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-rw-r--r--lib/Target/X86/X86FastISel.cpp311
1 files changed, 180 insertions, 131 deletions
diff --git a/lib/Target/X86/X86FastISel.cpp b/lib/Target/X86/X86FastISel.cpp
index 5bc3420..97f96ab 100644
--- a/lib/Target/X86/X86FastISel.cpp
+++ b/lib/Target/X86/X86FastISel.cpp
@@ -14,6 +14,7 @@
//===----------------------------------------------------------------------===//
#include "X86.h"
+#include "X86CallingConv.h"
#include "X86ISelLowering.h"
#include "X86InstrBuilder.h"
#include "X86RegisterInfo.h"
@@ -125,6 +126,8 @@ private:
return static_cast<const X86TargetMachine *>(&TM);
}
+ bool handleConstantAddresses(const Value *V, X86AddressMode &AM);
+
unsigned TargetMaterializeConstant(const Constant *C);
unsigned TargetMaterializeAlloca(const AllocaInst *C);
@@ -344,9 +347,126 @@ bool X86FastISel::X86FastEmitExtend(ISD::NodeType Opc, EVT DstVT,
return true;
}
+bool X86FastISel::handleConstantAddresses(const Value *V, X86AddressMode &AM) {
+ // Handle constant address.
+ if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
+ // Can't handle alternate code models yet.
+ if (TM.getCodeModel() != CodeModel::Small)
+ return false;
+
+ // Can't handle TLS yet.
+ if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV))
+ if (GVar->isThreadLocal())
+ return false;
+
+ // Can't handle TLS yet, part 2 (this is slightly crazy, but this is how
+ // it works...).
+ if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(GV))
+ if (const GlobalVariable *GVar =
+ dyn_cast_or_null<GlobalVariable>(GA->resolveAliasedGlobal(false)))
+ if (GVar->isThreadLocal())
+ return false;
+
+ // RIP-relative addresses can't have additional register operands, so if
+ // we've already folded stuff into the addressing mode, just force the
+ // global value into its own register, which we can use as the basereg.
+ if (!Subtarget->isPICStyleRIPRel() ||
+ (AM.Base.Reg == 0 && AM.IndexReg == 0)) {
+ // Okay, we've committed to selecting this global. Set up the address.
+ AM.GV = GV;
+
+ // Allow the subtarget to classify the global.
+ unsigned char GVFlags = Subtarget->ClassifyGlobalReference(GV, TM);
+
+ // If this reference is relative to the pic base, set it now.
+ if (isGlobalRelativeToPICBase(GVFlags)) {
+ // FIXME: How do we know Base.Reg is free??
+ AM.Base.Reg = getInstrInfo()->getGlobalBaseReg(FuncInfo.MF);
+ }
+
+ // Unless the ABI requires an extra load, return a direct reference to
+ // the global.
+ if (!isGlobalStubReference(GVFlags)) {
+ if (Subtarget->isPICStyleRIPRel()) {
+ // Use rip-relative addressing if we can. Above we verified that the
+ // base and index registers are unused.
+ assert(AM.Base.Reg == 0 && AM.IndexReg == 0);
+ AM.Base.Reg = X86::RIP;
+ }
+ AM.GVOpFlags = GVFlags;
+ return true;
+ }
+
+ // Ok, we need to do a load from a stub. If we've already loaded from
+ // this stub, reuse the loaded pointer, otherwise emit the load now.
+ DenseMap<const Value*, unsigned>::iterator I = LocalValueMap.find(V);
+ unsigned LoadReg;
+ if (I != LocalValueMap.end() && I->second != 0) {
+ LoadReg = I->second;
+ } else {
+ // Issue load from stub.
+ unsigned Opc = 0;
+ const TargetRegisterClass *RC = NULL;
+ X86AddressMode StubAM;
+ StubAM.Base.Reg = AM.Base.Reg;
+ StubAM.GV = GV;
+ StubAM.GVOpFlags = GVFlags;
+
+ // Prepare for inserting code in the local-value area.
