[PowerPC] Handle __builtin_xxpermdi the same way as GCC does
The codegen for this builtin was initially implemented to match GCC.
However, due to interest from users GCC changed behaviour to account for the
big endian bias of the instruction and correct it. This patch brings the
handling inline with GCC.
Fixes https://bugs.llvm.org/show_bug.cgi?id=38192
Differential Revision: https://reviews.llvm.org/D49424
llvm-svn: 337449
diff --git a/clang/lib/CodeGen/CGBuiltin.cpp b/clang/lib/CodeGen/CGBuiltin.cpp
index 9209134..7deeea8 100644
--- a/clang/lib/CodeGen/CGBuiltin.cpp
+++ b/clang/lib/CodeGen/CGBuiltin.cpp
@@ -10831,19 +10831,11 @@
Ops[0] = Builder.CreateBitCast(Ops[0], llvm::VectorType::get(Int64Ty, 2));
Ops[1] = Builder.CreateBitCast(Ops[1], llvm::VectorType::get(Int64Ty, 2));
- // Element zero comes from the first input vector and element one comes from
- // the second. The element indices within each vector are numbered in big
- // endian order so the shuffle mask must be adjusted for this on little
- // endian platforms (i.e. index is complemented and source vector reversed).
- unsigned ElemIdx0;
- unsigned ElemIdx1;
- if (getTarget().isLittleEndian()) {
- ElemIdx0 = (~Index & 1) + 2;
- ElemIdx1 = (~Index & 2) >> 1;
- } else { // BigEndian
- ElemIdx0 = (Index & 2) >> 1;
- ElemIdx1 = 2 + (Index & 1);
- }
+ // Account for endianness by treating this as just a shuffle. So we use the
+ // same indices for both LE and BE in order to produce expected results in
+ // both cases.
+ unsigned ElemIdx0 = (Index & 2) >> 1;;
+ unsigned ElemIdx1 = 2 + (Index & 1);;
Constant *ShuffleElts[2] = {ConstantInt::get(Int32Ty, ElemIdx0),
ConstantInt::get(Int32Ty, ElemIdx1)};