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https://github.com/PabloMK7/citra.git
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shader_jit_x64: Rewrite flow control to support arbitrary CALL and JMP instructions.
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bunnei
parent
135aec7bea
commit
4632791a40
2 changed files with 122 additions and 38 deletions
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@ -137,6 +137,15 @@ static const u8 NO_SRC_REG_SWIZZLE = 0x1b;
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/// Raw constant for the destination register enable mask that indicates all components are enabled
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static const u8 NO_DEST_REG_MASK = 0xf;
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/**
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* Get the vertex shader instruction for a given offset in the current shader program
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* @param offset Offset in the current shader program of the instruction
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* @return Instruction at the specified offset
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*/
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static Instruction GetVertexShaderInstruction(size_t offset) {
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return { g_state.vs.program_code[offset] };
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}
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/**
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* Loads and swizzles a source register into the specified XMM register.
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* @param instr VS instruction, used for determining how to load the source register
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@ -564,10 +573,23 @@ void JitCompiler::Compile_END(Instruction instr) {
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}
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void JitCompiler::Compile_CALL(Instruction instr) {
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unsigned offset = instr.flow_control.dest_offset;
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while (offset < (instr.flow_control.dest_offset + instr.flow_control.num_instructions)) {
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Compile_NextInstr(&offset);
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}
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// Need to advance the return address past the proceeding instructions, this is the number of bytes to skip
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constexpr unsigned SKIP = 21;
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const uintptr_t start = reinterpret_cast<uintptr_t>(GetCodePtr());
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// Push return address - not using CALL because we also want to push the offset of the return before jumping
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MOV(64, R(RAX), ImmPtr(GetCodePtr() + SKIP));
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PUSH(RAX);
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// Push offset of the return
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PUSH(32, Imm32(instr.flow_control.dest_offset + instr.flow_control.num_instructions));
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// Jump
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FixupBranch b = J(true);
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fixup_branches.push_back({ b, instr.flow_control.dest_offset });
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// Make sure that if the above code changes, SKIP gets updated
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ASSERT(reinterpret_cast<uintptr_t>(GetCodePtr()) - start == SKIP);
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}
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void JitCompiler::Compile_CALLC(Instruction instr) {
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@ -645,8 +667,8 @@ void JitCompiler::Compile_MAD(Instruction instr) {
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}
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void JitCompiler::Compile_IF(Instruction instr) {
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ASSERT_MSG(instr.flow_control.dest_offset > *offset_ptr, "Backwards if-statements (%d -> %d) not supported",
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*offset_ptr, instr.flow_control.dest_offset.Value());
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ASSERT_MSG(instr.flow_control.dest_offset > last_program_counter, "Backwards if-statements (%d -> %d) not supported",
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last_program_counter, instr.flow_control.dest_offset.Value());
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// Evaluate the "IF" condition
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if (instr.opcode.Value() == OpCode::Id::IFU) {
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@ -677,8 +699,8 @@ void JitCompiler::Compile_IF(Instruction instr) {
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}
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void JitCompiler::Compile_LOOP(Instruction instr) {
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ASSERT_MSG(instr.flow_control.dest_offset > *offset_ptr, "Backwards loops (%d -> %d) not supported",
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*offset_ptr, instr.flow_control.dest_offset.Value());
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ASSERT_MSG(instr.flow_control.dest_offset > last_program_counter, "Backwards loops (%d -> %d) not supported",
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last_program_counter, instr.flow_control.dest_offset.Value());
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ASSERT_MSG(!looping, "Nested loops not supported");
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looping = true;
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@ -706,9 +728,6 @@ void JitCompiler::Compile_LOOP(Instruction instr) {
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}
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void JitCompiler::Compile_JMP(Instruction instr) {
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ASSERT_MSG(instr.flow_control.dest_offset > *offset_ptr, "Backwards jumps (%d -> %d) not supported",
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*offset_ptr, instr.flow_control.dest_offset.Value());
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if (instr.opcode.Value() == OpCode::Id::JMPC)
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Compile_EvaluateCondition(instr);
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else if (instr.opcode.Value() == OpCode::Id::JMPU)
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@ -718,31 +737,42 @@ void JitCompiler::Compile_JMP(Instruction instr) {
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bool inverted_condition = (instr.opcode.Value() == OpCode::Id::JMPU) &&
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(instr.flow_control.num_instructions & 1);
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FixupBranch b = J_CC(inverted_condition ? CC_Z : CC_NZ, true);
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Compile_Block(instr.flow_control.dest_offset);
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SetJumpTarget(b);
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fixup_branches.push_back({ b, instr.flow_control.dest_offset });
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}
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void JitCompiler::Compile_Block(unsigned end) {
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// Save current offset pointer
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unsigned* prev_offset_ptr = offset_ptr;
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unsigned offset = *prev_offset_ptr;
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while (offset < end)
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Compile_NextInstr(&offset);
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// Restore current offset pointer
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offset_ptr = prev_offset_ptr;
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*offset_ptr = offset;
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while (program_counter < end) {
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Compile_NextInstr();
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}
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}
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void JitCompiler::Compile_NextInstr(unsigned* offset) {
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offset_ptr = offset;
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void JitCompiler::Compile_Return() {
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// Peek return offset on the stack and check if we're at that offset
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MOV(64, R(RAX), MDisp(RSP, 0));
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CMP(32, R(RAX), Imm32(program_counter));
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Instruction instr;
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std::memcpy(&instr, &g_state.vs.program_code[(*offset_ptr)++], sizeof(Instruction));
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// If so, jump back to before CALL
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FixupBranch b = J_CC(CC_NZ, true);
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ADD(64, R(RSP), Imm32(8)); // Ignore return offset that's on the stack
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POP(RAX); // Pop off return address
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JMPptr(R(RAX));
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SetJumpTarget(b);
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}
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void JitCompiler::Compile_NextInstr() {
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last_program_counter = program_counter;
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auto search = return_offsets.find(program_counter);
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if (search != return_offsets.end()) {
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Compile_Return();
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}
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ASSERT_MSG(code_ptr[program_counter] == nullptr, "Tried to compile already compiled shader location!");
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code_ptr[program_counter] = GetCodePtr();
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Instruction instr = GetVertexShaderInstruction(program_counter++);
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OpCode::Id opcode = instr.opcode.Value();
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auto instr_func = instr_table[static_cast<unsigned>(opcode)];
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@ -757,9 +787,24 @@ void JitCompiler::Compile_NextInstr(unsigned* offset) {
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}
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}
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void JitCompiler::FindReturnOffsets() {
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return_offsets.clear();
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for (size_t offset = 0; offset < g_state.vs.program_code.size(); ++offset) {
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Instruction instr = GetVertexShaderInstruction(offset);
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switch (instr.opcode.Value()) {
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case OpCode::Id::CALL:
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case OpCode::Id::CALLC:
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case OpCode::Id::CALLU:
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return_offsets.insert(instr.flow_control.dest_offset + instr.flow_control.num_instructions);
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break;
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}
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}
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}
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CompiledShader* JitCompiler::Compile() {
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const u8* start = GetCodePtr();
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unsigned offset = g_state.regs.vs.main_offset;
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// The stack pointer is 8 modulo 16 at the entry of a procedure
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ABI_PushRegistersAndAdjustStack(ABI_ALL_CALLEE_SAVED, 8);
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@ -782,10 +827,27 @@ CompiledShader* JitCompiler::Compile() {
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MOV(PTRBITS, R(RAX), ImmPtr(&neg));
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MOVAPS(NEGBIT, MatR(RAX));
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looping = false;
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// Find all `CALL` instructions and identify return locations
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FindReturnOffsets();
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while (offset < g_state.vs.program_code.size()) {
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Compile_NextInstr(&offset);
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// Reset flow control state
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last_program_counter = 0;
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program_counter = 0;
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looping = false;
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code_ptr.fill(nullptr);
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fixup_branches.clear();
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// Jump to start of the shader program
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if (g_state.regs.vs.main_offset != 0) {
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fixup_branches.push_back({ J(true), g_state.regs.vs.main_offset });
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}
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// Compile entire program
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Compile_Block(static_cast<unsigned>(g_state.vs.program_code.size()));
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// Set the target for any incomplete branches now that the entire shader program has been emitted
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for (const auto& branch : fixup_branches) {
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SetJumpTarget(branch.first, code_ptr[branch.second]);
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}
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return (CompiledShader*)start;
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@ -4,6 +4,9 @@
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#pragma once
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#include <set>
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#include <utility>
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#include <nihstro/shader_bytecode.h>
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#include "common/x64/emitter.h"
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@ -66,8 +69,9 @@ public:
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void Compile_MAD(Instruction instr);
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private:
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void Compile_Block(unsigned end);
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void Compile_NextInstr(unsigned* offset);
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void Compile_NextInstr();
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void Compile_SwizzleSrc(Instruction instr, unsigned src_num, SourceRegister src_reg, Gen::X64Reg dest);
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void Compile_DestEnable(Instruction instr, Gen::X64Reg dest);
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@ -81,13 +85,31 @@ private:
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void Compile_EvaluateCondition(Instruction instr);
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void Compile_UniformCondition(Instruction instr);
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/**
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* Emits the code to conditionally return from a subroutine envoked by the `CALL` instruction.
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*/
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void Compile_Return();
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BitSet32 PersistentCallerSavedRegs();
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/// Pointer to the variable that stores the current Pica code offset. Used to handle nested code blocks.
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unsigned* offset_ptr = nullptr;
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/**
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* Analyzes the entire shader program for `CALL` instructions before emitting any code,
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* identifying the locations where a return needs to be inserted.
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*/
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void FindReturnOffsets();
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/// Set to true if currently in a loop, used to check for the existence of nested loops
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bool looping = false;
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/// Mapping of Pica VS instructions to pointers in the emitted code
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std::array<const u8*, 1024> code_ptr;
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/// Offsets in code where a return needs to be inserted
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std::set<unsigned> return_offsets;
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unsigned last_program_counter; ///< Offset of the most recent instruction decoded
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unsigned program_counter; ///< Offset of the next instruction to decode
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bool looping = false; ///< True if compiling a loop, used to check for nested loops
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/// Branches that need to be fixed up once the entire shader program is compiled
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std::vector<std::pair<Gen::FixupBranch, unsigned>> fixup_branches;
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};
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} // Shader
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