.dir-locals.el

@@ -0,0 +1,2 @@
+((c-mode . ((tab-width . 4)
+            (indent-tabs-mode . t))))

.gitignore

@@ -6,4 +6,5 @@ config.h
 *~
 .direnv
 result
-.cache
+.cache
+.fuse_hidden*

all.h

@@ -159,12 +159,12 @@ enum J {
 #define JMPS(X)                                 \
 	X(retw)   X(retl)   X(rets)   X(retd)   \
 	X(retsb)  X(retub)  X(retsh)  X(retuh)  \
-	X(retc)   X(ret0)   X(jmp)    X(jnz)    \
+	X(retc)   X(ret0)   X(jmp)    X(jnz)	\
 	X(jfieq)  X(jfine)  X(jfisge) X(jfisgt) \
 	X(jfisle) X(jfislt) X(jfiuge) X(jfiugt) \
 	X(jfiule) X(jfiult) X(jffeq)  X(jffge)  \
 	X(jffgt)  X(jffle)  X(jfflt)  X(jffne)  \
-	X(jffo)   X(jffuo)  X(hlt)
+	X(jffo)   X(jffuo)  X(hlt) X(tail)
 #define X(j) J##j,
 	JMPS(X)
 #undef X

amd64/isel.c

@@ -602,7 +602,8 @@ seljmp(Blk *b, Fn *fn)
 
 	if (b->jmp.type == Jret0
 	|| b->jmp.type == Jjmp
-	|| b->jmp.type == Jhlt)
+	|| b->jmp.type == Jhlt
+	|| b->jmp.type == Jtail)
 		return;
 	assert(b->jmp.type == Jjnz);
 	r = b->jmp.arg;

amd64/sysv.c

@@ -167,7 +167,7 @@ argsclass(Ins *i0, Ins *i1, AClass *ac, int op, AClass *aret, Ref *env)
 	nsse = 8;
 	varc = 0;
 	envc = 0;
-	for (i=i0, a=ac; i<i1; i++, a++)
+	for (i=i0, a=ac; i<i1; i++, a++) {
 		switch (i->op - op + Oarg) {
 		case Oarg:
 			if (KBASE(i->cls) == 0)
@@ -211,8 +211,9 @@ argsclass(Ins *i0, Ins *i1, AClass *ac, int op, AClass *aret, Ref *env)
 			varc = 1;
 			break;
 		default:
-			die("unreachable");
+			die("218 unreachable");
 		}
+	}
 
 	if (varc && envc)
 		err("sysv abi does not support variadic env calls");
@@ -686,7 +687,7 @@ amd64_sysv_abi(Fn *fn)
 			continue;
 		curi = &insb[NIns];
 		selret(b, fn);
-		for (i=&b->ins[b->nins]; i!=b->ins;)
+		for (i=&b->ins[b->nins]; i!=b->ins;) {
 			switch ((--i)->op) {
 			default:
 				emiti(*i);
@@ -706,8 +707,13 @@ amd64_sysv_abi(Fn *fn)
 				break;
 			case Oarg:
 			case Oargc:
-				die("unreachable");
+			  if (b->jmp.type != Jtail) {
+				die("710 unreachable");
+			  } else {
+				
+			  }
 			}
+		}
 		if (b == fn->start)
 			for (; ral; ral=ral->link)
 				emiti(ral->i);

flake.nix

@@ -34,12 +34,8 @@
             gcc
             clang-analyzer
             clang-tools
+            gdbgui
 	  ];
-          # shellHook = ''
-          #   [[ ! -z "$LD_LIBRARY_PATH" ]] \
-          #     && export LD_LIBRARY_PATH=:$LD_LIBRARY_PATH
-          #   export LD_LIBRARY_PATH="${self.packages.${system}.default.libllvm.lib}/lib$LD_LIBRARY_PATH"
-          # '';
 	};
       });
     };

main.c

@@ -17,6 +17,7 @@ char debug['Z'+1] = {
 	['L'] = 0, /* liveness */
 	['S'] = 0, /* spilling */
 	['R'] = 0, /* reg. allocation */
+	['E'] = 0, /* enums */
 };
 
 extern Target T_amd64_sysv;

parse.c

@@ -53,6 +53,7 @@ enum Token {
 	Tphi,
 	Tjmp,
 	Tjnz,
+	Ttail,
 	Tret,
 	Thlt,
 	Texport,
@@ -113,6 +114,7 @@ static char *kwmap[Ntok] = {
 	[Tphi] = "phi",
 	[Tjmp] = "jmp",
 	[Tjnz] = "jnz",
+	[Ttail] = "tail",
 	[Tret] = "ret",
 	[Thlt] = "hlt",
 	[Texport] = "export",
@@ -664,6 +666,13 @@ parseline(PState ps)
 			curb->jmp.arg = r;
 		}
 		goto Close;
+	case Ttail:
+	  curb->jmp.type = Jtail;
+	  curb->jmp.arg = parseref ();
+	  /* Ins *restore = curi; */
+	  parserefl(1);
+	  /* curi = restore; */
+	  goto Close;
 	case Tjmp:
 		curb->jmp.type = Jjmp;
 		goto Jump;
@@ -1434,6 +1443,11 @@ printfn(Fn *fn, FILE *f)
 			if (b->s1 != b->link)
 				fprintf(f, "\tjmp @%s\n", b->s1->name);
 			break;
+		case Jtail:
+		  fprintf (f, "\ttail ");
+		  printref (b->jmp.arg, fn, f);
+		  fprintf (f, "\n");
+		  break;
 		default:
 			fprintf(f, "\t%s ", jtoa[b->jmp.type]);
 			if (b->jmp.type == Jjnz) {

result

@@ -1 +0,0 @@
-/nix/store/662p38x2aqlrk0hnx0nskcj4100as900-qbe-git

test/call-factorial.ssa

@@ -0,0 +1,11 @@
+function w $factorial (w %n, w %acc) {
+@start
+	jnz %n, @nz, @z
+@z
+	ret %acc
+@nz
+	%n_next =w sub %n, 1
+	%acc_next =w mul %n, %acc
+	%r =w call $factorial (w %n_next, w %acc)
+	ret %r
+}

test/tail.ssa

@@ -0,0 +1,10 @@
+function w $factorial (w %n, w %acc) {
+@start
+	jnz %n, @nz, @z
+@z
+	ret %acc
+@nz
+	%n_next =w sub %n, 1
+	%acc_next =w mul %n, %acc
+	tail $factorial (w %n_next, w %acc)
+}

util.c

@@ -261,6 +261,7 @@ igroup(Blk *b, Ins *i, Ins **i0, Ins **i1)
 
 	ib = b->ins;
 	ie = ib + b->nins;
+
 	switch (i->op) {
 	case Oblit0:
 		*i0 = i;
@@ -285,8 +286,12 @@ igroup(Blk *b, Ins *i, Ins **i0, Ins **i1)
 		*i0 = i;
 		for (; i<ie && i->op != Ocall; i++)
 			;
-		assert(i < ie);
-		*i1 = i + 1;
+		if (b->jmp.type == Jtail) {
+		  *i1 = ie;
+		} else {
+		  assert(i < ie);
+		  *i1 = i + 1;
+		}
 		return;
 	case Osel1:
 		for (; i>ib && (i-1)->op == Osel1; i--)