From 66649e00c91e30fdfc8dd64b43cde2632a831138 Mon Sep 17 00:00:00 2001 From: Ahmed Bougacha Date: Thu, 9 Apr 2015 20:04:47 +0000 Subject: [PATCH] [CodeGen] Combine concat_vector of trunc'd scalar to scalar_to_vector. We already do: concat_vectors(scalar, undef) -> scalar_to_vector(scalar) When the scalar is legal. When it's not, but is a truncated legal scalar, we can also do: concat_vectors(trunc(scalar), undef) -> scalar_to_vector(scalar) Which is equivalent, since the upper lanes are undef anyway. While there, teach the combine to look at more than 2 operands. Differential Revision: http://reviews.llvm.org/D8883 git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@234530 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 16 +++++++++++++--- .../AArch64/concat_vector-truncate-combine.ll | 2 ++ .../concat_vector-truncated-scalar-combine.ll | 18 ++++++++++++++++++ 3 files changed, 33 insertions(+), 3 deletions(-) create mode 100644 test/CodeGen/AArch64/concat_vector-truncated-scalar-combine.ll diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 3902d4ec969..2b169b755fe 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -11514,9 +11514,10 @@ SDValue DAGCombiner::visitCONCAT_VECTORS(SDNode *N) { if (ISD::allOperandsUndef(N)) return DAG.getUNDEF(VT); - // Optimize concat_vectors where one of the vectors is undef. - if (N->getNumOperands() == 2 && - N->getOperand(1)->getOpcode() == ISD::UNDEF) { + // Optimize concat_vectors where all but the first of the vectors are undef. + if (std::all_of(std::next(N->op_begin()), N->op_end(), [](const SDValue &Op) { + return Op.getOpcode() == ISD::UNDEF; + })) { SDValue In = N->getOperand(0); assert(In.getValueType().isVector() && "Must concat vectors"); @@ -11524,6 +11525,15 @@ SDValue DAGCombiner::visitCONCAT_VECTORS(SDNode *N) { if (In->getOpcode() == ISD::BITCAST && !In->getOperand(0)->getValueType(0).isVector()) { SDValue Scalar = In->getOperand(0); + + // If the bitcast type isn't legal, it might be a trunc of a legal type; + // look through the trunc so we can still do the transform: + // concat_vectors(trunc(scalar), undef) -> scalar_to_vector(scalar) + if (Scalar->getOpcode() == ISD::TRUNCATE && + !TLI.isTypeLegal(Scalar.getValueType()) && + TLI.isTypeLegal(Scalar->getOperand(0).getValueType())) + Scalar = Scalar->getOperand(0); + EVT SclTy = Scalar->getValueType(0); if (!SclTy.isFloatingPoint() && !SclTy.isInteger()) diff --git a/test/CodeGen/AArch64/concat_vector-truncate-combine.ll b/test/CodeGen/AArch64/concat_vector-truncate-combine.ll index c510e279fd0..ee527860042 100644 --- a/test/CodeGen/AArch64/concat_vector-truncate-combine.ll +++ b/test/CodeGen/AArch64/concat_vector-truncate-combine.ll @@ -2,6 +2,8 @@ target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128" +; Test the (concat_vectors (trunc), (trunc)) pattern. + define <4 x i16> @test_concat_truncate_v2i64_to_v4i16(<2 x i64> %a, <2 x i64> %b) #0 { entry: ; CHECK-LABEL: test_concat_truncate_v2i64_to_v4i16: diff --git a/test/CodeGen/AArch64/concat_vector-truncated-scalar-combine.ll b/test/CodeGen/AArch64/concat_vector-truncated-scalar-combine.ll new file mode 100644 index 00000000000..eb6c80df855 --- /dev/null +++ b/test/CodeGen/AArch64/concat_vector-truncated-scalar-combine.ll @@ -0,0 +1,18 @@ +; RUN: llc < %s -mtriple aarch64-unknown-unknown -asm-verbose=false | FileCheck %s + +target datalayout = "e-m:o-i64:64-i128:128-n32:64-S128" + +; Test the (concat_vectors (bitcast (trunc (scalar))), undef..) pattern. + +define <8 x i8> @test_concat_from_truncated_scalar(i32 %x) #0 { +entry: +; CHECK-LABEL: test_concat_from_truncated_scalar: +; CHECK-NEXT: fmov s0, w0 +; CHECK-NEXT: ret + %t = trunc i32 %x to i16 + %0 = bitcast i16 %t to <2 x i8> + %1 = shufflevector <2 x i8> %0, <2 x i8> undef, <8 x i32> + ret <8 x i8> %1 +} + +attributes #0 = { nounwind } -- 2.34.1