[PATCH] D132531: [AArch64] Reserve more physical registers

[Eli Friedman via Phabricator via llvm-commits]

efriedma added a comment.

> A reserved physical register doesn't mean it can't be used by compiler/linker, it just means it can't be used by register allocator, see the comments in TargetRegisterInfo::getReservedRegs().

The target feature to "reserve" a register is meant to be "don't use this register for anything".  For some registers, making sure the register isn't used by the register allocator is sufficient because the compiler/linker won't use them in any other way... but if the compiler uses a register outside register allocation, that doesn't work.

If you want a target feature to simulate high register pressure without any expectation that the resulting code actually works, please add a separate "regalloc-test-reserve-all-regs" feature or something like that.


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D132531/new/

https://reviews.llvm.org/D132531