[PATCH] D54685: [AArch64] Allow -mattr=use_el[1|2|3] and -mattr=use_sp_for_tp

[Oliver Stannard via Phabricator via llvm-commits]

olista01 added a comment.

What is the use-case for wanting to use SP_ELx for the thread pointer, instead of TPIDR_ELx?



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Comment at: lib/Target/AArch64/AArch64.td:244
+foreach i = 1-3 in
+    def FeatureUseEL#i : SubtargetFeature<"use-el"#i, "UseEL"#i, "true",
+                                          "Generate access to EL"#i#" registers">;
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Is this likely to be used for anything other than the TPIDR registers? I think it would be better to make the name more specific, unless we are also going to gate all system registers in the assembler on these features.


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Comment at: lib/Target/AArch64/AArch64ExpandPseudoInsts.cpp:938
+      else
+        report_fatal_error("SP can only be used for TP in EL1 or EL2");
+    } else {
----------------
Why can SP_EL3 not be used?


Repository:
  rL LLVM

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  https://reviews.llvm.org/D54685/new/

https://reviews.llvm.org/D54685