From 204a8fbd5348ae2b072bca63697a72adb4c357ae Mon Sep 17 00:00:00 2001
From: JosJuice <josjuice@gmail.com>
Date: Sat, 31 Aug 2024 16:03:02 +0200
Subject: [PATCH] Jit: Move subfx to ConstantPropagation

---
 .../Core/Core/PowerPC/Jit64/Jit_Integer.cpp   | 19 +---------
 .../PowerPC/JitArm64/JitArm64_Integer.cpp     | 36 +++----------------
 .../PowerPC/JitCommon/ConstantPropagation.cpp | 31 ++++++++++++++++
 .../PowerPC/JitCommon/ConstantPropagation.h   |  2 ++
 4 files changed, 39 insertions(+), 49 deletions(-)

diff --git a/Source/Core/Core/PowerPC/Jit64/Jit_Integer.cpp b/Source/Core/Core/PowerPC/Jit64/Jit_Integer.cpp
index cdca3274af0..f10bca3cf3d 100644
--- a/Source/Core/Core/PowerPC/Jit64/Jit_Integer.cpp
+++ b/Source/Core/Core/PowerPC/Jit64/Jit_Integer.cpp
@@ -1097,24 +1097,7 @@ void Jit64::subfx(UGeckoInstruction inst)
   int a = inst.RA, b = inst.RB, d = inst.RD;
   const bool carry = !(inst.SUBOP10 & (1 << 5));
 
-  if (a == b)
-  {
-    gpr.SetImmediate32(d, 0);
-    if (carry)
-      FinalizeCarry(true);
-    if (inst.OE)
-      GenerateConstantOverflow(false);
-  }
-  else if (gpr.IsImm(a, b))
-  {
-    s32 i = gpr.SImm32(b), j = gpr.SImm32(a);
-    gpr.SetImmediate32(d, i - j);
-    if (carry)
-      FinalizeCarry(j == 0 || Interpreter::Helper_Carry((u32)i, 0u - (u32)j));
-    if (inst.OE)
-      GenerateConstantOverflow((s64)i - (s64)j);
-  }
-  else if (gpr.IsImm(a))
+  if (gpr.IsImm(a))
   {
     s32 j = gpr.SImm32(a);
     RCOpArg Rb = gpr.Use(b, RCMode::Read);
diff --git a/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp b/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
index 1a4027059cd..fe5a401b6a9 100644
--- a/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
+++ b/Source/Core/Core/PowerPC/JitArm64/JitArm64_Integer.cpp
@@ -1122,26 +1122,10 @@ void JitArm64::subfx(UGeckoInstruction inst)
 
   int a = inst.RA, b = inst.RB, d = inst.RD;
 
-  if (a == b)
-  {
-    gpr.SetImmediate(d, 0);
-    if (inst.Rc)
-      ComputeRC0(gpr.GetImm(d));
-  }
-  else if (gpr.IsImm(a) && gpr.IsImm(b))
-  {
-    u32 i = gpr.GetImm(a), j = gpr.GetImm(b);
-    gpr.SetImmediate(d, j - i);
-    if (inst.Rc)
-      ComputeRC0(gpr.GetImm(d));
-  }
-  else
-  {
-    gpr.BindToRegister(d, d == a || d == b);
-    SUB(gpr.R(d), gpr.R(b), gpr.R(a));
-    if (inst.Rc)
-      ComputeRC0(gpr.R(d));
-  }
+  gpr.BindToRegister(d, d == a || d == b);
+  SUB(gpr.R(d), gpr.R(b), gpr.R(a));
+  if (inst.Rc)
+    ComputeRC0(gpr.R(d));
 }
 
 void JitArm64::subfex(UGeckoInstruction inst)
@@ -1283,17 +1267,7 @@ void JitArm64::subfcx(UGeckoInstruction inst)
 
   int a = inst.RA, b = inst.RB, d = inst.RD;
 
