commit 2eb0c7d9d788f25032944b92823867115b2402d7
parent 992c8cc15c1e7ae225711195b82fbadcf384327a
Author: Ryan Sepassi <rsepassi@gmail.com>
Date: Thu, 23 Apr 2026 14:30:07 -0700
post updates
Diffstat:
1 file changed, 8 insertions(+), 10 deletions(-)
diff --git a/post.md b/post.md
@@ -140,8 +140,8 @@ enough of a C compiler in Scheme to compile the tcc source.
m1pp is a small macro expander layered on top of M0, with an aim of making it
bearable enough to write assembly programs that you might just want to linger
for a moment way down here near the bottom of the sea. It adds three things M0
-doesn't have: user-defined macros with named parameters, integer expressions
-that evaluate at expand time, and conditional expansion.
+doesn't have: macros with named parameters, integer expressions that evaluate
+at expand time, and conditional expansion.
Features:
@@ -203,8 +203,9 @@ Registers:
- `sp` — stack pointer.
That's a modest budget — twelve visible registers. The goal is small backends
-and uniform source across a 32-bit RISC-V, an aarch64, and an x86-64. Anything beyond this that a backend needs for encoding (scratch regs,
-link register, zero register) is backend-private and exposed only through the
+and uniform source across a 32-bit RISC-V, an aarch64, and an x86-64. Anything
+beyond this that a backend needs for encoding (scratch regs, link register,
+zero register) is backend-private and exposed only through the
portable ops. `LA_BR` is the one exception on the source side: it loads a
label into a hidden *branch-target register* that the immediately following
direct control-flow op (`B`, `CALL`, `TAIL`, or any conditional branch) then
@@ -235,9 +236,6 @@ Ops:
hard-coding the frame layout.
- System: `SYSCALL`.
-No floating point. P1 is a scalar-integer world; enough for a Scheme and a
-C compiler.
-
Calling convention:
- `a0`-`a3` hold the first four argument words; extras live in an incoming
@@ -262,9 +260,9 @@ P1 ships as a pair of files you catm before any P1 source:
Concrete sizes for what's landed today:
-- `m1pp.M1`: ~2.5 KLOC — the M1 source of the macro expander itself.
-- `P1.M1pp`: 224 LOC — the portable P1 interface.
-- `P1-aarch64.M1pp`: ~500 LOC — one arch backend.
+- `m1pp.M1`: XX KLOC — the M1 source of the macro expander itself.
+- `P1.M1pp`: ~150 LOC — the portable P1 interface.
+- `P1-aarch64.M1pp`: ~460 LOC — one arch backend.
The pitch of this rewrite — shrinking the pre-Scheme KLOC count — can't be
fully cashed in until scheme.P1 and cc.scm land; that's where the 30KLOC of
