Merge pull request #3145 from MerryMage/lg2-ex2

shader_jit_x64_compiler: Remove ABI overhead of LG2 and EX2

src/tests/CMakeLists.txt

@@ -14,11 +14,17 @@ set(HEADERS
             core/arm/arm_test_common.h
             )
 
+if (ARCHITECTURE_x86_64)
+    set(SRCS ${SRCS}
+            video_core/shader/shader_jit_x64_compiler.cpp
+            )
+endif()
+
 create_directory_groups(${SRCS} ${HEADERS})
 
 add_executable(tests ${SRCS} ${HEADERS})
-target_link_libraries(tests PRIVATE common core)
+target_link_libraries(tests PRIVATE common core video_core)
 target_link_libraries(tests PRIVATE glad) # To support linker work-around
-target_link_libraries(tests PRIVATE ${PLATFORM_LIBRARIES} catch-single-include Threads::Threads)
+target_link_libraries(tests PRIVATE ${PLATFORM_LIBRARIES} catch-single-include nihstro-headers Threads::Threads)
 
 add_test(NAME tests COMMAND tests)

src/tests/video_core/shader/shader_jit_x64_compiler.cpp

@@ -0,0 +1,91 @@
+// Copyright 2017 Citra Emulator Project
+// Licensed under GPLv2 or any later version
+// Refer to the license.txt file included.
+
+#include <algorithm>
+#include <cmath>
+#include <memory>
+#include <catch.hpp>
+#include <nihstro/inline_assembly.h>
+#include "video_core/shader/shader_jit_x64_compiler.h"
+
+using float24 = Pica::float24;
+using JitShader = Pica::Shader::JitShader;
+
+using DestRegister = nihstro::DestRegister;
+using OpCode = nihstro::OpCode;
+using SourceRegister = nihstro::SourceRegister;
+
+static std::unique_ptr<JitShader> CompileShader(std::initializer_list<nihstro::InlineAsm> code) {
+    const auto shbin = nihstro::InlineAsm::CompileToRawBinary(code);
+
+    std::array<u32, Pica::Shader::MAX_PROGRAM_CODE_LENGTH> program_code{};
+    std::array<u32, Pica::Shader::MAX_SWIZZLE_DATA_LENGTH> swizzle_data{};
+
+    std::transform(shbin.program.begin(), shbin.program.end(), program_code.begin(),
+                   [](const auto& x) { return x.hex; });
+    std::transform(shbin.swizzle_table.begin(), shbin.swizzle_table.end(), swizzle_data.begin(),
+                   [](const auto& x) { return x.hex; });
+
+    auto shader = std::make_unique<JitShader>();
+    shader->Compile(&program_code, &swizzle_data);
+
+    return shader;
+}
+
+class ShaderTest {
+public:
+    explicit ShaderTest(std::initializer_list<nihstro::InlineAsm> code)
+        : shader(CompileShader(code)) {}
+
+    float Run(float input) {
+        Pica::Shader::ShaderSetup shader_setup;
+        Pica::Shader::UnitState shader_unit;
+
+        shader_unit.registers.input[0].x = float24::FromFloat32(input);
+        shader->Run(shader_setup, shader_unit, 0);
+        return shader_unit.registers.output[0].x.ToFloat32();
+    }
+
+public:
+    std::unique_ptr<JitShader> shader;
+};
+
+TEST_CASE("LG2", "[video_core][shader][shader_jit]") {
+    const auto sh_input = SourceRegister::MakeInput(0);
+    const auto sh_output = DestRegister::MakeOutput(0);
+
+    auto shader = ShaderTest({
+        // clang-format off
+        {OpCode::Id::LG2, sh_output, sh_input},
+        {OpCode::Id::END},
+        // clang-format on
+    });
+
+    REQUIRE(std::isnan(shader.Run(NAN)));
+    REQUIRE(std::isnan(shader.Run(-1.f)));
+    REQUIRE(std::isinf(shader.Run(0.f)));
+    REQUIRE(shader.Run(4.f) == Approx(2.f));
+    REQUIRE(shader.Run(64.f) == Approx(6.f));
+    REQUIRE(shader.Run(1.e24f) == Approx(79.7262742773f));
+}
+
+TEST_CASE("EX2", "[video_core][shader][shader_jit]") {
+    const auto sh_input = SourceRegister::MakeInput(0);
+    const auto sh_output = DestRegister::MakeOutput(0);
+
+    auto shader = ShaderTest({
+        // clang-format off
+        {OpCode::Id::EX2, sh_output, sh_input},
+        {OpCode::Id::END},
+        // clang-format on
+    });
+
+    REQUIRE(std::isnan(shader.Run(NAN)));
+    REQUIRE(shader.Run(-800.f) == Approx(0.f));
+    REQUIRE(shader.Run(0.f) == Approx(1.f));
+    REQUIRE(shader.Run(2.f) == Approx(4.f));
+    REQUIRE(shader.Run(6.f) == Approx(64.f));
+    REQUIRE(shader.Run(79.7262742773f) == Approx(1.e24f));
+    REQUIRE(std::isinf(shader.Run(800.f)));
+}

