is not likely to be a win.)
-
- // It might be safe to remove this restriction on non-Darwin.
// Thumb1 PIC calls to external symbols use BX, so they can be tail calls,
// but we need to make sure there are enough registers; the only valid
// registers are the 4 used for parameters. We don't currently do this
// case.
- if (isa<ExternalSymbolSDNode>(Callee))
- return false;
-
- if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee)) {
- const GlobalValue *GV = G->getGlobal();
- if (GV->isDeclaration() || GV->isWeakForLinker())
- return false;
- }
+ if (Subtarget->isThumb1Only())
+ return false;
// If the calling conventions do not match, then we'd better make sure the
// results are returned in the same way as what the caller expects.
@@ -1720,6 +1703,58 @@ ARMTargetLowering::LowerReturn(SDValue Chain,
return result;
}
+bool ARMTargetLowering::isUsedByReturnOnly(SDNode *N) const {
+ if (N->getNumValues() != 1)
+ return false;
+ if (!N->hasNUsesOfValue(1, 0))
+ return false;
+
+ unsigned NumCopies = 0;
+ SDNode* Copies[2];
+ SDNode *Use = *N->use_begin();
+ if (Use->getOpcode() == ISD::CopyToReg) {
+ Copies[NumCopies++] = Use;
+ } else if (Use->getOpcode() == ARMISD::VMOVRRD) {
+ // f64 returned in a pair of GPRs.
+ for (SDNode::use_iterator UI = Use->use_begin(), UE = Use->use_end();
+ UI != UE; ++UI) {
+ if (UI->getOpcode() != ISD::CopyToReg)
+ return false;
+ Copies[UI.getUse().getResNo()] = *UI;
+ ++NumCopies;
+ }
+ } else if (Use->getOpcode() == ISD::BITCAST) {
+ // f32 returned in a single GPR.
+ if (!Use->hasNUsesOfValue(1, 0))
+ return false;
+ Use = *Use->use_begin();
+ if (Use->getOpcode() != ISD::CopyToReg || !Use->hasNUsesOfValue(1, 0))
+ return false;
+ Copies[NumCopies++] = Use;
+ } else {
+ return false;
+ }
+
+ if (NumCopies != 1 && NumCopies != 2)
+ return false;
+ for (unsigned i = 0; i < NumCopies; ++i) {
+ SDNode *Copy = Copies[i];
+ for (SDNode::use_iterator UI = Copy->use_begin(), UE = Copy->use_end();
+ UI != UE; ++UI) {
+ if (UI->getOpcode() == ISD::CopyToReg) {
+ SDNode *Use = *UI;
+ if (Use == Copies[0] || Use == Copies[1])
+ continue;
+ return false;
+ }
+ if (UI->getOpcode() != ARMISD::RET_FLAG)
+ return false;
+ }
+ }
+
+ return true;
+}
+
// 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
diff --git a/lib/Target/ARM/ARMISelLowering.h b/lib/Target/ARM/ARMISelLowering.h
index 38f7399110..6d11bad357 100644
--- a/lib/Target/ARM/ARMISelLowering.h
+++ b/lib/Target/ARM/ARMISelLowering.h
@@ -421,6 +421,8 @@ namespace llvm {
const SmallVectorImpl<SDValue> &OutVals,
DebugLoc dl, SelectionDAG &DAG) const;
+ virtual bool isUsedByReturnOnly(SDNode *N) const;
+
SDValue getARMCmp(SDValue LHS, SDValue RHS, ISD::CondCode CC,
SDValue &ARMcc, SelectionDAG &DAG, DebugLoc dl) const;
SDValue getVFPCmp(SDValue LHS, SDValue RHS,
diff --git a/lib/Target/X86/README.txt b/lib/Target/X86/README.txt
index e67fab1090..a305ae6ec5 100644
--- a/lib/Target/X86/README.txt
+++ b/lib/Target/X86/README.txt
@@ -895,24 +895,6 @@ compare:
//===---------------------------------------------------------------------===//
-Linux is missing some basic tail call support:
-
-#include <math.h>
-double foo(double a) { return sin(a); }
-
-This compiles into this on x86-64 Linux (but not darwin):
-foo:
- subq $8, %rsp
- call sin
- addq $8, %rsp
- ret
-vs:
-
-foo:
- jmp sin
-
-//===---------------------------------------------------------------------===//
-
Tail call optimization improvements: Tail call optimization currently
pushes all arguments on the top of the stack (their normal place for
non-tail call optimized calls) that source from the callers arguments
diff --git a/lib/Target/X86/X86FrameInfo.cpp b/lib/Target/X86/X86FrameInfo.cpp
index 494e905028..c47b0fa697 100644
--- a/lib/Target/X86/X86FrameInfo.cpp
+++ b/lib/Target/X86/X86FrameInfo.cpp
@@ -712,10 +712,17 @@ void X86FrameInfo::emitEpilogue(MachineFunction &MF,
// Jump to label or value in register.
if (RetOpcode == X86::TCRETURNdi || RetOpcode == X86::TCRETURNdi64) {
- BuildMI(MBB, MBBI, DL, TII.get((RetOpcode == X86::TCRETURNdi)
- ? X86::TAILJMPd : X86::TAILJMPd64)).
- addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
- JumpTarget.getTargetFlags());
+ MachineInstrBuilder MIB =
+ BuildMI(MBB, MBBI, DL, TII.get((RetOpcode == X86::TCRETURNdi)
+ ? X86::TAILJMPd : X86::TAILJMPd64));
+ if (JumpTarget.isGlobal())
+ MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
+ JumpTarget.getTargetFlags());
+ else {
+ assert(JumpTarget.isSymbol());
+ MIB.addExternalSymbol(JumpTarget.getSymbolName(),
+ JumpTarget.getTargetFlags());
+ }
} else if (RetOpcode == X86::TCRETURNmi || RetOpcode == X86::TCRETURNmi64) {
MachineInstrBuilder MIB =
BuildMI(MBB, MBBI, DL, TII.get((RetOpcode == X86::TCRETURNmi)
diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index 6d6d83d557..bc6d84eeec 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -1338,6 +1338,23 @@ X86TargetLowering::LowerReturn(SDValue Chain,
MVT::Other, &RetOps[0], RetOps.size());
}
+bool X86TargetLowering::isUsedByReturnOnly(SDNode *N) const {
+ if (N->getNumValues() != 1)
+ return false;
+ if (!N->hasNUsesOfValue(1, 0))
+ return false;
+
+ SDNode *Copy = *N->use_begin();
+ if (Copy->getOpcode() != ISD::CopyToReg)
+ return false;
+ for (SDNode::use_iterator UI = Copy->use_begin(), UE = Copy->use_end();
+ UI != UE; ++UI)
+ if (UI->getOpcode() != X86ISD::RET_FLAG)
+ return false;
+
+ return true;
+}
+
/// LowerCallResult - Lower the result values of a call into the
/// appropriate copies out of appropriate physical registers.
///
@@ -2142,17 +2159,19 @@ X86TargetLowering::LowerCall(SDValue Chain, SDValue Callee,
} else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(Callee)) {
unsigned char OpFlags = 0;
- // On ELF targets, in either X86-64 or X86-32 mode, direct calls to external
- // symbols should go through the PLT.
- if (Subtarget->isTargetELF() &&
- getTargetMachine().getRelocationModel() == Reloc::PIC_) {
- OpFlags = X86II::MO_PLT;
- } else if (Subtarget->isPICStyleStubAny() &&
- Subtarget->getDarwinVers() < 9) {
- // PC-relative references to external symbols should go through $stub,
- // unless we're building with the leopard linker or later, which
- // automatically synthesizes these stubs.
- OpFlags = X86II::MO_DARWIN_STUB;
+ if (!isTailCall) {
+ // On ELF targets, in either X86-64 or X86-32 mode, direct calls to
+ // external symbols should go through the PLT.
+ if (Subtarget->isTargetELF() &&
+ getTargetMachine().getRelocationModel() == Reloc::PIC_) {
+ OpFlags = X86II::MO_PLT;
+ } else if (Subtarget->isPICStyleStubAny() &&
+ Subtarget->getDarwinVers() < 9) {
+ // PC-relative references to external symbols should go through $stub,
+ // unless we're building with the leopard linker or later, which
+ // automatically synthesizes these stubs.
+ OpFlags = X86II::MO_DARWIN_STUB;
+ }
}
Callee = DAG.getTargetExternalSymbol(S->getSymbol(), getPointerTy(),
diff --git a/lib/Target/X86/X86ISelLowering.h b/lib/Target/X86/X86ISelLowering.h
index b521702013..edcdceb39a 100644
--- a/lib/Target/X86/X86ISelLowering.h
+++ b/lib/Target/X86/X86ISelLowering.h
@@ -805,6 +805,8 @@ namespace llvm {
const SmallVectorImpl<SDValue> &OutVals,
DebugLoc dl, SelectionDAG &DAG) const;
+ virtual bool isUsedByReturnOnly(SDNode *N) const;
+
virtual bool
CanLowerReturn(CallingConv::ID CallConv, bool isVarArg,
const SmallVectorImpl<ISD::OutputArg> &Outs,
generated by cgit v1.2.3-18-g5258 (git 2.32.0) at 2025-07-16 11:49:02 +0000