[PATCH] D130919: [MRI] isConstantPhysReg should also check if the register is clobbered by a RegMask

[Guozhi Wei via Phabricator via llvm-commits]

Carrot added inline comments.


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Comment at: llvm/lib/CodeGen/RegUsageInfoPropagate.cpp:147-149
+  if (Changed)
+    MF.getRegInfo().recollectUsedPhysRegMask();
+
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arsenm wrote:
> Won't this be reflected in the regmask updates (BTW I think this pass needs to be changed to directly modify the regmasks in the instruction instead of the analysis)?
Query register information through MRI is precise through the linked Register operands. But RegMask is different, all RegMask information is cumulated in MRI.UsedPhysRegMask. So usually we can only add new used physical registers into UsedPhysRegMask. This pass is used to reduce used physical registers, we need to reset UsedPhysRegMask and collect RegMask again.


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  https://reviews.llvm.org/D130919/new/

https://reviews.llvm.org/D130919