From b077cf338bd85a6a7397ec88d65278f02f0ed06f Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Wed, 5 Oct 2011 00:01:46 +0000 Subject: [PATCH] Also add flags when coalescing sub-registers. RegisterCoalescer can create sub-register defs when it is joining a register with a sub-register. Add flags to these new sub-register defs where appropriate. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@141138 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/RegisterCoalescer.cpp | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/lib/CodeGen/RegisterCoalescer.cpp b/lib/CodeGen/RegisterCoalescer.cpp index 990ef370bb3..361ae7a63f0 100644 --- a/lib/CodeGen/RegisterCoalescer.cpp +++ b/lib/CodeGen/RegisterCoalescer.cpp @@ -967,6 +967,14 @@ RegisterCoalescer::UpdateRegDefsUses(const CoalescerPair &CP) { Kills |= MO.isKill(); Deads |= MO.isDead(); + // Make sure we don't create read-modify-write defs accidentally. We + // assume here that a SrcReg def cannot be joined into a live DstReg. If + // RegisterCoalescer starts tracking partially live registers, we will + // need to check the actual LiveInterval to determine if DstReg is live + // here. + if (SubIdx && !Reads) + MO.setIsUndef(); + if (DstIsPhys) MO.substPhysReg(DstReg, *TRI); else