From 19f7969f816000cf5ddf8a19163193b5feb9bc0a Mon Sep 17 00:00:00 2001 From: Chris Lattner Date: Sat, 8 Mar 2008 22:59:52 +0000 Subject: [PATCH] 1) Improve comments. 2) Don't try to insert an i64 value into the low part of a vector with movq on an x86-32 target. This allows us to compile: __m128i doload64(short x) {return _mm_set_epi16(0,0,0,0,0,0,0,1);} into: _doload64: movaps LCPI1_0, %xmm0 ret instead of: _doload64: subl $28, %esp movl $0, 4(%esp) movl $1, (%esp) movq (%esp), %xmm0 addl $28, %esp ret git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@48057 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/Target/X86/X86ISelLowering.cpp | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp index 6219f929210..71e0d68c00f 100644 --- a/lib/Target/X86/X86ISelLowering.cpp +++ b/lib/Target/X86/X86ISelLowering.cpp @@ -3055,7 +3055,15 @@ X86TargetLowering::LowerBUILD_VECTOR(SDOperand Op, SelectionDAG &DAG) { if (NumNonZero == 1 && NumElems <= 4) { unsigned Idx = CountTrailingZeros_32(NonZeros); SDOperand Item = Op.getOperand(Idx); - if (Idx == 0) { + + // If we have a constant or non-constant insertion into the low element of + // a vector, we can do this with SCALAR_TO_VECTOR + shuffle of zero into + // the rest of the elements. This will be matched as movd/movq/movss/movsd + // depending on what the source datatype is. Because we can only get here + // when NumElems <= 4, this only needs to handle i32/f32/i64/f64. + if (Idx == 0 && + // Don't do this for i64 values on x86-32. + (EVT != MVT::i64 || Subtarget->is64Bit())) { Item = DAG.getNode(ISD::SCALAR_TO_VECTOR, VT, Item); // Turn it into a MOVL (i.e. movss, movsd, or movd) to a zero vector. return getShuffleVectorZeroOrUndef(Item, VT, NumElems, Idx, @@ -3065,6 +3073,11 @@ X86TargetLowering::LowerBUILD_VECTOR(SDOperand Op, SelectionDAG &DAG) { if (IsAllConstants) // Otherwise, it's better to do a constpool load. return SDOperand(); + // Otherwise, if this is a vector with i32 or f32 elements, and the element + // is a non-constant being inserted into an element other than the low one, + // we can't use a constant pool load. Instead, use SCALAR_TO_VECTOR (aka + // movd/movss) to move this into the low element, then shuffle it into + // place. if (EVTBits == 32) { Item = DAG.getNode(ISD::SCALAR_TO_VECTOR, VT, Item); -- 2.34.1