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[X86] Simplify some X86 address mode folding code, NFCI 

This code should really do exactly the same thing for 32-bit x86 and
64-bit small code models, with the exception that RIP-relative
addressing can't use base and index registers.

llvm-svn: 332893
This commit is contained in:
Reid Kleckner 2018-05-21 21:03:19 +00:00
parent dc3bf90447
commit 537917d13c
1 changed files with 52 additions and 83 deletions
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135
llvm/lib/Target/X86/X86ISelDAGToDAG.cpp
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@ -877,9 +877,14 @@ static bool isDispSafeForFrameIndex(int64_t Val) {
bool X86DAGToDAGISel::foldOffsetIntoAddress(uint64_t Offset,
X86ISelAddressMode &AM) {
// If there's no offset to fold, we don't need to do any work.
if (Offset == 0)
return false;
// Cannot combine ExternalSymbol displacements with integer offsets.
if (Offset != 0 && (AM.ES || AM.MCSym))
if (AM.ES || AM.MCSym)
return true;
int64_t Val = AM.Disp + Offset;
CodeModel::Model M = TM.getCodeModel();
if (Subtarget->is64Bit()) {
@ -933,94 +938,58 @@ bool X86DAGToDAGISel::matchWrapper(SDValue N, X86ISelAddressMode &AM) {
if (AM.hasSymbolicDisplacement())
return true;
SDValue N0 = N.getOperand(0);
bool IsRIPRel = N.getOpcode() == X86ISD::WrapperRIP;
// Only do this address mode folding for 64-bit if we're in the small code
// model.
// FIXME: But we can do GOTPCREL addressing in the medium code model.
CodeModel::Model M = TM.getCodeModel();
if (Subtarget->is64Bit() && M != CodeModel::Small && M != CodeModel::Kernel)
return true;
// Handle X86-64 rip-relative addresses. We check this before checking direct
// folding because RIP is preferable to non-RIP accesses.
if (Subtarget->is64Bit() && N.getOpcode() == X86ISD::WrapperRIP &&
// Under X86-64 non-small code model, GV (and friends) are 64-bits, so
// they cannot be folded into immediate fields.
// FIXME: This can be improved for kernel and other models?
(M == CodeModel::Small || M == CodeModel::Kernel)) {
// Base and index reg must be 0 in order to use %rip as base.
if (AM.hasBaseOrIndexReg())
return true;
if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(N0)) {
X86ISelAddressMode Backup = AM;
AM.GV = G->getGlobal();
AM.SymbolFlags = G->getTargetFlags();
if (foldOffsetIntoAddress(G->getOffset(), AM)) {
AM = Backup;
return true;
}
} else if (ConstantPoolSDNode *CP = dyn_cast<ConstantPoolSDNode>(N0)) {
X86ISelAddressMode Backup = AM;
AM.CP = CP->getConstVal();
AM.Align = CP->getAlignment();
AM.SymbolFlags = CP->getTargetFlags();
if (foldOffsetIntoAddress(CP->getOffset(), AM)) {
AM = Backup;
return true;
}
} else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(N0)) {
AM.ES = S->getSymbol();
AM.SymbolFlags = S->getTargetFlags();
} else if (auto *S = dyn_cast<MCSymbolSDNode>(N0)) {
AM.MCSym = S->getMCSymbol();
} else if (JumpTableSDNode *J = dyn_cast<JumpTableSDNode>(N0)) {
AM.JT = J->getIndex();
AM.SymbolFlags = J->getTargetFlags();
} else if (BlockAddressSDNode *BA = dyn_cast<BlockAddressSDNode>(N0)) {
X86ISelAddressMode Backup = AM;
AM.BlockAddr = BA->getBlockAddress();
AM.SymbolFlags = BA->getTargetFlags();
if (foldOffsetIntoAddress(BA->getOffset(), AM)) {
AM = Backup;
return true;
}
} else
llvm_unreachable("Unhandled symbol reference node.");
// Base and index reg must be 0 in order to use %rip as base.
if (IsRIPRel && AM.hasBaseOrIndexReg())
return true;
if (N.getOpcode() == X86ISD::WrapperRIP)
AM.setBaseReg(CurDAG->getRegister(X86::RIP, MVT::i64));
return false;
// Make a local copy in case we can't do this fold.
X86ISelAddressMode Backup = AM;
int64_t Offset = 0;
SDValue N0 = N.getOperand(0);
if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(N0)) {
AM.GV = G->getGlobal();
AM.SymbolFlags = G->getTargetFlags();
Offset = G->getOffset();
} else if (ConstantPoolSDNode *CP = dyn_cast<ConstantPoolSDNode>(N0)) {
AM.CP = CP->getConstVal();
AM.Align = CP->getAlignment();
AM.SymbolFlags = CP->getTargetFlags();
Offset = CP->getOffset();
} else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(N0)) {
AM.ES = S->getSymbol();
AM.SymbolFlags = S->getTargetFlags();
} else if (auto *S = dyn_cast<MCSymbolSDNode>(N0)) {
AM.MCSym = S->getMCSymbol();
} else if (JumpTableSDNode *J = dyn_cast<JumpTableSDNode>(N0)) {
AM.JT = J->getIndex();
AM.SymbolFlags = J->getTargetFlags();
} else if (BlockAddressSDNode *BA = dyn_cast<BlockAddressSDNode>(N0)) {
AM.BlockAddr = BA->getBlockAddress();
AM.SymbolFlags = BA->getTargetFlags();
Offset = BA->getOffset();
} else
llvm_unreachable("Unhandled symbol reference node.");
if (foldOffsetIntoAddress(Offset, AM)) {
AM = Backup;
return true;
}
// Handle the case when globals fit in our immediate field: This is true for
// X86-32 always and X86-64 when in -mcmodel=small mode. In 64-bit
// mode, this only applies to a non-RIP-relative computation.
if (!Subtarget->is64Bit() ||
M == CodeModel::Small || M == CodeModel::Kernel) {
assert(N.getOpcode() != X86ISD::WrapperRIP &&
"RIP-relative addressing already handled");
if (GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(N0)) {
AM.GV = G->getGlobal();
AM.Disp += G->getOffset();
AM.SymbolFlags = G->getTargetFlags();
} else if (ConstantPoolSDNode *CP = dyn_cast<ConstantPoolSDNode>(N0)) {
AM.CP = CP->getConstVal();
AM.Align = CP->getAlignment();
AM.Disp += CP->getOffset();
AM.SymbolFlags = CP->getTargetFlags();
} else if (ExternalSymbolSDNode *S = dyn_cast<ExternalSymbolSDNode>(N0)) {
AM.ES = S->getSymbol();
AM.SymbolFlags = S->getTargetFlags();
} else if (auto *S = dyn_cast<MCSymbolSDNode>(N0)) {
AM.MCSym = S->getMCSymbol();
} else if (JumpTableSDNode *J = dyn_cast<JumpTableSDNode>(N0)) {
AM.JT = J->getIndex();
AM.SymbolFlags = J->getTargetFlags();
} else if (BlockAddressSDNode *BA = dyn_cast<BlockAddressSDNode>(N0)) {
AM.BlockAddr = BA->getBlockAddress();
AM.Disp += BA->getOffset();
AM.SymbolFlags = BA->getTargetFlags();
} else
llvm_unreachable("Unhandled symbol reference node.");
return false;
}
if (IsRIPRel)
AM.setBaseReg(CurDAG->getRegister(X86::RIP, MVT::i64));
return true;
// Commit the changes now that we know this fold is safe.
return false;
}
/// Add the specified node to the specified addressing mode, returning true if