+ SavePoint SaveInsertPt = enterLocalValueArea();
+
+ if (TLI.getPointerTy() == MVT::i64) {
+ Opc = X86::MOV64rm;
+ RC = &X86::GR64RegClass;
+
+ if (Subtarget->isPICStyleRIPRel())
+ StubAM.Base.Reg = X86::RIP;
+ } else {
+ Opc = X86::MOV32rm;
+ RC = &X86::GR32RegClass;
+ }
+
+ LoadReg = createResultReg(RC);
+ MachineInstrBuilder LoadMI =
+ BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(Opc), LoadReg);
+ addFullAddress(LoadMI, StubAM);
+
+ // Ok, back to normal mode.
+ leaveLocalValueArea(SaveInsertPt);
+
+ // Prevent loading GV stub multiple times in same MBB.
+ LocalValueMap[V] = LoadReg;
+ }
+
+ // Now construct the final address. Note that the Disp, Scale,
+ // and Index values may already be set here.
+ AM.Base.Reg = LoadReg;
+ AM.GV = 0;
+ return true;
+ }
+ }
+
+ // If all else fails, try to materialize the value in a register.
+ if (!AM.GV || !Subtarget->isPICStyleRIPRel()) {
+ if (AM.Base.Reg == 0) {
+ AM.Base.Reg = getRegForValue(V);
+ return AM.Base.Reg != 0;
+ }
+ if (AM.IndexReg == 0) {
+ assert(AM.Scale == 1 && "Scale with no index!");
+ AM.IndexReg = getRegForValue(V);
+ return AM.IndexReg != 0;
+ }
+ }
+
+ return false;
+}
+
/// X86SelectAddress - Attempt to fill in an address from the given value.
///
bool X86FastISel::X86SelectAddress(const Value *V, X86AddressMode &AM) {
+ SmallVector<const Value *, 32> GEPs;
+redo_gep:
const User *U = NULL;
unsigned Opcode = Instruction::UserOp1;
if (const Instruction *I = dyn_cast<Instruction>(V)) {
@@ -441,13 +561,8 @@ bool X86FastISel::X86SelectAddress(const Value *V, X86AddressMode &AM) {
Disp += CI->getSExtValue() * S;
break;
}
- if (isa<AddOperator>(Op) &&
- (!isa<Instruction>(Op) ||
- FuncInfo.MBBMap[cast<Instruction>(Op)->getParent()]
- == FuncInfo.MBB) &&
- isa<ConstantInt>(cast<AddOperator>(Op)->getOperand(1))) {
- // An add (in the same block) with a constant operand. Fold the
- // constant.
+ if (canFoldAddIntoGEP(U, Op)) {
+ // A compatible add with a constant operand. Fold the constant.
ConstantInt *CI =
cast<ConstantInt>(cast<AddOperator>(Op)->getOperand(1));
Disp += CI->getSExtValue() * S;
@@ -469,139 +584,43 @@ bool X86FastISel::X86SelectAddress(const Value *V, X86AddressMode &AM) {
goto unsupported_gep;
}
}
+
// Check for displacement overflow.
if (!isInt<32>(Disp))
break;
- // Ok, the GEP indices were covered by constant-offset and scaled-index
- // addressing. Update the address state and move on to examining the base.
+
AM.IndexReg = IndexReg;
AM.Scale = Scale;
AM.Disp = (uint32_t)Disp;
- if (X86SelectAddress(U->getOperand(0), AM))
+ GEPs.push_back(V);
+
+ if (const GetElementPtrInst *GEP =
+ dyn_cast<GetElementPtrInst>(U->getOperand(0))) {
+ // Ok, the GEP indices were covered by constant-offset and scaled-index
+ // addressing. Update the address state and move on to examining the base.
+ V = GEP;
+ goto redo_gep;
+ } else if (X86SelectAddress(U->getOperand(0), AM)) {
return true;
+ }
// If we couldn't merge the gep value into this addr mode, revert back to
// our address and just match the value instead of completely failing.
AM = SavedAM;
- break;
- unsupported_gep:
- // Ok, the GEP indices weren't all covered.
- break;
- }
- }
-
- // Handle constant address.
- if (const GlobalValue *GV = dyn_cast<GlobalValue>(V)) {
- // Can't handle alternate code models yet.
- if (TM.getCodeModel() != CodeModel::Small)
- return false;
- // Can't handle TLS yet.
