[PATCH olang v1 0/1] deref operation returning value

[PATCH olang v1 0/1] deref operation returning value

[Carlos Maniero]

We had discussed over IRC about may adding some extra information on the
deref operation to support this feature, but there are two reasons why I
opted to keep this on code gen:

1) Modifying the AST would require changing the unary data structure
from a struct to an union, but no other operator would be beneficed by
this since only the deref needs some extra information.

2) The assign operation is required to identify if its LHS is a deref,
once the mov instruction will differ from a simple ref: The simple ref
will mov the expression result to a RBP offset and the deref will mov
the expression result to the pointer location.

Also, once we have the IR, this logic could easily fit the layer that
will build the IR.

Carlos Maniero (1):
  codegen: x64: deref returns pointer value

 src/codegen_x86_64.c | 61 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 52 insertions(+), 9 deletions(-)

-- 
2.46.1

[PATCH olang v1 1/1] codegen: x64: deref returns pointer value

[Carlos Maniero]

Deref is context dependent, when doing an assignment:

  *a = 1

It is expected for the deref codegen to return the pointer location, so
than the assignment binop would be able to assign a new value at that
location.

On another hand, when performing:

  return *a

It is expected for deref to actually returns the pointer location value.
The codegen of both behaviors were defined in new functions to avoid
indiscriminately increase the codegen_x86_64_emit_expression
switch/case.

Register choice:
================

Since the operation *mov (%rax), %rax* is not possible, I arbitrarily
choose R10 as it is a caller-saved register.

Signed-off-by: Carlos Maniero <carlos@maniero.me>
---
 src/codegen_x86_64.c | 61 +++++++++++++++++++++++++++++++++++++-------
 1 file changed, 52 insertions(+), 9 deletions(-)

diff --git a/src/codegen_x86_64.c b/src/codegen_x86_64.c
index deb7e24..db1b77a 100644
--- a/src/codegen_x86_64.c
+++ b/src/codegen_x86_64.c
@@ -52,6 +52,8 @@ typedef enum x86_64_register_type
     REG_R15
 } x86_64_register_type_t;
 
+typedef size_t size_in_bytes_t;
+
 /**
  * Arch/ABI      arg1  arg2  arg3  arg4  arg5  arg6  arg7  Notes
  * ──────────────────────────────────────────────────────────────
@@ -76,6 +78,14 @@ codegen_x86_64_put_stack_offset(codegen_x86_64_t *codegen,
 static size_t
 codegen_x86_64_get_stack_offset(codegen_x86_64_t *codegen, symbol_t *symbol);
 
+static size_in_bytes_t
+codegen_x86_64_emit_unary_deref_address(codegen_x86_64_t *codegen,
+                                              ast_unary_op_t *unary_op);
+
+static size_in_bytes_t
+codegen_x86_64_emit_unary_deref_value(codegen_x86_64_t *codegen,
+                                            ast_unary_op_t *unary_op);
+
 static size_t
 type_to_bytes(type_t *type);
 
@@ -126,8 +136,6 @@ codegen_x86_64_get_next_label(codegen_x86_64_t *codegen)
     return ++codegen->label_index;
 }
 
-typedef size_t size_in_bytes_t;
-
 static size_in_bytes_t
 codegen_x86_64_emit_expression(codegen_x86_64_t *codegen, ast_node_t *expr_node)
 {
@@ -619,7 +627,8 @@ codegen_x86_64_emit_expression(codegen_x86_64_t *codegen, ast_node_t *expr_node)
                                        AST_UNARY_DEREFERENCE &&
                                    "unsupported assignment lhs");
 
-                            codegen_x86_64_emit_expression(codegen, bin_op.lhs);
+                            codegen_x86_64_emit_unary_deref_address(
+                                codegen, &bin_op.lhs->as_unary_op);
 
                             fprintf(codegen->out, "    push %%rax\n");
 
