[PowerPC] Support -mabi=ieeelongdouble and -mabi=ibmlongdouble

gcc PowerPC supports 3 representations of long double:

* -mlong-double-64

  long double has the same representation of double but is mangled as `e`.
  In clang, this is the default on AIX, FreeBSD and Linux musl.

* -mlong-double-128

  2 possible 128-bit floating point representations:

  + -mabi=ibmlongdouble
    IBM extended double format. Mangled as `g`
    In clang, this is the default on Linux glibc.
  + -mabi=ieeelongdouble
    IEEE 754 quadruple-precision format. Mangled as `u9__ieee128` (`U10__float128` before gcc 8.2)
    This is currently unavailable.

This patch adds -mabi=ibmlongdouble and -mabi=ieeelongdouble, and thus
makes the IEEE 754 quadruple-precision long double available for
languages supported by clang.

Reviewed By: hfinkel

Differential Revision: https://reviews.llvm.org/D64283

llvm-svn: 366044

1 files changed, 14 insertions, 5 deletions

diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index c84cb480f1a..6a83e1a480a 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -1803,12 +1803,21 @@ void Clang::AddPPCTargetArgs(const ArgList &Args,
       break;
     }
 
-  if (Arg *A = Args.getLastArg(options::OPT_mabi_EQ))
-    // The ppc64 linux abis are all "altivec" abis by default. Accept and ignore
-    // the option if given as we don't have backend support for any targets
-    // that don't use the altivec abi.
-    if (StringRef(A->getValue()) != "altivec")
+  bool IEEELongDouble = false;
+  for (const Arg *A : Args.filtered(options::OPT_mabi_EQ)) {
+    StringRef V = A->getValue();
+    if (V == "ieeelongdouble")
+      IEEELongDouble = true;
+    else if (V == "ibmlongdouble")
+      IEEELongDouble = false;
+    else if (V != "altivec")
+      // The ppc64 linux abis are all "altivec" abis by default. Accept and ignore
+      // the option if given as we don't have backend support for any targets
+      // that don't use the altivec abi.
       ABIName = A->getValue();
+  }
+  if (IEEELongDouble)
+    CmdArgs.push_back("-mabi=ieeelongdouble");
 
   ppc::FloatABI FloatABI =
       ppc::getPPCFloatABI(getToolChain().getDriver(), Args);