[llvm-commits] CVS: llvm/lib/Target/X86/MachineCodeEmitter.cpp
Chris Lattner
lattner at cs.uiuc.edu
Sun Jun 1 18:25:00 PDT 2003
Changes in directory llvm/lib/Target/X86:
MachineCodeEmitter.cpp updated: 1.22 -> 1.23
---
Log message:
Move X86 specific code out of the JIT into the X86 backend
---
Diffs of the changes:
Index: llvm/lib/Target/X86/MachineCodeEmitter.cpp
diff -u llvm/lib/Target/X86/MachineCodeEmitter.cpp:1.22 llvm/lib/Target/X86/MachineCodeEmitter.cpp:1.23
--- llvm/lib/Target/X86/MachineCodeEmitter.cpp:1.22 Thu May 8 22:28:13 2003
+++ llvm/lib/Target/X86/MachineCodeEmitter.cpp Sun Jun 1 18:23:50 2003
@@ -14,11 +14,125 @@
#include "llvm/Value.h"
namespace {
+ class JITResolver {
+ MachineCodeEmitter &MCE;
+
+ // LazyCodeGenMap - Keep track of call sites for functions that are to be
+ // lazily resolved.
+ std::map<unsigned, Function*> LazyCodeGenMap;
+
+ // LazyResolverMap - Keep track of the lazy resolver created for a
+ // particular function so that we can reuse them if necessary.
+ std::map<Function*, unsigned> LazyResolverMap;
+ public:
+ JITResolver(MachineCodeEmitter &mce) : MCE(mce) {}
+ unsigned getLazyResolver(Function *F);
+ unsigned addFunctionReference(unsigned Address, Function *F);
+
+ private:
+ unsigned emitStubForFunction(Function *F);
+ static void CompilationCallback();
+ unsigned resolveFunctionReference(unsigned RetAddr);
+ };
+
+ JITResolver *TheJITResolver;
+}
+
+
+/// addFunctionReference - This method is called when we need to emit the
+/// address of a function that has not yet been emitted, so we don't know the
+/// address. Instead, we emit a call to the CompilationCallback method, and
+/// keep track of where we are.
+///
+unsigned JITResolver::addFunctionReference(unsigned Address, Function *F) {
+ LazyCodeGenMap[Address] = F;
+ return (intptr_t)&JITResolver::CompilationCallback;
+}
+
+unsigned JITResolver::resolveFunctionReference(unsigned RetAddr) {
+ std::map<unsigned, Function*>::iterator I = LazyCodeGenMap.find(RetAddr);
+ assert(I != LazyCodeGenMap.end() && "Not in map!");
+ Function *F = I->second;
+ LazyCodeGenMap.erase(I);
+ return MCE.forceCompilationOf(F);
+}
+
+unsigned JITResolver::getLazyResolver(Function *F) {
+ std::map<Function*, unsigned>::iterator I = LazyResolverMap.lower_bound(F);
+ if (I != LazyResolverMap.end() && I->first == F) return I->second;
+
+//std::cerr << "Getting lazy resolver for : " << ((Value*)F)->getName() << "\n";
+
+ unsigned Stub = emitStubForFunction(F);
+ LazyResolverMap.insert(I, std::make_pair(F, Stub));
+ return Stub;
+}
+
+void JITResolver::CompilationCallback() {
+ unsigned *StackPtr = (unsigned*)__builtin_frame_address(0);
+ unsigned RetAddr = (unsigned)__builtin_return_address(0);
+
+ assert(StackPtr[1] == RetAddr &&
+ "Could not find return address on the stack!");
+ bool isStub = ((unsigned char*)RetAddr)[0] == 0xCD; // Interrupt marker?
+
+ // The call instruction should have pushed the return value onto the stack...
+ RetAddr -= 4; // Backtrack to the reference itself...
+
+#if 0
+ DEBUG(std::cerr << "In callback! Addr=0x" << std::hex << RetAddr
+ << " ESP=0x" << (unsigned)StackPtr << std::dec
+ << ": Resolving call to function: "
+ << TheVM->getFunctionReferencedName((void*)RetAddr) << "\n");
+#endif
+
+ // Sanity check to make sure this really is a call instruction...
+ assert(((unsigned char*)RetAddr)[-1] == 0xE8 && "Not a call instr!");
+
+ unsigned NewVal = TheJITResolver->resolveFunctionReference(RetAddr);
+
+ // Rewrite the call target... so that we don't fault every time we execute
+ // the call.
+ *(unsigned*)RetAddr = NewVal-RetAddr-4;
+
+ if (isStub) {
+ // If this is a stub, rewrite the call into an unconditional branch
+ // instruction so that two return addresses are not pushed onto the stack
+ // when the requested function finally gets called. This also makes the
+ // 0xCD byte (interrupt) dead, so the marker doesn't effect anything.
