general: Mark hash functions as noexcept

Generally hash functions shouldn't throw exceptions. It's also a
requirement for the standard library-provided hash functions to not
throw exceptions.

An exception to this rule is made for user-defined specializations,
however we can just be consistent with the standard library on this to
allow it to play nicer with it.

While we're at it, we can also make the std::less specializations
noexcpet as well, since they also can't throw.

src/backend/x64/a32_jitstate.cpp

@@ -196,7 +196,7 @@ void A32JitState::SetFpscr(u32 FPSCR) {
     }
 }
 
-u64 A32JitState::GetUniqueHash() const {
+u64 A32JitState::GetUniqueHash() const noexcept {
     return CPSR_et | FPSCR_mode | (static_cast<u64>(Reg[15]) << 32);
 }
 

src/backend/x64/a32_jitstate.h

@@ -76,7 +76,7 @@ struct A32JitState {
     u32 Fpscr() const;
     void SetFpscr(u32 FPSCR);
 
-    u64 GetUniqueHash() const;
+    u64 GetUniqueHash() const noexcept;
 };
 
 #ifdef _MSC_VER

src/backend/x64/a64_jitstate.cpp

@@ -10,9 +10,9 @@
 
 namespace Dynarmic::BackendX64 {
 
-u64 A64JitState::GetUniqueHash() const {
-    u64 fpcr_u64 = static_cast<u64>(fpcr & A64::LocationDescriptor::FPCR_MASK) << 37;
-    u64 pc_u64 = pc & A64::LocationDescriptor::PC_MASK;
+u64 A64JitState::GetUniqueHash() const noexcept {
+    const u64 fpcr_u64 = static_cast<u64>(fpcr & A64::LocationDescriptor::FPCR_MASK) << 37;
+    const u64 pc_u64 = pc & A64::LocationDescriptor::PC_MASK;
     return pc_u64 | fpcr_u64;
 }
 

src/backend/x64/a64_jitstate.h

@@ -81,7 +81,7 @@ struct A64JitState {
     void SetFpcr(u32 new_fpcr);
     void SetFpsr(u32 new_fpcr);
 
-    u64 GetUniqueHash() const;
+    u64 GetUniqueHash() const noexcept;
 };
 
 #ifdef _MSC_VER

src/frontend/A32/location_descriptor.h

@@ -79,13 +79,13 @@ public:
         return LocationDescriptor(arm_pc, cpsr, A32::FPSCR{new_fpscr & FPSCR_MODE_MASK});
     }
 
-    u64 UniqueHash() const {
+    u64 UniqueHash() const noexcept {
         // This value MUST BE UNIQUE.
         // This calculation has to match up with EmitX64::EmitTerminalPopRSBHint
-        u64 pc_u64 = u64(arm_pc) << 32;
-        u64 fpscr_u64 = u64(fpscr.Value());
-        u64 t_u64 = cpsr.T() ? 1 : 0;
-        u64 e_u64 = cpsr.E() ? 2 : 0;
+        const u64 pc_u64 = u64(arm_pc) << 32;
+        const u64 fpscr_u64 = u64(fpscr.Value());
+        const u64 t_u64 = cpsr.T() ? 1 : 0;
+        const u64 e_u64 = cpsr.E() ? 2 : 0;
         return pc_u64 | fpscr_u64 | t_u64 | e_u64;
     }
 
@@ -112,13 +112,13 @@ std::ostream& operator<<(std::ostream& o, const LocationDescriptor& descriptor);
 namespace std {
 template <>
 struct less<Dynarmic::A32::LocationDescriptor> {
-    bool operator()(const Dynarmic::A32::LocationDescriptor& x, const Dynarmic::A32::LocationDescriptor& y) const {
+    bool operator()(const Dynarmic::A32::LocationDescriptor& x, const Dynarmic::A32::LocationDescriptor& y) const noexcept {
         return x.UniqueHash() < y.UniqueHash();
     }
 };
 template <>
 struct hash<Dynarmic::A32::LocationDescriptor> {
-    size_t operator()(const Dynarmic::A32::LocationDescriptor& x) const {
+    size_t operator()(const Dynarmic::A32::LocationDescriptor& x) const noexcept {
         return std::hash<u64>()(x.UniqueHash());
     }
 };

src/frontend/A64/location_descriptor.h

@@ -51,10 +51,10 @@ public:
         return LocationDescriptor(static_cast<u64>(pc + amount), fpcr);
     }
 
-    u64 UniqueHash() const {
+    u64 UniqueHash() const noexcept {
         // This value MUST BE UNIQUE.
         // This calculation has to match up with EmitTerminalPopRSBHint
-        u64 fpcr_u64 = static_cast<u64>(fpcr.Value()) << 37;
+        const u64 fpcr_u64 = static_cast<u64>(fpcr.Value()) << 37;
         return pc | fpcr_u64;
     }
 
@@ -80,13 +80,13 @@ std::ostream& operator<<(std::ostream& o, const LocationDescriptor& descriptor);
 namespace std {
 template <>
 struct less<Dynarmic::A64::LocationDescriptor> {
-    bool operator()(const Dynarmic::A64::LocationDescriptor& x, const Dynarmic::A64::LocationDescriptor& y) const {
+    bool operator()(const Dynarmic::A64::LocationDescriptor& x, const Dynarmic::A64::LocationDescriptor& y) const noexcept {
         return x.UniqueHash() < y.UniqueHash();
     }
 };
 template <>
 struct hash<Dynarmic::A64::LocationDescriptor> {
-    size_t operator()(const Dynarmic::A64::LocationDescriptor& x) const {
+    size_t operator()(const Dynarmic::A64::LocationDescriptor& x) const noexcept {
         return std::hash<u64>()(x.UniqueHash());
     }
 };

src/frontend/ir/location_descriptor.h

@@ -38,13 +38,13 @@ std::ostream& operator<<(std::ostream& o, const LocationDescriptor& descriptor);
 namespace std {
 template <>
 struct less<Dynarmic::IR::LocationDescriptor> {
-    bool operator()(const Dynarmic::IR::LocationDescriptor& x, const Dynarmic::IR::LocationDescriptor& y) const {
+    bool operator()(const Dynarmic::IR::LocationDescriptor& x, const Dynarmic::IR::LocationDescriptor& y) const noexcept {
         return x.Value() < y.Value();
     }
 };
 template <>
 struct hash<Dynarmic::IR::LocationDescriptor> {
-    size_t operator()(const Dynarmic::IR::LocationDescriptor& x) const {
+    size_t operator()(const Dynarmic::IR::LocationDescriptor& x) const noexcept {
         return std::hash<u64>()(x.Value());
     }
 };