gl_shader_decompiler: Implement XMAD instruction.

2 files changed, 120 insertions, 4 deletions

diff --git a/src/video_core/engines/shader_bytecode.h b/src/video_core/engines/shader_bytecode.h
index 9f64b248b..2526ebf28 100644
--- a/src/video_core/engines/shader_bytecode.h
+++ b/src/video_core/engines/shader_bytecode.h
@@ -200,6 +200,14 @@ enum class IMinMaxExchange : u64 {
     XHi = 3,
 };
 
+enum class XmadMode : u64 {
+    None = 0,
+    CLo = 1,
+    CHi = 2,
+    CSfu = 3,
+    CBcc = 4,
+};
+
 enum class FlowCondition : u64 {
     Always = 0xF,
     Fcsm_Tr = 0x1C, // TODO(bunnei): What is this used for?
@@ -457,6 +465,18 @@ union Instruction {
     } bra;
 
     union {
+        BitField<20, 16, u64> imm20_16;
+        BitField<36, 1, u64> product_shift_left;
+        BitField<37, 1, u64> merge_37;
+        BitField<48, 1, u64> sign_a;
+        BitField<49, 1, u64> sign_b;
+        BitField<50, 3, XmadMode> mode;
+        BitField<52, 1, u64> high_b;
+        BitField<53, 1, u64> high_a;
+        BitField<56, 1, u64> merge_56;
+    } xmad;
+
+    union {
         BitField<20, 14, u64> offset;
         BitField<34, 5, u64> index;
     } cbuf34;
@@ -593,6 +613,7 @@ public:
         IntegerSetPredicate,
         PredicateSetPredicate,
         Conversion,
+        Xmad,
         Unknown,
     };
 
