fix UB in constant folding of double -> signed integer conversion

Guest0x0 committed 2 years ago

Commit b8b6a5f1 parent 12acbf33 files · +18 −1Browse files

Unified · Split

3 files

tccgen.c +4 −1
tests/tests2/134_double_to_signed.c +10 −0
tests/tests2/134_double_to_signed.expect +4 −0

@@ -3249,7 +3249,10 @@ error: · 3248 unmodified lines
3249	3249	vtop->c.i = (vtop->c.ld != 0);
3250	3250	} else {
3251	3251	if(sf)
3252		− vtop->c.i = vtop->c.ld;
	3252	+ /* the range of [int64_t] is enough to hold the integer part of any float value.
	3253	+ Meanwhile, converting negative double to unsigned integer is UB.
	3254	+ So first convert to [int64_t] here. */
	3255	+ vtop->c.i = (int64_t)vtop->c.ld;
3253	3256	else if (sbt_bt == VT_LLONG \|\| (PTR_SIZE == 8 && sbt == VT_PTR))
3254	3257	;
3255	3258	else if (sbt & VT_UNSIGNED)

tests/tests2/134_double_to_signed.c+10−0

@@ -0,0 +1,10 @@
	1	+#include <stdio.h>
	2	+int main() {
	3	+ printf("%d\n", (int)-1.0);
	4	+ double d = -1.0;
	5	+ printf("%d\n", (int)d);
	6	+
	7	+ printf("%d\n", (int)-2147483648.0);
	8	+ d = -2147483648.0;
	9	+ printf("%d\n", (int)d);
	10	+}

tests/tests2/134_double_to_signed.expect+4−0

@@ -0,0 +1,4 @@
	1	+-1
	2	+-1
	3	+-2147483648
	4	+-2147483648