https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106365
--- Comment #4 from Richard Biener <rguenth at gcc dot gnu.org> --- int __attribute__((noinline,noclone)) foo (int *out) { int mask[] = { 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1 }; int i; for (i = 0; i < 32; ++i) { if (mask[i]) out[i] = i; } return out[7]; } testcase for x86_64 and .MASK_STORE, could be optimized to return 1. FRE sees .MASK_STORE (out_41(D), 32B, mask__7.9_47, { 0, 1, 2, 3, 4, 5, 6, 7 }); _10 = &mask[8] + 32; MEM <vector(8) int> [(int *)_10] = { 0, 1, 0, 1, 0, 1, 0, 1 }; and 'mask' having address taken makes it clobbered by .MASK_STORE. There's also the older issue that when mask is incoming but marked __restrict that isn't good enough because __restrict and calls doesn't work. The IL with .LEN_STORE might suffer similar issues at the point FRE gets to see it. We might be able to improve BB SLP to not code-gen _10 = &mask[8] + 32; MEM <vector(8) int> [(int *)_10] = { 0, 1, 0, 1, 0, 1, 0, 1 }; here, making 'mask' addressable again. I have a patch for this in testing.