From a4e969f4965059196ca948db781e52f7cfebf19e Mon Sep 17 00:00:00 2001
From: Lorry Tar Creator <lorry-tar-importer@lorry>
Date: Tue, 24 May 2016 08:28:08 +0000
Subject: webkitgtk-2.12.3

---
 .../JavaScriptCore/dfg/DFGOSRExitCompiler32_64.cpp | 245 ++++++++-------------
 1 file changed, 90 insertions(+), 155 deletions(-)

(limited to 'Source/JavaScriptCore/dfg/DFGOSRExitCompiler32_64.cpp')

diff --git a/Source/JavaScriptCore/dfg/DFGOSRExitCompiler32_64.cpp b/Source/JavaScriptCore/dfg/DFGOSRExitCompiler32_64.cpp
index 9402d115e..e419941dd 100644
--- a/Source/JavaScriptCore/dfg/DFGOSRExitCompiler32_64.cpp
+++ b/Source/JavaScriptCore/dfg/DFGOSRExitCompiler32_64.cpp
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2011, 2013 Apple Inc. All rights reserved.
+ * Copyright (C) 2011, 2013-2015 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -31,23 +31,25 @@
 #include "DFGOperations.h"
 #include "DFGOSRExitCompilerCommon.h"
 #include "DFGSpeculativeJIT.h"
-#include "Operations.h"
+#include "JSCInlines.h"
 #include <wtf/DataLog.h>
 
 namespace JSC { namespace DFG {
 
 void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecovery>& operands, SpeculationRecovery* recovery)
 {
-    // 1) Pro-forma stuff.
+    // Pro-forma stuff.
     if (Options::printEachOSRExit()) {
         SpeculationFailureDebugInfo* debugInfo = new SpeculationFailureDebugInfo;
         debugInfo->codeBlock = m_jit.codeBlock();
+        debugInfo->kind = exit.m_kind;
+        debugInfo->bytecodeOffset = exit.m_codeOrigin.bytecodeIndex;
         
         m_jit.debugCall(debugOperationPrintSpeculationFailure, debugInfo);
     }
     
-    // 2) Perform speculation recovery. This only comes into play when an operation
-    //    starts mutating state before verifying the speculation it has already made.
+    // Perform speculation recovery. This only comes into play when an operation
+    // starts mutating state before verifying the speculation it has already made.
     
     if (recovery) {
         switch (recovery->type()) {
@@ -63,7 +65,7 @@ void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecov
         }
     }
 
-    // 3) Refine some value profile, if appropriate.
+    // Refine some value profile, if appropriate.
     
     if (!!exit.m_jsValueSource) {
         if (exit.m_kind == BadCache || exit.m_kind == BadIndexingType) {
@@ -100,13 +102,8 @@ void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecov
                 scratch1 = AssemblyHelpers::selectScratchGPR(usedRegister1, usedRegister2);
                 scratch2 = AssemblyHelpers::selectScratchGPR(usedRegister1, usedRegister2, scratch1);
                 
-#if CPU(ARM64)
-                m_jit.pushToSave(scratch1);
-                m_jit.pushToSave(scratch2);
-#else
                 m_jit.push(scratch1);
                 m_jit.push(scratch2);
-#endif
                 
                 GPRReg value;
                 if (exit.m_jsValueSource.isAddress()) {
@@ -115,20 +112,15 @@ void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecov
                 } else
                     value = exit.m_jsValueSource.payloadGPR();
                 
-                m_jit.loadPtr(AssemblyHelpers::Address(value, JSCell::structureOffset()), scratch1);
-                m_jit.storePtr(scratch1, arrayProfile->addressOfLastSeenStructure());
+                m_jit.loadPtr(AssemblyHelpers::Address(value, JSCell::structureIDOffset()), scratch1);
+                m_jit.storePtr(scratch1, arrayProfile->addressOfLastSeenStructureID());
                 m_jit.load8(AssemblyHelpers::Address(scratch1, Structure::indexingTypeOffset()), scratch1);
                 m_jit.move(AssemblyHelpers::TrustedImm32(1), scratch2);
                 m_jit.lshift32(scratch1, scratch2);
                 m_jit.or32(scratch2, AssemblyHelpers::AbsoluteAddress(arrayProfile->addressOfArrayModes()));
                 
