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487399a60f
The original version of the pass could underestimate the length of a backward
branch in cases like:
alignment to N bytes or more
...
relaxable branch A
...
foo: (aligned to M<N bytes)
...
bar: (aligned to N bytes)
...
relaxable branch B to foo
We don't add any misalignment gap for "bar" because N bytes of alignment
had already been reached earlier in the function. In this case, assuming
that A is relaxed can push "foo" closer to "bar", and make B appear to be
in range. Similar problems can occur for forward branches.
I don't think it's possible to create blocks with mixed alignments as
things stand, not least because we haven't yet defined getPrefLoopAlignment()
for SystemZ (that would need benchmarking). So I don't think we can test
this yet.
Thanks to Rafael Espíndola for spotting the bug.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182460 91177308-0d34-0410-b5e6-96231b3b80d8
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