shader_decode: Implement HFMA2

src/video_core/engines/shader_bytecode.h

@@ -648,6 +648,7 @@ union Instruction {
             BitField<37, 2, HalfPrecision> precision;
             BitField<32, 1, u64> saturate;
 
+            BitField<31, 1, u64> negate_b;
             BitField<30, 1, u64> negate_c;
             BitField<35, 2, HalfType> type_c;
         } rr;

src/video_core/shader/decode/hfma2.cpp

@@ -2,6 +2,8 @@
 // Licensed under GPLv2 or any later version
 // Refer to the license.txt file included.
 
+#include <tuple>
+
 #include "common/assert.h"
 #include "common/common_types.h"
 #include "video_core/engines/shader_bytecode.h"
@@ -9,6 +11,8 @@
 
 namespace VideoCommon::Shader {
 
+using Tegra::Shader::HalfPrecision;
+using Tegra::Shader::HalfType;
 using Tegra::Shader::Instruction;
 using Tegra::Shader::OpCode;
 
@@ -16,7 +20,55 @@ u32 ShaderIR::DecodeHfma2(BasicBlock& bb, u32 pc) {
     const Instruction instr = {program_code[pc]};
     const auto opcode = OpCode::Decode(instr);
 
-    UNIMPLEMENTED();
+    if (opcode->get().GetId() == OpCode::Id::HFMA2_RR) {
+        UNIMPLEMENTED_IF(instr.hfma2.rr.precision != HalfPrecision::None);
+    } else {
+        UNIMPLEMENTED_IF(instr.hfma2.precision != HalfPrecision::None);
+    }
+
+    constexpr auto identity = HalfType::H0_H1;
+
+    const HalfType type_a = instr.hfma2.type_a;
+    const Node op_a = GetRegister(instr.gpr8);
+
+    bool neg_b{}, neg_c{};
+    auto [saturate, type_b, op_b, type_c,
+          op_c] = [&]() -> std::tuple<bool, HalfType, Node, HalfType, Node> {
+        switch (opcode->get().GetId()) {
+        case OpCode::Id::HFMA2_CR:
+            neg_b = instr.hfma2.negate_b;
+            neg_c = instr.hfma2.negate_c;
+            return {instr.hfma2.saturate, instr.hfma2.type_b,
+                    GetConstBuffer(instr.cbuf34.index, instr.cbuf34.offset), instr.hfma2.type_reg39,
+                    GetRegister(instr.gpr39)};
+        case OpCode::Id::HFMA2_RC:
+            neg_b = instr.hfma2.negate_b;
+            neg_c = instr.hfma2.negate_c;
+            return {instr.hfma2.saturate, instr.hfma2.type_reg39, GetRegister(instr.gpr39),
+                    instr.hfma2.type_b, GetConstBuffer(instr.cbuf34.index, instr.cbuf34.offset)};
+        case OpCode::Id::HFMA2_RR:
+            neg_b = instr.hfma2.rr.negate_b;
+            neg_c = instr.hfma2.rr.negate_c;
+            return {instr.hfma2.rr.saturate, instr.hfma2.type_b, GetRegister(instr.gpr20),
+                    instr.hfma2.rr.type_c, GetRegister(instr.gpr39)};
+        case OpCode::Id::HFMA2_IMM_R:
+            neg_c = instr.hfma2.negate_c;
+            return {instr.hfma2.saturate, identity, UnpackHalfImmediate(instr, true),
+                    instr.hfma2.type_reg39, GetRegister(instr.gpr39)};
+        default:
+            return {false, identity, Immediate(0), identity, Immediate(0)};
+        }
+    }();
+    UNIMPLEMENTED_IF_MSG(saturate, "HFMA2 saturation is not implemented");
+
+    op_b = GetOperandAbsNegHalf(op_b, false, neg_b);
+    op_c = GetOperandAbsNegHalf(op_c, false, neg_c);
+
+    MetaHalfArithmetic meta{true, {type_a, type_b, type_c}};
+    Node value = Operation(OperationCode::HFma, meta, op_a, op_b, op_c);
+    value = HalfMerge(GetRegister(instr.gpr0), value, instr.hfma2.merge);
+
+    SetRegister(bb, instr.gpr0, value);
 
     return pc;
 }

src/video_core/shader/glsl_decompiler.cpp

@@ -762,9 +762,9 @@ private:
         return GenerateBinaryInfix(operation, "/", type, type, type);
     }
 
-    std::string FFma(Operation operation) {
-        return GenerateTernary(operation, "fma", Type::Float, Type::Float, Type::Float,
-                               Type::Float);
+    template <Type type>
+    std::string Fma(Operation operation) {
+        return GenerateTernary(operation, "fma", type, type, type, type);
     }
 
     template <Type type>
@@ -1231,7 +1231,7 @@ private:
         &Add<Type::Float>,
         &Mul<Type::Float>,
         &Div<Type::Float>,
-        &FFma,
+        &Fma<Type::Float>,
         &Negate<Type::Float>,
         &Absolute<Type::Float>,
         &FClamp,
@@ -1289,6 +1289,7 @@ private:
 
         &Add<Type::HalfFloat>,
         &Mul<Type::HalfFloat>,
+        &Fma<Type::HalfFloat>,
         &Absolute<Type::HalfFloat>,
         &HNegate,
         &HMergeF32,

src/video_core/shader/shader_ir.h

@@ -110,6 +110,7 @@ enum class OperationCode {
 
     HAdd,      /// (MetaHalfArithmetic, f16vec2 a, f16vec2 b) -> f16vec2
     HMul,      /// (MetaHalfArithmetic, f16vec2 a, f16vec2 b) -> f16vec2
+    HFma,      /// (MetaHalfArithmetic, f16vec2 a, f16vec2 b, f16vec2 c) -> f16vec2
     HAbsolute, /// (f16vec2 a) -> f16vec2
     HNegate,   /// (f16vec2 a, bool first, bool second) -> f16vec2
     HMergeF32, /// (f16vec2 src) -> float