From f9d970a0535ec3ae4aaff6842788a89b139cfdaa Mon Sep 17 00:00:00 2001
From: Leo Tenenbaum <pommicket@gmail.com>
Date: Fri, 1 May 2020 17:48:09 -0400
Subject: made output for void pointer arithmetic standard-compliant

---
 cgen.c                        | 32 +++++++++++++++++++++++++++-----
 main.c                        |  2 --
 test.toc                      | 30 +++++++++++++++++++++++++++++-
 tests/ptr_arithmetic.toc      | 33 +++++++++++++++++++++++++++++++++
 tests/ptr_arithmetic_expected |  2 ++
 tests/test.sh                 |  1 +
 6 files changed, 92 insertions(+), 8 deletions(-)
 create mode 100644 tests/ptr_arithmetic.toc
 create mode 100644 tests/ptr_arithmetic_expected

diff --git a/cgen.c b/cgen.c
index 128ad16..2f98565 100644
--- a/cgen.c
+++ b/cgen.c
@@ -1288,8 +1288,10 @@ static void cgen_expr(CGenerator *g, Expression *e) {
 	case EXPR_BINARY_OP: {
 		const char *s = "";
 		Expression *lhs = e->binary.lhs, *rhs = e->binary.rhs;
+		Type *lhs_type = &lhs->type;
 		bool handled = false;
-		switch (e->binary.op) {
+		BinaryOp op = e->binary.op;
+		switch (op) {
 		case BINARY_SUB:
 			s = "-"; break;
 		case BINARY_ADD:
@@ -1327,13 +1329,11 @@ static void cgen_expr(CGenerator *g, Expression *e) {
 		case BINARY_SET_MOD:
 			s = "%="; break;
 		case BINARY_AT_INDEX: {
-			Type *lhs_type = &lhs->type;
 			bool uses_ptr = false;
 			if (lhs_type->kind == TYPE_PTR) {
 				uses_ptr = true;
 				lhs_type = lhs_type->ptr;
 			}
-			cgen_write(g, "(");
 			switch (lhs_type->kind) {
 			case TYPE_ARR:
 				if (uses_ptr) cgen_write(g, "(*");
@@ -1368,11 +1368,10 @@ static void cgen_expr(CGenerator *g, Expression *e) {
 				assert(0);
 				break;
 			}
-			cgen_write(g, ")");
 			handled = true;
 		} break;
 		case BINARY_DOT: {
-			Type *struct_type = &lhs->type;
+			Type *struct_type = lhs_type;
 			if (struct_type->kind == TYPE_PTR) struct_type = struct_type->ptr;
 			if (struct_type->kind == TYPE_STRUCT) {
 				cgen_write(g, "(");
@@ -1396,6 +1395,29 @@ static void cgen_expr(CGenerator *g, Expression *e) {
 			handled = true;
 		} break;
 		}
+		if (lhs_type->kind == TYPE_PTR && type_is_void(lhs_type->ptr)) {
+			if (op == BINARY_ADD || op == BINARY_SUB) {
+				cgen_write(g, "((");
+				cgen_type_pre(g, &e->type);
+				cgen_type_post(g, &e->type);
+				cgen_write(g, ")((char*)");
+				cgen_expr(g, lhs);
+				cgen_write(g, "%s", s);
+				cgen_expr(g, rhs);
+				cgen_write(g, "))");
+			} else if (op == BINARY_SET_ADD || op == BINARY_SET_SUB) {
+				/* lhs could have side effects so we can't just do lhs = (char *)lhs + rhs */
+				cgen_write(g, "{");
+					cgen_write(g, "void **t_ = &");
+				cgen_expr(g, lhs);
+				cgen_write(g, ";");
+				cgen_write(g, "*t_ = (char *)*t_ %c ", s[0]);
+				cgen_expr(g, rhs);
+				cgen_write(g, ";}");
+			}
+			handled = true;
+		}
+
 		if (handled) break;
 		cgen_write(g, "(");
 		cgen_expr(g, lhs);
diff --git a/main.c b/main.c
index 4ef211e..561dac6 100644
--- a/main.c
+++ b/main.c
@@ -8,8 +8,6 @@
 
 /* 
 @TODO:
-fix eval pointer arithmetic - are we not multiplying by the size?
-	- pointer arithmetic test
 fix including something twice - just use the non-namespacey version if it exists or pick one namespace to use everywhere otherwise
 	- maybe store info about namespaces which are secretly the same as inline blocks/other namespaces in the Typer
 &&, ||
diff --git a/test.toc b/test.toc
index d0f74fb..05975e8 100644
--- a/test.toc
+++ b/test.toc
@@ -1,5 +1,33 @@
 #include "std/io.toc";
+#include "std/mem.toc";
 
-main ::= fn() {
+ptr_arithmetic_test ::= fn() total := 0 {
+	foo := news(int, 10);
+	for p, i := &foo {
+		*p = i;
+	}
+	p := &foo[0];
+	
+	p += 2;
+	total += *p;
+	total += *(p + 3);
+	total += *(p - 1);
+
+	voidp : &void = &foo[7];
+	total += *(voidp as &int);
+	voidp = voidp + 8;
+	total += *(voidp as &int);
+	voidp += 8;
+	total += *(voidp as &int);
+	voidp = voidp - 8;
+	total += *(voidp as &int);
+	voidp -= 8;
+	total += *(voidp as &int);
+}
 
+main ::= fn() {
+	x ::= ptr_arithmetic_test();
+	y := ptr_arithmetic_test();
+	puti(x);
+	puti(y);
 }
diff --git a/tests/ptr_arithmetic.toc b/tests/ptr_arithmetic.toc
new file mode 100644
index 0000000..05975e8
--- /dev/null
+++ b/tests/ptr_arithmetic.toc
@@ -0,0 +1,33 @@
+#include "std/io.toc";
+#include "std/mem.toc";
+
+ptr_arithmetic_test ::= fn() total := 0 {
+	foo := news(int, 10);
+	for p, i := &foo {
+		*p = i;
+	}
+	p := &foo[0];
+	
+	p += 2;
+	total += *p;
+	total += *(p + 3);
+	total += *(p - 1);
+
+	voidp : &void = &foo[7];
+	total += *(voidp as &int);
+	voidp = voidp + 8;
+	total += *(voidp as &int);
+	voidp += 8;
+	total += *(voidp as &int);
+	voidp = voidp - 8;
+	total += *(voidp as &int);
+	voidp -= 8;
+	total += *(voidp as &int);
+}
+
+main ::= fn() {
+	x ::= ptr_arithmetic_test();
+	y := ptr_arithmetic_test();
+	puti(x);
+	puti(y);
+}
diff --git a/tests/ptr_arithmetic_expected b/tests/ptr_arithmetic_expected
new file mode 100644
index 0000000..930ba1a
--- /dev/null
+++ b/tests/ptr_arithmetic_expected
@@ -0,0 +1,2 @@
+47
+47
diff --git a/tests/test.sh b/tests/test.sh
index 75697ef..bf58042 100755
--- a/tests/test.sh
+++ b/tests/test.sh
@@ -4,6 +4,7 @@ tests='bf
 control_flow
 types
 arrs_slices
+ptr_arithmetic
 defer
 sizeof
 new
-- 
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