[SimplifyCFG] Skip merging return blocks if it would break a CallBr. #204
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SimplifyCFG should not merge empty return blocks and leave a CallBr behind with a duplicated destination since the verifier will then trigger an assert. This patch checks for this case and avoids the transformation. CodeGenPrepare has a similar check which also has a FIXME comment about why this is needed. It seems perhaps better if these two passes would eventually instead update the CallBr instruction instead of just checking and avoiding. This fixes https://bugs.llvm.org/show_bug.cgi?id=45062. Review: Craig Topper Differential Revision: https://reviews.llvm.org/D75620 (cherry picked from commit c2dafe1)
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SimplifyCFG should not merge empty return blocks and leave a CallBr behind
with a duplicated destination since the verifier will then trigger an
assert. This patch checks for this case and avoids the transformation.
CodeGenPrepare has a similar check which also has a FIXME comment about why
this is needed. It seems perhaps better if these two passes would eventually
instead update the CallBr instruction instead of just checking and avoiding.
This fixes https://bugs.llvm.org/show_bug.cgi?id=45062.
Review: Craig Topper
Differential Revision: https://reviews.llvm.org/D75620
(cherry picked from commit c2dafe1)