[all-commits] [llvm/llvm-project] 3d5e8e: [PAC][CodeGen] Do not emit trivial 'mov xN, xN' on...

[Daniil Kovalev via All-commits]

  Branch: refs/heads/main
  Home:   https://github.com/llvm/llvm-project
  Commit: 3d5e8e4693a51cd3ba336cec0c1a17fe389828a7
      https://github.com/llvm/llvm-project/commit/3d5e8e4693a51cd3ba336cec0c1a17fe389828a7
  Author: Daniil Kovalev <dkovalev at accesssoftek.com>
  Date:   2024-09-19 (Thu, 19 Sep 2024)

  Changed paths:
    M llvm/lib/Target/AArch64/AArch64AsmPrinter.cpp
    M llvm/test/CodeGen/AArch64/ptrauth-call.ll

  Log Message:
  -----------
  [PAC][CodeGen] Do not emit trivial 'mov xN, xN' on tail call (#109100)

Under some conditions, a trivial `mov xN xN` instruction was emitted on
tail calls. Consider the following code:

```
class Test {
public:
  virtual void f() {}
};

void call_f(Test *t) {
  t->f();
}
```

Correponding assembly:

```
_Z6call_fP4Test:
        ldr     x16, [x0]
        mov     x17, x0
        movk    x17, #6503, lsl #48
        autda   x16, x17
        ldr     x1, [x16]
 =====> mov     x16, x16
        movk    x16, #54167, lsl #48
        braa    x1, x16
```

This patch makes such movs being omitted.

Co-authored-by: Anatoly Trosinenko <atrosinenko at accesssoftek.com>



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