[mips] Support for +abs2008 attribute

Instruction abs.[ds] is not generating correct result when working
with NaNs for revisions prior mips32r6 and mips64r6.

To generate a sequence which always produce a correct result, but also
to allow user more control on how his code is compiled, attribute
+abs2008 is added, so user can choose legacy or 2008.

By default legacy mode is used on revisions prior R6. Mips32r6 and
mips64r6 use abs2008 mode by default.

Differential Revision: https://reviews.llvm.org/D35983

llvm-svn: 352370

1 files changed, 2 insertions, 0 deletions

diff --git a/llvm/lib/Target/Mips/MipsInstrInfo.td b/llvm/lib/Target/Mips/MipsInstrInfo.td
index 1943168ac42..f18877f9a7a 100644
--- a/llvm/lib/Target/Mips/MipsInstrInfo.td
+++ b/llvm/lib/Target/Mips/MipsInstrInfo.td
@@ -220,6 +220,8 @@ def IsNotN64    :     Predicate<"!Subtarget->isABI_N64()">;
 def RelocNotPIC :     Predicate<"!TM.isPositionIndependent()">;
 def RelocPIC    :     Predicate<"TM.isPositionIndependent()">;
 def NoNaNsFPMath :    Predicate<"TM.Options.NoNaNsFPMath">;
+def UseAbs :          Predicate<"Subtarget->inAbs2008Mode() ||"
+                                "TM.Options.NoNaNsFPMath">;
 def HasStdEnc :       Predicate<"Subtarget->hasStandardEncoding()">,
                       AssemblerPredicate<"!FeatureMips16">;
 def NotDSP :          Predicate<"!Subtarget->hasDSP()">;