Index: lib/CodeGen/SelectionDAG/DAGCombiner.cpp =================================================================== --- lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -8359,7 +8359,7 @@ // Fold truncate of a bitcast of a vector to an extract of the low vector // element. // - // e.g. trunc (i64 (bitcast v2i32:x)) -> extract_vector_elt v2i32:x, 0 + // e.g. trunc (i64 (bitcast v2i32:x)) -> extract_vector_elt v2i32:x, idx if (N0.getOpcode() == ISD::BITCAST && !VT.isVector()) { SDValue VecSrc = N0.getOperand(0); EVT SrcVT = VecSrc.getValueType(); @@ -8369,8 +8369,9 @@ SDLoc SL(N); EVT IdxVT = TLI.getVectorIdxTy(DAG.getDataLayout()); + unsigned Idx = isLE ? 0 : SrcVT.getVectorNumElements() - 1; return DAG.getNode(ISD::EXTRACT_VECTOR_ELT, SL, VT, - VecSrc, DAG.getConstant(0, SL, IdxVT)); + VecSrc, DAG.getConstant(Idx, SL, IdxVT)); } } Index: test/CodeGen/Mips/pr33682.ll =================================================================== --- /dev/null +++ test/CodeGen/Mips/pr33682.ll @@ -0,0 +1,28 @@ +; RUN: llc -march=mips -mcpu=mips32 < %s | FileCheck %s --check-prefixes=ALL,BE +; RUN: llc -march=mipsel -mcpu=mips32 < %s | FileCheck %s --check-prefixes=ALL,LE + +; Verify visitTRUNCATE respects endianness when transforming truncates to extract vector element. + +; ALL-LABEL: a: +; BE: lw $2, 4($4) +; LE: lw $2, 0($4) + +define i32 @a(<2 x i32> * %a) { +entry: +%0 = load <2 x i32>, <2 x i32> * %a +%1 = bitcast <2 x i32> %0 to i64 +%2 = trunc i64 %1 to i32 +ret i32 %2 +} + +; ALL-LABEL: b: +; BE: lw $2, 12($4) +; LE: lw $2, 0($4) + +define i32 @b(<4 x i32> * %a) { +entry: +%0 = load <4 x i32>, <4 x i32> * %a +%1 = bitcast <4 x i32> %0 to i128 +%2 = trunc i128 %1 to i32 +ret i32 %2 +}