From 784a55a15ddc65b59cc4709e54453238438eae48 Mon Sep 17 00:00:00 2001
From: Erik Verbruggen <erik.verbruggen@qt.io>
Date: Tue, 9 Oct 2018 14:58:01 +0200
Subject: V4: Collect trace information in the interpreter

Collect type information about values used in a function. These include
all parameters, and the results of many bytecode instructions. For array
loads/stores, it also tracks if the access is in-bounds of a
SimpleArrayData.

Collection is only enabled when the qml-tracing feature is turned on
while configuring.

In subsequent patches this is used to generated optimized JITted code.

Change-Id: I63985c334c3fdc55fca7fb4addfe3e535989aac5
Reviewed-by: Ulf Hermann <ulf.hermann@qt.io>
---
 src/qml/compiler/qv4bytecodegenerator_p.h | 60 +++++++++++++++++++++++++------
 1 file changed, 50 insertions(+), 10 deletions(-)

(limited to 'src/qml/compiler/qv4bytecodegenerator_p.h')

diff --git a/src/qml/compiler/qv4bytecodegenerator_p.h b/src/qml/compiler/qv4bytecodegenerator_p.h
index 4f3dc27acc..5a27d3948c 100644
--- a/src/qml/compiler/qv4bytecodegenerator_p.h
+++ b/src/qml/compiler/qv4bytecodegenerator_p.h
@@ -51,6 +51,7 @@
 // We mean it.
 //
 #include <private/qv4instr_moth_p.h>
+#include <private/qv4compileddata_p.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -65,6 +66,8 @@ namespace Moth {
 
 class BytecodeGenerator {
 public:
+    typedef CompiledData::Function::TraceInfoCount TraceInfoCount;
+
     BytecodeGenerator(int line, bool debug)
         : startLine(line), debugMode(debug) {}
 
@@ -161,6 +164,15 @@ public:
         addInstructionHelper(Moth::Instr::Type(InstrT), genericInstr);
     }
 
+    // Same as addInstruction, but also add a trace slot. Move only, because the instruction cannot
+    // be reused afterwards.
+    template<int InstrT>
+    void addTracingInstruction(InstrData<InstrT> data)
+    {
+        data.traceSlot = nextTraceInfo();
+        addInstruction(data);
+    }
+
     Q_REQUIRED_RESULT Jump jump()
     {
 QT_WARNING_PUSH
@@ -172,14 +184,12 @@ QT_WARNING_POP
 
     Q_REQUIRED_RESULT Jump jumpTrue()
     {
-        Instruction::JumpTrue data;
-        return addJumpInstruction(data);
+        return addTracingJumpInstruction(Instruction::JumpTrue());
     }
 
     Q_REQUIRED_RESULT Jump jumpFalse()
     {
-        Instruction::JumpFalse data;
-        return addJumpInstruction(data);
+        return addTracingJumpInstruction(Instruction::JumpFalse());
     }
 
     Q_REQUIRED_RESULT Jump jumpNotUndefined()
@@ -198,16 +208,16 @@ QT_WARNING_POP
     {
         Instruction::CmpStrictEqual cmp;
         cmp.lhs = lhs;
-        addInstruction(cmp);
-        addJumpInstruction(Instruction::JumpTrue()).link(target);
+        addInstruction(std::move(cmp));
+        addTracingJumpInstruction(Instruction::JumpTrue()).link(target);
     }
 
     void jumpStrictNotEqual(const StackSlot &lhs, const Label &target)
     {
         Instruction::CmpStrictNotEqual cmp;
         cmp.lhs = lhs;
-        addInstruction(cmp);
-        addJumpInstruction(Instruction::JumpTrue()).link(target);
+        addInstruction(std::move(cmp));
+        addTracingJumpInstruction(Instruction::JumpTrue()).link(target);
     }
 
     void setUnwindHandler(ExceptionHandler *handler)
@@ -247,6 +257,13 @@ QT_WARNING_POP
 
     void finalize(Compiler::Context *context);
 
+    template<int InstrT>
+    Jump addTracingJumpInstruction(InstrData<InstrT> &&data)
+    {
+        data.traceSlot = nextTraceInfo();
+        return addJumpInstruction(data);
+    }
+
     template<int InstrT>
     Jump addJumpInstruction(const InstrData<InstrT> &data)
     {
@@ -258,9 +275,9 @@ QT_WARNING_POP
     void addCJumpInstruction(bool jumpOnFalse, const Label *trueLabel, const Label *falseLabel)
     {
         if (jumpOnFalse)
-            addJumpInstruction(Instruction::JumpFalse()).link(*falseLabel);
+            addTracingJumpInstruction(Instruction::JumpFalse()).link(*falseLabel);
         else
-            addJumpInstruction(Instruction::JumpTrue()).link(*trueLabel);
+            addTracingJumpInstruction(Instruction::JumpTrue()).link(*trueLabel);
     }
 
     void clearLastInstruction()
@@ -268,6 +285,27 @@ QT_WARNING_POP
         lastInstrType = -1;
     }
 
+    TraceInfoCount nextTraceInfo()
+    {
+        // If tracing is disabled, use slot 0 to unconditionally store all trace info
+        if (nTraceInfos == CompiledData::Function::NoTracing())
+            return TraceInfoCount(0);
+        return nTraceInfos++;
+    }
+
+    void setTracing(bool onoff, int argumentCount)
+    {
+        if (onoff)
+            nTraceInfos = argumentCount;
+        else
+            nTraceInfos = CompiledData::Function::NoTracing();
+    }
+
+    TraceInfoCount traceInfoCount() const
+    {
+        return nTraceInfos;
+    }
+
 private:
     friend struct Jump;
     friend struct Label;
@@ -302,6 +340,8 @@ private:
 
     int lastInstrType = -1;
     Moth::Instr lastInstr;
+
+    TraceInfoCount nTraceInfos = TraceInfoCount(0);
 };
 
 }
-- 
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