qbe: Switch to unary negation

This fixes bugs involving floating point negative zero.

2 files changed, 2 insertions, 1 deletions

diff --git a/ops.h b/ops.h
index b8b461a..9b2d48b 100644
--- a/ops.h
+++ b/ops.h
@@ -1,6 +1,7 @@
 /* arithmetic and bits */
 OP(IADD,     "add")
 OP(ISUB,     "sub")
+OP(INEG,     "neg")
 OP(IDIV,     "div")
 OP(IMUL,     "mul")
 OP(IUDIV,    "udiv")
diff --git a/qbe.c b/qbe.c
index 81ed566..41a38da 100644
--- a/qbe.c
+++ b/qbe.c
@@ -803,7 +803,7 @@ funcexpr(struct func *f, struct expr *e)
 			return funcload(f, e->type, (struct lvalue){r});
 		case TSUB:
 			r = funcexpr(f, e->base);
-			return funcinst(f, ISUB, qbetype(e->type).base, mkintconst(0), r);
+			return funcinst(f, INEG, qbetype(e->type).base, r, NULL);
 		}
 		fatal("internal error; unknown unary expression");
 		break;