Notes: arenas, backend, linear types, interface in .so/.dll, stdlib implHEADmain

1 files changed, 129 insertions, 0 deletions

diff --git a/notes/stdlib_in_slul.txt b/notes/stdlib_in_slul.txt
index 0479024..99c7953 100644
--- a/notes/stdlib_in_slul.txt
+++ b/notes/stdlib_in_slul.txt
@@ -32,6 +32,27 @@ Write those things in:
    e.g. Hare uses QBE, which has somewhat limited target support)
 * Formally-verified IR/assembler (see below)
 
+Discourage people from writing in the unsafe language
+-----------------------------------------------------
+
+It would be sad if the safe SLUL language loses out to an unsafe cousin
+language. So IF an unsafe cousin language is ever created, it should
+1) be very clear that it is NOT slul, and 2) discourage it's use by making
+it an "unappealing" language.
+
+Make it explicitly a different language:
+* Different name (uhoh? oops? noo? slunsafe?)
+* Different file extension (.rtlc? .stdlib? .lul? .uhoh? .rtlu? .noo? .rsy? .slunsafe?)
+* Different syntax
+
+Make it ugly but still readable:
+* Use uppercase keywords?
+* Or use some sigill?
+
+Make unsafe stuff really stand out:
+* Maybe require an UNSAFE_xxx keyword around anything unsafe
+
+
 Hard-core solution: formally verified IR/assembler
 --------------------------------------------------
 
@@ -55,3 +76,111 @@ For registers, and for fields in structs in memory:
 * not null
 * length of field F
 * etc.
+
+Hard-code solution 2: write a C compiler in SLUL
+------------------------------------------------
+
+Could write a C compiler in SLUL, using the same backend as the SLUL
+compiler will use.
+
+This could even be a subset of C89 (+ some things like uint64_t etc.).
+Candidates for things to remove/forbid:
+* digraphs/trigraphs
+* float/double
+* varargs (both usage, declarations and va_list etc.)
+* multi-char chars
+* octal literals and escape sequences
+* assuming char is either signed or unsigned, i.e. assigning < 0 or >= 128
+* strange control structures:
+    - case not directly under switch
+    - statements between switch and first case
+    - not using {} when block comes on a separate line
+* some types:
+    - void *
+    - wchat_t
+* several casts:
+    - pointer to/from int
+    - function ptr to/from other data pointer types
+* depending on operator precedence of:
+    - & vs && levels
+* declarations:
+    - * vs [] precedence
+    - prototypes: `f()`
+    - auto/register storage classes
+    - common initialization: `static int i;` or `int i;` at top-level.
+    - volatile
+    - new struct/enum inside function parameter list
+* unwanted macros:
+    - __DATE__, __TIME__
+    - #pragma
+* stdlib except for:
+    - memset, memcmp, memcpy, strlen
+
+
+Syntax test
+-----------
+
+Using UNSAFE_ everywhere to make unsafe stuff stand out and to make the
+language more ugly.
+
+Using __ in identifiers to avoid collisions and also for increased ugliness.
+
+Using % before all keywords for even more ugliness.
+
+
+    %func __init_arena
+    %code
+        [UNSAFEPointer base_ptr, UNSAFESize pgsize] = __sys_mmap 1
+        ArenaBase base_info %UNSAFE_OVERLAY base_ptr
+            .chunk = [
+                # ability to merge base pointers and offsets?
+                #.info = %UNSAFE_ADDROF .base %UNSAFE_PTRADD %UNSAFE_OFFSETOF .freespace
+                .baseptr = %UNSAFE_ADDROF .base
+                .alloced = %UNSAFE_OFFSETOF .freespace
+                .size = pgsize
+            ]
+            .base = [
+                # capability info, list of chunks, ...
+            ]
+            .freespace = []
+        %end
+    %end
+
+    %UNSAFE_GLOBAL __pagesize
+
+    %func __sys_mmap
+        int npages
+    %code
+        %%SYS_if os linux
+            __syscall6 NR_mmap2 ...
+        %%SYS_elif os windows
+            __sys_VirtualAlloc ...
+        %%SYS_endif
+    %end
+
+    %%SYS_switch os
+    %%SYS_case linux
+    %func __syscall6
+        int syscall_number
+        unsigned long arg1
+        ...
+        unsigned long arg6
+    %code
+        %SYS_switch cpu
+        %SYS_case aarch64
+            %UNSAFE_asmdef $sysc($n) $w32_le(...)
+            ...
+        %SYS_case i386
+            %UNSAFE_asmdef $int($n) CD $n
+            # Should probably use the vdso instead...
+            %UNSAFE_machinecode $int(80)
+        %SYS_case x86_64
+            ...
+        %SYS_endswitch
+    %end
+    %%SYS_case windows
+    %func __sys_VirtualAlloc
+        ...
+    %dllimport "kernel32.dll" "VirtualAlloc"
+    %end
+    %%SYS_endswitch