aboutsummaryrefslogtreecommitdiffhomepage
diff options
context:
space:
mode:
authorlemon <lsof@mailbox.org>2023-06-19 11:26:50 +0200
committerlemon <lsof@mailbox.org>2023-06-19 11:26:50 +0200
commit08649c95cc15b5ad99e6b8899d639f6c3b63266b (patch)
tree68981085c3a6088b3d4a6c001116a4e1fe849623
parentd1cdebc88ea1a83e580299683ed27e6ca5d26683 (diff)
frontend: add for, break, continue statements
Diffstat
-rw-r--r--c.c273
-rw-r--r--parse.h2
-rw-r--r--todo.txt2
3 files changed, 202 insertions, 75 deletions
diff --git a/c.c b/c.c
index 021080d..582d3fe 100644
--- a/c.c
+++ b/c.c
@@ -1118,7 +1118,7 @@ cvt(struct function *fn, enum typetag to, enum typetag from, union ref ref)
if (from == TYBOOL) return ref;
if (ref.t == RTMP)
/* these instrs already have output range of [0,1] */
- if (instrtab[ref.i].op == Onot || oiscmp(instrtab[ref.i].op))
+ if (oiscmp(instrtab[ref.i].op))
return ref;
ins.op = Oneq, ins.r = ZEROREF;
}
@@ -1593,13 +1593,35 @@ stmtterm(struct parser *pr)
}
static void block(struct parser *pr, struct function *fn);
+static bool stmt(struct parser *pr, struct function *fn);
+static void localdecl(struct parser *pr, struct function *fn);
-static bool /* return 1 if stmt is terminating (all codepaths return) */
+static bool
+loopbody(struct parser *pr, struct function *fn, struct block *brk, struct block *cont)
+{
+ struct block *save[2];
+ bool terminates = 0;
+
+ save[0] = pr->loopbreak, save[1] = pr->loopcont;
+ pr->loopbreak = brk, pr->loopcont = cont;
+ ++pr->loopdepth;
+
+ terminates = stmt(pr, fn);
+
+ --pr->loopdepth;
+ pr->loopbreak = save[0], pr->loopcont = save[1];
+
+ return terminates;
+}
+
+static bool /* return 1 if stmt is terminating (ends with a jump) */
stmt(struct parser *pr, struct function *fn)
{
struct block *tr, *fl, *end, *begin;
struct expr ex;
+ struct env e;
union ref r;
+ struct token tk;
bool terminates = 0;
const bool doemit = fn->curblk;
@@ -1608,12 +1630,9 @@ stmt(struct parser *pr, struct function *fn)
switch (peek(pr, NULL)) {
case '{':
lex(pr, NULL);
- {
- struct env e;
- envdown(pr, &e);
- block(pr, fn);
- envup(pr);
- }
+ envdown(pr, &e);
+ block(pr, fn);
+ envup(pr);
break;
case ';':
lex(pr, NULL);
@@ -1649,7 +1668,7 @@ stmt(struct parser *pr, struct function *fn)
}
EMITS if (!terminates) useblk(fn, end);
break;
- case TKWwhile:
+ case TKWwhile: /* while ( <cond> ) <body> */
lex(pr, NULL);
expect(pr, '(', NULL);
ex = commaexpr(pr);
@@ -1657,27 +1676,46 @@ stmt(struct parser *pr, struct function *fn)
if (!isscalar(ex.ty))
error(&ex.span, "'while' condition is not a scalar (%ty)", ex.ty);
tr = begin = end = NULL;
+ /* @begin:
+ * <cond>
+ * b <cond>, @tr, @end
+ * @tr:
+ * <body>
+ * b @begin
+ * @end:
+ * <-
+ */
EMITS {
- begin = newblk(fn);
- putbranch(fn, begin);
+ putbranch(fn, begin = newblk(fn));
useblk(fn, begin);
condjump(fn, &ex, tr = newblk(fn), end = newblk(fn));
useblk(fn, tr);
}
- terminates = stmt(pr, fn);
+ terminates = loopbody(pr, fn, end, begin);
EMITS {
if (!terminates) putbranch(fn, begin);
useblk(fn, end);
}
break;
- case TKWdo:
+ case TKWdo: /* do <body> while ( <cond> ) ; */
lex(pr, NULL);
- begin = end = NULL;
+ begin = tr = end = NULL;
+ /* @begin:
+ * <body>
+ * b @tr
+ * @tr: <- necessary for continue stmt
