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more work on frame-pointer-less unwinding
This fixes the tails=true build (at least for x86_64) and eliminates the need for a frame table in the tails=false build. In the tails=true build, we still need a frame table on x86(_64) to help determine whether we've caught a thread executing code to do a tail call or pop arguments off the stack. However, I've not yet written the code to actually use this table, and it is only needed to handle asynchronous unwinds via Thread.getStackTrace.
This commit is contained in:
Joel Dice
155
src/arm.cpp
155
src/arm.cpp
@ -164,13 +164,13 @@ inline int carry16(intptr_t v) { return static_cast<int16_t>(v) < 0 ? 1 : 0; }
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inline bool isOfWidth(long long i, int size) { return static_cast<unsigned long long>(i) >> size == 0; }
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inline bool isOfWidth(int i, int size) { return static_cast<unsigned>(i) >> size == 0; }
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const unsigned FrameFooterSize = 2;
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const unsigned FrameHeaderSize = 0;
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const unsigned FrameHeaderSize = (UseFramePointer ? 2 : 1);
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const unsigned StackAlignmentInBytes = 8;
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const unsigned StackAlignmentInWords = StackAlignmentInBytes / BytesPerWord;
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const int ThreadRegister = 8;
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const int FrameRegister = 12;
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const int StackRegister = 13;
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const int LinkRegister = 14;
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const int ProgramCounter = 15;
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@ -1701,6 +1701,9 @@ class MyArchitecture: public Assembler::Architecture {
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virtual bool reserved(int register_) {
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switch (register_) {
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case FrameRegister:
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return UseFramePointer;
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case LinkRegister:
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case StackRegister:
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case ThreadRegister:
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@ -1781,8 +1784,8 @@ class MyArchitecture: public Assembler::Architecture {
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}
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virtual unsigned alignFrameSize(unsigned sizeInWords) {
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const unsigned alignment = StackAlignmentInBytes / BytesPerWord;
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return (ceiling(sizeInWords + FrameFooterSize, alignment) * alignment);
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return pad(sizeInWords + FrameHeaderSize, StackAlignmentInWords)
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- FrameHeaderSize;
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}
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virtual void* frameIp(void* stack) {
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@ -1798,15 +1801,15 @@ class MyArchitecture: public Assembler::Architecture {
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}
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virtual unsigned frameFooterSize() {
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return FrameFooterSize;
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return 0;
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}
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virtual int returnAddressOffset() {
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return 1;
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return -1;
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}
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virtual int framePointerOffset() {
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return 0;
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return -2;
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}
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virtual void nextFrame(void** stack, void**) {
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@ -2006,11 +2009,14 @@ class MyAssembler: public Assembler {
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return arch_;
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}
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virtual void saveFrame(unsigned stackOffset, unsigned) {
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virtual void saveFrame(unsigned stackOffset) {
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appendFrameSizeEvent(&c, FrameSizePoison);
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// ???
