Hi,
In PR 86311 Valgrind flags a call to memcpy with overlapping buffers. This can
happen in reorder{23,45} helpers when we're reordering in-place, and the 3rd/5th
element doesn't need to be moved: in that case the middle memcpy is called
with source == destination.
The fix is simple: just use a temporary, just like for other elements.
I'm a bit surprised at this though: when I looked, gcc turned those fixed-size
memcpy calls to MEMs even at -O0, so Valgrind wouldn't see them.
Bootstrapped on x86_64, OK to apply?
Thanks.
Alexander
PR middle-end/86311
* sort.cc (REORDER_23): Avoid memcpy with same destination and source.
(REORDER_45): Likewise.
diff --git a/gcc/sort.cc b/gcc/sort.cc
index a48a477d4e8..baabc39044f 100644
--- a/gcc/sort.cc
+++ b/gcc/sort.cc
@@ -64,12 +64,15 @@ reorder23 (sort_ctx *c, char *e0, char *e1, char *e2)
{
#define REORDER_23(TYPE, STRIDE, OFFSET) \
do { \
- TYPE t0, t1; \
+ TYPE t0, t1, t2; \
memcpy (&t0, e0 + OFFSET, sizeof (TYPE)); \
memcpy (&t1, e1 + OFFSET, sizeof (TYPE)); \
char *out = c->out + OFFSET; \
if (likely (c->n == 3)) \
- memcpy (out + 2*STRIDE, e2 + OFFSET, sizeof (TYPE)); \
+ { \
+ memcpy (&t2, e2 + OFFSET, sizeof (TYPE)); \
+ memcpy (out + 2*STRIDE, &t2, sizeof (TYPE)); \
+ } \
memcpy (out, &t0, sizeof (TYPE)); out += STRIDE; \
memcpy (out, &t1, sizeof (TYPE)); \
} while (0)
@@ -94,14 +97,17 @@ reorder45 (sort_ctx *c, char *e0, char *e1, char *e2, char
*e3, char *e4)
{
#define REORDER_45(TYPE, STRIDE, OFFSET) \
do { \
- TYPE t0, t1, t2, t3; \
+ TYPE t0, t1, t2, t3, t4; \
memcpy (&t0, e0 + OFFSET, sizeof (TYPE)); \
memcpy (&t1, e1 + OFFSET, sizeof (TYPE)); \
memcpy (&t2, e2 + OFFSET, sizeof (TYPE)); \
memcpy (&t3, e3 + OFFSET, sizeof (TYPE)); \
char *out = c->out + OFFSET; \
if (likely (c->n == 5)) \
- memcpy (out + 4*STRIDE, e4 + OFFSET, sizeof (TYPE)); \
+ { \
+ memcpy (&t4, e4 + OFFSET, sizeof (TYPE)); \
+ memcpy (out + 4*STRIDE, &t4, sizeof (TYPE)); \
+ } \
memcpy (out, &t0, sizeof (TYPE)); out += STRIDE; \
memcpy (out, &t1, sizeof (TYPE)); out += STRIDE; \
memcpy (out, &t2, sizeof (TYPE)); out += STRIDE; \
