From 09dc23f97188a4fa5ea03556a9187bfbefef1d78 Mon Sep 17 00:00:00 2001
From: ameerj <52414509+ameerj@users.noreply.github.com>
Date: Wed, 5 May 2021 00:37:05 -0400
Subject: [PATCH] shader: ISET.X implementation

---
 .../impl/integer_compare_and_set.cpp          | 66 ++++++++++++++++---
 1 file changed, 58 insertions(+), 8 deletions(-)

diff --git a/src/shader_recompiler/frontend/maxwell/translate/impl/integer_compare_and_set.cpp b/src/shader_recompiler/frontend/maxwell/translate/impl/integer_compare_and_set.cpp
index a2cd8d7c6..34fa7345c 100644
--- a/src/shader_recompiler/frontend/maxwell/translate/impl/integer_compare_and_set.cpp
+++ b/src/shader_recompiler/frontend/maxwell/translate/impl/integer_compare_and_set.cpp
@@ -9,7 +9,56 @@
 
 namespace Shader::Maxwell {
 namespace {
-void ISET(TranslatorVisitor& v, u64 insn, const IR::U32& src_a) {
+IR::U1 ExtendedIntegerCompare(IR::IREmitter& ir, const IR::U32& operand_1, const IR::U32& operand_2,
+                              CompareOp compare_op, bool is_signed) {
+    const IR::U32 zero{ir.Imm32(0)};
+    const IR::U32 carry{ir.Select(ir.GetCFlag(), ir.Imm32(1), zero)};
+    const IR::U1 z_flag{ir.GetZFlag()};
+    const IR::U32 intermediate{ir.IAdd(ir.IAdd(operand_1, ir.BitwiseNot(operand_2)), carry)};
+    const IR::U1 flip_logic{is_signed ? ir.Imm1(false)
+                                      : ir.LogicalXor(ir.ILessThan(operand_1, zero, true),
+                                                      ir.ILessThan(operand_2, zero, true))};
+    switch (compare_op) {
+    case CompareOp::False:
+        return ir.Imm1(false);
+    case CompareOp::LessThan:
+        return IR::U1{ir.Select(flip_logic, ir.IGreaterThanEqual(intermediate, zero, true),
+                                ir.ILessThan(intermediate, zero, true))};
+    case CompareOp::Equal:
+        return ir.LogicalAnd(ir.IEqual(intermediate, zero), z_flag);
+    case CompareOp::LessThanEqual: {
+        const IR::U1 base_cmp{ir.Select(flip_logic, ir.IGreaterThanEqual(intermediate, zero, true),
+                                        ir.ILessThan(intermediate, zero, true))};
+        return ir.LogicalOr(base_cmp, ir.LogicalAnd(ir.IEqual(intermediate, zero), z_flag));
+    }
+    case CompareOp::GreaterThan: {
+        const IR::U1 base_cmp{ir.Select(flip_logic, ir.ILessThanEqual(intermediate, zero, true),
+                                        ir.IGreaterThan(intermediate, zero, true))};
+        const IR::U1 not_z{ir.LogicalNot(z_flag)};
+        return ir.LogicalOr(base_cmp, ir.LogicalAnd(ir.IEqual(intermediate, zero), not_z));
+    }
+    case CompareOp::NotEqual:
+        return ir.LogicalOr(ir.INotEqual(intermediate, zero),
+                            ir.LogicalAnd(ir.IEqual(intermediate, zero), ir.LogicalNot(z_flag)));
+    case CompareOp::GreaterThanEqual: {
+        const IR::U1 base_cmp{ir.Select(flip_logic, ir.ILessThan(intermediate, zero, true),
+                                        ir.IGreaterThanEqual(intermediate, zero, true))};
+        return ir.LogicalOr(base_cmp, ir.LogicalAnd(ir.IEqual(intermediate, zero), z_flag));
+    }
+    case CompareOp::True:
+        return ir.Imm1(true);
+    default:
+        throw NotImplementedException("Invalid compare op {}", compare_op);
+    }
+}
+
+IR::U1 IsetCompare(IR::IREmitter& ir, const IR::U32& operand_1, const IR::U32& operand_2,
+                   CompareOp compare_op, bool is_signed, bool x) {
+    return x ? ExtendedIntegerCompare(ir, operand_1, operand_2, compare_op, is_signed)
+             : IntegerCompare(ir, operand_1, operand_2, compare_op, is_signed);
+}
+
+void ISET(TranslatorVisitor& v, u64 insn, const IR::U32& src_b) {
     union {
         u64 insn;
         BitField<0, 8, IR::Reg> dest_reg;
@@ -24,27 +73,28 @@ void ISET(TranslatorVisitor& v, u64 insn, const IR::U32& src_a) {
         BitField<49, 3, CompareOp> compare_op;
     } const iset{insn};
 
-    if (iset.x != 0) {
-        throw NotImplementedException("ISET.X");
-    }
-
-    const IR::U32 src_reg{v.X(iset.src_reg)};
+    const IR::U32 src_a{v.X(iset.src_reg)};
     const bool is_signed{iset.is_signed != 0};
+    const IR::U32 zero{v.ir.Imm32(0)};
+    const bool x{iset.x != 0};
+    const IR::U1 cmp_result{IsetCompare(v.ir, src_a, src_b, iset.compare_op, is_signed, x)};
+
     IR::U1 pred{v.ir.GetPred(iset.pred)};
     if (iset.neg_pred != 0) {
         pred = v.ir.LogicalNot(pred);
     }
-    const IR::U1 cmp_result{IntegerCompare(v.ir, src_reg, src_a, iset.compare_op, is_signed)};
     const IR::U1 bop_result{PredicateCombine(v.ir, cmp_result, pred, iset.bop)};
 
     const IR::U32 one_mask{v.ir.Imm32(-1)};
     const IR::U32 fp_one{v.ir.Imm32(0x3f800000)};
-    const IR::U32 zero{v.ir.Imm32(0)};
     const IR::U32 pass_result{iset.bf == 0 ? one_mask : fp_one};
     const IR::U32 result{v.ir.Select(bop_result, pass_result, zero)};
 
     v.X(iset.dest_reg, result);
     if (iset.cc != 0) {
+        if (x) {
+            throw NotImplementedException("ISET.CC + X");
+        }
         const IR::U1 is_zero{v.ir.IEqual(result, zero)};
         v.SetZFlag(is_zero);
         if (iset.bf != 0) {