+ ((unsigned char*)RetAddr)[-1] = 0xE9;
+ }
+
+ // Change the return address to reexecute the call instruction...
+ StackPtr[1] -= 5;
+}
+
+/// emitStubForFunction - This method is used by the JIT when it needs to emit
+/// the address of a function for a function whose code has not yet been
+/// generated. In order to do this, it generates a stub which jumps to the lazy
+/// function compiler, which will eventually get fixed to call the function
+/// directly.
+///
+unsigned JITResolver::emitStubForFunction(Function *F) {
+ MCE.startFunctionStub(*F, 6);
+ MCE.emitByte(0xE8); // Call with 32 bit pc-rel destination...
+
+ unsigned Address = addFunctionReference(MCE.getCurrentPCValue(), F);
+ MCE.emitWord(Address-MCE.getCurrentPCValue()-4);
+
+ MCE.emitByte(0xCD); // Interrupt - Just a marker identifying the stub!
+ return (intptr_t)MCE.finishFunctionStub(*F);
+}
+
+
+
+namespace {
class Emitter : public MachineFunctionPass {
const X86InstrInfo *II;
MachineCodeEmitter &MCE;
+ std::map<BasicBlock*, unsigned> BasicBlockAddrs;
+ std::vector<std::pair<BasicBlock*, unsigned> > BBRefs;
public:
-
Emitter(MachineCodeEmitter &mce) : II(0), MCE(mce) {}
bool runOnMachineFunction(MachineFunction &MF);
@@ -31,6 +145,11 @@
void emitBasicBlock(MachineBasicBlock &MBB);
void emitInstruction(MachineInstr &MI);
+ void emitPCRelativeBlockAddress(BasicBlock *BB);
+ void emitMaybePCRelativeValue(unsigned Address, bool isPCRelative);
+ void emitGlobalAddressForCall(GlobalValue *GV);
+ void emitGlobalAddressForPtr(GlobalValue *GV);
+
void emitRegModRMByte(unsigned ModRMReg, unsigned RegOpcodeField);
void emitSIBByte(unsigned SS, unsigned Index, unsigned Base);
void emitConstant(unsigned Val, unsigned Size);
@@ -61,16 +180,91 @@
for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
emitBasicBlock(*I);
MCE.finishFunction(MF);
+
+ // Resolve all forward branches now...
+ for (unsigned i = 0, e = BBRefs.size(); i != e; ++i) {
+ unsigned Location = BasicBlockAddrs[BBRefs[i].first];
+ unsigned Ref = BBRefs[i].second;
+ *(unsigned*)Ref = Location-Ref-4;
+ }
+ BBRefs.clear();
+ BasicBlockAddrs.clear();
return false;
}
void Emitter::emitBasicBlock(MachineBasicBlock &MBB) {
- MCE.startBasicBlock(MBB);
+ if (uint64_t Addr = MCE.getCurrentPCValue())
+ BasicBlockAddrs[MBB.getBasicBlock()] = Addr;
+
for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end(); I != E; ++I)
emitInstruction(**I);
}
+/// emitPCRelativeBlockAddress - This method emits the PC relative address of
+/// the specified basic block, or if the basic block hasn't been emitted yet
+/// (because this is a forward branch), it keeps track of the information
+/// necessary to resolve this address later (and emits a dummy value).
+///
+void Emitter::emitPCRelativeBlockAddress(BasicBlock *BB) {
+ // FIXME: Emit backward branches directly
+ BBRefs.push_back(std::make_pair(BB, MCE.getCurrentPCValue()));
+ MCE.emitWord(0); // Emit a dummy value
+}
+
+/// emitMaybePCRelativeValue - Emit a 32-bit address which may be PC relative.
+///
+void Emitter::emitMaybePCRelativeValue(unsigned Address, bool isPCRelative) {
+ if (isPCRelative)
+ MCE.emitWord(Address-MCE.getCurrentPCValue()-4);
+ else
+ MCE.emitWord(Address);
+}
+
+/// emitGlobalAddressForCall - Emit the specified address to the code stream
+/// assuming this is part of a function call, which is PC relative.
+///
+void Emitter::emitGlobalAddressForCall(GlobalValue *GV) {
+ // Get the address from the backend...
+ unsigned Address = MCE.getGlobalValueAddress(GV);
+
+ // If the machine code emitter doesn't know what the address IS yet, we have
+ // to take special measures.
+ //
+ if (Address == 0) {
+ // FIXME: this is JIT specific!
+ if (TheJITResolver == 0)
+ TheJITResolver = new JITResolver(MCE);
+ Address = TheJITResolver->addFunctionReference(MCE.getCurrentPCValue(),
+ (Function*)GV);
+ }
+ emitMaybePCRelativeValue(Address, true);
+}
+
+/// emitGlobalAddress - Emit the specified address to the code stream assuming
+/// this is part of a "take the address of a global" instruction, which is not
+/// PC relative.
