constant_propagation_pass: Handle GetCarryFromOp for MostSignificantWord

src/ir_opt/constant_propagation_pass.cpp

@@ -158,11 +158,16 @@ void FoldMostSignificantBit(IR::Inst& inst) {
 }
 
 void FoldMostSignificantWord(IR::Inst& inst) {
+    IR::Inst* carry_inst = inst.GetAssociatedPseudoOperation(IR::Opcode::GetCarryFromOp);
+
     if (!inst.AreAllArgsImmediates()) {
         return;
     }
 
     const auto operand = inst.GetArg(0);
+    if (carry_inst) {
+        carry_inst->ReplaceUsesWith(IR::Value{Common::Bit<31>(operand.GetImmediateAsU64())});
+    }
     inst.ReplaceUsesWith(IR::Value{static_cast<u32>(operand.GetImmediateAsU64() >> 32)});
 }
 

tests/A32/test_arm_instructions.cpp

@@ -0,0 +1,44 @@
+/* This file is part of the dynarmic project.
+ * Copyright (c) 2016 MerryMage
+ * This software may be used and distributed according to the terms of the GNU
+ * General Public License version 2 or any later version.
+ */
+
+#include <catch.hpp>
+#include <dynarmic/A32/a32.h>
+
+#include "A32/testenv.h"
+
+using namespace Dynarmic;
+
+static A32::UserConfig GetUserConfig(ArmTestEnv* testenv) {
+    A32::UserConfig user_config;
+    user_config.enable_fast_dispatch = false;
+    user_config.callbacks = testenv;
+    return user_config;
+}
+
+TEST_CASE("arm: Opt Failure: Const folding in MostSignificantWord", "[arm][A32]") {
+    // This was a randomized test-case that was failing.
+    // This was due to constant folding for MostSignificantWord
+    // failing to take into account an associated GetCarryFromOp
+    // pseudoinstruction.
+
+    ArmTestEnv test_env;
+    A32::Jit jit{GetUserConfig(&test_env)};
+    test_env.code_mem = {
+        0xe30ad071, // movw, sp, #41073
+        0xe75efd3d, // smmulr lr, sp, sp
+        0xa637af1e, // shadd16ge r10, r7, lr
+        0xf57ff01f, // clrex
+        0x86b98879, // sxtahhi r8, r9, r9, ror #16
+        0xeafffffe, // b +#0
+    };
+
+    jit.SetCpsr(0x000001d0); // User-mode
+
+    test_env.ticks_left = 6;
+    jit.Run();
+
+    // If we don't trigger the GetCarryFromOp ASSERT, we're fine.
+}

tests/CMakeLists.txt

@@ -1,5 +1,6 @@
 add_executable(dynarmic_tests
     A32/test_arm_disassembler.cpp
+    A32/test_arm_instructions.cpp
     A32/test_thumb_instructions.cpp
     A32/testenv.h
     A64/a64.cpp