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shader_jit_x64: Rewrite flow control to support arbitrary CALL and JMP instructions.

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This commit is contained in:
bunnei 2016-03-17 19:45:09 -04:00
parent 135aec7bea
commit 4632791a40
2 changed files with 122 additions and 38 deletions
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128
src/video_core/shader/shader_jit_x64.cpp
View File

@ -137,6 +137,15 @@ static const u8 NO_SRC_REG_SWIZZLE = 0x1b;
/// Raw constant for the destination register enable mask that indicates all components are enabled
static const u8 NO_DEST_REG_MASK = 0xf;
/**
* Get the vertex shader instruction for a given offset in the current shader program
* @param offset Offset in the current shader program of the instruction
* @return Instruction at the specified offset
*/
static Instruction GetVertexShaderInstruction(size_t offset) {
return { g_state.vs.program_code[offset] };
}
/**
* Loads and swizzles a source register into the specified XMM register.
* @param instr VS instruction, used for determining how to load the source register
@ -564,10 +573,23 @@ void JitCompiler::Compile_END(Instruction instr) {
}
void JitCompiler::Compile_CALL(Instruction instr) {
unsigned offset = instr.flow_control.dest_offset;
while (offset < (instr.flow_control.dest_offset + instr.flow_control.num_instructions)) {
Compile_NextInstr(&offset);
}
// Need to advance the return address past the proceeding instructions, this is the number of bytes to skip
constexpr unsigned SKIP = 21;
const uintptr_t start = reinterpret_cast<uintptr_t>(GetCodePtr());
// Push return address - not using CALL because we also want to push the offset of the return before jumping
MOV(64, R(RAX), ImmPtr(GetCodePtr() + SKIP));
PUSH(RAX);
// Push offset of the return
PUSH(32, Imm32(instr.flow_control.dest_offset + instr.flow_control.num_instructions));
// Jump
FixupBranch b = J(true);
fixup_branches.push_back({ b, instr.flow_control.dest_offset });
// Make sure that if the above code changes, SKIP gets updated
ASSERT(reinterpret_cast<uintptr_t>(GetCodePtr()) - start == SKIP);
}
void JitCompiler::Compile_CALLC(Instruction instr) {
@ -645,8 +667,8 @@ void JitCompiler::Compile_MAD(Instruction instr) {
}
void JitCompiler::Compile_IF(Instruction instr) {
ASSERT_MSG(instr.flow_control.dest_offset > *offset_ptr, "Backwards if-statements (%d -> %d) not supported",
*offset_ptr, instr.flow_control.dest_offset.Value());
ASSERT_MSG(instr.flow_control.dest_offset > last_program_counter, "Backwards if-statements (%d -> %d) not supported",
last_program_counter, instr.flow_control.dest_offset.Value());
// Evaluate the "IF" condition
if (instr.opcode.Value() == OpCode::Id::IFU) {
@ -677,8 +699,8 @@ void JitCompiler::Compile_IF(Instruction instr) {
}
void JitCompiler::Compile_LOOP(Instruction instr) {
ASSERT_MSG(instr.flow_control.dest_offset > *offset_ptr, "Backwards loops (%d -> %d) not supported",
*offset_ptr, instr.flow_control.dest_offset.Value());
ASSERT_MSG(instr.flow_control.dest_offset > last_program_counter, "Backwards loops (%d -> %d) not supported",
last_program_counter, instr.flow_control.dest_offset.Value());
ASSERT_MSG(!looping, "Nested loops not supported");
looping = true;
@ -706,9 +728,6 @@ void JitCompiler::Compile_LOOP(Instruction instr) {
}
void JitCompiler::Compile_JMP(Instruction instr) {
ASSERT_MSG(instr.flow_control.dest_offset > *offset_ptr, "Backwards jumps (%d -> %d) not supported",
*offset_ptr, instr.flow_control.dest_offset.Value());
if (instr.opcode.Value() == OpCode::Id::JMPC)
Compile_EvaluateCondition(instr);
else if (instr.opcode.Value() == OpCode::Id::JMPU)
@ -718,31 +737,42 @@ void JitCompiler::Compile_JMP(Instruction instr) {
bool inverted_condition = (instr.opcode.Value() == OpCode::Id::JMPU) &&
(instr.flow_control.num_instructions & 1);
FixupBranch b = J_CC(inverted_condition ? CC_Z : CC_NZ, true);
Compile_Block(instr.flow_control.dest_offset);
SetJumpTarget(b);
fixup_branches.push_back({ b, instr.flow_control.dest_offset });
}
void JitCompiler::Compile_Block(unsigned end) {
// Save current offset pointer
unsigned* prev_offset_ptr = offset_ptr;
unsigned offset = *prev_offset_ptr;
while (offset < end)
Compile_NextInstr(&offset);
// Restore current offset pointer
offset_ptr = prev_offset_ptr;
*offset_ptr = offset;
while (program_counter < end) {
Compile_NextInstr();
}
}
void JitCompiler::Compile_NextInstr(unsigned* offset) {
offset_ptr = offset;
void JitCompiler::Compile_Return() {
// Peek return offset on the stack and check if we're at that offset
MOV(64, R(RAX), MDisp(RSP, 0));
CMP(32, R(RAX), Imm32(program_counter));
Instruction instr;
std::memcpy(&instr, &g_state.vs.program_code[(*offset_ptr)++], sizeof(Instruction));
// If so, jump back to before CALL
FixupBranch b = J_CC(CC_NZ, true);
ADD(64, R(RSP), Imm32(8)); // Ignore return offset that's on the stack
POP(RAX); // Pop off return address
JMPptr(R(RAX));
SetJumpTarget(b);
}
void JitCompiler::Compile_NextInstr() {
last_program_counter = program_counter;
auto search = return_offsets.find(program_counter);
if (search != return_offsets.end()) {
Compile_Return();
}
ASSERT_MSG(code_ptr[program_counter] == nullptr, "Tried to compile already compiled shader location!");
code_ptr[program_counter] = GetCodePtr();
Instruction instr = GetVertexShaderInstruction(program_counter++);
OpCode::Id opcode = instr.opcode.Value();
auto instr_func = instr_table[static_cast<unsigned>(opcode)];
@ -757,9 +787,24 @@ void JitCompiler::Compile_NextInstr(unsigned* offset) {
}
}
void JitCompiler::FindReturnOffsets() {
return_offsets.clear();
for (size_t offset = 0; offset < g_state.vs.program_code.size(); ++offset) {
Instruction instr = GetVertexShaderInstruction(offset);
switch (instr.opcode.Value()) {
case OpCode::Id::CALL:
case OpCode::Id::CALLC:
case OpCode::Id::CALLU:
return_offsets.insert(instr.flow_control.dest_offset + instr.flow_control.num_instructions);
break;
}
}
}
CompiledShader* JitCompiler::Compile() {
const u8* start = GetCodePtr();
unsigned offset = g_state.regs.vs.main_offset;
// The stack pointer is 8 modulo 16 at the entry of a procedure
ABI_PushRegistersAndAdjustStack(ABI_ALL_CALLEE_SAVED, 8);
@ -782,10 +827,27 @@ CompiledShader* JitCompiler::Compile() {
MOV(PTRBITS, R(RAX), ImmPtr(&neg));
MOVAPS(NEGBIT, MatR(RAX));
looping = false;
// Find all `CALL` instructions and identify return locations
FindReturnOffsets();
while (offset < g_state.vs.program_code.size()) {
Compile_NextInstr(&offset);
// Reset flow control state
last_program_counter = 0;
program_counter = 0;
looping = false;
code_ptr.fill(nullptr);
fixup_branches.clear();
// Jump to start of the shader program
if (g_state.regs.vs.main_offset != 0) {
fixup_branches.push_back({ J(true), g_state.regs.vs.main_offset });
}
// Compile entire program
Compile_Block(static_cast<unsigned>(g_state.vs.program_code.size()));
// Set the target for any incomplete branches now that the entire shader program has been emitted
for (const auto& branch : fixup_branches) {
SetJumpTarget(branch.first, code_ptr[branch.second]);
}
return (CompiledShader*)start;