- if (const GlobalVariable *GVar = dyn_cast<GlobalVariable>(GV))
- if (GVar->isThreadLocal())
- return false;
-
- // Can't handle TLS yet, part 2 (this is slightly crazy, but this is how
- // it works...).
- if (const GlobalAlias *GA = dyn_cast<GlobalAlias>(GV))
- if (const GlobalVariable *GVar =
- dyn_cast_or_null<GlobalVariable>(GA->resolveAliasedGlobal(false)))
- if (GVar->isThreadLocal())
- return false;
-
- // RIP-relative addresses can't have additional register operands, so if
- // we've already folded stuff into the addressing mode, just force the
- // global value into its own register, which we can use as the basereg.
- if (!Subtarget->isPICStyleRIPRel() ||
- (AM.Base.Reg == 0 && AM.IndexReg == 0)) {
- // Okay, we've committed to selecting this global. Set up the address.
- AM.GV = GV;
-
- // Allow the subtarget to classify the global.
- unsigned char GVFlags = Subtarget->ClassifyGlobalReference(GV, TM);
-
- // If this reference is relative to the pic base, set it now.
- if (isGlobalRelativeToPICBase(GVFlags)) {
- // FIXME: How do we know Base.Reg is free??
- AM.Base.Reg = getInstrInfo()->getGlobalBaseReg(FuncInfo.MF);
- }
-
- // Unless the ABI requires an extra load, return a direct reference to
- // the global.
- if (!isGlobalStubReference(GVFlags)) {
- if (Subtarget->isPICStyleRIPRel()) {
- // Use rip-relative addressing if we can. Above we verified that the
- // base and index registers are unused.
- assert(AM.Base.Reg == 0 && AM.IndexReg == 0);
- AM.Base.Reg = X86::RIP;
- }
- AM.GVOpFlags = GVFlags;
+ for (SmallVectorImpl<const Value *>::reverse_iterator
+ I = GEPs.rbegin(), E = GEPs.rend(); I != E; ++I)
+ if (handleConstantAddresses(*I, AM))
return true;
- }
-
- // Ok, we need to do a load from a stub. If we've already loaded from
- // this stub, reuse the loaded pointer, otherwise emit the load now.
- DenseMap<const Value*, unsigned>::iterator I = LocalValueMap.find(V);
- unsigned LoadReg;
- if (I != LocalValueMap.end() && I->second != 0) {
- LoadReg = I->second;
- } else {
- // Issue load from stub.
- unsigned Opc = 0;
- const TargetRegisterClass *RC = NULL;
- X86AddressMode StubAM;
- StubAM.Base.Reg = AM.Base.Reg;
- StubAM.GV = GV;
- StubAM.GVOpFlags = GVFlags;
-
- // Prepare for inserting code in the local-value area.
- SavePoint SaveInsertPt = enterLocalValueArea();
-
- if (TLI.getPointerTy() == MVT::i64) {
- Opc = X86::MOV64rm;
- RC = &X86::GR64RegClass;
- if (Subtarget->isPICStyleRIPRel())
- StubAM.Base.Reg = X86::RIP;
- } else {
- Opc = X86::MOV32rm;
- RC = &X86::GR32RegClass;
- }
-
- LoadReg = createResultReg(RC);
- MachineInstrBuilder LoadMI =
- BuildMI(*FuncInfo.MBB, FuncInfo.InsertPt, DL, TII.get(Opc), LoadReg);
- addFullAddress(LoadMI, StubAM);
-
- // Ok, back to normal mode.
- leaveLocalValueArea(SaveInsertPt);
-
- // Prevent loading GV stub multiple times in same MBB.
- LocalValueMap[V] = LoadReg;
- }
-
- // Now construct the final address. Note that the Disp, Scale,
- // and Index values may already be set here.
- AM.Base.Reg = LoadReg;
- AM.GV = 0;
- return true;
- }
+ return false;
+ unsupported_gep:
+ // Ok, the GEP indices weren't all covered.
+ break;
}
-
- // If all else fails, try to materialize the value in a register.
