From 7c193485e18f0c4e966e0736471a283a037d4830 Mon Sep 17 00:00:00 2001
From: MerryMage <MerryMage@users.noreply.github.com>
Date: Sun, 18 Feb 2018 13:04:45 +0000
Subject: [PATCH] a64/config: Allow NaN emulation accuracy to be set

---
 include/dynarmic/A64/config.h    | 12 ++++++++++++
 src/backend_x64/a64_emit_x64.cpp |  6 +++++-
 src/backend_x64/a64_emit_x64.h   |  1 +
 3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/include/dynarmic/A64/config.h b/include/dynarmic/A64/config.h
index c63d7f69..ffe5aa9b 100644
--- a/include/dynarmic/A64/config.h
+++ b/include/dynarmic/A64/config.h
@@ -126,6 +126,18 @@ struct UserConfig {
     /// This is only used if page_table is not nullptr.
     bool silently_mirror_page_table = true;
 
+    // The below options relate to accuracy of floating-point emulation.
+
+    /// Determines how accurate NaN handling is.
+    enum class NaNAccuracy {
+        /// Results of operations with NaNs will exactly match hardware.
+        Accurate,
+        /// Behave as if FPCR.DN is always set.
+        AlwaysForceDefaultNaN,
+        /// No special handling of NaN, other than setting default NaN when FPCR.DN is set.
+        NoChecks,
+    } floating_point_nan_accuracy = NaNAccuracy::Accurate;
+
     // Determines whether AddTicks and GetTicksRemaining are called.
     // If false, execution will continue until soon after Jit::HaltExecution is called.
     // bool enable_ticks = true; // TODO
diff --git a/src/backend_x64/a64_emit_x64.cpp b/src/backend_x64/a64_emit_x64.cpp
index dc691795..6630fc3a 100644
--- a/src/backend_x64/a64_emit_x64.cpp
+++ b/src/backend_x64/a64_emit_x64.cpp
@@ -48,7 +48,11 @@ bool A64EmitContext::FPSCR_FTZ() const {
 }
 
 bool A64EmitContext::FPSCR_DN() const {
-    return Location().FPCR().DN();
+    return Location().FPCR().DN() || conf.floating_point_nan_accuracy == A64::UserConfig::NaNAccuracy::AlwaysForceDefaultNaN;
+}
+
+bool A64EmitContext::AccurateNaN() const {
+    return conf.floating_point_nan_accuracy == A64::UserConfig::NaNAccuracy::Accurate;
 }
 
 A64EmitX64::A64EmitX64(BlockOfCode& code, A64::UserConfig conf)
diff --git a/src/backend_x64/a64_emit_x64.h b/src/backend_x64/a64_emit_x64.h
index 664ba5c1..8108bda7 100644
--- a/src/backend_x64/a64_emit_x64.h
+++ b/src/backend_x64/a64_emit_x64.h
@@ -26,6 +26,7 @@ struct A64EmitContext final : public EmitContext {
     bool FPSCR_RoundTowardsZero() const override;
     bool FPSCR_FTZ() const override;
     bool FPSCR_DN() const override;
+    bool AccurateNaN() const override;
 
     const A64::UserConfig& conf;
 };