[Clang] Add __ibm128 type to represent ppc_fp128

Currently, we have no front-end type for ppc_fp128 type in IR. PowerPC
target generates ppc_fp128 type from long double now, but there's option
(-mabi=(ieee|ibm)longdouble) to control it and we're going to do
transition from IBM extended double-double ppc_fp128 to IEEE fp128 in
the future.

This patch adds type __ibm128 which always represents ppc_fp128 in IR,
as what GCC did for that type. Without this type in Clang, compilation
will fail if compiling against future version of libstdcxx (which uses
__ibm128 in headers).

Although all operations in backend for __ibm128 is done by software,
only PowerPC enables support for it.

There's something not implemented in this commit, which can be done in
future ones:

- Literal suffix for __ibm128 type. w/W is suitable as GCC documented.
- __attribute__((mode(IF))) should be for __ibm128.
- Complex __ibm128 type.

Reviewed By: rjmccall

Differential Revision: https://reviews.llvm.org/D93377

1 files changed, 4 insertions, 1 deletions

diff --git a/clang/lib/CodeGen/CGExprScalar.cpp b/clang/lib/CodeGen/CGExprScalar.cpp
index 6c82fcb1e97f..fe62e63521a1 100644
--- a/clang/lib/CodeGen/CGExprScalar.cpp
+++ b/clang/lib/CodeGen/CGExprScalar.cpp
@@ -2680,7 +2680,8 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
       amt = llvm::ConstantFP::get(VMContext,
                                   llvm::APFloat(static_cast<double>(amount)));
     else {
-      // Remaining types are Half, LongDouble or __float128. Convert from float.
+      // Remaining types are Half, LongDouble, __ibm128 or __float128. Convert
+      // from float.
       llvm::APFloat F(static_cast<float>(amount));
       bool ignored;
       const llvm::fltSemantics *FS;
@@ -2690,6 +2691,8 @@ ScalarExprEmitter::EmitScalarPrePostIncDec(const UnaryOperator *E, LValue LV,
         FS = &CGF.getTarget().getFloat128Format();
       else if (value->getType()->isHalfTy())
         FS = &CGF.getTarget().getHalfFormat();
+      else if (value->getType()->isPPC_FP128Ty())
+        FS = &CGF.getTarget().getIbm128Format();
       else
         FS = &CGF.getTarget().getLongDoubleFormat();
       F.convert(*FS, llvm::APFloat::rmTowardZero, &ignored);