From fe54bb9de186661057639dcf3954304b45060a6d Mon Sep 17 00:00:00 2001 From: Akira Hatanaka Date: Tue, 7 Jun 2011 18:00:14 +0000 Subject: [PATCH] Add comments for wrapper node patterns in MipsInstrInfo.td. llvm-svn: 132717 --- lib/Target/Mips/MipsInstrInfo.td | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/lib/Target/Mips/MipsInstrInfo.td b/lib/Target/Mips/MipsInstrInfo.td index b32ae6faf86..329a002667a 100644 --- a/lib/Target/Mips/MipsInstrInfo.td +++ b/lib/Target/Mips/MipsInstrInfo.td @@ -87,7 +87,16 @@ def MipsDivRem : SDNode<"MipsISD::DivRem", SDT_MipsDivRem, def MipsDivRemU : SDNode<"MipsISD::DivRemU", SDT_MipsDivRem, [SDNPOutGlue]>; -// wrapper node +// Target constant nodes that are not part of any isel patterns and remain +// unchanged can cause instructions with illegal operands to be emitted. +// Wrapper node patterns give the instruction selector a chance to replace +// target constant nodes that would otherwise remain unchanged with ADDiu +// nodes. Without these wrapper node patterns, the following conditional move +// instrucion is emitted when function cmov2 in test/CodeGen/Mips/cmov.ll is +// compiled: +// movn %got(d)($gp), %got(c)($gp), $4 +// This instruction is illegal since movn can take only register operands. + def MipsWrapperPIC : SDNode<"MipsISD::WrapperPIC", SDTIntUnaryOp>; //===----------------------------------------------------------------------===//