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tree-optimization/105969 - FPE with array diagnostics 

For a [0][0] array we have to be careful when dividing by the element
size which is zero for the outermost dimension.  Luckily the division
is only for an overflow check which is pointless for array size zero.

2022-06-15  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/105969
	* gimple-ssa-sprintf.cc (get_origin_and_offset_r): Avoid division
	by zero in overflow check.

	* gcc.dg/pr105969.c: New testcase.

(cherry picked from commit edb9330c29)
This commit is contained in:
Richard Biener 2022-06-15 10:54:48 +02:00
parent 1fe7321a6c
commit 4f34a9e8d5
2 changed files with 14 additions and 1 deletions
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2
gcc/gimple-ssa-sprintf.cc
View File

@ -2319,7 +2319,7 @@ get_origin_and_offset_r (tree x, HOST_WIDE_INT *fldoff, HOST_WIDE_INT *fldsize,
if (byteoff < HOST_WIDE_INT_MAX
&& elbytes < HOST_WIDE_INT_MAX
&& byteoff / elbytes == idx)
&& (elbytes == 0 || byteoff / elbytes == idx))
{
/* For in-bounds constant offsets into constant-sized arrays
bump up *OFF, and for what's likely arrays or structs of

13
gcc/testsuite/gcc.dg/pr105969.c Normal file
View File

@ -0,0 +1,13 @@
/* { dg-do compile } */
/* { dg-options "-Wall" } */
struct A
{
char a[0][0][0];
};
extern struct A b[][2];
void f (void)
{
__builtin_sprintf (b[0][0].a[1][0], "%s", b[0][0].a[1][0]); /* { dg-warning "past the end" } */
/* { dg-warning "overlaps destination" "" { target *-*-* } .-1 } */
}