-#if CPU(ARM64)
-                m_jit.popToRestore(scratch2);
-                m_jit.popToRestore(scratch1);
-#else
                 m_jit.pop(scratch2);
                 m_jit.pop(scratch1);
-#endif
             }
         }
         
@@ -139,22 +131,14 @@ void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecov
                 // Save a register so we can use it.
                 GPRReg scratch = AssemblyHelpers::selectScratchGPR(exit.m_jsValueSource.base());
                 
-#if CPU(ARM64)
-                m_jit.pushToSave(scratch);
-#else
                 m_jit.push(scratch);
-#endif
 
                 m_jit.load32(exit.m_jsValueSource.asAddress(OBJECT_OFFSETOF(EncodedValueDescriptor, asBits.tag)), scratch);
                 m_jit.store32(scratch, &bitwise_cast<EncodedValueDescriptor*>(bucket)->asBits.tag);
                 m_jit.load32(exit.m_jsValueSource.asAddress(OBJECT_OFFSETOF(EncodedValueDescriptor, asBits.payload)), scratch);
                 m_jit.store32(scratch, &bitwise_cast<EncodedValueDescriptor*>(bucket)->asBits.payload);
                 
-#if CPU(ARM64)
-                m_jit.popToRestore(scratch);
-#else
                 m_jit.pop(scratch);
-#endif
             } else if (exit.m_jsValueSource.hasKnownTag()) {
                 m_jit.store32(AssemblyHelpers::TrustedImm32(exit.m_jsValueSource.tag()), &bitwise_cast<EncodedValueDescriptor*>(bucket)->asBits.tag);
                 m_jit.store32(exit.m_jsValueSource.payloadGPR(), &bitwise_cast<EncodedValueDescriptor*>(bucket)->asBits.payload);
@@ -168,7 +152,7 @@ void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecov
     // Do a simplified OSR exit. See DFGOSRExitCompiler64.cpp's comment regarding how and wny we
     // do this simple approach.
 
-    // 4) Save all state from GPRs into the scratch buffer.
+    // Save all state from GPRs into the scratch buffer.
     
     ScratchBuffer* scratchBuffer = m_jit.vm()->scratchBufferForSize(sizeof(EncodedJSValue) * operands.size());
     EncodedJSValue* scratch = scratchBuffer ? static_cast<EncodedJSValue*>(scratchBuffer->dataBuffer()) : 0;
@@ -201,12 +185,13 @@ void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecov
     
     // Now all GPRs are free to reuse.
     
-    // 5) Save all state from FPRs into the scratch buffer.
+    // Save all state from FPRs into the scratch buffer.
     
     for (size_t index = 0; index < operands.size(); ++index) {
         const ValueRecovery& recovery = operands[index];
         
         switch (recovery.technique()) {
+        case UnboxedDoubleInFPR:
         case InFPR:
             m_jit.move(AssemblyHelpers::TrustedImmPtr(scratch + index), GPRInfo::regT0);
             m_jit.storeDouble(recovery.fpr(), MacroAssembler::Address(GPRInfo::regT0));
@@ -219,9 +204,9 @@ void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecov
     
     // Now all FPRs are free to reuse.
     
-    // 6) Save all state from the stack into the scratch buffer. For simplicity we
-    //    do this even for state that's already in the right place on the stack.
-    //    It makes things simpler later.
+    // Save all state from the stack into the scratch buffer. For simplicity we
+    // do this even for state that's already in the right place on the stack.
+    // It makes things simpler later.
     
     for (size_t index = 0; index < operands.size(); ++index) {
         const ValueRecovery& recovery = operands[index];
@@ -251,19 +236,36 @@ void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecov
         }
     }
     
