[PATCH] D139450: Warn about unsupported ibmlongdouble

[Tulio Magno Quites Machado Filho via Phabricator via cfe-commits]

tuliom marked 3 inline comments as done.
tuliom added inline comments.


================
Comment at: clang/lib/Driver/ToolChains/PPCLinux.cpp:74
+    const Driver &D,
+    const llvm::opt::ArgList &Args) const {
+  if (Args.hasArg(options::OPT_nostdlib, options::OPT_nostdlibxx))
----------------
nikic wrote:
> I don't think this formatting is right. You may find clang/tools/clang-format/clang-format-diff.py helpful.
> 
> I use this script locally:
> ```
> #!/bin/sh
> git diff -U ${1:-HEAD} | clang/tools/clang-format/clang-format-diff.py -p1
> ```
> And then do something like `./clang_format_diff.sh | patch -p0` after checking that it did not reformat too much.
Thanks, this pointed out 2 errors.


================
Comment at: clang/lib/Driver/ToolChains/PPCLinux.cpp:96
   bool HasUnsupportedCXXLib =
-      StdLib == CST_Libcxx ||
+      (StdLib == CST_Libcxx && !defaultToIEEELongDouble()) ||
       (StdLib == CST_Libstdcxx &&
----------------
qiucf wrote:
> `SupportIEEEFloat128` checks the library version:
> 
> * If using libstdc++, then libstdc++ (GCC) >= 12.1.0 is okay.
> * If using libc++, then sorry, no libc++ supports `-mabi=ieeelongdouble` now.
> * Glibc should >= 2.32
> 
> If the assumptions are still right, this changes its meaning (and `supportIBMLongDouble` has different meaning from it).
@qiucf In operating systems that switched to IEEE long double by default, all libraries (and programs) are built with IEEE long double, including libc++.


================
Comment at: clang/test/Driver/lit.local.cfg:25
+
+if config.ppc_linux_default_ieeelongdouble == "ON":
+  config.available_features.add('ppc_linux_default_ieeelongdouble')
----------------
nikic wrote:
> I believe this isn't robust, because ON is not the only possible value. Instead, you'll want to canonicalize the variable: https://github.com/llvm/llvm-project/blob/03e6d9d9d1d48e43f3efc35eb75369b90d4510d5/clang/test/CMakeLists.txt#L4
Changed. This caused a few other modifications in the latest revision.


================
Comment at: clang/test/Driver/lit.local.cfg:26
+if config.ppc_linux_default_ieeelongdouble == "ON":
+  config.available_features.add('ppc_linux_default_ieeelongdouble')
----------------
qiucf wrote:
> Can we assume if we are compiling with `-mabi=ieeelongdouble`, then libc++ 'must' be built with the same long double ABI? If I understand correctly, they're unrelated.
@qiucf I didn't understand this part. Are you suggesting to remove the long double warnings because the way the compiler was built is unrelated to the way libc++ was built?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D139450/new/

https://reviews.llvm.org/D139450