- if (!AM.GV || !Subtarget->isPICStyleRIPRel()) {
- if (AM.Base.Reg == 0) {
- AM.Base.Reg = getRegForValue(V);
- return AM.Base.Reg != 0;
- }
- if (AM.IndexReg == 0) {
- assert(AM.Scale == 1 && "Scale with no index!");
- AM.IndexReg = getRegForValue(V);
- return AM.IndexReg != 0;
- }
}
- return false;
+ return handleConstantAddresses(V, AM);
}
/// X86SelectCallAddress - Attempt to fill in an address from the given value.
@@ -609,9 +628,35 @@ bool X86FastISel::X86SelectAddress(const Value *V, X86AddressMode &AM) {
bool X86FastISel::X86SelectCallAddress(const Value *V, X86AddressMode &AM) {
const User *U = NULL;
unsigned Opcode = Instruction::UserOp1;
- if (const Instruction *I = dyn_cast<Instruction>(V)) {
+ const Instruction *I = dyn_cast<Instruction>(V);
+ // Record if the value is defined in the same basic block.
+ //
+ // This information is crucial to know whether or not folding an
+ // operand is valid.
+ // Indeed, FastISel generates or reuses a virtual register for all
+ // operands of all instructions it selects. Obviously, the definition and
+ // its uses must use the same virtual register otherwise the produced
+ // code is incorrect.
+ // Before instruction selection, FunctionLoweringInfo::set sets the virtual
+ // registers for values that are alive across basic blocks. This ensures
+ // that the values are consistently set between across basic block, even
+ // if different instruction selection mechanisms are used (e.g., a mix of
+ // SDISel and FastISel).
+ // For values local to a basic block, the instruction selection process
+ // generates these virtual registers with whatever method is appropriate
+ // for its needs. In particular, FastISel and SDISel do not share the way
+ // local virtual registers are set.
+ // Therefore, this is impossible (or at least unsafe) to share values
+ // between basic blocks unless they use the same instruction selection
+ // method, which is not guarantee for X86.
+ // Moreover, things like hasOneUse could not be used accurately, if we
+ // allow to reference values across basic blocks whereas they are not
+ // alive across basic blocks initially.
+ bool InMBB = true;
+ if (I) {
Opcode = I->getOpcode();
U = I;
+ InMBB = I->getParent() == FuncInfo.MBB->getBasicBlock();
} else if (const ConstantExpr *C = dyn_cast<ConstantExpr>(V)) {
Opcode = C->getOpcode();
U = C;
@@ -620,18 +665,22 @@ bool X86FastISel::X86SelectCallAddress(const Value *V, X86AddressMode &AM) {
switch (Opcode) {
default: break;
case Instruction::BitCast:
- // Look past bitcasts.
- return X86SelectCallAddress(U->getOperand(0), AM);
+ // Look past bitcasts if its operand is in the same BB.
+ if (InMBB)
+ return X86SelectCallAddress(U->getOperand(0), AM);
+ break;
case Instruction::IntToPtr:
- // Look past no-op inttoptrs.
- if (TLI.getValueType(U->getOperand(0)->getType()) == TLI.getPointerTy())
+ // Look past no-op inttoptrs if its operand is in the same BB.
+ if (InMBB &&
+ TLI.getValueType(U->getOperand(0)->getType()) == TLI.getPointerTy())
return X86SelectCallAddress(U->getOperand(0), AM);
break;
case Instruction::PtrToInt:
- // Look past no-op ptrtoints.
- if (TLI.getValueType(U->getType()) == TLI.getPointerTy())
+ // Look past no-op ptrtoints if its operand is in the same BB.
+ if (InMBB &&
+ TLI.getValueType(U->getType()) == TLI.getPointerTy())
return X86SelectCallAddress(U->getOperand(0), AM);
break;
}
@@ -1026,7 +1075,7 @@ bool X86FastISel::X86SelectZExt(const Instruction *I) {
return false;
// Handle zero-extension from i1 to i8, which is common.
- MVT SrcVT = TLI.getValueType(I->getOperand(0)->getType()).getSimpleVT();
+ MVT SrcVT = TLI.getSimpleValueType(I->getOperand(0)->getType());
if (SrcVT.SimpleTy == MVT::i1) {
// Set the high bits to zero.
ResultReg = FastEmitZExtFromI1(MVT::i8, ResultReg, /*TODO: Kill=*/false);
generated by cgit v1.1 at 2024-05-17 21:10:31 +0000