[PATCH] D124836: [AArch64] Add support for -fzero-call-used-regs

[Nick Desaulniers via Phabricator via cfe-commits]

nickdesaulniers added inline comments.


================
Comment at: llvm/lib/Target/AArch64/AArch64FrameLowering.cpp:776-778
+      // For GPRs, we only care to clear out the 64-bit register.
+      if (MCRegister XReg = getRegisterOrZero(Reg))
+        GPRsToZero.set(XReg);
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nickdesaulniers wrote:
> so for 32b registers, we clear the whole 64b register?
Perhaps a more descriptive method name like `getWidestRegisterAlias` or the like? Perhaps we should simply assert if we get a non GPR rather than return 0, which might actually be a Register?

Also, TargetRegisterClass has some notion of sub and super register classes. I wonder if have existing machinery to say, given a register class, what's the equivalent/aliases super register class (if that's even what a super register is).


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  https://reviews.llvm.org/D124836/new/

https://reviews.llvm.org/D124836