GlobalISel: Add maskedValueIsZero and signBitIsZero to known bits

I dropped the DemandedElts since it seems to be missing from some of
the new interfaces, but not others.

llvm-svn: 370389

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
index 31e28f5ed5c..0870aa3812f 100644
--- a/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/GISelKnownBits.cpp
@@ -75,6 +75,12 @@ KnownBits GISelKnownBits::getKnownBits(Register R) {
   return Known;
 }
 
+bool GISelKnownBits::signBitIsZero(Register R) {
+  LLT Ty = MRI.getType(R);
+  unsigned BitWidth = Ty.getScalarSizeInBits();
+  return maskedValueIsZero(R, APInt::getSignMask(BitWidth));
+}
+
 APInt GISelKnownBits::getKnownZeroes(Register R) {
   return getKnownBits(R).Zero;
 }