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[Shader JIT] Improve call/return

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wheremyfoodat 2023-06-10 21:50:05 +03:00
parent 7e6f267462
commit 158cbb8be1
1 changed files with 19 additions and 18 deletions
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37
src/core/PICA/dynapica/shader_rec_emitter_x64.cpp
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@ -35,10 +35,12 @@ void ShaderEmitter::compile(const PICAShader& shaderUnit) {
// If we add integer register allocations they should be pushed here, and the rsp should be properly fixed up
// However most of the PICA is floating point so yeah
// Allocate shadow stack on Windows
if constexpr (isWindows()) {
sub(rsp, 32);
}
// Push a return guard on the stack. This happens due to the way we handle the PICA callstack, by pushing the return PC to stack
// By pushing ffff'ffff, we make it impossible for a return check to erroneously pass
push(qword, 0xffffffff);
// Allocate 32 bytes of shadow stack on windows, and 8 more bytes to realign stack to 16 bytes after our 4-byte push
sub(rsp, isWindows() ? (8 + 32) : 8);
// Tail call to shader code entrypoint
jmp(arg2);
align(16);
@ -84,7 +86,7 @@ void ShaderEmitter::compileInstruction(const PICAShader& shaderUnit) {
if (std::binary_search(returnPCs.begin(), returnPCs.end(), recompilerPC)) {
// This is the offset we need to add to rsp to peek the next return address in the callstack
// Ie the PICA PC address which, when reached, will trigger a return
const auto stackOffsetForPC = isWindows() ? (16 + 32) : 16;
const auto stackOffsetForPC = isWindows() ? (8 + 32) : 8;
Label end;
// Check if return address == recompilerPC, ie if we should return
@ -335,10 +337,8 @@ void ShaderEmitter::checkBoolUniform(const PICAShader& shader, u32 instruction)
void ShaderEmitter::recEND(const PICAShader& shader, u32 instruction) {
// Undo anything the prologue did and return
// Dellocate shadow stack on Windows
if constexpr (isWindows()) {
add(rsp, 32);
}
// Dellocate shadow stack on Windows, and deallocate the stack space taken up for the return guard
add(rsp, isWindows() ? (16 + 32) : 16);
// Restore registers
pop(statePointer);
@ -550,8 +550,8 @@ void ShaderEmitter::recCMP(const PICAShader& shader, u32 instruction) {
const u8 compareFuncX = conditionCodes[cmpX];
const u8 compareFuncY = conditionCodes[cmpY];
static_assert(sizeof(bool) == 1 && sizeof(shader.cmpRegister) == 2); // The code below relies on bool being 1 byte exactly
const size_t cmpRegXOffset = uintptr_t(&shader.cmpRegister) - uintptr_t(&shader);
static_assert(sizeof(shader.cmpRegister[0]) == 1 && sizeof(shader.cmpRegister) == 2); // The code below relies on bool being 1 byte exactly
const size_t cmpRegXOffset = uintptr_t(&shader.cmpRegister[0]) - uintptr_t(&shader);
const size_t cmpRegYOffset = cmpRegXOffset + sizeof(bool);
// Cmp x and y are the same compare function, we can use a single cmp instruction
@ -597,7 +597,7 @@ void ShaderEmitter::recIFC(const PICAShader& shader, u32 instruction) {
if (num == 0) { // Else block is empty,
L(elseBlock);
} else { // Else block is NOT empty
jmp(endIf, T_NEAR);
jmp(endIf, T_NEAR); // Skip executing the else branch if the if branch was ran
L(elseBlock);
compileUntil(shader, dest + num);
L(endIf);
@ -621,9 +621,8 @@ void ShaderEmitter::recIFU(const PICAShader& shader, u32 instruction) {
if (num == 0) { // Else block is empty,
L(elseBlock);
}
else { // Else block is NOT empty
jmp(endIf, T_NEAR);
} else { // Else block is NOT empty
jmp(endIf, T_NEAR); // Skip executing the else branch if the if branch was ran
L(elseBlock);
compileUntil(shader, dest + num);
L(endIf);
@ -637,14 +636,16 @@ void ShaderEmitter::recCALL(const PICAShader& shader, u32 instruction) {
// Push return PC as stack parameter. This is a decently fast solution and Citra does the same but we should probably switch to a proper PICA-like
// Callstack, because it's not great to have an infinitely expanding call stack where popping from empty stack is undefined as hell
push(qword, dest + num);
// Realign stack to 64 bits and allocate 32 bytes of shadow space on windows
sub(rsp, isWindows() ? (8 + 32) : 8);
if constexpr (isWindows()) {
// Allocate 32 bytes of shadow space on windows
sub(rsp, 32);
}
// Call subroutine, Xbyak will update the label if it hasn't been initialized yet
call(instructionLabels[dest]);
// Fix up stack after returning. The 8 from before becomes a 16 because we're also skipping the qword we pushed
add(rsp, isWindows() ? (16 + 32) : 16);
add(rsp, isWindows() ? (8 + 32) : 8);
}
#endif