On Thu, 13 May 2021, Richard Earnshaw via Gcc-patches wrote: > > Normally we expect the gimple optimizers to fold away comparisons that > are always true, but at some lower optimization levels this is not > always the case, so the back-end has to be able to generate correct > code in these cases. > > In this example, we have a comparison of the form > > (unsigned long long) op <= ~0ULL > > which, of course is always true. > > Normally, in the arm back-end we handle these expansions where the > immediate cannot be handled directly by adding 1 to the constant and > then adjusting the comparison operator: > > (unsigned long long) op < CONST + 1 > > but we cannot do that when the constant is already the largest value.
Sounds like a target-independent bug in the making, lurking and waiting for a target to do the above adjustment but missing the bounds-check. > gcc/testsuite/gcc.dg/pr100563.c | 9 +++++++++ > 2 files changed, 34 insertions(+), 4 deletions(-) > create mode 100644 gcc/testsuite/gcc.dg/pr100563.c I'll therefore humbly suggest the test-case adjusted to be a run-time check (and if not done by others, projecting to do that myself...some time late next summer9. brgds, H-P
