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+//===-- llvm/IR/Statepoint.h - gc.statepoint utilities ------ --*- C++ -*-===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains utility functions and a wrapper class analogous to
+// CallSite for accessing the fields of gc.statepoint, gc.relocate, and
+// gc.result intrinsics
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef __LLVM_IR_STATEPOINT_H
+#define __LLVM_IR_STATEPOINT_H
+
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/IR/BasicBlock.h"
+#include "llvm/IR/CallSite.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/Support/Compiler.h"
+
+namespace llvm {
+
+class GCRelocateOperands;
+class ImmutableStatepoint;
+
+bool isStatepoint(const ImmutableCallSite &CS);
+bool isStatepoint(const Value *inst);
+bool isStatepoint(const Value &inst);
+
+bool isGCRelocate(const Value *inst);
+bool isGCRelocate(const ImmutableCallSite &CS);
+
+bool isGCResult(const Value *inst);
+bool isGCResult(const ImmutableCallSite &CS);
+
+/// Analogous to CallSiteBase, this provides most of the actual
+/// functionality for Statepoint and ImmutableStatepoint. It is
+/// templatized to allow easily specializing of const and non-const
+/// concrete subtypes. This is structured analogous to CallSite
+/// rather than the IntrinsicInst.h helpers since we want to support
+/// invokable statepoints in the near future.
+/// TODO: This does not currently allow the if(Statepoint S = ...)
+/// idiom used with CallSites. Consider refactoring to support.
+template <typename InstructionTy, typename ValueTy, typename CallSiteTy>
+class StatepointBase {
+ CallSiteTy StatepointCS;
+ void *operator new(size_t, unsigned) = delete;
+ void *operator new(size_t s) = delete;
+
+ protected:
+ explicit StatepointBase(InstructionTy *I) : StatepointCS(I) {
+ assert(isStatepoint(I));
+ }
+ explicit StatepointBase(CallSiteTy CS) : StatepointCS(CS) {
+ assert(isStatepoint(CS));
+ }
+
+ public:
+ typedef typename CallSiteTy::arg_iterator arg_iterator;
+
+ /// Return the underlying CallSite.
+ CallSiteTy getCallSite() {
+ return StatepointCS;
+ }
+
+ /// Return the value actually being called or invoked.
+ ValueTy *actualCallee() {
+ return StatepointCS.getArgument(0);
+ }
+ /// Number of arguments to be passed to the actual callee.
+ int numCallArgs() {
+ return cast<ConstantInt>(StatepointCS.getArgument(1))->getZExtValue();
+ }
+ /// Number of additional arguments excluding those intended
+ /// for garbage collection.
+ int numTotalVMSArgs() {
+ return cast<ConstantInt>(StatepointCS.getArgument(3 + numCallArgs()))->getZExtValue();
+ }
+
+ typename CallSiteTy::arg_iterator call_args_begin() {
+ // 3 = callTarget, #callArgs, flag
+ int Offset = 3;
+ assert(Offset <= (int)StatepointCS.arg_size());
+ return StatepointCS.arg_begin() + Offset;
+ }
+ typename CallSiteTy::arg_iterator call_args_end() {
+ int Offset = 3 + numCallArgs();
+ assert(Offset <= (int)StatepointCS.arg_size());
+ return StatepointCS.arg_begin() + Offset;
+ }
+
+ /// range adapter for call arguments
+ iterator_range<arg_iterator> call_args() {
+ return iterator_range<arg_iterator>(call_args_begin(), call_args_end());
+ }
+
+ typename CallSiteTy::arg_iterator vm_state_begin() {
+ return call_args_end();
+ }
+ typename CallSiteTy::arg_iterator vm_state_end() {
+ int Offset = 3 + numCallArgs() + 1 + numTotalVMSArgs();
+ assert(Offset <= (int)StatepointCS.arg_size());
+ return StatepointCS.arg_begin() + Offset;
+ }
+
+ /// range adapter for vm state arguments
+ iterator_range<arg_iterator> vm_state_args() {
+ return iterator_range<arg_iterator>(vm_state_begin(), vm_state_end());
+ }
+
+ typename CallSiteTy::arg_iterator first_vm_state_stack_begin() {
+ // 6 = numTotalVMSArgs, 1st_objectID, 1st_bci,
+ // 1st_#stack, 1st_#local, 1st_#monitor
+ return vm_state_begin() + 6;
+ }
+
+ typename CallSiteTy::arg_iterator gc_args_begin() {
+ return vm_state_end();
+ }
+ typename CallSiteTy::arg_iterator gc_args_end() {
+ return StatepointCS.arg_end();
+ }
+
+ /// range adapter for gc arguments
+ iterator_range<arg_iterator> gc_args() {
+ return iterator_range<arg_iterator>(gc_args_begin(), gc_args_end());
+ }
+
+ /// Get list of all gc reloactes linked to this statepoint
+ /// May contain several relocations for the same base/derived pair.
+ /// For example this could happen due to relocations on unwinding
+ /// path of invoke.
+ std::vector<GCRelocateOperands> getRelocates(ImmutableStatepoint &IS);
+
+#ifndef NDEBUG
+ /// Asserts if this statepoint is malformed. Common cases for failure
+ /// include incorrect length prefixes for variable length sections or
+ /// illegal values for parameters.
+ void verify() {
+ assert(numCallArgs() >= 0 &&
+ "number of arguments to actually callee can't be negative");
+
+ // The internal asserts in the iterator accessors do the rest.
