nickdesaulniers added inline comments.
================ Comment at: llvm/lib/Target/X86/X86FrameLowering.cpp:595 + continue; + XorOp = X86::PXORrr; + } else if (X86::VR256RegClass.contains(Reg)) { ---------------- void wrote: > nickdesaulniers wrote: > > Is there any way to figure the `XorOp` outside of this loop? Seems > > unfortunate to repeatedly scan almost every register class for every used > > register. > > > > Like instead of querying each register set whether a given register is in > > it, is it possible to ask a register what register class it's in? Or can a > > register belong to more than one register class? > There's a function in TRI that you can call to grab the RegClass of a > register, but it calls a "`contains`" on each register class to see if it > belongs in it, so it would be worse than this code. > > In practice, the register classes won't have many members in it. It sucks, > but it's probably something like `16*16` in a worst case scenario. > > (I think registers can belong to multiple register classes (e.g. sub- and > super-classes), but I don't quote me on that.) Right, I just get a sinking feeling that we're going to repeatedly scan these RegClass lists for every MachineFunction, when the answer doesn't change; we should eventually be able to map these O(1). ================ Comment at: llvm/lib/Target/X86/X86RegisterInfo.cpp:629-633 + if (!ST.is64Bit()) + return llvm::any_of( + SmallVector<MCRegister>{X86::EAX, X86::ECX, X86::EDX}, + [&](MCRegister &RegA) { return IsSubReg(RegA, Reg); }) || + (ST.hasMMX() && X86::VR64RegClass.contains(Reg)); ---------------- Do we need to clear stack slots for i386? The Linux kernel uses `-mreg-param=3` to use a faster, though custom calling convention. This corresponds to the `inreg` parameter attribute in LLVM IR. Otherwise, perhaps a todo and diagnose `-m32` in the front end? Repository: rG LLVM Github Monorepo CHANGES SINCE LAST ACTION https://reviews.llvm.org/D110869/new/ https://reviews.llvm.org/D110869 _______________________________________________ cfe-commits mailing list cfe-commits@lists.llvm.org https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits