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We have been always parsing a single function. Since we want to have
multiple functions in a near future, this patch introduces an namespace
that represents an entire file.
To ensure a function is defined inside a namespace, a helper function
was created. Today our ast_node structure is highly exposed, and this is
something that Johnny and I have been discussed. So then, this is a
first step to try to protected the code generation from our ast tree.
Signed-off-by: Carlos Maniero <carlos@maniero.me>
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Before this commit, function declarations were making syscalls to
interrupt the flow. This is a fair approach considering all our examples
just have a main function. But won't work if the namespace has more then
a single function.
The return now always sets the return value on RAX and jumps to the
function return label.
The function return label, will restore RBP and jump back to callee's
next instruction using RET instruction.
Function labels are kept, which means that a function called my_fn will
have the assembly label my_fn, so then, they can have INTEROP with other
languages.
Signed-off-by: Carlos Maniero <carlos@maniero.me>
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When the assignment value is a literal, it just assigns zero or one to
the variable stack's location. If the value is an expression, it
compiles the expression and assign zeros and ones based on expression
result.
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Now if statements are complete! The function
%gas_assembly_generator_compile_condition% is generic and will be used
for any other flow-control statment. The only requirement to it work is
having two labels: One to jump when the condition is true, and another
one when the condition is false.
Signed-off-by: Carlos Maniero <carlos@maniero.me>
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If statements are now working, the only exception is for the comparators
|| and && that will be addressed in a further commit. Checks tested:
fn main(): i32 {
let n: i32 = 11;
if (n == 11) {
if n != 12 {
if n < 12 {
if n <= 11 {
if n > 10 {
if n >= 11 {
return 42;
}
}
}
}
}
}
return n;
}
To compile the && and || a precedence issue must be addressed: they must
have the highest precedence, witch is not working now:
1 == 2 || 3 != 2
The or should be the higher level of the tree in the example above.
Signed-off-by: Carlos Maniero <carlos@maniero.me>
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We were moving the stack data for variable reference to another stack
position ending up with two pointer to the same value.
// a: i32 = 1;
mov $1, -8(%rbp)
// b: i32 = a;
mov -8(%rbp), %rax
mov %rax, -24(%rbp)
mov -24(%rbp), %rax
mov %rax, -16(%rbp)
After this changes, we wont create a new temp space on stack if we don't
need it. See bellow the example after the optimization:
// a: i32 = 1;
mov $1, -8(%rbp)
// b: i32 = a;
mov -8(%rbp), %rax
mov %rax, -16(%rbp)
Signed-off-by: Johnny Richard <johnny@johnnyrichard.com>
Co-authored-by: Carlos Maniero <carlosmaniero@gmail.com>
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Signed-off-by: Johnny Richard <johnny@johnnyrichard.com>
Co-authored-by: Carlos Maniero <carlosmaniero@gmail.com>
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Until now, every computation was pushed onto stack witch creates
unnecessary stack manipulation and makes the generated code hard to read
and understand.
Now, the latest computation is stored and could be either a literal or a
value on a register.
When it is a register we may need to push the value to stack to avoid
data loss. Now if it is a literal, hence, we can just set the value onto
a register.
example/main.pipa before this commit:
.global _start
.text
_start:
push %rbp
mov %rsp, %rbp
mov $69, %rax ; <- There is no reason to store data in rax
mov %rax, %rdi
mov $60, %rax
syscall
pop %rbp
example/main.pipa after this commit:
.global _start
.text
_start:
push %rbp
mov %rsp, %rbp
mov $69, %rdi ; <- Fixed!
mov $60, %rax
syscall
pop %rbp
example/variables.pipa before this commit:
.global _start
.text
_start:
push %rbp
mov %rsp, %rbp
mov $12, %rax
mov %rax, -8(%rbp)
mov $32, %rax
mov %rax, -16(%rbp)
mov -8(%rbp), %rax
mov %rax, -32(%rbp)
mov -16(%rbp), %rax
mov -32(%rbp), %rcx
add %rcx, %rax
mov %rax, -32(%rbp)
mov $2, %rax
mov -32(%rbp), %rcx
mul %rcx
mov %rax, -24(%rbp)
mov $1, %rax
mov %rax, -40(%rbp)
mov $33, %rax
mov %rax, -48(%rbp)
mov -24(%rbp), %rax
mov -48(%rbp), %rcx
sub %rcx, %rax
mov -40(%rbp), %rcx
add %rcx, %rax
mov %rax, -32(%rbp)
mov $2, %rax
mov %rax, -40(%rbp)
mov -32(%rbp), %rax
mov -40(%rbp), %rcx
xor %rdx, %rdx
div %rcx
mov %rax, %rdi
mov $60, %rax
syscall
pop %rbp
example/variables.pipa after this commit:
.global _start
.text
_start:
push %rbp
mov %rsp, %rbp
mov $12, -8(%rbp)
mov $32, -16(%rbp)
mov -8(%rbp), %rax
mov %rax, -32(%rbp)
mov -16(%rbp), %rax
mov -32(%rbp), %rcx
add %rcx, %rax
mov %rax, -32(%rbp)
mov -32(%rbp), %rcx
mov $2, %rax
mul %rcx
mov %rax, -24(%rbp)
mov -24(%rbp), %rax
mov $33, %rcx
sub %rcx, %rax
mov $1, %rcx
add %rcx, %rax
mov %rax, -32(%rbp)
mov -32(%rbp), %rax
mov $2, %rcx
xor %rdx, %rdx
div %rcx
mov %rax, %rdi
mov $60, %rax
syscall
pop %rbp
Less 8 instructions!
Signed-off-by: Carlos Maniero <carlosmaniero@gmail.com>
Reviewed-by: Johnny Richard <johnny@johnnyrichard.com>
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This patch adds the variable compilation and uses a scope (a stack of
map) to lookup for identities.
Today we use a vector + ref_entry structs in order to achieve the scope
implementation. The ref_entry lacks memory management, we are still no
sure who will be the owner of the pointer.
We also want to replace the scope a hashtable_t type as soon as we get
one.
Signed-off-by: Johnny Richard <johnny@johnnyrichard.com>
Co-authored-by: Carlos Maniero <carlosmaniero@gmail.com>
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I decided to remove the visitor pattern due to the lack of Object
Oriented Programming support for C. Now if you want to navigate through
the AST, you should do it with switch case and recursion.
The code looks way simpler without visitor pattern.
I have added a CFLAG -Werror which validates if the switch statement
covers all branches for a given enum at compile time.
Signed-off-by: Johnny Richard <johnny@johnnyrichard.com>
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We want to keep the code style consistent, this first commit adds a
.clang-format in order to "document" our style code.
This patch also adds a target *linter* to Makefile which will complain
if we have any style issue on test and src dirs.
I have run the follow command to create the .clang-format file:
$ clang-format -style=mozilla -dump-config > .clang-format
And I also made some adjusts to .clang-format changing the following
properties:
PointerAlignment: Right
ColumnLimit: 120
Commands executed to fix the current styling:
$ find . -name *.h | xargs clang-format -i
$ find . -name *.c | xargs clang-format -i
Signed-off-by: Johnny Richard <johnny@johnnyrichard.com>
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In the future we want to have the possibility of traverse the tree and
pretty print it or generate binary for other platform like LLVM or
transpile to C.
This solution also implements the gas assembly x86_64 Linux code
generation by using the visitor interface.
Signed-off-by: Johnny Richard <johnny@johnnyrichard.com>
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