[maxwell] ATOM() has cases where it acts like a NOP (#2907)

ATOM should be NOP in these cases
May break games? May not break games! - But it **should** be correct to do this

Signed-off-by: lizzie <lizzie@eden-emu.dev>

Co-authored-by: Caio Oliveira <caiooliveirafarias0@gmail.com>
Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/2907
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: Caio Oliveira <caiooliveirafarias0@gmail.com>
Co-authored-by: lizzie <lizzie@eden-emu.dev>
Co-committed-by: lizzie <lizzie@eden-emu.dev>

src/shader_recompiler/frontend/maxwell/translate/impl/atomic_operations_global_memory.cpp

@@ -1,3 +1,6 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
 // SPDX-FileCopyrightText: Copyright 2021 yuzu Emulator Project
 // SPDX-License-Identifier: GPL-2.0-or-later
 
@@ -29,8 +32,8 @@ enum class AtomSize : u64 {
     S64,
 };
 
-IR::U32U64 ApplyIntegerAtomOp(IR::IREmitter& ir, const IR::U32U64& offset, const IR::U32U64& op_b,
-                              AtomOp op, bool is_signed) {
+IR::U32U64 ApplyIntegerAtomOp(IR::IREmitter& ir, const IR::U32U64& offset, const IR::U32U64& op_b, AtomOp op, AtomSize size) {
+    bool const is_signed = size == AtomSize::S64 || size == AtomSize::S32;
     switch (op) {
     case AtomOp::ADD:
         return ir.GlobalAtomicIAdd(offset, op_b);
@@ -90,30 +93,34 @@ IR::U64 AtomOffset(TranslatorVisitor& v, u64 insn) {
     } const mem{insn};
 
     const IR::U64 address{[&]() -> IR::U64 {
-        if (mem.e == 0) {
+        if (mem.e == 0)
             return v.ir.UConvert(64, v.X(mem.addr_reg));
-        }
         return v.L(mem.addr_reg);
     }()};
     const u64 addr_offset{[&]() -> u64 {
         if (mem.addr_reg == IR::Reg::RZ) {
             // When RZ is used, the address is an absolute address
-            return static_cast<u64>(mem.rz_addr_offset.Value());
+            return u64(mem.rz_addr_offset.Value());
         } else {
-            return static_cast<u64>(mem.addr_offset.Value());
+            return u64(mem.addr_offset.Value());
         }
     }()};
     return v.ir.IAdd(address, v.ir.Imm64(addr_offset));
 }
 
+// INC, DEC for U32/S32/U64 does nothing
+// ADD, INC, DEC for S64 does nothing
+// Only ADD does something for F32
+// Only ADD, MIN and MAX does something for F16x2
 bool AtomOpNotApplicable(AtomSize size, AtomOp op) {
     // TODO: SAFEADD
     switch (size) {
+    case AtomSize::U32:
     case AtomSize::S32:
     case AtomSize::U64:
         return (op == AtomOp::INC || op == AtomOp::DEC);
     case AtomSize::S64:
-        return !(op == AtomOp::MIN || op == AtomOp::MAX);
+        return (op == AtomOp::ADD || op == AtomOp::INC || op == AtomOp::DEC);
     case AtomSize::F32:
         return op != AtomOp::ADD;
     case AtomSize::F16x2:
@@ -159,15 +166,14 @@ IR::Value ApplyAtomOp(TranslatorVisitor& v, IR::Reg operand_reg, const IR::U64&
     switch (size) {
     case AtomSize::U32:
     case AtomSize::S32:
-        return ApplyIntegerAtomOp(v.ir, offset, v.X(operand_reg), op, size == AtomSize::S32);
+        return ApplyIntegerAtomOp(v.ir, offset, v.X(operand_reg), op, size);
     case AtomSize::U64:
     case AtomSize::S64:
-        return ApplyIntegerAtomOp(v.ir, offset, v.L(operand_reg), op, size == AtomSize::S64);
+        return ApplyIntegerAtomOp(v.ir, offset, v.L(operand_reg), op, size);
     case AtomSize::F32:
         return ApplyFpAtomOp(v.ir, offset, v.F(operand_reg), op, size);
-    case AtomSize::F16x2: {
+    case AtomSize::F16x2:
         return ApplyFpAtomOp(v.ir, offset, v.ir.UnpackFloat2x16(v.X(operand_reg)), op, size);
-    }
     default:
         throw NotImplementedException("Atom Size {}", size);
     }
@@ -175,15 +181,11 @@ IR::Value ApplyAtomOp(TranslatorVisitor& v, IR::Reg operand_reg, const IR::U64&
 
 void GlobalAtomic(TranslatorVisitor& v, IR::Reg dest_reg, IR::Reg operand_reg,
                   const IR::U64& offset, AtomSize size, AtomOp op, bool write_dest) {
-    IR::Value result;
-    if (AtomOpNotApplicable(size, op)) {
-        result = LoadGlobal(v.ir, offset, size);
-    } else {
-        result = ApplyAtomOp(v, operand_reg, offset, size, op);
-    }
-    if (write_dest) {
+    IR::Value result = AtomOpNotApplicable(size, op)
+        ? LoadGlobal(v.ir, offset, size)
+        : ApplyAtomOp(v, operand_reg, offset, size, op);
+    if (write_dest)
         StoreResult(v, dest_reg, result, size);
-    }
 }
 } // Anonymous namespace