From 76b07d6646e2b5ff127f690cef3b21cbe28844dd Mon Sep 17 00:00:00 2001
From: MerryMage <MerryMage@users.noreply.github.com>
Date: Mon, 23 Jul 2018 20:21:33 +0100
Subject: [PATCH] u128: StickyLogicalShiftRight requires special-casing for
 amount == 64

In this case (128 - amount) == 64, and this invokes undefined behaviour
---
 src/common/u128.cpp | 10 ++++++++++
 tests/A64/a64.cpp   | 19 +++++++++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/src/common/u128.cpp b/src/common/u128.cpp
index 8bad425f..4837c87f 100644
--- a/src/common/u128.cpp
+++ b/src/common/u128.cpp
@@ -112,6 +112,16 @@ u128 StickyLogicalShiftRight(u128 operand, int amount) {
         return result;
     }
 
+    if (amount == 64) {
+        u128 result;
+        result.lower = operand.upper;
+        // Sticky bit
+        if (operand.lower != 0) {
+            result.lower |= 1;
+        }
+        return result;
+    }
+
     if (amount < 128) {
         u128 result;
         result.lower = operand.upper >> (amount - 64);
diff --git a/tests/A64/a64.cpp b/tests/A64/a64.cpp
index dc48db68..9a13e4ca 100644
--- a/tests/A64/a64.cpp
+++ b/tests/A64/a64.cpp
@@ -371,3 +371,22 @@ TEST_CASE("A64: FNMSUB 2", "[a64]") {
 
     REQUIRE(jit.GetVector(14) == Vector{0x0000000080045284, 0x0000000000000000});
 }
+
+TEST_CASE("A64: FMADD", "[a64]") {
+    TestEnv env;
+    Dynarmic::A64::Jit jit{Dynarmic::A64::UserConfig{&env}};
+
+    env.code_mem[0] = 0x1f5e0e4a; // FMADD D10, D18, D30, D3
+    env.code_mem[1] = 0x14000000; // B .
+
+    jit.SetPC(0);
+    jit.SetVector(18, {0x8000007600800000, 0x7ff812347f800000});
+    jit.SetVector(30, {0xff984a3700000000, 0xe73a513480800000});
+    jit.SetVector(3, {0x3f000000ff7fffff, 0x8139843780000000});
+    jit.SetFpcr(0x00400000);
+
+    env.ticks_left = 2;
+    jit.Run();
+
+    REQUIRE(jit.GetVector(10) == Vector{0x3f059921bf0dbfff, 0x0000000000000000});
+}