src/video_core/CMakeLists.txt

@@ -87,7 +87,7 @@ target_link_libraries(video_core PUBLIC common core)
 target_link_libraries(video_core PRIVATE glad nihstro-headers)
 
 if (ARCHITECTURE_x86_64)
-    target_link_libraries(video_core PRIVATE xbyak)
+    target_link_libraries(video_core PUBLIC xbyak)
 endif()
 
 if (PNG_FOUND)

src/video_core/shader/shader_jit_x64_compiler.cpp

@@ -432,27 +432,13 @@ void JitShader::Compile_DPH(Instruction instr) {
 
 void JitShader::Compile_EX2(Instruction instr) {
     Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
-    movss(xmm0, SRC1); // ABI_PARAM1
-
-    ABI_PushRegistersAndAdjustStack(*this, PersistentCallerSavedRegs(), 0);
-    CallFarFunction(*this, exp2f);
-    ABI_PopRegistersAndAdjustStack(*this, PersistentCallerSavedRegs(), 0);
-
-    shufps(xmm0, xmm0, _MM_SHUFFLE(0, 0, 0, 0)); // ABI_RETURN
-    movaps(SRC1, xmm0);
+    call(exp2_subroutine);
     Compile_DestEnable(instr, SRC1);
 }
 
 void JitShader::Compile_LG2(Instruction instr) {
     Compile_SwizzleSrc(instr, 1, instr.common.src1, SRC1);
-    movss(xmm0, SRC1); // ABI_PARAM1
-
-    ABI_PushRegistersAndAdjustStack(*this, PersistentCallerSavedRegs(), 0);
-    CallFarFunction(*this, log2f);
-    ABI_PopRegistersAndAdjustStack(*this, PersistentCallerSavedRegs(), 0);
-
-    shufps(xmm0, xmm0, _MM_SHUFFLE(0, 0, 0, 0)); // ABI_RETURN
-    movaps(SRC1, xmm0);
+    call(log2_subroutine);
     Compile_DestEnable(instr, SRC1);
 }
 
@@ -935,7 +921,179 @@ void JitShader::Compile(const std::array<u32, MAX_PROGRAM_CODE_LENGTH>* program_
     LOG_DEBUG(HW_GPU, "Compiled shader size=%lu", getSize());
 }
 
