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-rw-r--r--js/src/jit/x64/Assembler-x64.cpp246
1 files changed, 246 insertions, 0 deletions
diff --git a/js/src/jit/x64/Assembler-x64.cpp b/js/src/jit/x64/Assembler-x64.cpp
new file mode 100644
index 0000000000..e00e34e830
--- /dev/null
+++ b/js/src/jit/x64/Assembler-x64.cpp
@@ -0,0 +1,246 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
+ * vim: set ts=8 sts=2 et sw=2 tw=80:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jit/x64/Assembler-x64.h"
+
+#include "gc/Tracer.h"
+#include "util/Memory.h"
+
+using namespace js;
+using namespace js::jit;
+
+ABIArgGenerator::ABIArgGenerator()
+ :
+#if defined(XP_WIN)
+ regIndex_(0),
+ stackOffset_(ShadowStackSpace),
+#else
+ intRegIndex_(0),
+ floatRegIndex_(0),
+ stackOffset_(0),
+#endif
+ current_() {
+}
+
+ABIArg ABIArgGenerator::next(MIRType type) {
+#if defined(XP_WIN)
+ static_assert(NumIntArgRegs == NumFloatArgRegs);
+ if (regIndex_ == NumIntArgRegs) {
+ if (type == MIRType::Simd128) {
+ // On Win64, >64 bit args need to be passed by reference. However, wasm
+ // doesn't allow passing SIMD values to JS, so the only way to reach this
+ // is wasm to wasm calls. Ergo we can break the native ABI here and use
+ // the Wasm ABI instead.
+ stackOffset_ = AlignBytes(stackOffset_, SimdMemoryAlignment);
+ current_ = ABIArg(stackOffset_);
+ stackOffset_ += Simd128DataSize;
+ } else {
+ current_ = ABIArg(stackOffset_);
+ stackOffset_ += sizeof(uint64_t);
+ }
+ return current_;
+ }
+ switch (type) {
+ case MIRType::Int32:
+ case MIRType::Int64:
+ case MIRType::Pointer:
+ case MIRType::RefOrNull:
+ case MIRType::StackResults:
+ current_ = ABIArg(IntArgRegs[regIndex_++]);
+ break;
+ case MIRType::Float32:
+ current_ = ABIArg(FloatArgRegs[regIndex_++].asSingle());
+ break;
+ case MIRType::Double:
+ current_ = ABIArg(FloatArgRegs[regIndex_++]);
+ break;
+ case MIRType::Simd128:
+ // On Win64, >64 bit args need to be passed by reference, but wasm
+ // doesn't allow passing SIMD values to FFIs. The only way to reach
+ // here is asm to asm calls, so we can break the ABI here.
+ current_ = ABIArg(FloatArgRegs[regIndex_++].asSimd128());
+ break;
+ default:
+ MOZ_CRASH("Unexpected argument type");
+ }
+ return current_;
+#else
+ switch (type) {
+ case MIRType::Int32:
+ case MIRType::Int64:
+ case MIRType::Pointer:
+ case MIRType::RefOrNull:
+ case MIRType::StackResults:
+ if (intRegIndex_ == NumIntArgRegs) {
+ current_ = ABIArg(stackOffset_);
+ stackOffset_ += sizeof(uint64_t);
+ break;
+ }
+ current_ = ABIArg(IntArgRegs[intRegIndex_++]);
+ break;
+ case MIRType::Double:
+ case MIRType::Float32:
+ if (floatRegIndex_ == NumFloatArgRegs) {
+ current_ = ABIArg(stackOffset_);
+ stackOffset_ += sizeof(uint64_t);
+ break;
+ }
+ if (type == MIRType::Float32) {
+ current_ = ABIArg(FloatArgRegs[floatRegIndex_++].asSingle());
+ } else {
+ current_ = ABIArg(FloatArgRegs[floatRegIndex_++]);
+ }
+ break;
+ case MIRType::Simd128:
+ if (floatRegIndex_ == NumFloatArgRegs) {
+ stackOffset_ = AlignBytes(stackOffset_, SimdMemoryAlignment);
+ current_ = ABIArg(stackOffset_);
+ stackOffset_ += Simd128DataSize;
+ break;
+ }
+ current_ = ABIArg(FloatArgRegs[floatRegIndex_++].asSimd128());
+ break;
+ default:
+ MOZ_CRASH("Unexpected argument type");
+ }
+ return current_;
+#endif
+}
+
+void Assembler::addPendingJump(JmpSrc src, ImmPtr target,
+ RelocationKind reloc) {
+ MOZ_ASSERT(target.value != nullptr);
+
+ // Emit reloc before modifying the jump table, since it computes a 0-based
+ // index. This jump is not patchable at runtime.
