thumb32: Implement exclusive loads

Implements the remaining loads for ARMv7

src/frontend/A32/decoder/thumb32.inc

@@ -12,7 +12,7 @@ INST(thumb32_LDMDB,          "LDMDB/LDMEA",              "1110100100W1nnnniiiiii
 
 // Load/Store Dual, Load/Store Exclusive, Table Branch
 INST(thumb32_STREX,          "STREX",                    "111010000100nnnnttttddddiiiiiiii")
-//INST(thumb32_LDREX,          "LDREX",                    "111010000101--------------------")
+INST(thumb32_LDREX,          "LDREX",                    "111010000101nnnntttt1111iiiiiiii")
 INST(thumb32_STRD_imm_1,     "STRD (imm)",               "11101000U110nnnnttttssssiiiiiiii")
 INST(thumb32_STRD_imm_2,     "STRD (imm)",               "11101001U1W0nnnnttttssssiiiiiiii")
 INST(thumb32_LDRD_lit_1,     "LDRD (lit)",               "11101000U1111111ttttssssiiiiiiii")
@@ -24,9 +24,9 @@ INST(thumb32_STREXH,         "STREXH",                   "111010001100nnnntttt11
 INST(thumb32_STREXD,         "STREXD",                   "111010001100nnnnttttuuuu0111dddd")
 INST(thumb32_TBB,            "TBB",                      "111010001101nnnn111100000000mmmm")
 INST(thumb32_TBH,            "TBH",                      "111010001101nnnn111100000001mmmm")
-//INST(thumb32_LDREXB,         "LDREXB",                   "111010001101------------0100----")
+INST(thumb32_LDREXB,         "LDREXB",                   "111010001101nnnntttt111101001111")
-//INST(thumb32_LDREXH,         "LDREXH",                   "111010001101------------0101----")
+INST(thumb32_LDREXH,         "LDREXH",                   "111010001101nnnntttt111101011111")
-//INST(thumb32_LDREXD,         "LDREXD",                   "111010001101------------0111----")
+INST(thumb32_LDREXD,         "LDREXD",                   "111010001101nnnnttttuuuu01111111")
 
 // Data Processing (Shifted Register)
 INST(thumb32_TST_reg,        "TST (reg)",                "111010100001nnnn0vvv1111vvttmmmm")

src/frontend/A32/translate/impl/thumb32_load_store_dual.cpp

@@ -135,6 +135,56 @@ bool ThumbTranslatorVisitor::thumb32_STRD_imm_2(bool U, bool W, Reg n, Reg t, Re
     return StoreDual(*this, true, U, W, n, t, t2, imm8);
 }
 
+bool ThumbTranslatorVisitor::thumb32_LDREX(Reg n, Reg t, Imm<8> imm8) {
+    if (t == Reg::PC || n == Reg::PC) {
+        return UnpredictableInstruction();
+    }
+
+    const auto address = ir.Add(ir.GetRegister(n), ir.Imm32(imm8.ZeroExtend() << 2));
+    const auto value = ir.ExclusiveReadMemory32(address);
+
+    ir.SetRegister(t, value);
+    return true;
+}
+
+bool ThumbTranslatorVisitor::thumb32_LDREXB(Reg n, Reg t) {
+    if (t == Reg::PC || n == Reg::PC) {
+        return UnpredictableInstruction();
+    }
+
+    const auto address = ir.GetRegister(n);
+    const auto value = ir.ZeroExtendToWord(ir.ExclusiveReadMemory8(address));
+
+    ir.SetRegister(t, value);
+    return true;
+}
+
+bool ThumbTranslatorVisitor::thumb32_LDREXD(Reg n, Reg t, Reg t2) {
+    if (t == Reg::PC || t2 == Reg::PC || t == t2 || n == Reg::PC) {
+        return UnpredictableInstruction();
+    }
+
+    const auto address = ir.GetRegister(n);
+    const auto [lo, hi] = ir.ExclusiveReadMemory64(address);
+
+    // DO NOT SWAP hi AND lo IN BIG ENDIAN MODE, THIS IS CORRECT BEHAVIOUR
+    ir.SetRegister(t, lo);
+    ir.SetRegister(t2, hi);
+    return true;
+}
+
+bool ThumbTranslatorVisitor::thumb32_LDREXH(Reg n, Reg t) {
+    if (t == Reg::PC || n == Reg::PC) {
+        return UnpredictableInstruction();
+    }
+
+    const auto address = ir.GetRegister(n);
+    const auto value = ir.ZeroExtendToWord(ir.ExclusiveReadMemory16(address));
+
+    ir.SetRegister(t, value);
+    return true;
+}
+
 bool ThumbTranslatorVisitor::thumb32_STREX(Reg n, Reg t, Reg d, Imm<8> imm8) {
     if (d == Reg::PC || t == Reg::PC || n == Reg::PC) {
         return UnpredictableInstruction();

src/frontend/A32/translate/impl/translate_thumb.h

@@ -186,6 +186,10 @@ struct ThumbTranslatorVisitor final {
     bool thumb32_LDRD_lit_2(bool U, bool W, Reg t, Reg t2, Imm<8> imm8);
     bool thumb32_STRD_imm_1(bool U, Reg n, Reg t, Reg t2, Imm<8> imm8);
     bool thumb32_STRD_imm_2(bool U, bool W, Reg n, Reg t, Reg t2, Imm<8> imm8);
+    bool thumb32_LDREX(Reg n, Reg t, Imm<8> imm8);
+    bool thumb32_LDREXD(Reg n, Reg t, Reg t2);
+    bool thumb32_LDREXB(Reg n, Reg t);
+    bool thumb32_LDREXH(Reg n, Reg t);
     bool thumb32_STREX(Reg n, Reg t, Reg d, Imm<8> imm8);
     bool thumb32_STREXB(Reg n, Reg t, Reg d);
     bool thumb32_STREXD(Reg n, Reg t, Reg t2, Reg d);

tests/A32/fuzz_arm.cpp

@@ -168,6 +168,10 @@ std::vector<u16> GenRandomThumbInst(u32 pc, bool is_last_inst, A32::ITState it_s
             "thumb16_SETEND",
 
             // Exclusive load/stores
+            "thumb32_LDREX",
+            "thumb32_LDREXB",
+            "thumb32_LDREXD",
+            "thumb32_LDREXH",
             "thumb32_STREX",
             "thumb32_STREXB",
             "thumb32_STREXD",