From 9b817fe8085a59747af0d27bdeae2bfc2768c66b Mon Sep 17 00:00:00 2001
From: Lephenixnoir <sebastien.michelland@protonmail.com>
Date: Tue, 26 Dec 2023 16:07:36 +0100
Subject: [PATCH] fxos: improve analysis of move-register when value is known

---
 include/fxos/analysis.h |  5 +----
 include/fxos/lang.h     |  6 ++++--
 lib/analysis.cpp        | 25 +++++++++++++++++++------
 lib/lang.cpp            | 11 ++++++++++-
 lib/view/assembly.cpp   |  7 ++++---
 5 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/include/fxos/analysis.h b/include/fxos/analysis.h
index 7cb978c..911a589 100644
--- a/include/fxos/analysis.h
+++ b/include/fxos/analysis.h
@@ -30,10 +30,7 @@ struct ProgramState
         setBottom();
     }
 
-    RelConst getRegister(int n) const
-    {
-        return ((unsigned)n >= 16) ? RelConstDomain().bottom() : m_regs[n];
-    }
+    RelConst getRegister(CpuRegister reg) const;
 
     // TODO: More value in program state
 
diff --git a/include/fxos/lang.h b/include/fxos/lang.h
index 37f0f3f..664477d 100644
--- a/include/fxos/lang.h
+++ b/include/fxos/lang.h
@@ -89,7 +89,9 @@ public:
     }
 
     /* Get the register number for r0 ... r15, -1 for other registers. */
-    int getR() const;
+    int getRn() const;
+    /* Make an r0 ... r15 register name from its number. */
+    static CpuRegister makeRn(int n);
 
 private:
     CpuRegisterName m_name;
@@ -160,7 +162,7 @@ struct AsmOperand
     std::string str() const;
 
     /* Is this operand a register? */
-    bool isReg() const
+    bool isRegister() const
     {
         return m_kind == Reg;
     }
diff --git a/lib/analysis.cpp b/lib/analysis.cpp
index 11b4366..4df7b9f 100644
--- a/lib/analysis.cpp
+++ b/lib/analysis.cpp
@@ -12,6 +12,14 @@
 
 namespace FxOS {
 
+RelConst ProgramState::getRegister(CpuRegister reg) const
+{
+    int n = reg.getRn();
+    if(n >= 0)
+        return m_regs[n];
+    return RelConstDomain().top();
+}
+
 void ProgramState::setFunctionInit()
 {
     // TODO: Analysis: Set symbolic parameters at function entry
@@ -45,8 +53,9 @@ void ProgramState::applyDiff(ProgramStateDiff const &diff)
 
     case ProgramStateDiff::BaseType::RegisterUpdate: {
         CpuRegister reg = diff.registerName();
-        if(reg.getR() >= 0)
-            m_regs[reg.getR()] = diff.registerValue();
+        int n = reg.getRn();
+        if(n >= 0)
+            m_regs[n] = diff.registerValue();
         break;
     }
     }
@@ -69,7 +78,7 @@ void ProgramState::joinWith(ProgramState const &other)
     RelConstDomain RCD;
 
     for(int i = 0; i < 16; i++) {
-        m_regs[i] = RCD.join(m_regs[i], other.getRegister(i));
+        m_regs[i] = RCD.join(m_regs[i], other.m_regs[i]);
     }
 }
 
@@ -78,7 +87,7 @@ bool ProgramState::le(ProgramState const &other) const
     RelConstDomain RCD;
 
     for(int i = 0; i < 16; i++) {
-        if(!RCD.le(m_regs[i], other.getRegister(i)))
+        if(!RCD.le(m_regs[i], other.m_regs[i]))
             return false;
     }
     return true;
@@ -202,12 +211,16 @@ static ProgramStateDiff interpretInstruction(
         AsmOperand src = asmins.operand(0);
         AsmOperand dst = asmins.operand(1);
 
-        if(!dst.isReg())
+        if(!dst.isRegister())
             diff.setNoOp();
         else if(src.isConstant()) {
             RelConst c = RCD.constant(computeConstantOperand(ins, src));
             diff.setRegisterUpdate(dst.base(), c);
         }
+        else if(src.isRegister()) {
+            RelConst v = PS.getRegister(src.base());
+            diff.setRegisterUpdate(dst.base(), v);
+        }
         else
             diff.setRegisterTouched(dst.base());
         break;
@@ -231,7 +244,7 @@ static ProgramStateDiff interpretInstruction(
     case AsmInstruction::SH_shll16:
     case AsmInstruction::SH_shlr16: {
         AsmOperand op = asmins.operand(0);
-        assert(op.isReg());
+        assert(op.isRegister());
         diff.setRegisterTouched(op.base());
         break;
     }
diff --git a/lib/lang.cpp b/lib/lang.cpp
index e2385fc..3e36282 100644
--- a/lib/lang.cpp
+++ b/lib/lang.cpp
@@ -53,7 +53,7 @@ std::string CpuRegister::str() const noexcept
     return regnames[i];
 }
 
-int CpuRegister::getR() const
+int CpuRegister::getRn() const
 {
     if(m_name >= R0 && m_name <= R7)
         return m_name - R0;
@@ -63,6 +63,15 @@ int CpuRegister::getR() const
     return -1;
 }
 
+CpuRegister CpuRegister::makeRn(int n)
+{
+    assert(n >= 0 && n < 16 && "makeRn: invalid number");
+    CpuRegister r;
+    int name = (n >= 8) ? (R8 + (n - 8)) : (R0 + n);
+    r.m_name = static_cast<CpuRegisterName>(name);
+    return r;
+}
+
 //---
 // Instruction operands
 //---
diff --git a/lib/view/assembly.cpp b/lib/view/assembly.cpp
index a58a240..2fbefb5 100644
--- a/lib/view/assembly.cpp
+++ b/lib/view/assembly.cpp
@@ -246,7 +246,8 @@ static void viewProgramState(ProgramState const &PS, std::string lineStart)
     RelConstDomain RCD;
     std::cout << "\e[36m";
     viewStrings(std::views::iota(0, 16) | std::views::transform([&](int i) {
-        return fmt::format("r{}:{}", i, PS.getRegister(i).str(false));
+        auto ri = CpuRegister::makeRn(i);
+        return fmt::format("r{}:{}", i, PS.getRegister(ri).str(false));
     }),
         opts);
     std::cout << "\e[0m";
@@ -306,8 +307,8 @@ void viewAssemblyInstruction(
     case AsmInstruction::SH_jmp:
     case AsmInstruction::SH_jsr:
         if(PS) {
-            int n = ins.opcode().operand(0).base().getR();
-            RelConst target = PS->getRegister(n);
+            CpuRegister targetReg = ins.opcode().operand(0).base();
+            RelConst target = PS->getRegister(targetReg);
             comments.emplace_back(
                 target.str(false), fmt::fg(fmt::terminal_color::yellow));
         }