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Optimize binary_op generation to use less stack if possible

This commit is contained in:
Bananymous 2024-04-29 18:18:24 +03:00
parent 56bcad6fc1
commit 79ca8e78b3
1 changed files with 54 additions and 13 deletions
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67
04_semantics_and_running/main.py
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@ -487,23 +487,64 @@ def compile_ast(node: ASTnode, compile_data: CompileData) -> None:
else:
assert node.child_rhs.type == 'int'
# calculate LHS and store it on stack
old_code = compile_data.code
# compile LHS
compile_data.code = []
compile_ast(node.child_lhs, compile_data)
compile_data.code.append(Instruction('subq', ['$16', '%rsp']))
compile_data.code.append(Instruction('movq', ['%rax', '0(%rsp)']))
lhs_code = compile_data.code
# calculate RHS and store it in RCX
# compile RHS
compile_data.code = []
compile_ast(node.child_rhs, compile_data)
if node.child_lhs.type == 'date' and node.child_rhs.type == 'int':
# multiply RHS by number of seconds in a day so we can perform arithmetic on dates
compile_data.code.append(Instruction('imulq', ['$86400', '%rax', '%rcx']))
else:
compile_data.code.append(Instruction('movq', ['%rax', '%rcx']))
rhs_code = compile_data.code
# prepare registers, RAX contains LHS and RCX contains RHS
# and restore restore stack
compile_data.code.append(Instruction('movq', ['0(%rsp)', '%rax']))
compile_data.code.append(Instruction('addq', ['$16', '%rsp']))
compile_data.code = old_code
# check if we can use temporary registers instead of stack
temp_registers = ['%rcx', '%r8', '%r9', '%r10', '%r11']
temp_reg = None
for reg in temp_registers:
valid = True
for instruction in lhs_code:
if reg in instruction.operands:
valid = False
break
if valid:
temp_reg = reg
break
# check if lhs uses call, this determines whether we need to align stack
lhs_call = False
for instruction in lhs_code:
if instruction.opcode == 'call':
lhs_call = True
break
# Add code for RHS calculation
compile_data.code += rhs_code
if temp_reg is not None:
compile_data.code.append(Instruction('movq', ['%rax', temp_reg]))
elif not lhs_call:
compile_data.code.append(Instruction('pushq', ['%rax']))
else:
compile_data.code.append(Instruction('subq', ['$16', '%rsp']))
compile_data.code.append(Instruction('movq', ['%rax', '0(%rsp)']))
# Add code for LHS calculation
compile_data.code += lhs_code
if temp_reg is not None:
compile_data.code.append(Instruction('movq', [temp_reg, '%rcx']))
elif not lhs_call:
compile_data.code.append(Instruction('popq', ['%rcx']))
else:
compile_data.code.append(Instruction('movq', ['0(%rsp)', '%rcx']))
compile_data.code.append(Instruction('addq', ['$16', '%rsp']))
# If we are adding or subtracting dates with integers, multiply the integer by number of seconds in a day
if node.child_lhs.type == 'date' and node.child_rhs.type == 'int':
compile_data.code.append(Instruction('imulq', ['$86400', '%rcx']))
# perform operation
if node.value == '+':