@@ -679,12 +688,8 @@ codegen_x86_64_emit_expression(codegen_x86_64_t *codegen, ast_node_t *expr_node)
                     return 8;
                 }
                 case AST_UNARY_DEREFERENCE: {
-                    // FIXME: support dereference of dereference (**)
-                    assert(unary_op.expr->kind == AST_NODE_REF &&
-                           "unsupported unary expression for dereference (*)");
-
-                    return codegen_x86_64_emit_expression(codegen,
-                                                          unary_op.expr);
+                    return codegen_x86_64_emit_unary_deref_value(
+                        codegen, &unary_op);
                 }
                 default: {
                     assert(0 && "unsupported unary operation");
@@ -829,6 +834,44 @@ codegen_x86_64_emit_if(codegen_x86_64_t *codegen, ast_if_stmt_t if_stmt)
     fprintf(codegen->out, ".L%ld:\n", end_else_label);
 }
 
+static size_in_bytes_t
+codegen_x86_64_emit_unary_deref_address(codegen_x86_64_t *codegen,
+                                              ast_unary_op_t *unary_op)
+{
+    assert(unary_op->kind == AST_UNARY_DEREFERENCE);
+    // FIXME: support dereference of dereference (**)
+    assert(unary_op->expr->kind == AST_NODE_REF &&
+           "unsupported unary expression for dereference (*)");
+
+    return codegen_x86_64_emit_expression(codegen, unary_op->expr);
+}
+
+static size_in_bytes_t
+codegen_x86_64_emit_unary_deref_value(codegen_x86_64_t *codegen,
+                                            ast_unary_op_t *unary_op)
+{
+    codegen_x86_64_emit_unary_deref_address(codegen, unary_op);
+
+    ast_ref_t ref = unary_op->expr->as_ref;
+
+    symbol_t *symbol = scope_lookup(ref.scope, ref.id);
+
+    assert(symbol->type->kind == TYPE_PTR);
+
+    size_in_bytes_t deref_size = type_to_bytes(symbol->type->as_ptr.type);
+
+    fprintf(codegen->out,
+            "    mov (%%rax), %s\n",
+            get_reg_for(REG_R10, deref_size));
+
+    fprintf(codegen->out,
+            "    mov %s, %s\n",
+            get_reg_for(REG_R10, deref_size),
+            get_reg_for(REG_ACCUMULATOR, deref_size));
+
+    return deref_size;
+}
+
 static size_t
 type_to_bytes(type_t *type)
 {
-- 
2.46.1

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 20s

[deref operation returning value][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/55515
[1]: mailto:carlos@maniero.me

✗ #1352279 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1352279

Re: [olang/patches/.build.yml] build failed

[Carlos Maniero]

I broke the format :(

I'll wait for the review before submitting a v2.

Re: [olang/patches/.build.yml] build failed

[Carlos Maniero]

There is an issue unrelated to my changes. The spec that does not allows
comments inside.

I sent another patch [1] that will fix the spec.

[1]: Message-ID: <20241015225750.211129-2-carlos@maniero.me>.

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 28s

[fix: codegen: prevent stack overwrite][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/55483
[1]: mailto:carlos@maniero.me

✗ #1350731 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1350731

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 21s

[fix: build: add missing dependencies for check-spec][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/55427
[1]: mailto:johnny@johnnyrichard.com

✗ #1348643 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1348643

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 18s

[parser: conform block line feeds with the spec][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/55389
[1]: mailto:carlos@maniero.me

✗ #1346505 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1346505

Re: [olang/patches/.build.yml] build failed

[Johnny Richard]

My bad... I have made these changes on top of patches not applied on
main branch.

