LiveInterval: Document and enforce rules about empty subranges.
Empty subranges are not allowed in a LiveInterval and must be removed
instead: Check this in the verifiers, put a reminder for this in the
comment of the shrinkToUses variant for a single lane and make it
automatic for the shrinkToUses variant for a LiveInterval.
llvm-svn: 242431
diff --git a/llvm/lib/CodeGen/MachineVerifier.cpp b/llvm/lib/CodeGen/MachineVerifier.cpp
index ca35ec5..a5e5bc9 100644
--- a/llvm/lib/CodeGen/MachineVerifier.cpp
+++ b/llvm/lib/CodeGen/MachineVerifier.cpp
@@ -1671,6 +1671,8 @@
report("Lane masks of sub ranges overlap in live interval", MF, LI);
if ((SR.LaneMask & ~MaxMask) != 0)
report("Subrange lanemask is invalid", MF, LI);
+ if (SR.empty())
+ report("Subrange must not be empty", MF, SR, LI.reg, SR.LaneMask);
Mask |= SR.LaneMask;
verifyLiveRange(SR, LI.reg, SR.LaneMask);
if (!LI.covers(SR))