[PATCH] D65653: [AArch64] Change location of frame-record within callee-save area.

[Sander de Smalen via Phabricator via llvm-commits]

sdesmalen marked an inline comment as done.
sdesmalen added inline comments.


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Comment at: test/CodeGen/AArch64/wineh-try-catch-realign.ll:13
+; CHECK:      stp     x29, x30, [sp, #-32]!
+; CHECK-NEXT: stp     x28, x19, [sp, #16]
 ; CHECK-NEXT: add     x0, x19, #64
----------------
efriedma wrote:
> I don't think this is legal. On Windows, paired stores in the prologue must be in the form "stp xN, xN+1, [...]"; otherwise, there is no way to represent the store in the unwind format. (See https://docs.microsoft.com/en-us/cpp/build/arm64-exception-handling?view=vs-2019#unwind-codes )
The merging of two separate STR instructions into one STP seems to done by the LoadStoreOptimizer, not PEI. The unwind information generated seems correct.

Running with `stop-after=prologepilog`:
```    frame-setup STRXui killed $x28, $sp, 2 :: (store 8 into %stack.2)
    frame-setup SEH_SaveReg 28, 16
    frame-setup STRXui killed $x19, $sp, 3 :: (store 8 into %stack.1)
    frame-setup SEH_SaveReg 19, 24```

Running `readobj --unwind` on the binary produced by this test gives:
```      Prologue [
        0xd003              ; str x19, [sp, #24]
        0xd242              ; str x28, [sp, #16]
        0x83                ; stp x29, x30, [sp, #-32]!
        0xe4                ; end
      ]```


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D65653/new/

https://reviews.llvm.org/D65653