From 7bb5696d9548df51278bedbb43a7276ca35ca17a Mon Sep 17 00:00:00 2001
From: JosJuice <josjuice@gmail.com>
Date: Sat, 31 Aug 2024 17:38:49 +0200
Subject: [PATCH] PowerPC: Simplify subfic/subfcx carry calculation

---
 .../PowerPC/Interpreter/Interpreter_Integer.cpp  | 16 ++++++++--------
 Source/Core/Core/PowerPC/Jit64/Jit_Integer.cpp   |  8 ++++----
 .../Core/PowerPC/JitArm64/JitArm64_Integer.cpp   |  6 +++---
 3 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/Source/Core/Core/PowerPC/Interpreter/Interpreter_Integer.cpp b/Source/Core/Core/PowerPC/Interpreter/Interpreter_Integer.cpp
index f1fef874fd..13c76b09a0 100644
--- a/Source/Core/Core/PowerPC/Interpreter/Interpreter_Integer.cpp
+++ b/Source/Core/Core/PowerPC/Interpreter/Interpreter_Integer.cpp
@@ -141,10 +141,10 @@ void Interpreter::oris(Interpreter& interpreter, UGeckoInstruction inst)
 void Interpreter::subfic(Interpreter& interpreter, UGeckoInstruction inst)
 {
   auto& ppc_state = interpreter.m_ppc_state;
-  const s32 a = s32(ppc_state.gpr[inst.RA]);
-  const s32 immediate = inst.SIMM_16;
-  ppc_state.gpr[inst.RD] = u32(immediate - a);
-  ppc_state.SetCarry((a == 0) || (Helper_Carry(0 - u32(a), u32(immediate))));
+  const u32 a = ppc_state.gpr[inst.RA];
+  const u32 immediate = u32(s32(inst.SIMM_16));
+  ppc_state.gpr[inst.RD] = immediate - a;
+  ppc_state.SetCarry(immediate >= a);
 }
 
 void Interpreter::twi(Interpreter& interpreter, UGeckoInstruction inst)
@@ -622,15 +622,15 @@ void Interpreter::subfx(Interpreter& interpreter, UGeckoInstruction inst)
 void Interpreter::subfcx(Interpreter& interpreter, UGeckoInstruction inst)
 {
   auto& ppc_state = interpreter.m_ppc_state;
-  const u32 a = ~ppc_state.gpr[inst.RA];
+  const u32 a = ppc_state.gpr[inst.RA];
   const u32 b = ppc_state.gpr[inst.RB];
-  const u32 result = a + b + 1;
+  const u32 result = b - a;
 
   ppc_state.gpr[inst.RD] = result;
-  ppc_state.SetCarry(a == 0xFFFFFFFF || Helper_Carry(b, a + 1));
+  ppc_state.SetCarry(b >= a);
 
   if (inst.OE)
-    ppc_state.SetXER_OV(HasAddOverflowed(a, b, result));
+    ppc_state.SetXER_OV(HasAddOverflowed(~a, b, result));
 
   if (inst.Rc)
     Helper_UpdateCR0(ppc_state, result);
diff --git a/Source/Core/Core/PowerPC/Jit64/Jit_Integer.cpp b/Source/Core/Core/PowerPC/Jit64/Jit_Integer.cpp
index 65d2a4296b..f7e89d6324 100644
--- a/Source/Core/Core/PowerPC/Jit64/Jit_Integer.cpp
+++ b/Source/Core/Core/PowerPC/Jit64/Jit_Integer.cpp
@@ -1104,7 +1104,7 @@ void Jit64::subfic(UGeckoInstruction inst)
   {
     u32 i = imm, j = gpr.Imm32(a);
     gpr.SetImmediate32(d, i - j);
-    FinalizeCarry(j == 0 || (i > j - 1));
+    FinalizeCarry(i >= j);
     return;
   }
 
@@ -1165,12 +1165,12 @@ void Jit64::subfx(UGeckoInstruction inst)
   }
   else if (gpr.IsImm(a, b))
   {
-    s32 i = gpr.SImm32(b), j = gpr.SImm32(a);
+    u32 i = gpr.Imm32(b), j = gpr.Imm32(a);
     gpr.SetImmediate32(d, i - j);
     if (carry)
-      FinalizeCarry(j == 0 || Interpreter::Helper_Carry((u32)i, 0u - (u32)j));
+      FinalizeCarry(i >= j);
     if (inst.OE)
-      GenerateConstantOverflow((s64)i - (s64)j);
+      GenerateConstantOverflow(s64(s32(i)) - s64(s32(j)));
   }
   else if (gpr.IsImm(a))
   {
diff --git a/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp b/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
index f3d263379c..54190eb80d 100644
--- a/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
+++ b/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
@@ -1310,7 +1310,7 @@ void JitArm64::subfcx(UGeckoInstruction inst)
     u32 a_imm = gpr.GetImm(a), b_imm = gpr.GetImm(b);
 
     gpr.SetImmediate(d, b_imm - a_imm);
-    ComputeCarry(a_imm == 0 || Interpreter::Helper_Carry(b_imm, 0u - a_imm));
+    ComputeCarry(b_imm >= a_imm);
 
     if (inst.Rc)
       ComputeRC0(gpr.GetImm(d));
@@ -1381,14 +1381,14 @@ void JitArm64::subfic(UGeckoInstruction inst)
   JITDISABLE(bJITIntegerOff);
 
   int a = inst.RA, d = inst.RD;
-  s32 imm = inst.SIMM_16;
+  u32 imm = s32(inst.SIMM_16);
 
   if (gpr.IsImm(a))
   {
     u32 a_imm = gpr.GetImm(a);
 
     gpr.SetImmediate(d, imm - a_imm);
-    ComputeCarry(a_imm == 0 || Interpreter::Helper_Carry(imm, 0u - a_imm));
+    ComputeCarry(imm >= a_imm);
   }
   else
   {