[PATCH] D146463: [CodeGen][RISCV] Change Shadow Call Stack Register to X3

[Jessica Clarke via Phabricator via cfe-commits]

jrtc27 added inline comments.


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Comment at: clang/docs/ShadowCallStack.rst:157
+linker. This can be done with the ``--no-relax-gp`` flag in GNU ld. It may also
+be useful to compile with ``-msmall-data-limit=0``.
 
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This doesn't really achieve anything other than not do one optimisation (which may or not matter; the grouping of small data may have a noticeable cache locality effect)


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Comment at: clang/lib/Driver/SanitizerArgs.cpp:573
+                                 Kinds & SanitizerKind::ShadowCallStack)
+          << "-msmall-data-limit=0";
+    }
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Why is this an error? It may be a misguided thing to enable but it is 100% supported to combine this. All the limit does is put things in .sdata, but they can still be addressed just fine.


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Comment at: clang/lib/Driver/ToolChains/Clang.cpp:2072
     if (Args.hasArg(options::OPT_G)) {
       D.Diag(diag::warn_drv_unsupported_sdata);
     }
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If you're modelling it on this warning (note, not an error) then this is crap too, there are legitimate reasons to use -G with -fPIC (and the -shared handling is even more questionable).


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D146463/new/

https://reviews.llvm.org/D146463