[PATCH] D94098: [Clang][AArch64] Inline assembly support for the ACLE type 'data512_t'.

[Alexandros Lamprineas via Phabricator via cfe-commits]

labrinea added a comment.

In D94098#2868751 <https://reviews.llvm.org/D94098#2868751>, @efriedma wrote:

> The part I'm confused about is that you're forcing it to use "*r".  At the IR level, LLVM handles something like `call void asm sideeffect "#$0", "r"([8 x i64] %c)` fine.  You'll have to do a bit of work to teach clang to emit that, but it shouldn't be that hard.  I think you can deal with it on the isel end with some relatively small changes to D94097 <https://reviews.llvm.org/D94097>.

If you discard my patch and look at the codegen for `__asm__ volatile ("st64b %0,[%1]" : : "r" (*input), "r" (addr) : "memory" );`, which uses the struct foo as an input operand, you'll see that clang is already passing it by reference. All I am doing is making this behavior consistent for output operands too. Whether llvm can deal with indirect asm register operands or not is a separate story (see llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp:8740). I think that making clang emit what you sugggested (to pass [8 x i64] by value) is inevitably going to be inelegant in a similar way that the previous revision of this patch was. Moreover, taking this route entails introducing more inelegant changes in D94097 <https://reviews.llvm.org/D94097> (workarounds for MVT::i64x8 in getCopyToParts() of the same file I previously mentioned). I have been unsuccessfully trying all the above and I can continue my efforts for a little more, but in my honest opinion I don't see the benefit.


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https://reviews.llvm.org/D94098