-  if (gpr.IsImm(a) && gpr.IsImm(b))
-  {
-    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));
-
-    if (inst.Rc)
-      ComputeRC0(gpr.GetImm(d));
-  }
-  else if (gpr.IsImm(a, 0))
+  if (gpr.IsImm(a, 0))
   {
     if (d != b)
     {
diff --git a/Source/Core/Core/PowerPC/JitCommon/ConstantPropagation.cpp b/Source/Core/Core/PowerPC/JitCommon/ConstantPropagation.cpp
index 980347062b4..f794af1653c 100644
--- a/Source/Core/Core/PowerPC/JitCommon/ConstantPropagation.cpp
+++ b/Source/Core/Core/PowerPC/JitCommon/ConstantPropagation.cpp
@@ -213,6 +213,8 @@ ConstantPropagationResult ConstantPropagation::EvaluateTable31AB(UGeckoInstructi
       return EvaluateTable31ABOneRegisterKnown(inst, flags, GetGPR(inst.RA));
     else if (has_b)
       return EvaluateTable31ABOneRegisterKnown(inst, flags, GetGPR(inst.RB));
+    else if (inst.RA == inst.RB)
+      return EvaluateTable31ABIdenticalRegisters(inst, flags);
     else
       return {};
   }
@@ -224,6 +226,13 @@ ConstantPropagationResult ConstantPropagation::EvaluateTable31AB(UGeckoInstructi
 
   switch (inst.SUBOP10)
   {
+  case 8:    // subfcx
+  case 40:   // subfx
+  case 520:  // subfcox
+  case 552:  // subfox
+    d = u64(u32(~a)) + u64(b) + 1;
+    d_overflow = s64(s32(b)) - s64(s32(a));
+    break;
   case 10:   // addcx
   case 522:  // addcox
   case 266:  // addx
@@ -276,6 +285,28 @@ ConstantPropagation::EvaluateTable31ABOneRegisterKnown(UGeckoInstruction inst, u
   return {};
 }
 
+ConstantPropagationResult
+ConstantPropagation::EvaluateTable31ABIdenticalRegisters(UGeckoInstruction inst, u64 flags) const
+{
+  switch (inst.SUBOP10)
+  {
+  case 8:    // subfcx
+  case 40:   // subfx
+  case 520:  // subfcox
+  case 552:  // subfox
+  {
+    ConstantPropagationResult result(inst.RD, 0, inst.Rc);
+    if (flags & FL_SET_CA)
+      result.carry = true;
+    if (flags & FL_SET_OE)
+      result.overflow = false;
+    return result;
+  }
+  default:
+    return {};
+  }
+}
+
 ConstantPropagationResult ConstantPropagation::EvaluateTable31SB(UGeckoInstruction inst) const
 {
   const bool has_s = HasGPR(inst.RS);
diff --git a/Source/Core/Core/PowerPC/JitCommon/ConstantPropagation.h b/Source/Core/Core/PowerPC/JitCommon/ConstantPropagation.h
index 4ff7823aa44..7b4759c0aeb 100644
--- a/Source/Core/Core/PowerPC/JitCommon/ConstantPropagation.h
+++ b/Source/Core/Core/PowerPC/JitCommon/ConstantPropagation.h
@@ -89,6 +89,8 @@ private:
   ConstantPropagationResult EvaluateTable31AB(UGeckoInstruction inst, u64 flags) const;
   ConstantPropagationResult EvaluateTable31ABOneRegisterKnown(UGeckoInstruction inst, u64 flags,
                                                               u32 value) const;
+  ConstantPropagationResult EvaluateTable31ABIdenticalRegisters(UGeckoInstruction inst,
+                                                                u64 flags) const;
   ConstantPropagationResult EvaluateTable31SB(UGeckoInstruction inst) const;
   ConstantPropagationResult EvaluateTable31SBOneRegisterKnown(UGeckoInstruction inst, u32 value,
                                                               bool known_reg_is_b) const;