tree 32509b4b1b7c90dce22594a031c2be702b7b8cc1
parent 783f5a435aa61388740bd73543f1092eee7cbb84
author Malhar Jajoo <malhar.jajoo@arm.com> 1618587907 +0100
committer Copybara-Service <copybara-worker@google.com> 1618603912 -0700

[ARM] Prevent phi-node-elimination from generating copy above t2WhileLoopStartLR

This patch prevents phi-node-elimination from generating a COPY
operation for the register defined by t2WhileLoopStartLR, as it is a
terminator that defines a value.

This happens because of the presence of phi-nodes in the loop body (the
Preheader of which is the block containing the t2WhileLoopStartLR). If
this is not done, the COPY is generated above/before the terminator
(t2WhileLoopStartLR here), and since it uses the value defined by
t2WhileLoopStartLR, MachineVerifier throws a 'use before define' error.

This essentially adds on to the change in differential D91887/D97729.

Differential Revision: https://reviews.llvm.org/D100376

GitOrigin-RevId: 093f1828e58c685d74afba8ad963809a3236f83d