+ * <cond>
+ * b <cond>, @begin, @end
+ * @end:
+ * <-
+ */
EMITS {
putbranch(fn, begin = newblk(fn));
useblk(fn, begin);
+ tr = newblk(fn);
+ end = newblk(fn);
}
- terminates = stmt(pr, fn);
+ terminates = loopbody(pr, fn, end, tr);
expect(pr, TKWwhile, NULL);
expect(pr, '(', NULL);
ex = commaexpr(pr);
@@ -1686,11 +1724,93 @@ stmt(struct parser *pr, struct function *fn)
error(&ex.span, "'while' condition is not a scalar (%ty)", ex.ty);
stmtterm(pr);
EMITS {
- end = newblk(fn);
- if (!terminates) condjump(fn, &ex, begin, end);
+ if (!terminates) putbranch(fn, tr);
+ useblk(fn, tr);
+ condjump(fn, &ex, begin, end);
useblk(fn, end);
}
break;
+ case TKWfor: /* for ( <init>? ; <cond>? ; <iter>? ) <body> */
+ lex(pr, NULL);
+ begin = tr = end = fl = NULL;
+ expect(pr, '(', NULL);
+ /* ->
+ * <init>
+ * b @begin
+ * @begin:
+ * <cond>
+ * b <cond>, @tr, @fl
+ * @tr:
+ * <body>
+ * b @end
+ * @end: <- necessary for continue stmt
+ * <iter>
+ * b @begin
+ * @fl:
+ * <-
+ *
+ * if cond omitted, tr = begin
+ * if iter omitted, end = begin
+ */
+ envdown(pr, &e);
+ if (!match(pr, NULL, ';')) { /* init */
+ if (isdecltok(pr)) {
+ localdecl(pr, fn);
+ } else {
+ ex = commaexpr(pr);
+ EMITS expreffects(fn, &ex);
+ expect(pr, ';', NULL);
+ }
+ }
+ EMITS {
+ putbranch(fn, end = tr = begin = newblk(fn));
+ useblk(fn, begin);
+ fl = newblk(fn);
+ }
+ if (!match(pr, NULL, ';')) { /* cond */
+ ex = commaexpr(pr);
+ expect(pr, ';', NULL);
+ if (!isscalar(ex.ty))
+ error(&ex.span, "'for' condition is not a scalar (%ty)", ex.ty);
+ EMITS {
+ tr = newblk(fn);
+ condjump(fn, &ex, tr, fl);
+ useblk(fn, tr);
+ }
+ }
+ if (!match(pr, NULL, ')')) { /* iter */
+ ex = commaexpr(pr);
+ end = newblk(fn);
+ expect(pr, ')', NULL);
+ }
+
+ terminates = loopbody(pr, fn, fl, end);
+
+ EMITS {
+ if (end != begin) { /* have iter */
+ if (!terminates) putbranch(fn, end);
+ useblk(fn, end);
+ expreffects(fn, &ex);
+ putbranch(fn, begin);
+ } else if (!terminates) putbranch(fn, begin);
+ useblk(fn, fl);
+ }
+ envup(pr);
+ break;
+ case TKWbreak:
+ lex(pr, &tk);
+ if (!pr->loopdepth && !pr->switchdepth)
+ error(&tk.span, "'break' outside of loop or switch statement");
+ EMITS putbranch(fn, pr->loopbreak);
+ stmtterm(pr);
+ break;
+ case TKWcontinue:
+ lex(pr, &tk);
+ if (!pr->loopdepth)
+ error(&tk.span, "'continue' outside of loop");
+ EMITS putbranch(fn, pr->loopcont);
+ stmtterm(pr);
+ break;
case TKWreturn:
lex(pr, NULL);
if (fn->retty.t != TYVOID) {
@@ -1723,69 +1843,74 @@ stmt(struct parser *pr, struct function *fn)
}
static void
+localdecl(struct parser *pr, struct function *fn)
+{
+ struct expr ini;
+ const bool doemit = fn->curblk;
+ struct declstate st = { DFUNCVAR };
+ do {
+ struct decl decl = pdecl(&st, pr);
+ if (decl.name) {
+ static int staticid;
+ bool put = 0;
+
+ switch (decl.scls) {
+ case SCSTATIC:
+ decl.id = ++staticid;
+ break;
+ case SCNONE:
+ decl.scls = SCAUTO;
+ case SCAUTO:
+ case SCREGISTER:
+ if (isincomplete(decl.ty) || decl.ty.t == TYFUNC) {
+ error(&decl.span,
+ "declaring variable '%s' with %s type '%ty'",
+ decl.name, decl.ty.t == TYFUNC ? "function" : "incomplete",
+ decl.ty);
+ goto Err;
+ }
+ EMITS {
+ decl.id = addinstr(fn, mkalloca(typesize(decl.ty), typealign(decl.ty))).i;
+ }