-    // 7) Do all data format conversions and store the results into the stack.
+    // Need to ensure that the stack pointer accounts for the worst-case stack usage at exit. This
+    // could toast some stack that the DFG used. We need to do it before storing to stack offsets
+    // used by baseline.
+    m_jit.addPtr(
+        CCallHelpers::TrustedImm32(
+            -m_jit.codeBlock()->jitCode()->dfgCommon()->requiredRegisterCountForExit * sizeof(Register)),
+        CCallHelpers::framePointerRegister, CCallHelpers::stackPointerRegister);
     
-    bool haveArguments = false;
+    // Restore the DFG callee saves and then save the ones the baseline JIT uses.
+    m_jit.emitRestoreCalleeSaves();
+    m_jit.emitSaveCalleeSavesFor(m_jit.baselineCodeBlock());
+
+    if (exit.isExceptionHandler())
+        m_jit.copyCalleeSavesToVMCalleeSavesBuffer();
+
+    // Do all data format conversions and store the results into the stack.
     
     for (size_t index = 0; index < operands.size(); ++index) {
         const ValueRecovery& recovery = operands[index];
-        int operand = operands.operandForIndex(index);
-        
+        VirtualRegister reg = operands.virtualRegisterForIndex(index);
+
+        if (reg.isLocal() && reg.toLocal() < static_cast<int>(m_jit.baselineCodeBlock()->calleeSaveSpaceAsVirtualRegisters()))
+            continue;
+
+        int operand = reg.offset();
+
         switch (recovery.technique()) {
         case InPair:
-        case InFPR:
         case DisplacedInJSStack:
-        case DoubleDisplacedInJSStack:
+        case InFPR:
             m_jit.load32(
                 &bitwise_cast<EncodedValueDescriptor*>(scratch + index)->asBits.tag,
                 GPRInfo::regT0);
@@ -278,6 +280,14 @@ void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecov
                 AssemblyHelpers::payloadFor(operand));
             break;
             
+        case UnboxedDoubleInFPR:
+        case DoubleDisplacedInJSStack:
+            m_jit.move(AssemblyHelpers::TrustedImmPtr(scratch + index), GPRInfo::regT0);
+            m_jit.loadDouble(MacroAssembler::Address(GPRInfo::regT0), FPRInfo::fpRegT0);
+            m_jit.purifyNaN(FPRInfo::fpRegT0);
+            m_jit.storeDouble(FPRInfo::fpRegT0, AssemblyHelpers::addressFor(operand));
+            break;
+
         case UnboxedInt32InGPR:
         case Int32DisplacedInJSStack:
             m_jit.load32(
@@ -326,14 +336,9 @@ void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecov
                 AssemblyHelpers::payloadFor(operand));
             break;
             
-        case ArgumentsThatWereNotCreated:
-            haveArguments = true;
-            m_jit.store32(
-                AssemblyHelpers::TrustedImm32(JSValue().tag()),
-                AssemblyHelpers::tagFor(operand));
-            m_jit.store32(
-                AssemblyHelpers::TrustedImm32(JSValue().payload()),
-                AssemblyHelpers::payloadFor(operand));
+        case DirectArgumentsThatWereNotCreated:
+        case ClonedArgumentsThatWereNotCreated:
+            // Don't do this, yet.
             break;
             
         default:
@@ -341,127 +346,57 @@ void OSRExitCompiler::compileExit(const OSRExit& exit, const Operands<ValueRecov
         }
     }
     
