| Message ID | YTBNI4p9FgaFXhc9@squeak.grove.modra.org |
|---|---|
| State | New |
| Headers | show |
| Series | obstack.h __PTR_ALIGN vs. ubsan | expand |
On 9/1/2021 10:03 PM, Alan Modra via Binutils wrote: > Current ubsan complains on every use of __PTR_ALIGN (when ptrdiff_t is > as large as a pointer), due to making calculations relative to a NULL > pointer. This patch avoids the problem by extracting out and > simplifying __BPTR_ALIGN for the usual case. I've continued to use > ptrdiff_t here, where it might be better to throw away __BPTR_ALIGN > entirely and just assume uintptr_t exists. > > OK to apply for gcc? > > * obstack.h (__PTR_ALIGN): Expand and simplify __BPTR_ALIGN > rather than calculating relative to a NULL pointer. OK jeff
diff --git a/include/obstack.h b/include/obstack.h index a6eb6c95587..0d8746f835b 100644 --- a/include/obstack.h +++ b/include/obstack.h @@ -137,9 +137,9 @@ relative to B. Otherwise, use the faster strategy of computing the alignment relative to 0. */ -#define __PTR_ALIGN(B, P, A) \ - __BPTR_ALIGN (sizeof (ptrdiff_t) < sizeof (void *) ? (B) : (char *) 0, \ - P, A) +#define __PTR_ALIGN(B, P, A) \ + (sizeof (ptrdiff_t) < sizeof (void *) ? __BPTR_ALIGN (B, P, A) \ + : (char *) (((ptrdiff_t) (P) + (A)) & ~(A))) #ifndef __attribute_pure__ # if defined __GNUC_MINOR__ && __GNUC__ * 1000 + __GNUC_MINOR__ >= 2096