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Properly handle reloading and spilling around partial redefines in

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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.

<rdar://problem/8518892>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@116210 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen 2010-10-11 18:10:36 +00:00
parent ffa0e71c33
commit 40ef4fe82a
1 changed files with 14 additions and 0 deletions
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14
lib/CodeGen/VirtRegRewriter.cpp
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@ -1894,6 +1894,20 @@ void LocalRewriter::ProcessUses(MachineInstr &MI, AvailableSpills &Spills,
VirtUseOps.insert(VirtUseOps.begin(), i); VirtUseOps.insert(VirtUseOps.begin(), i);
else else
VirtUseOps.push_back(i); 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. // Process all of the spilled uses and all non spilled reg references.