32
src/video_core/shader/shader_jit_x64.h
View File

@ -4,6 +4,9 @@
#pragma once
#include <set>
#include <utility>
#include <nihstro/shader_bytecode.h>
#include "common/x64/emitter.h"
@ -66,8 +69,9 @@ public:
void Compile_MAD(Instruction instr);
private:
void Compile_Block(unsigned end);
void Compile_NextInstr(unsigned* offset);
void Compile_NextInstr();
void Compile_SwizzleSrc(Instruction instr, unsigned src_num, SourceRegister src_reg, Gen::X64Reg dest);
void Compile_DestEnable(Instruction instr, Gen::X64Reg dest);
@ -81,13 +85,31 @@ private:
void Compile_EvaluateCondition(Instruction instr);
void Compile_UniformCondition(Instruction instr);
/**
* Emits the code to conditionally return from a subroutine envoked by the `CALL` instruction.
*/
void Compile_Return();
BitSet32 PersistentCallerSavedRegs();
/// Pointer to the variable that stores the current Pica code offset. Used to handle nested code blocks.
unsigned* offset_ptr = nullptr;
/**
* Analyzes the entire shader program for `CALL` instructions before emitting any code,
* identifying the locations where a return needs to be inserted.
*/
void FindReturnOffsets();
/// Set to true if currently in a loop, used to check for the existence of nested loops
bool looping = false;
/// Mapping of Pica VS instructions to pointers in the emitted code
std::array<const u8*, 1024> code_ptr;
/// Offsets in code where a return needs to be inserted
std::set<unsigned> return_offsets;
unsigned last_program_counter; ///< Offset of the most recent instruction decoded
unsigned program_counter; ///< Offset of the next instruction to decode
bool looping = false; ///< True if compiling a loop, used to check for nested loops
/// Branches that need to be fixed up once the entire shader program is compiled
std::vector<std::pair<Gen::FixupBranch, unsigned>> fixup_branches;
};
} // Shader