The current code detects and warns on division by zero but
only when the left-hand side is a constant value.
Fix that by moving up the code which detect such divisions
before checking if the LHS is a constant.
Signed-off-by: Luc Van Oostenryck <luc.vanoostenryck@xxxxxxxxx>
---
expand.c | 18 ++++++++++--------
validation/div-by-zero-fp.c | 24 ++++++++++++++++++++++++
2 files changed, 34 insertions(+), 8 deletions(-)
create mode 100644 validation/div-by-zero-fp.c
diff --git a/expand.c b/expand.c
index 71fbf209c..6b0dbf656 100644
--- a/expand.c
+++ b/expand.c
@@ -325,19 +325,23 @@ static int simplify_float_binop(struct expression *expr)
unsigned long mod = expr->ctype->ctype.modifiers;
long double l, r, res;
- if (left->type != EXPR_FVALUE || right->type != EXPR_FVALUE)
+ if (right->type != EXPR_FVALUE)
return 0;
- l = left->fvalue;
r = right->fvalue;
+ if (!r && expr->op == '/')
+ goto Div;
+
+ if (left->type != EXPR_FVALUE)
+ return 0;
+ l = left->fvalue;
if (mod & MOD_LONGLONG) {
switch (expr->op) {
case '+': res = l + r; break;
case '-': res = l - r; break;
case '*': res = l * r; break;
- case '/': if (!r) goto Div;
- res = l / r; break;
+ case '/': res = l / r; break;
default: return 0;
}
} else if (mod & MOD_LONG) {
@@ -345,8 +349,7 @@ static int simplify_float_binop(struct expression *expr)
case '+': res = (double) l + (double) r; break;
case '-': res = (double) l - (double) r; break;
case '*': res = (double) l * (double) r; break;
- case '/': if (!r) goto Div;
- res = (double) l / (double) r; break;
+ case '/': res = (double) l / (double) r; break;
default: return 0;
}
} else {
@@ -354,8 +357,7 @@ static int simplify_float_binop(struct expression *expr)
case '+': res = (float)l + (float)r; break;
case '-': res = (float)l - (float)r; break;
case '*': res = (float)l * (float)r; break;
- case '/': if (!r) goto Div;
- res = (float)l / (float)r; break;
+ case '/': res = (float)l / (float)r; break;
default: return 0;
}
}
diff --git a/validation/div-by-zero-fp.c b/validation/div-by-zero-fp.c
new file mode 100644
index 000000000..957bc732c
--- /dev/null
+++ b/validation/div-by-zero-fp.c
@@ -0,0 +1,24 @@
+double fbad(double a) { return 2.0 / 0; }
+double gbad(double a) { return 2.0 / 0.0; }
+double fool(double a) { return a / 0; }
+double ffoo(double a) { return a / 0.0; }
+
+double fbar(double a) { if (a && 0) a / 0.0; return 0; }
+double fbaz(double a) { return a /= 0.0; }
+double fquz(double a) { return a / (a && 0); }
+
+/*
+ * check-name: div-by-zero-fp.c
+ * check-command: sparse -Wno-decl $file
+ * check-known-to-fail
+ *
+ * check-error-start
+div-by-zero-fp.c:1:36: warning: division by zero
+div-by-zero-fp.c:2:36: warning: division by zero
+div-by-zero-fp.c:3:34: warning: division by zero
+div-by-zero-fp.c:4:34: warning: division by zero
+div-by-zero-fp.c:6:39: warning: division by zero
+div-by-zero-fp.c:7:34: warning: division by zero
+div-by-zero-fp.c:8:34: warning: division by zero
+ * check-error-end
+ */
--
2.13.0
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