nooc

commit 0061900f933341976ce447469d0570370bc62f5a
parent 80f83723f1690bf4f9393f3764c6f1f92c6d479b
Author: Nihal Jere <nihal@nihaljere.xyz>
Date:   Wed, 15 Dec 2021 23:35:12 -0600

only allocate a register when necessary, fix clearreg

Diffstat:
M
main.c
 | 
8
++++++--
M
x64.c
 | 
2
+-

2 files changed, 7 insertions(+), 3 deletions(-)
diff --git a/main.c b/main.c
@@ -452,6 +452,7 @@ genblock(char *buf, struct block *block, bool toplevel)
 				assert(binary->kind == EXPR_BINARY);
 				enum reg reg = getreg();
 				total += genexpr(buf ? buf + total : NULL, expr->d.cond.cond, reg);
+				freereg(reg);
 				size_t iflen = genblock(NULL, &expr->d.cond.bif, false) + jmp(NULL, 0);
 				size_t elselen = genblock(NULL, &expr->d.cond.belse, false);
 				switch (binary->d.op) {
@@ -475,24 +476,28 @@ genblock(char *buf, struct block *block, bool toplevel)
 			struct decl *decl = &block->decls.data[item->idx];
 			struct expr *expr = &exprs.data[decl->val];
 			uint64_t addr;
-			enum reg reg = getreg();
+			enum reg reg;
 
 			decl->kind = toplevel ? DECL_DATA : DECL_STACK;
 			decl_alloc(block, decl);
 
 			switch (expr->class) {
 			case C_INT:
+				reg = getreg();
 				// FIXME: we can store literals at compile time
 				total += genexpr(buf ? buf + total : NULL, block->decls.data[item->idx].val, reg);
 				total += decl_fromreg(buf ? buf + total : NULL, decl, reg);
+				freereg(reg);
 				break;
 			// FIXME: we assume that any string is a literal, may break if we add binary operands on strings in the future.
 			case C_STR:
+				reg = getreg();
 				if (buf) {
 					addr = data_push(expr->d.v.v.s.data, expr->d.v.v.s.len);
 				}
 				total += mov_r64_imm(buf ? buf + total : NULL, reg, addr);
 				total += decl_fromreg(buf ? buf + total : NULL, decl, reg);
+				freereg(reg);
 				break;
 			case C_PROC:
 				block->decls.data[item->idx].loc.addr = total + TEXT_OFFSET;
@@ -506,7 +511,6 @@ genblock(char *buf, struct block *block, bool toplevel)
 			}
 
 			decl->declared = true;
-			freereg(reg);
 		} else if (item->kind == ITEM_ASSGN) {
 			struct expr *expr = &exprs.data[assgns.data[item->idx].val];
 			struct assgn *assgn = &assgns.data[item->idx];
diff --git a/x64.c b/x64.c
@@ -28,7 +28,7 @@ unsigned short used_reg;
 void
 clearreg()
 {
-	used_reg = RBP | RSP;
+	used_reg = (1 << RBP) | (1 << RSP);
 }
 
 enum reg