-JitShader::JitShader() : Xbyak::CodeGenerator(MAX_SHADER_SIZE) {}
+JitShader::JitShader() : Xbyak::CodeGenerator(MAX_SHADER_SIZE) {
+    CompilePrelude();
+}
+
+void JitShader::CompilePrelude() {
+    log2_subroutine = CompilePrelude_Log2();
+    exp2_subroutine = CompilePrelude_Exp2();
+}
+
+Xbyak::Label JitShader::CompilePrelude_Log2() {
+    Xbyak::Label subroutine;
+
+    // SSE does not have a log instruction, thus we must approximate.
+    // We perform this approximation first performaing a range reduction into the range [1.0, 2.0).
+    // A minimax polynomial which was fit for the function log2(x) / (x - 1) is then evaluated.
+    // We multiply the result by (x - 1) then restore the result into the appropriate range.
+
+    // Coefficients for the minimax polynomial.
+    // f(x) computes approximately log2(x) / (x - 1).
+    // f(x) = c4 + x * (c3 + x * (c2 + x * (c1 + x * c0)).
+    align(64);
+    const void* c0 = getCurr();
+    dd(0x3d74552f);
+    const void* c1 = getCurr();
+    dd(0xbeee7397);
+    const void* c2 = getCurr();
+    dd(0x3fbd96dd);
+    const void* c3 = getCurr();
+    dd(0xc02153f6);
+    const void* c4 = getCurr();
+    dd(0x4038d96c);
+
+    align(16);
+    const void* negative_infinity_vector = getCurr();
+    dd(0xff800000);
+    dd(0xff800000);
+    dd(0xff800000);
+    dd(0xff800000);
+    const void* default_qnan_vector = getCurr();
+    dd(0x7fc00000);
+    dd(0x7fc00000);
+    dd(0x7fc00000);
+    dd(0x7fc00000);
+
+    Xbyak::Label input_is_nan, input_is_zero, input_out_of_range;
+
+    align(16);
+    L(input_out_of_range);
+    je(input_is_zero);
+    movaps(SRC1, xword[rip + default_qnan_vector]);
+    ret();
+    L(input_is_zero);
+    movaps(SRC1, xword[rip + negative_infinity_vector]);
+    ret();
+
+    align(16);
+    L(subroutine);
+
+    // Here we handle edge cases: input in {NaN, 0, -Inf, Negative}.
+    xorps(SCRATCH, SCRATCH);
+    ucomiss(SCRATCH, SRC1);
+    jp(input_is_nan);
+    jae(input_out_of_range);
+
+    // Split input
+    movd(eax, SRC1);
+    mov(edx, eax);
+    and_(eax, 0x7f800000);
+    and_(edx, 0x007fffff);
+    movss(SCRATCH, xword[rip + c0]); // Preload c0.
+    or_(edx, 0x3f800000);
+    movd(SRC1, edx);
+    // SRC1 now contains the mantissa of the input.
+    mulss(SCRATCH, SRC1);
+    shr(eax, 23);
+    sub(eax, 0x7f);
+    cvtsi2ss(SCRATCH2, eax);
+    // SCRATCH2 now contains the exponent of the input.
+
+    // Complete computation of polynomial
+    addss(SCRATCH, xword[rip + c1]);
+    mulss(SCRATCH, SRC1);
+    addss(SCRATCH, xword[rip + c2]);
+    mulss(SCRATCH, SRC1);
+    addss(SCRATCH, xword[rip + c3]);
+    mulss(SCRATCH, SRC1);
+    subss(SRC1, ONE);
+    addss(SCRATCH, xword[rip + c4]);
+    mulss(SCRATCH, SRC1);
+    addss(SCRATCH2, SCRATCH);
+
+    // Duplicate result across vector
+    xorps(SRC1, SRC1); // break dependency chain
+    movss(SRC1, SCRATCH2);
+    L(input_is_nan);
+    shufps(SRC1, SRC1, _MM_SHUFFLE(0, 0, 0, 0));
+
+    ret();
+
+    return subroutine;
+}
+
+Xbyak::Label JitShader::CompilePrelude_Exp2() {
+    Xbyak::Label subroutine;
+
+    // SSE does not have a exp instruction, thus we must approximate.
+    // We perform this approximation first performaing a range reduction into the range [-0.5, 0.5).
+    // A minimax polynomial which was fit for the function exp2(x) is then evaluated.
+    // We then restore the result into the appropriate range.
+
+    align(64);
+    const void* input_max = getCurr();
+    dd(0x43010000);
+    const void* input_min = getCurr();
+    dd(0xc2fdffff);
+    const void* c0 = getCurr();
+    dd(0x3c5dbe69);
+    const void* half = getCurr();
+    dd(0x3f000000);
+    const void* c1 = getCurr();
+    dd(0x3d5509f9);
+    const void* c2 = getCurr();
+    dd(0x3e773cc5);
+    const void* c3 = getCurr();
+    dd(0x3f3168b3);
+    const void* c4 = getCurr();
+    dd(0x3f800016);
+
+    Xbyak::Label ret_label;
+
+    align(16);
+    L(subroutine);
+
+    // Handle edge cases
+    ucomiss(SRC1, SRC1);
+    jp(ret_label);
+    // Clamp to maximum range since we shift the value directly into the exponent.
+    minss(SRC1, xword[rip + input_max]);
+    maxss(SRC1, xword[rip + input_min]);
+
+    // Decompose input
+    movss(SCRATCH, SRC1);
+    movss(SCRATCH2, xword[rip + c0]); // Preload c0.
+    subss(SCRATCH, xword[rip + half]);
+    cvtss2si(eax, SCRATCH);
+    cvtsi2ss(SCRATCH, eax);
+    // SCRATCH now contains input rounded to the nearest integer.
+    add(eax, 0x7f);
+    subss(SRC1, SCRATCH);
+    // SRC1 contains input - round(input), which is in [-0.5, 0.5).
+    mulss(SCRATCH2, SRC1);
+    shl(eax, 23);
+    movd(SCRATCH, eax);
+    // SCRATCH contains 2^(round(input)).
+
+    // Complete computation of polynomial.
+    addss(SCRATCH2, xword[rip + c1]);
+    mulss(SCRATCH2, SRC1);
+    addss(SCRATCH2, xword[rip + c2]);
+    mulss(SCRATCH2, SRC1);
+    addss(SCRATCH2, xword[rip + c3]);
+    mulss(SRC1, SCRATCH2);
+    addss(SRC1, xword[rip + c4]);
+    mulss(SRC1, SCRATCH);
+
+    // Duplicate result across vector
+    L(ret_label);
+    shufps(SRC1, SRC1, _MM_SHUFFLE(0, 0, 0, 0));
+
+    ret();
+
+    return subroutine;
+}
 
 } // namespace Shader
 

src/video_core/shader/shader_jit_x64_compiler.h

@@ -106,6 +106,13 @@ private:
      */
     void FindReturnOffsets();
 
+    /**
+     * Emits data and code for utility functions.
+     */
+    void CompilePrelude();
+    Xbyak::Label CompilePrelude_Log2();
+    Xbyak::Label CompilePrelude_Exp2();
+
     const std::array<u32, MAX_PROGRAM_CODE_LENGTH>* program_code = nullptr;
     const std::array<u32, MAX_SWIZZLE_DATA_LENGTH>* swizzle_data = nullptr;
 
@@ -120,6 +127,9 @@ private:
 
     using CompiledShader = void(const void* setup, void* state, const u8* start_addr);
     CompiledShader* program = nullptr;
+
+    Xbyak::Label log2_subroutine;
+    Xbyak::Label exp2_subroutine;
 };
 
 } // Shader