-    // 8) Adjust the old JIT's execute counter. Since we are exiting OSR, we know
-    //    that all new calls into this code will go to the new JIT, so the execute
-    //    counter only affects call frames that performed OSR exit and call frames
-    //    that were still executing the old JIT at the time of another call frame's
-    //    OSR exit. We want to ensure that the following is true:
+    // Now that things on the stack are recovered, do the arguments recovery. We assume that arguments
+    // recoveries don't recursively refer to each other. But, we don't try to assume that they only
+    // refer to certain ranges of locals. Hence why we need to do this here, once the stack is sensible.
+    // Note that we also roughly assume that the arguments might still be materialized outside of its
+    // inline call frame scope - but for now the DFG wouldn't do that.
+    
+    emitRestoreArguments(operands);
+
+    // Adjust the old JIT's execute counter. Since we are exiting OSR, we know
+    // that all new calls into this code will go to the new JIT, so the execute
+    // counter only affects call frames that performed OSR exit and call frames
+    // that were still executing the old JIT at the time of another call frame's
+    // OSR exit. We want to ensure that the following is true:
     //
-    //    (a) Code the performs an OSR exit gets a chance to reenter optimized
-    //        code eventually, since optimized code is faster. But we don't
-    //        want to do such reentery too aggressively (see (c) below).
+    // (a) Code the performs an OSR exit gets a chance to reenter optimized
+    //     code eventually, since optimized code is faster. But we don't
+    //     want to do such reentery too aggressively (see (c) below).
     //
-    //    (b) If there is code on the call stack that is still running the old
-    //        JIT's code and has never OSR'd, then it should get a chance to
-    //        perform OSR entry despite the fact that we've exited.
+    // (b) If there is code on the call stack that is still running the old
+    //     JIT's code and has never OSR'd, then it should get a chance to
+    //     perform OSR entry despite the fact that we've exited.
     //
-    //    (c) Code the performs an OSR exit should not immediately retry OSR
-    //        entry, since both forms of OSR are expensive. OSR entry is
-    //        particularly expensive.
+    // (c) Code the performs an OSR exit should not immediately retry OSR
+    //     entry, since both forms of OSR are expensive. OSR entry is
+    //     particularly expensive.
     //
-    //    (d) Frequent OSR failures, even those that do not result in the code
-    //        running in a hot loop, result in recompilation getting triggered.
+    // (d) Frequent OSR failures, even those that do not result in the code
+    //     running in a hot loop, result in recompilation getting triggered.
     //
-    //    To ensure (c), we'd like to set the execute counter to
-    //    counterValueForOptimizeAfterWarmUp(). This seems like it would endanger
-    //    (a) and (b), since then every OSR exit would delay the opportunity for
-    //    every call frame to perform OSR entry. Essentially, if OSR exit happens
-    //    frequently and the function has few loops, then the counter will never
-    //    become non-negative and OSR entry will never be triggered. OSR entry
-    //    will only happen if a loop gets hot in the old JIT, which does a pretty
-    //    good job of ensuring (a) and (b). But that doesn't take care of (d),
-    //    since each speculation failure would reset the execute counter.
-    //    So we check here if the number of speculation failures is significantly
-    //    larger than the number of successes (we want 90% success rate), and if
-    //    there have been a large enough number of failures. If so, we set the
-    //    counter to 0; otherwise we set the counter to
-    //    counterValueForOptimizeAfterWarmUp().
+    // To ensure (c), we'd like to set the execute counter to
+    // counterValueForOptimizeAfterWarmUp(). This seems like it would endanger
+    // (a) and (b), since then every OSR exit would delay the opportunity for
+    // every call frame to perform OSR entry. Essentially, if OSR exit happens
+    // frequently and the function has few loops, then the counter will never
+    // become non-negative and OSR entry will never be triggered. OSR entry
+    // will only happen if a loop gets hot in the old JIT, which does a pretty
+    // good job of ensuring (a) and (b). But that doesn't take care of (d),
+    // since each speculation failure would reset the execute counter.
+    // So we check here if the number of speculation failures is significantly
+    // larger than the number of successes (we want 90% success rate), and if
+    // there have been a large enough number of failures. If so, we set the
+    // counter to 0; otherwise we set the counter to
+    // counterValueForOptimizeAfterWarmUp().
     
     handleExitCounts(m_jit, exit);
     
-    // 9) Reify inlined call frames.
+    // Reify inlined call frames.
     
     reifyInlinedCallFrames(m_jit, exit);
     
