https://gcc.gnu.org/bugzilla/show_bug.cgi?id=86889
Bug ID: 86889
Summary: s390x gcc build fails when configured with
--disable-checking
Product: gcc
Version: 9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
Assignee: unassigned at gcc dot gnu.org
Reporter: iii at linux dot ibm.com
Target Milestone: ---
Host: s390x-linux-gnu
Target: s390x-linux-gnu
Build: s390x-linux-gnu
Seen on master (18d371d3):
build$ ../configure --disable-checking
build$ make -j$(getconf _NPROCESSORS_ONLN)
../../gcc/bitmap.c: In function ‘unsigned int
bitmap_last_set_bit(const_bitmap)’:
../../gcc/bitmap.c:841:26: error: array subscript -1 is below array bounds of
‘const BITMAP_WORD [2]’ {aka ‘const long unsigned int [2]’}
[-Werror=array-bounds]
word = elt->bits[ix];
The code in question is:
839 for (ix = BITMAP_ELEMENT_WORDS - 1; ix >= 0; ix--)
840 {
841 word = elt->bits[ix];
842 if (word)
843 goto found_bit;
844 }
BITMAP_ELEMENT_WORDS on s390x is 2.
I narrowed this down to cunrolli pass, which unrolls this loop 3 times instead
of 2, so ix=[1, 0, -1] instead of just [1, 0].
And indeed, building this individual file with -fdisable-tree-cunrolli helps.