@@ -782,10 +803,10 @@ private:
             INST("010010110101----", Id::ISET_C, Type::IntegerSet, "ISET_C"),
             INST("0011011-0101----", Id::ISET_IMM, Type::IntegerSet, "ISET_IMM"),
             INST("0101000010010---", Id::PSETP, Type::PredicateSetPredicate, "PSETP"),
-            INST("0011011-00------", Id::XMAD_IMM, Type::Arithmetic, "XMAD_IMM"),
-            INST("0100111---------", Id::XMAD_CR, Type::Arithmetic, "XMAD_CR"),
-            INST("010100010-------", Id::XMAD_RC, Type::Arithmetic, "XMAD_RC"),
-            INST("0101101100------", Id::XMAD_RR, Type::Arithmetic, "XMAD_RR"),
+            INST("0011011-00------", Id::XMAD_IMM, Type::Xmad, "XMAD_IMM"),
+            INST("0100111---------", Id::XMAD_CR, Type::Xmad, "XMAD_CR"),
+            INST("010100010-------", Id::XMAD_RC, Type::Xmad, "XMAD_RC"),
+            INST("0101101100------", Id::XMAD_RR, Type::Xmad, "XMAD_RR"),
         };
 #undef INST
         std::stable_sort(table.begin(), table.end(), [](const auto& a, const auto& b) {
diff --git a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
index 7e038ac86..6834d7085 100644
--- a/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
+++ b/src/video_core/renderer_opengl/gl_shader_decompiler.cpp
@@ -376,6 +376,8 @@ public:
             return value;
         } else if (type == GLSLRegister::Type::Integer) {
             return "floatBitsToInt(" + value + ')';
+        } else if (type == GLSLRegister::Type::UnsignedInteger) {
+            return "floatBitsToUint(" + value + ')';
         } else {
             UNREACHABLE();
         }
@@ -1630,6 +1632,99 @@ private:
             }
             break;
         }
+        case OpCode::Type::Xmad: {
+            ASSERT_MSG(!instr.xmad.sign_a, "Unimplemented");
+            ASSERT_MSG(!instr.xmad.sign_b, "Unimplemented");
+
+            std::string op_a{regs.GetRegisterAsInteger(instr.gpr8, 0, instr.xmad.sign_a)};
+            std::string op_b;
+            std::string op_c;
+
+            // TODO(bunnei): Needs to be fixed once op_a or op_b is signed
+            ASSERT_MSG(instr.xmad.sign_a == instr.xmad.sign_b, "Unimplemented");
+            const bool is_signed{instr.xmad.sign_a == 1};
+
+            bool is_merge{};
+            switch (opcode->GetId()) {
+            case OpCode::Id::XMAD_CR: {
+                is_merge = instr.xmad.merge_56;
+                op_b += regs.GetUniform(instr.cbuf34.index, instr.cbuf34.offset,
+                                        instr.xmad.sign_b ? GLSLRegister::Type::Integer
+                                                          : GLSLRegister::Type::UnsignedInteger);
+                op_c += regs.GetRegisterAsInteger(instr.gpr39, 0, is_signed);
+                break;
+            }
+            case OpCode::Id::XMAD_RR: {
+                is_merge = instr.xmad.merge_37;
+                op_b += regs.GetRegisterAsInteger(instr.gpr20, 0, instr.xmad.sign_b);
+                op_c += regs.GetRegisterAsInteger(instr.gpr39, 0, is_signed);
+                break;
+            }
+            case OpCode::Id::XMAD_RC: {
+                op_b += regs.GetRegisterAsInteger(instr.gpr39, 0, instr.xmad.sign_b);
+                op_c += regs.GetUniform(instr.cbuf34.index, instr.cbuf34.offset,
+                                        is_signed ? GLSLRegister::Type::Integer
+                                                  : GLSLRegister::Type::UnsignedInteger);
+                break;
+            }
+            case OpCode::Id::XMAD_IMM: {
+                is_merge = instr.xmad.merge_37;
+                op_b += std::to_string(instr.xmad.imm20_16);
+                op_c += regs.GetRegisterAsInteger(instr.gpr39, 0, is_signed);
+                break;
+            }
+            default: {
+                LOG_CRITICAL(HW_GPU, "Unhandled XMAD instruction: {}", opcode->GetName());
+                UNREACHABLE();
+            }
+            }
+
+            // TODO(bunnei): Ensure this is right with signed operands
+            if (instr.xmad.high_a) {
+                op_a = "((" + op_a + ") >> 16)";
+            } else {
+                op_a = "((" + op_a + ") & 0xFFFF)";
+            }
+
+            std::string src2 = '(' + op_b + ')'; // Preserve original source 2
+            if (instr.xmad.high_b) {
+                op_b = '(' + src2 + " >> 16)";
+            } else {
+                op_b = '(' + src2 + " & 0xFFFF)";
+            }
+
+            std::string product = '(' + op_a + " * " + op_b + ')';
+            if (instr.xmad.product_shift_left) {
+                product = '(' + product + " << 16)";
+            }
+
+            switch (instr.xmad.mode) {
+            case Tegra::Shader::XmadMode::None:
+                break;
+            case Tegra::Shader::XmadMode::CLo:
+                op_c = "((" + op_c + ") & 0xFFFF)";
+                break;
+            case Tegra::Shader::XmadMode::CHi:
+                op_c = "((" + op_c + ") >> 16)";
+                break;
+            case Tegra::Shader::XmadMode::CBcc:
+                op_c = "((" + op_c + ") + (" + src2 + "<< 16))";
+                break;
+            default: {
+                LOG_CRITICAL(HW_GPU, "Unhandled XMAD mode: {}",
+                             static_cast<u32>(instr.xmad.mode.Value()));
+                UNREACHABLE();
+            }
+            }
+
+            std::string sum{'(' + product + " + " + op_c + ')'};
+            if (is_merge) {
+                sum = "((" + sum + " & 0xFFFF) | (" + src2 + "<< 16))";
+            }
+
+            regs.SetRegisterToInteger(instr.gpr0, is_signed, 0, sum, 1, 1);
+            break;
+        }
         default: {
             switch (opcode->GetId()) {
             case OpCode::Id::EXIT: {