N-archive/citra
1
0
Fork 0
Code Issues Pull requests Packages Projects Releases Wiki Activity

shader_jit_x64: Use CALL/RET instead of JMP for subroutines.

Browse source
This commit is contained in:
bunnei 2016-04-09 17:46:13 -04:00
parent 507e0b5989
commit 60749f2cda
1 changed files with 7 additions and 17 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

24
src/video_core/shader/shader_jit_x64.cpp
View file

@ -583,23 +583,15 @@ void JitCompiler::Compile_END(Instruction instr) {
} }
void JitCompiler::Compile_CALL(Instruction instr) { void JitCompiler::Compile_CALL(Instruction instr) {
// 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 offset of the return
PUSH(32, Imm32(instr.flow_control.dest_offset + instr.flow_control.num_instructions)); PUSH(64, Imm32(instr.flow_control.dest_offset + instr.flow_control.num_instructions));
// Jump // Call the subroutine
FixupBranch b = J(true); FixupBranch b = CALL();
fixup_branches.push_back({ b, instr.flow_control.dest_offset }); fixup_branches.push_back({ b, instr.flow_control.dest_offset });
// Make sure that if the above code changes, SKIP gets updated // Skip over the return offset that's on the stack
ASSERT(reinterpret_cast<ptrdiff_t>(GetCodePtr()) - start == SKIP); ADD(64, R(RSP), Imm32(8));
} }
void JitCompiler::Compile_CALLC(Instruction instr) { void JitCompiler::Compile_CALLC(Instruction instr) {
@ -758,14 +750,12 @@ void JitCompiler::Compile_Block(unsigned end) {
void JitCompiler::Compile_Return() { void JitCompiler::Compile_Return() {
// Peek return offset on the stack and check if we're at that offset // Peek return offset on the stack and check if we're at that offset
MOV(64, R(RAX), MDisp(RSP, 0)); MOV(64, R(RAX), MDisp(RSP, 8));
CMP(32, R(RAX), Imm32(program_counter)); CMP(32, R(RAX), Imm32(program_counter));
// If so, jump back to before CALL // If so, jump back to before CALL
FixupBranch b = J_CC(CC_NZ, true); FixupBranch b = J_CC(CC_NZ, true);
ADD(64, R(RSP), Imm32(8)); // Ignore return offset that's on the stack RET();
POP(RAX); // Pop off return address
JMPptr(R(RAX));
SetJumpTarget(b); SetJumpTarget(b);
} }