+///
+void Emitter::emitGlobalAddressForPtr(GlobalValue *GV) {
+ // Get the address from the backend...
+ unsigned Address = MCE.getGlobalValueAddress(GV);
+
+ // If the machine code emitter doesn't know what the address IS yet, we have
+ // to take special measures.
+ //
+ if (Address == 0) {
+ // FIXME: this is JIT specific!
+ if (TheJITResolver == 0)
+ TheJITResolver = new JITResolver(MCE);
+ Address = TheJITResolver->getLazyResolver((Function*)GV);
+ }
+
+ emitMaybePCRelativeValue(Address, false);
+}
+
+
+
+
namespace N86 { // Native X86 Register numbers...
enum {
EAX = 0, ECX = 1, EDX = 2, EBX = 3, ESP = 4, EBP = 5, ESI = 6, EDI = 7
@@ -134,11 +328,12 @@
unsigned Op, unsigned RegOpcodeField) {
const MachineOperand &Disp = MI.getOperand(Op+3);
if (MI.getOperand(Op).isConstantPoolIndex()) {
- // Emit a direct address reference [disp32] where the displacement is
- // controlled by the MCE.
+ // Emit a direct address reference [disp32] where the displacement of the
+ // constant pool entry is controlled by the MCE.
MCE.emitByte(ModRMByte(0, RegOpcodeField, 5));
unsigned Index = MI.getOperand(Op).getConstantPoolIndex();
- MCE.emitFunctionConstantValueAddress(Index, Disp.getImmedValue());
+ unsigned Address = MCE.getConstantPoolEntryAddress(Index);
+ MCE.emitWord(Address+Disp.getImmedValue());
return;
}
@@ -219,7 +414,7 @@
}
}
-unsigned sizeOfPtr(const TargetInstrDescriptor &Desc) {
+static unsigned sizeOfPtr(const TargetInstrDescriptor &Desc) {
switch (Desc.TSFlags & X86II::ArgMask) {
case X86II::Arg8: return 1;
case X86II::Arg16: return 2;
@@ -232,7 +427,6 @@
}
}
-
void Emitter::emitInstruction(MachineInstr &MI) {
unsigned Opcode = MI.getOpcode();
const TargetInstrDescriptor &Desc = II->get(Opcode);
@@ -267,11 +461,15 @@
if (MI.getNumOperands() == 1) {
MachineOperand &MO = MI.getOperand(0);
if (MO.isPCRelativeDisp()) {
- MCE.emitPCRelativeDisp(MO.getVRegValue());
+ // Conditional branch... FIXME: this should use an MBB destination!
+ emitPCRelativeBlockAddress(cast<BasicBlock>(MO.getVRegValue()));
} else if (MO.isGlobalAddress()) {
- MCE.emitGlobalAddress(MO.getGlobal(), MO.isPCRelative());
+ assert(MO.isPCRelative() && "Call target is not PC Relative?");
+ emitGlobalAddressForCall(MO.getGlobal());
} else if (MO.isExternalSymbol()) {
- MCE.emitGlobalAddress(MO.getSymbolName(), MO.isPCRelative());
+ unsigned Address = MCE.getGlobalValueAddress(MO.getSymbolName());
+ assert(Address && "Unknown external symbol!");
+ emitMaybePCRelativeValue(Address, MO.isPCRelative());
} else {
assert(0 && "Unknown RawFrm operand!");
}
@@ -287,13 +485,17 @@
unsigned Size = sizeOfPtr(Desc);
if (Value *V = MO1.getVRegValueOrNull()) {
assert(Size == 4 && "Don't know how to emit non-pointer values!");
- MCE.emitGlobalAddress(cast<GlobalValue>(V), false);
+ emitGlobalAddressForPtr(cast<GlobalValue>(V));
} else if (MO1.isGlobalAddress()) {
assert(Size == 4 && "Don't know how to emit non-pointer values!");
- MCE.emitGlobalAddress(MO1.getGlobal(), MO1.isPCRelative());
+ assert(!MO1.isPCRelative() && "Function pointer ref is PC relative?");
+ emitGlobalAddressForPtr(MO1.getGlobal());
} else if (MO1.isExternalSymbol()) {
assert(Size == 4 && "Don't know how to emit non-pointer values!");
- MCE.emitGlobalAddress(MO1.getSymbolName(), MO1.isPCRelative());
+
+ unsigned Address = MCE.getGlobalValueAddress(MO1.getSymbolName());
+ assert(Address && "Unknown external symbol!");
+ emitMaybePCRelativeValue(Address, MO1.isPCRelative());
} else {
emitConstant(MO1.getImmedValue(), Size);
}
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