[llvm] [AArch64] Fix handling of x29/x30 in inline assembly clobbers (PR #167783)

[David Spickett via llvm-commits]

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@@ -0,0 +1,36 @@
+; RUN: llc -mtriple=aarch64 -verify-machineinstrs < %s | FileCheck %s
+
+; Test that both numeric register names (x29, x30) and their architectural
+; aliases (fp, lr) work correctly as clobbers in inline assembly.
+
+define void @clobber_x29() nounwind {
+; CHECK-LABEL: clobber_x29:
+; CHECK:       str x29, [sp
+; CHECK:       ldr x29, [sp
+  tail call void asm sideeffect "", "~{x29}"()
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DavidSpickett wrote:

I know these are marked tailcall so in theory we should never get load/stores for stack frame management.

However, if you put a nop in the asm statement, you could make this into:
CHECK: str
CHECK-NEXT: nop
CHECK-NEXT: ldr

And it would be bit more robust and immediately clear what the intended behaviour is.

https://github.com/llvm/llvm-project/pull/167783