-    // 10) Create arguments if necessary and place them into the appropriate aliased
-    //     registers.
-    
-    if (haveArguments) {
-        HashSet<InlineCallFrame*, DefaultHash<InlineCallFrame*>::Hash,
-            NullableHashTraits<InlineCallFrame*>> didCreateArgumentsObject;
-
-        for (size_t index = 0; index < operands.size(); ++index) {
-            const ValueRecovery& recovery = operands[index];
-            if (recovery.technique() != ArgumentsThatWereNotCreated)
-                continue;
-            int operand = operands.operandForIndex(index);
-            // Find the right inline call frame.
-            InlineCallFrame* inlineCallFrame = 0;
-            for (InlineCallFrame* current = exit.m_codeOrigin.inlineCallFrame;
-                 current;
-                 current = current->caller.inlineCallFrame) {
-                if (current->stackOffset >= operand) {
-                    inlineCallFrame = current;
-                    break;
-                }
-            }
-
-            if (!m_jit.baselineCodeBlockFor(inlineCallFrame)->usesArguments())
-                continue;
-            VirtualRegister argumentsRegister = m_jit.baselineArgumentsRegisterFor(inlineCallFrame);
-            if (didCreateArgumentsObject.add(inlineCallFrame).isNewEntry) {
-                // We know this call frame optimized out an arguments object that
-                // the baseline JIT would have created. Do that creation now.
-                if (inlineCallFrame) {
-                    m_jit.setupArgumentsWithExecState(
-                        AssemblyHelpers::TrustedImmPtr(inlineCallFrame));
-                    m_jit.move(
-                        AssemblyHelpers::TrustedImmPtr(
-                            bitwise_cast<void*>(operationCreateInlinedArguments)),
-                        GPRInfo::nonArgGPR0);
-                } else {
-                    m_jit.setupArgumentsExecState();
-                    m_jit.move(
-                        AssemblyHelpers::TrustedImmPtr(
-                            bitwise_cast<void*>(operationCreateArguments)),
-                        GPRInfo::nonArgGPR0);
-                }
-                m_jit.call(GPRInfo::nonArgGPR0);
-                m_jit.store32(
-                    AssemblyHelpers::TrustedImm32(JSValue::CellTag),
-                    AssemblyHelpers::tagFor(argumentsRegister));
-                m_jit.store32(
-                    GPRInfo::returnValueGPR,
-                    AssemblyHelpers::payloadFor(argumentsRegister));
-                m_jit.store32(
-                    AssemblyHelpers::TrustedImm32(JSValue::CellTag),
-                    AssemblyHelpers::tagFor(unmodifiedArgumentsRegister(argumentsRegister)));
-                m_jit.store32(
-                    GPRInfo::returnValueGPR,
-                    AssemblyHelpers::payloadFor(unmodifiedArgumentsRegister(argumentsRegister)));
-                m_jit.move(GPRInfo::returnValueGPR, GPRInfo::regT0); // no-op move on almost all platforms.
-            }
-
-            m_jit.load32(AssemblyHelpers::payloadFor(argumentsRegister), GPRInfo::regT0);
-            m_jit.store32(
-                AssemblyHelpers::TrustedImm32(JSValue::CellTag),
-                AssemblyHelpers::tagFor(operand));
-            m_jit.store32(GPRInfo::regT0, AssemblyHelpers::payloadFor(operand));
-        }
-    }
-
-#if ENABLE(GGC) 
-    // 11) Write barrier the owner executable because we're jumping into a different block.
-    for (CodeOrigin codeOrigin = exit.m_codeOrigin; ; codeOrigin = codeOrigin.inlineCallFrame->caller) {
-        CodeBlock* baselineCodeBlock = m_jit.baselineCodeBlockFor(codeOrigin);
-        m_jit.move(AssemblyHelpers::TrustedImmPtr(baselineCodeBlock->ownerExecutable()), GPRInfo::nonArgGPR0); 
-        SpeculativeJIT::osrWriteBarrier(m_jit, GPRInfo::nonArgGPR0, GPRInfo::nonArgGPR1, GPRInfo::nonArgGPR2);
-        if (!codeOrigin.inlineCallFrame)
-            break;
-    }
-#endif
-
-    // 12) And finish.
+    // And finish.
     adjustAndJumpToTarget(m_jit, exit);
 }
 
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