NVPTX/dont-introduce-addrspacecast.ll required manually removing a check for
a bitcast.
AArch64/combine-address-mode.ll required rerunning update_test_checks
Mips required some manual updates due to a CHECK-NEXT coming after a
deleted bitcast.
ARM/sink-addrmode.ll needed one small manual fix.
Excludes one X86 function which needs more attention.
We often see code like the following after running SCCP:
switch (x) { case 42: phi(42, ...); }
This tends to produce bad code as we currently materialize the constant
phi-argument in the switch-block. This increases register pressure and
if the pattern repeats for `n` case statements, we end up generating `n`
constant values.
This changes CodeGenPrepare to catch this pattern and revert it back to:
switch (x) { case 42: phi(x, ...); }
Differential Revision: https://reviews.llvm.org/D124552
