[clang] [flang] [clang][driver] When -fveclib=ArmPL flag is in use, always link against libamath (PR #116432)

[Tom Eccles via cfe-commits]

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@@ -490,6 +490,16 @@ void tools::AddLinkerInputs(const ToolChain &TC, const InputInfoList &Inputs,
     else
       A.renderAsInput(Args, CmdArgs);
   }
+  if (const Arg *A = Args.getLastArg(options::OPT_fveclib)) {
+    if (A->getNumValues() == 1) {
+      StringRef V = A->getValue();
+      if (V == "ArmPL") {
+        CmdArgs.push_back(Args.MakeArgString("-lamath"));
+        CmdArgs.push_back(Args.MakeArgString("-lm"));
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tblah wrote:

Flang and ArmPL both support Windows. I don't see why Windows should get second-class support. I would prefer to see this PR extended to also include any flags required on Windows.

I agree with the general concept of this PR. This makes ArmPL easier to use, and we know for sure what the armpl libraries will called. Flang already has a hack for a different veclib implementation on darwin https://github.com/llvm/llvm-project/blob/6bf8f08989420ccd10efed5fac88052ca16e1250/clang/lib/Driver/ToolChains/Flang.cpp#L441

https://github.com/llvm/llvm-project/pull/116432