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Register returnAddress(LinkRegister);
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Memory returnAddressDst
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(StackRegister, arch_->returnAddressOffset() * BytesPerWord);
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moveRM(&c, BytesPerWord, &returnAddress, BytesPerWord, &returnAddressDst);
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Memory returnAddressDst(StackRegister, - BytesPerWord);
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moveAndUpdateRM(&c, BytesPerWord, &returnAddress, BytesPerWord,
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&returnAddressDst);
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Register stack(StackRegister);
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Memory stackDst(ThreadRegister, stackOffset);
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@ -2059,33 +2065,53 @@ class MyAssembler: public Assembler {
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}
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virtual void allocateFrame(unsigned footprint) {
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Register returnAddress(LinkRegister);
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Register stack(StackRegister);
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Constant footprintConstant(resolved(&c, footprint * BytesPerWord));
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subCR(&c, BytesPerWord, &footprintConstant, BytesPerWord, &stack,
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BytesPerWord, &stack);
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Memory returnAddressDst(StackRegister, arch_->returnAddressOffset() * BytesPerWord);
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appendFrameSizeEvent(&c, footprint);
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Register returnAddress(LinkRegister);
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Memory returnAddressDst(StackRegister, (footprint - 1) * BytesPerWord);
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moveRM(&c, BytesPerWord, &returnAddress, BytesPerWord, &returnAddressDst);
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Register stack(StackRegister);
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Memory stackDst(StackRegister, -footprint * BytesPerWord);
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moveAndUpdateRM(&c, BytesPerWord, &stack, BytesPerWord, &stackDst);
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if (UseFramePointer) {
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Register frame(FrameRegister);
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Memory frameDst(StackRegister, (footprint - 2) * BytesPerWord);
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moveRM(&c, BytesPerWord, &frame, BytesPerWord, &frameDst);
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}
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}
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virtual void adjustFrame(unsigned footprint) {
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Register nextStack(5);
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Memory stackSrc(StackRegister, 0);
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moveMR(&c, BytesPerWord, &stackSrc, BytesPerWord, &nextStack);
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virtual void adjustFrame(unsigned difference) {
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appendFrameSizeEvent(&c, - difference);
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Memory stackDst(StackRegister, -footprint * BytesPerWord);
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moveAndUpdateRM(&c, BytesPerWord, &nextStack, BytesPerWord, &stackDst);
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Register stack(StackRegister);
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Constant differenceConstant(resolved(&c, difference * BytesPerWord));
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subCR(&c, BytesPerWord, &differenceConstant, BytesPerWord, &stack,
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BytesPerWord, &stack);
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appendFrameSizeEvent(&c, difference);
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}
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virtual void popFrame() {
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Register stack(StackRegister);
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Memory stackSrc(StackRegister, arch_->framePointerOffset() * BytesPerWord);
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moveMR(&c, BytesPerWord, &stackSrc, BytesPerWord, &stack);
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virtual void popFrame(unsigned frameFootprint) {
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if (UseFramePointer) {
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Register frame(FrameRegister);
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Memory frameSrc(StackRegister, (frameFootprint - 1) * BytesPerWord);
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moveMR(&c, BytesPerWord, &frameSrc, BytesPerWord, &frame);
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}
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Register returnAddress(LinkRegister);
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Memory returnAddressSrc(StackRegister, arch_->returnAddressOffset() * BytesPerWord);
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Memory returnAddressSrc
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(StackRegister, (frameFootprint - 1) * BytesPerWord);
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moveMR(&c, BytesPerWord, &returnAddressSrc, BytesPerWord, &returnAddress);
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Register stack(StackRegister);
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Constant differenceConstant(resolved(&c, frameFootprint * BytesPerWord));
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addCR(&c, BytesPerWord, &differenceConstant, BytesPerWord, &stack,
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BytesPerWord, &stack);
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appendFrameSizeEvent(&c, - frameFootprint);
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}
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virtual void popFrameForTailCall(unsigned footprint,
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@ -2095,80 +2121,85 @@ class MyAssembler: public Assembler {
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{
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if (TailCalls) {
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if (offset) {
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if (UseFramePointer) {
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Register frame(FrameRegister);
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Memory frameSrc(StackRegister, (footprint - 1) * BytesPerWord);
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moveMR(&c, BytesPerWord, &frameSrc, BytesPerWord, &frame);
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}
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Register link(LinkRegister);
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Memory returnAddressSrc
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(StackRegister, BytesPerWord + (footprint * BytesPerWord));
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(StackRegister, (footprint - 1) * BytesPerWord);
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moveMR(&c, BytesPerWord, &returnAddressSrc, BytesPerWord, &link);