+ if (reloc == RelocationKind::JITCODE) {
+ jumpRelocations_.writeUnsigned(src.offset());
+ }
+
+ static_assert(MaxCodeBytesPerProcess <= uint64_t(2) * 1024 * 1024 * 1024,
+ "Code depends on using int32_t for cross-JitCode jump offsets");
+
+ MOZ_ASSERT_IF(reloc == RelocationKind::JITCODE,
+ AddressIsInExecutableMemory(target.value));
+
+ RelativePatch patch(src.offset(), target.value, reloc);
+ if (reloc == RelocationKind::JITCODE ||
+ AddressIsInExecutableMemory(target.value)) {
+ enoughMemory_ &= codeJumps_.append(patch);
+ } else {
+ enoughMemory_ &= extendedJumps_.append(patch);
+ }
+}
+
+void Assembler::finish() {
+ if (oom()) {
+ return;
+ }
+
+ AutoCreatedBy acb(*this, "Assembler::finish");
+
+ if (!extendedJumps_.length()) {
+ // Since we may be folowed by non-executable data, eagerly insert an
+ // undefined instruction byte to prevent processors from decoding
+ // gibberish into their pipelines. See Intel performance guides.
+ masm.ud2();
+ return;
+ }
+
+ // Emit the jump table.
+ masm.haltingAlign(SizeOfJumpTableEntry);
+ extendedJumpTable_ = masm.size();
+
+ // Zero the extended jumps table.
+ for (size_t i = 0; i < extendedJumps_.length(); i++) {
+#ifdef DEBUG
+ size_t oldSize = masm.size();
+#endif
+ MOZ_ASSERT(hasCreator());
+ masm.jmp_rip(2);
+ MOZ_ASSERT_IF(!masm.oom(), masm.size() - oldSize == 6);
+ // Following an indirect branch with ud2 hints to the hardware that
+ // there's no fall-through. This also aligns the 64-bit immediate.
+ masm.ud2();
+ MOZ_ASSERT_IF(!masm.oom(), masm.size() - oldSize == 8);
+ masm.immediate64(0);
+ MOZ_ASSERT_IF(!masm.oom(), masm.size() - oldSize == SizeOfExtendedJump);
+ MOZ_ASSERT_IF(!masm.oom(), masm.size() - oldSize == SizeOfJumpTableEntry);
+ }
+}
+
+void Assembler::executableCopy(uint8_t* buffer) {
+ AssemblerX86Shared::executableCopy(buffer);
+
+ for (RelativePatch& rp : codeJumps_) {
+ uint8_t* src = buffer + rp.offset;
+ MOZ_ASSERT(rp.target);
+
+ MOZ_RELEASE_ASSERT(X86Encoding::CanRelinkJump(src, rp.target));
+ X86Encoding::SetRel32(src, rp.target);
+ }
+
+ for (size_t i = 0; i < extendedJumps_.length(); i++) {
+ RelativePatch& rp = extendedJumps_[i];
+ uint8_t* src = buffer + rp.offset;
+ MOZ_ASSERT(rp.target);
+
+ if (X86Encoding::CanRelinkJump(src, rp.target)) {
+ X86Encoding::SetRel32(src, rp.target);
+ } else {
+ // An extended jump table must exist, and its offset must be in
+ // range.
+ MOZ_ASSERT(extendedJumpTable_);
+ MOZ_ASSERT((extendedJumpTable_ + i * SizeOfJumpTableEntry) <=
+ size() - SizeOfJumpTableEntry);
+
+ // Patch the jump to go to the extended jump entry.
+ uint8_t* entry = buffer + extendedJumpTable_ + i * SizeOfJumpTableEntry;
+ X86Encoding::SetRel32(src, entry);
+
+ // Now patch the pointer, note that we need to align it to
+ // *after* the extended jump, i.e. after the 64-bit immedate.
+ X86Encoding::SetPointer(entry + SizeOfExtendedJump, rp.target);
+ }
+ }
+}
+
+class RelocationIterator {
+ CompactBufferReader reader_;
+ uint32_t offset_ = 0;
+
+ public:
+ explicit RelocationIterator(CompactBufferReader& reader) : reader_(reader) {}
+
+ bool read() {
+ if (!reader_.more()) {
+ return false;
+ }
+ offset_ = reader_.readUnsigned();
+ return true;
+ }
+
+ uint32_t offset() const { return offset_; }
+};
+
+JitCode* Assembler::CodeFromJump(JitCode* code, uint8_t* jump) {
+ uint8_t* target = (uint8_t*)X86Encoding::GetRel32Target(jump);
+
+ MOZ_ASSERT(!code->containsNativePC(target),
+ "Extended jump table not used for cross-JitCode jumps");
+
+ return JitCode::FromExecutable(target);
+}
+
+void Assembler::TraceJumpRelocations(JSTracer* trc, JitCode* code,
+ CompactBufferReader& reader) {
+ RelocationIterator iter(reader);
+ while (iter.read()) {
+ JitCode* child = CodeFromJump(code, code->raw() + iter.offset());
+ TraceManuallyBarrieredEdge(trc, &child, "rel32");
+ MOZ_ASSERT(child == CodeFromJump(code, code->raw() + iter.offset()));
+ }
+}
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