[Hexagon] Check if register is non-null before calling subregs_inclusive
D151036 adds an assertions that prohibits iterating over sub- and
super-registers of a null register. This is already the case when
iterating over register units of a null register, and worked by
accident for sub- and super-registers.
Reviewed By: kparzysz
Differential Revision: https://reviews.llvm.org/D151406
GitOrigin-RevId: c37e6a269ef3df0cde217feca945edfa8fcf68fe
diff --git a/lib/Target/Hexagon/HexagonFrameLowering.cpp b/lib/Target/Hexagon/HexagonFrameLowering.cpp
index 5d55661..231ac08 100644
--- a/lib/Target/Hexagon/HexagonFrameLowering.cpp
+++ b/lib/Target/Hexagon/HexagonFrameLowering.cpp
@@ -307,6 +307,9 @@
return true;
if (MO.isReg()) {
Register R = MO.getReg();
+ // Debug instructions may refer to $noreg.
+ if (!R)
+ continue;
// Virtual registers will need scavenging, which then may require
// a stack slot.
if (R.isVirtual())
