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singlepass/codegen: Optimize need_check path.

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This commit is contained in:
losfair
2020-06-05 23:37:27 +08:00
parent f070858c8c
commit aabadf9776
1 changed files with 33 additions and 43 deletions
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76
lib/compiler-singlepass/src/codegen_x64.rs
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@@ -1236,7 +1236,6 @@ impl<'a> FuncGen<'a> {
MemoryStyle::Dynamic => true,
};
let tmp_addr = self.machine.acquire_temp_gpr().unwrap();
let tmp_base = self.machine.acquire_temp_gpr().unwrap();
// Reusing `tmp_addr` for temporary indirection here, since it's not used before the last reference to `{base,bound}_loc`.
let (base_loc, bound_loc) = if self.module.num_imported_memories != 0 {
@@ -1261,61 +1260,39 @@ impl<'a> FuncGen<'a> {
)
};
let tmp_base = self.machine.acquire_temp_gpr().unwrap();
let tmp_bound = self.machine.acquire_temp_gpr().unwrap();
// Load base into temporary register.
self.assembler
.emit_mov(Size::S64, base_loc, Location::GPR(tmp_base));
// Load bound into temporary register, if needed.
if need_check {
let tmp_bound = self.machine.acquire_temp_gpr().unwrap();
self.assembler
.emit_mov(Size::S32, bound_loc, Location::GPR(tmp_bound));
self.assembler
.emit_mov(Size::S32, addr, Location::GPR(tmp_addr));
// Add offset to memory address.
if memarg.offset != 0 {
self.assembler.emit_add(
Size::S32,
Location::Imm32(memarg.offset),
Location::GPR(tmp_addr),
);
// Overflow is checked outside the `need_check` block, so we don't need to check it here.
}
// Trap if the start address of the requested area is equal to or above that of the linear memory.
self.assembler
.emit_cmp(Size::S32, Location::GPR(tmp_bound), Location::GPR(tmp_addr));
self.assembler
.emit_jmp(Condition::AboveEqual, self.special_labels.heap_access_oob);
// Calculate end of word.
if value_size != 0 {
self.assembler.emit_add(
Size::S32,
Location::Imm32(value_size as u32),
Location::GPR(tmp_addr),
);
self.assembler
.emit_jmp(Condition::Carry, self.special_labels.heap_access_oob);
}
// Trap if the end address of the requested area is above that of the linear memory.
self.assembler
.emit_cmp(Size::S64, Location::GPR(tmp_bound), Location::GPR(tmp_addr));
self.assembler
.emit_jmp(Condition::Above, self.special_labels.heap_access_oob);
self.machine.release_temp_gpr(tmp_bound);
// Wasm -> Effective.
// Assuming we never underflow - should always be true on Linux/macOS,
// since the first page from 0x0 to 0x1000 is not accepted by mmap.
self.assembler.emit_lea(
Size::S64,
Location::MemoryAddTriple(tmp_bound, tmp_base, -(value_size as i32)),
Location::GPR(tmp_bound),
);
}
// Calculates the real address, and loads from it.
// Load effective address.
// `base_loc` and `bound_loc` becomes INVALID after this line, because `tmp_addr`
// might be reused.
self.assembler
.emit_mov(Size::S32, addr, Location::GPR(tmp_addr));
// Add offset to memory address.
if memarg.offset != 0 {
self.assembler.emit_add(
Size::S64,
Location::Imm32(memarg.offset as u32),
Size::S32,
Location::Imm32(memarg.offset),
Location::GPR(tmp_addr),
);
@@ -1323,8 +1300,20 @@ impl<'a> FuncGen<'a> {
self.assembler
.emit_jmp(Condition::Carry, self.special_labels.heap_access_oob);
}
// Wasm linear memory -> real memory
self.assembler
.emit_add(Size::S64, Location::GPR(tmp_base), Location::GPR(tmp_addr));
if need_check {
// Trap if the end address of the requested area is above that of the linear memory.
self.assembler
.emit_cmp(Size::S64, Location::GPR(tmp_bound), Location::GPR(tmp_addr));
self.assembler
.emit_jmp(Condition::Above, self.special_labels.heap_access_oob);
}
self.machine.release_temp_gpr(tmp_bound);
self.machine.release_temp_gpr(tmp_base);
let align = match memarg.flags & 3 {
@@ -1355,7 +1344,8 @@ impl<'a> FuncGen<'a> {
self.machine.release_temp_gpr(tmp_aligncheck);
}
self.mark_range_with_trap_code(TrapCode::HeapAccessOutOfBounds, |this| cb(this, tmp_addr))?;
//self.mark_range_with_trap_code(TrapCode::HeapAccessOutOfBounds, |this| cb(this, tmp_addr))?;
cb(self, tmp_addr);
self.machine.release_temp_gpr(tmp_addr);
Ok(())