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Register tmp(c.client->acquireTemporary());
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Memory stackSrc(StackRegister, footprint * BytesPerWord);
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moveMR(&c, BytesPerWord, &stackSrc, BytesPerWord, &tmp);
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Register stack(StackRegister);
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Constant footprintConstant
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(resolved(&c, (footprint - offset + 1) * BytesPerWord));
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addCR(&c, BytesPerWord, &footprintConstant, BytesPerWord, &stack);
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Memory stackDst(StackRegister, (footprint - offset) * BytesPerWord);
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moveAndUpdateRM(&c, BytesPerWord, &tmp, BytesPerWord, &stackDst);
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c.client->releaseTemporary(tmp.low);
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appendFrameSizeEvent(&c, - (frameFootprint - offset + 1));
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if (returnAddressSurrogate != NoRegister) {
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assert(&c, offset > 0);
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Register ras(returnAddressSurrogate);
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Memory dst(StackRegister, BytesPerWord + (offset * BytesPerWord));
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Memory dst(StackRegister, (offset - 1) * BytesPerWord);
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moveRM(&c, BytesPerWord, &ras, BytesPerWord, &dst);
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}
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if (framePointerSurrogate != NoRegister) {
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assert(&c, offset > 0);
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Register fps(framePointerSurrogate);
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Memory dst(StackRegister, offset * BytesPerWord);
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moveRM(&c, BytesPerWord, &fps, BytesPerWord, &dst);
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Register las(framePointerSurrogate);
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Memory dst(StackRegister, (offset - 2) * BytesPerWord);
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moveRM(&c, BytesPerWord, &las, BytesPerWord, &dst);
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}
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} else {
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popFrame();
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popFrame(footprint);
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}
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} else {
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abort(&c);
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}
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}
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virtual void popFrameAndPopArgumentsAndReturn(unsigned argumentFootprint) {
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popFrame();
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virtual void popFrameAndPopArgumentsAndReturn(unsigned frameFootprint,
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unsigned argumentFootprint)
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{
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popFrame(frameFootprint);
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assert(&c, argumentFootprint >= StackAlignmentInWords);
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assert(&c, (argumentFootprint % StackAlignmentInWords) == 0);
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unsigned offset;
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if (TailCalls and argumentFootprint > StackAlignmentInWords) {
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Register tmp(5);
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Memory stackSrc(StackRegister, 0);
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moveMR(&c, BytesPerWord, &stackSrc, BytesPerWord, &tmp);
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offset = argumentFootprint - StackAlignmentInWords;
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Memory stackDst(StackRegister,
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(argumentFootprint - StackAlignmentInWords)
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* BytesPerWord);
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moveAndUpdateRM(&c, BytesPerWord, &tmp, BytesPerWord, &stackDst);
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Register stack(StackRegister);
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Constant adjustment(resolved(&c, offset * BytesPerWord));
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addCR(&c, BytesPerWord, &adjustment, BytesPerWord, &stack);
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appendFrameSizeEvent(&c, - offset);
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} else {
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offset = 0;
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}
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return_(&c);
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// todo: this is not necessary if there are no instructions to
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// follow:
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appendFrameSizeEvent(&c, frameFootprint + offset);
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}
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virtual void popFrameAndUpdateStackAndReturn(unsigned stackOffsetFromThread)
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virtual void popFrameAndUpdateStackAndReturn(unsigned frameFootprint,
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unsigned stackOffsetFromThread)
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{
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popFrame();
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appendFrameSizeEvent(&c, FrameSizePoison);
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Register tmp1(6);
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Memory stackSrc(StackRegister, 0);
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moveMR(&c, BytesPerWord, &stackSrc, BytesPerWord, &tmp1);
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Register tmp2(5);
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Memory newStackSrc(ThreadRegister, stackOffsetFromThread);
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moveMR(&c, BytesPerWord, &newStackSrc, BytesPerWord, &tmp2);
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popFrame(frameFootprint);
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Register stack(StackRegister);
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subR(&c, BytesPerWord, &stack, &tmp2, &tmp2);
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Memory stackDst(StackRegister, 0, tmp2.low);
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moveAndUpdateRM(&c, BytesPerWord, &tmp1, BytesPerWord, &stackDst);
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Memory newStackSrc(ThreadRegister, stackOffsetFromThread);
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moveMR(&c, BytesPerWord, &newStackSrc, BytesPerWord, &stack);
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return_(&c);
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}
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