+ (void)call_args_begin();
+ (void)call_args_end();
+ (void)vm_state_begin();
+ (void)vm_state_end();
+ (void)gc_args_begin();
+ (void)gc_args_end();
+ }
+#endif
+};
+
+/// A specialization of it's base class for read only access
+/// to a gc.statepoint.
+class ImmutableStatepoint
+ : public StatepointBase<const Instruction, const Value,
+ ImmutableCallSite> {
+ typedef StatepointBase<const Instruction, const Value, ImmutableCallSite>
+ Base;
+
+public:
+ explicit ImmutableStatepoint(const Instruction *I) : Base(I) {}
+ explicit ImmutableStatepoint(ImmutableCallSite CS) : Base(CS) {}
+};
+
+/// A specialization of it's base class for read-write access
+/// to a gc.statepoint.
+class Statepoint : public StatepointBase<Instruction, Value, CallSite> {
+ typedef StatepointBase<Instruction, Value, CallSite> Base;
+
+public:
+ explicit Statepoint(Instruction *I) : Base(I) {}
+ explicit Statepoint(CallSite CS) : Base(CS) {}
+};
+
+/// Wraps a call to a gc.relocate and provides access to it's operands.
+/// TODO: This should likely be refactored to resememble the wrappers in
+/// InstrinsicInst.h.
+class GCRelocateOperands {
+ ImmutableCallSite RelocateCS;
+
+ public:
+ GCRelocateOperands(const User* U) : RelocateCS(U) {
+ assert(isGCRelocate(U));
+ }
+ GCRelocateOperands(const Instruction *inst) : RelocateCS(inst) {
+ assert(isGCRelocate(inst));
+ }
+ GCRelocateOperands(CallSite CS) : RelocateCS(CS) {
+ assert(isGCRelocate(CS));
+ }
+
+ /// Return true if this relocate is tied to the invoke statepoint.
+ /// This includes relocates which are on the unwinding path.
+ bool isTiedToInvoke() const {
+ const Value *Token = RelocateCS.getArgument(0);
+
+ return isa<ExtractValueInst>(Token) ||
+ isa<InvokeInst>(Token);
+ }
+
+ /// Get enclosed relocate intrinsic
+ ImmutableCallSite getUnderlyingCallSite() {
+ return RelocateCS;
+ }
+
+ /// The statepoint with which this gc.relocate is associated.
+ const Instruction *statepoint() {
+ const Value *token = RelocateCS.getArgument(0);
+
+ // This takes care both of relocates for call statepoints and relocates
+ // on normal path of invoke statepoint.
+ if (!isa<ExtractValueInst>(token)) {
+ return cast<Instruction>(token);
+ }
+
+ // This relocate is on exceptional path of an invoke statepoint
+ const BasicBlock *invokeBB =
+ cast<Instruction>(token)->getParent()->getUniquePredecessor();
+
+ assert(invokeBB && "safepoints should have unique landingpads");
+ assert(invokeBB->getTerminator() && "safepoint block should be well formed");
+ assert(isStatepoint(invokeBB->getTerminator()));
+
+ return invokeBB->getTerminator();
+ }
+ /// The index into the associate statepoint's argument list
+ /// which contains the base pointer of the pointer whose
+ /// relocation this gc.relocate describes.
+ unsigned basePtrIndex() {
+ return cast<ConstantInt>(RelocateCS.getArgument(1))->getZExtValue();
+ }
+ /// The index into the associate statepoint's argument list which
+ /// contains the pointer whose relocation this gc.relocate describes.
+ unsigned derivedPtrIndex() {
+ return cast<ConstantInt>(RelocateCS.getArgument(2))->getZExtValue();
+ }
+ Value *basePtr() {
+ ImmutableCallSite CS(statepoint());
+ return *(CS.arg_begin() + basePtrIndex());
+ }
+ Value *derivedPtr() {
+ ImmutableCallSite CS(statepoint());
+ return *(CS.arg_begin() + derivedPtrIndex());
+ }
+};
+
+template <typename InstructionTy, typename ValueTy, typename CallSiteTy>
+std::vector<GCRelocateOperands>
+ StatepointBase<InstructionTy, ValueTy, CallSiteTy>::
+ getRelocates(ImmutableStatepoint &IS) {
+
+ std::vector<GCRelocateOperands> res;
+
+ ImmutableCallSite StatepointCS = IS.getCallSite();
+
+ // Search for relocated pointers. Note that working backwards from the
+ // gc_relocates ensures that we only get pairs which are actually relocated
+ // and used after the statepoint.
+ for (const User *U : StatepointCS.getInstruction()->users()) {
+ if (isGCRelocate(U)) {
+ res.push_back(GCRelocateOperands(U));
+ }
+ }
+
+ if (!StatepointCS.isInvoke()) {
+ return res;
+ }
+
+ // We need to scan thorough exceptional relocations if it is invoke statepoint
+ LandingPadInst *LandingPad =
+ cast<InvokeInst>(StatepointCS.getInstruction())->getLandingPadInst();
+
+ // Search for extract value from landingpad instruction to which
+ // gc relocates will be attached
+ for (const User *LandingPadUser : LandingPad->users()) {
+ if (!isa<ExtractValueInst>(LandingPadUser)) {
+ continue;
+ }
+
+ // gc relocates should be attached to this extract value
+ for (const User *U : LandingPadUser->users()) {
+ if (isGCRelocate(U)) {
+ res.push_back(GCRelocateOperands(U));
+ }
+ }
+ }
+ return res;
+}
+
+}
+#endif
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