+ if (st.varini) {
+ putdecl(pr, &decl);
+ put = 1;
+ ini = expr(pr);
+ pdecl(&st, pr);
+ if (!assigncheck(decl.ty, &ini)) {
+ struct span span = decl.span;
+ joinspan(&span.ex, ini.span.ex);
+ error(&span, "cannot initialize '%ty' variable with '%ty'",
+ decl.ty, ini.ty);
+ }
+ EMITS {
+ if (isagg(decl.ty))
+ structcopy(fn, decl.ty, mkref(RTMP, decl.id), expraddr(fn, &ini));
+ else
+ genstore(fn, decl.ty, mkref(RTMP, decl.id), exprvalue(fn, &ini));
+ }
+ }
+ break;
+ case SCTYPEDEF: break;
+ case SCEXTERN: break;
+ default: assert(0);
+ }
+ Err:
+ if (!put) putdecl(pr, &decl);
+ }
+ } while (st.more);
+}
+
+static void
block(struct parser *pr, struct function *fn)
{
struct token tk;
- const bool doemit = fn->curblk;
while (!match(pr, &tk, '}')) {
- if (isdecltok(pr)) { /* decl */
- struct expr ini;
- struct declstate st = { DFUNCVAR };
- do {
- struct decl decl = pdecl(&st, pr);
- if (decl.name) {
- static int staticid;
- bool put = 0;
-
- switch (decl.scls) {
- case SCSTATIC:
- decl.id = ++staticid;
- break;
- case SCNONE:
- decl.scls = SCAUTO;
- case SCAUTO:
- case SCREGISTER:
- if (isincomplete(decl.ty) || decl.ty.t == TYFUNC) {
- error(&decl.span,
- "declaring variable '%s' with %s type '%ty'",
- decl.name, decl.ty.t == TYFUNC ? "function" : "incomplete",
- decl.ty);
- goto Err;
- }
- EMITS {
- decl.id = addinstr(fn, mkalloca(typesize(decl.ty), typealign(decl.ty))).i;
- }
- if (st.varini) {
- putdecl(pr, &decl);
- put = 1;
- ini = expr(pr);
- pdecl(&st, pr);
- if (!assigncheck(decl.ty, &ini)) {
- struct span span = decl.span;
- joinspan(&span.ex, ini.span.ex);
- error(&span, "cannot initialize '%ty' variable with '%ty'",
- decl.ty, ini.ty);
- }
- EMITS {
- if (isagg(decl.ty))
- structcopy(fn, decl.ty, mkref(RTMP, decl.id), expraddr(fn, &ini));
- else
- genstore(fn, decl.ty, mkref(RTMP, decl.id), exprvalue(fn, &ini));
- }
- }
- break;
- case SCTYPEDEF: break;
- case SCEXTERN: break;
- default: assert(0);
- }
- Err:
- if (!put) putdecl(pr, &decl);
- }
- } while (st.more);
- } else {
+ if (isdecltok(pr))
+ localdecl(pr, fn);
+ else
stmt(pr, fn);
- }
}
pr->fnblkspan = tk.span;
}
diff --git a/parse.h b/parse.h
index be5f81e..4cd2e5f 100644
--- a/parse.h
+++ b/parse.h
@@ -104,6 +104,8 @@ struct parser {
struct env *env;
struct arena *fnarena, *exarena;
struct span fnblkspan;
+ uint loopdepth, switchdepth;
+ struct block *loopbreak, *loopcont;
};
const char *intern(const char *);
diff --git a/todo.txt b/todo.txt
index 627daba..3a5ef2f 100644
--- a/todo.txt
+++ b/todo.txt
@@ -3,6 +3,6 @@ Things to finish before moving onto compiler optimizations, C extensions, other
- regalloc: fix phi-eliminating moves
- frontend: try to repr vars as ssa temps until they have their address taken or are mutated (to reduce no. of mem instrs)??
- ir: implement mem2reg
-- frontend: finish C impl: initializers, preprocessor (#include, fn-like macros, etc), forward declarations, for, switch, break-continue, goto
+- frontend: finish C impl: initializers, preprocessor (#include, fn-like macros, etc), forward declarations, switch, goto
at some point add another backend like arm64 to make sure the non target specific stuff is generic enough..
generated by cgit v1.2.3 (git 2.39.1) at 2026-05-01 21:15:42 +0000