From 40ef4fe82aefc3333f2cdeffb6ad28d9dfaccb8c Mon Sep 17 00:00:00 2001 From: Jakob Stoklund Olesen Date: Mon, 11 Oct 2010 18:10:36 +0000 Subject: [PATCH] Properly handle reloading and spilling around partial redefines in LocalRewriter. This is a bit of a hack that adds an implicit use operand to model the read-modify-write nature of a partial redef. Uses and defs are rewritten in separate passes, and a single operand would never be processed twice. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116210 91177308-0d34-0410-b5e6-96231b3b80d8 --- lib/CodeGen/VirtRegRewriter.cpp | 14 ++++++++++++++ 1 file changed, 14 insertions(+) diff --git a/lib/CodeGen/VirtRegRewriter.cpp b/lib/CodeGen/VirtRegRewriter.cpp index f44eccd40cc..5baedb98db1 100644 --- a/lib/CodeGen/VirtRegRewriter.cpp +++ b/lib/CodeGen/VirtRegRewriter.cpp @@ -1894,6 +1894,20 @@ void LocalRewriter::ProcessUses(MachineInstr &MI, AvailableSpills &Spills, VirtUseOps.insert(VirtUseOps.begin(), i); else VirtUseOps.push_back(i); + + // A partial def causes problems because the same operand both reads and + // writes the register. This rewriter is designed to rewrite uses and defs + // separately, so a partial def would already have been rewritten to a + // physreg by the time we get to processing defs. + // Add an implicit use operand to model the partial def. + if (MO.isDef() && MO.getSubReg() && MI.readsVirtualRegister(VirtReg) && + MI.findRegisterUseOperandIdx(VirtReg) == -1) { + VirtUseOps.insert(VirtUseOps.begin(), MI.getNumOperands()); + MI.addOperand(MachineOperand::CreateReg(VirtReg, + false, // isDef + true)); // isImplicit + DEBUG(dbgs() << "Partial redef: " << MI); + } } // Process all of the spilled uses and all non spilled reg references. -- 2.34.1