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 29s

[refactor: ast: inline union typedefs][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/54446
[1]: mailto:johnny@johnnyrichard.com

✗ #1302361 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1302361

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 39s

[build: rename linter to format to avoid confusion][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/51175
[1]: mailto:johnny@johnnyrichard.com

✗ #1200225 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1200225

Re: [olang/patches/.build.yml] build failed

[Johnny Richard]

On Thu, Mar 28, 2024 at 02:59:02PM +0000, builds.sr.ht wrote:
> olang/patches/.build.yml: FAILED in 36s
> 
> [fe: lexer: add single line comments support][0] from [Johnny Richard][1]
> 
> [0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50503
> [1]: mailto:johnny@johnnyrichard.com
> 
> ✗ #1181030 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1181030

This build is failing due to a clang bumped version on Arch Linux
repositories.  It was a major bump from 16 to 17 (it has breaking
changes).

We can solve this problem by fixing the version or by bumping our clang
locally.  I will upgrade my clang meanwhile.

Please, consider the patch to fix it.

---->8----
Subject: [PATCH olang] fixup! fe: lexer: add single line comments support


diff --git a/src/pretty_print_ast.c b/src/pretty_print_ast.c
index e950796..129f090 100644
--- a/src/pretty_print_ast.c
+++ b/src/pretty_print_ast.c
@@ -26,7 +26,7 @@
 
 #define ANSI_COLOR_MAGENTA "\x1b[35m"
 #define ANSI_COLOR_RESET "\x1b[0m"
-#define PP_IS_BIT_SET(data, index) ((data)&1 << index)
+#define PP_IS_BIT_SET(data, index) ((data) & 1 << index)
 
 typedef struct pretty_print_node
 {

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 36s

[fe: lexer: add single line comments support][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50503
[1]: mailto:johnny@johnnyrichard.com

✗ #1181030 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1181030

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 35s

[docs: variables specification][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50474
[1]: mailto:carlos@maniero.me

✗ #1179573 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1179573

Re: [olang/patches/.build.yml] build failed

[Carlos Maniero]

oops!

s/see/be

Re: [olang/patches/.build.yml] build failed

[Carlos Maniero]

The failed pipeline seems to see a sourcehut issue.

Tested locally and all fine.

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 40s

[Introduce CLI option for improved AST tree visualization][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50448
[1]: mailto:johnny@johnnyrichard.com

✗ #1178386 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1178386

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 31s

[refactor: rename zero programming language to olang][0] v3 from [Fabio Maciel][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50187
[1]: mailto:fabio@fabiomaciel.com

✗ #1167852 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1167852

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 30s

[parser: abort when parser identifies a syntax error][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/50088
[1]: mailto:johnny@johnnyrichard.com

✗ #1164684 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1164684

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 12s

[implement assembly linux x86_64 compiler][0] v2 from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49994
[1]: mailto:johnny@johnnyrichard.com

✗ #1162085 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1162085

Re: [olang/patches/.build.yml] build failed

[Carlos Maniero]

The checks passed just fine in my environment too.

Re: [olang/patches/.build.yml] build failed

[Johnny Richard]

On Mon, Mar 04, 2024 at 06:33:31PM +0000, builds.sr.ht wrote:
> olang/patches/.build.yml: FAILED in 12s
> 
> [implement assembly linux x86_64 compiler][0] from [Johnny Richard][1]
> 
> [0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49981
> [1]: mailto:johnny@johnnyrichard.com
> 
> ✗ #1161742 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1161742

I not sure what is happening, the build works find on my machine.  Looks
like the CI machines are failing to setup the environment, nothing to do
with my changes I believe:

    [#1161745] 2024/03/04 18:36:41 Booting image archlinux (default) on port 22563
    [#1161745] 2024/03/04 18:36:42 Waiting for guest to settle
    [#1161745] 2024/03/04 18:36:49 Sending tasks
    [#1161745] 2024/03/04 18:36:52 Sending build environment
    [#1161745] 2024/03/04 18:36:53 Installing packages
    Warning: Permanently added '[localhost]:22563' (ED25519) to the list of known hosts.
    :: Synchronizing package databases...
     core downloading...
     extra downloading...
     multilib downloading...
    warning: archlinux-keyring-20240208-1 is up to date -- skipping
     there is nothing to do
    Warning: Permanently added '[localhost]:22563' (ED25519) to the list of known hosts.
    error: missing dependency 'initramfs' for package 'linux'
    linux: ignoring package upgrade (6.7.6.arch1-1 => 6.7.8.arch1-1)
    mkinitcpio: ignoring package upgrade (37.3-1 => 38-3)
    Resolving dependencies...
    Checking package conflicts...
    :: uninstalling package 'mkinitcpio-37.3-1' due to conflict with 'cryptsetup-2.7.0-3'
    [#1161745] 2024/03/04 18:36:54 Processing post-failed triggers...
    [#1161745] 2024/03/04 18:36:54 Sending webhook...
    [#1161745] 2024/03/04 18:36:54 Webhook response: 200
    [#1161745] 2024/03/04 18:36:54 Thanks!
    [#1161745] 2024/03/04 18:36:54 Build failed.
    [#1161745] 2024/03/04 18:36:54 The build environment will be kept alive for 10 minutes.
    [#1161745] 2024/03/04 18:36:54 To log in with SSH and examine it, use the following command:
    [#1161745] 2024/03/04 18:36:54
    [#1161745] 2024/03/04 18:36:54 	ssh -t builds@fra02.builds.sr.ht connect 1161745
    [#1161745] 2024/03/04 18:36:54
    [#1161745] 2024/03/04 18:36:54 After logging in, the deadline is increased to your remaining build time.

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 12s

[implement assembly linux x86_64 compiler][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49981
[1]: mailto:johnny@johnnyrichard.com

✗ #1161742 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1161742

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 36s

[string_view: fix stack buffer overflow on to_u32][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49949
[1]: mailto:johnny@johnnyrichard.com

✗ #1160713 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1160713

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 40s

[string_view: add n + 1 test to string_view_to_u32 function][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49946
[1]: mailto:johnny@johnnyrichard.com

✗ #1160663 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1160663

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 36s

[utils: add arena][0] v2 from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49708
[1]: mailto:carlos@maniero.me

✗ #1154158 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1154158

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 36s

[utils: add arena][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49707
[1]: mailto:carlos@maniero.me

✗ #1154146 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1154146

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 42s

[Create --dump-tokens on compiler cli][0] v4 from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49682
[1]: mailto:johnny@johnnyrichard.com

✗ #1153624 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1153624

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 34s

[Create --dump-tokens on compiler cli][0] v2 from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49641
[1]: mailto:johnny@johnnyrichard.com

✗ #1153051 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1153051

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 31s

[Create --dump-tokens on compiler cli][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49640
[1]: mailto:johnny@johnnyrichard.com

✗ #1153048 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1153048

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 18s

[remove sphinx dependency][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49598
[1]: mailto:carlos@maniero.me

✗ #1151949 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1151949

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 19s

[docs: add HACKING documentation][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49586
[1]: mailto:carlos@maniero.me

✗ #1151773 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1151773

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 15s

[Add integration tests][0] v2 from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49556
[1]: mailto:carlos@maniero.me

✗ #1151085 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1151085

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 16s

[style: fix clang-format format indentation][0] from [Carlos Maniero][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49522
[1]: mailto:carlos@maniero.me

✗ #1150343 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1150343

[olang/patches/.build.yml] build failed

[builds.sr.ht]

olang/patches/.build.yml: FAILED in 13s

[build: enable continuous integration through .build.yml][0] from [Johnny Richard][1]

[0]: https://lists.sr.ht/~johnnyrichard/olang-devel/patches/49459
[1]: mailto:johnny@johnnyrichard.com

✗ #1149170 FAILED olang/patches/.build.yml https://builds.sr.ht/~johnnyrichard/job/1149170