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Remove an assertion to fix PR9872.

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It can happen that a live debug variable is the last use of a sub-register, and
the register allocator will pick a larger register class for the virtual
register.  If the allocated register doesn't support the sub-register index,
just use %noreg for the debug variables instead of asserting.

In PR9872, a debug variable ends up in the sub_8bit_hi part of a GR32_ABCD
register. The register is split and one part is inflated to GR32 and assigned
%ESI because there are no more normal uses of sub_8bit_hi.

Since %ESI doesn't have that sub-register, substPhysReg asserted. Now it will
simply insert a %noreg instead, and the debug variable will be marked
unavailable in that range.

We don't currently have a way of saying: !"value" is in bits 8-15 of %ESI, I
don't know if DWARF even supports that.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@131073 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Jakob Stoklund Olesen
2011-05-08 19:21:08 +00:00
parent f51190b697
commit cf724f0786
2 changed files with 6 additions and 1 deletions
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3
lib/CodeGen/MachineInstr.cpp
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@ -125,7 +125,8 @@ void MachineOperand::substPhysReg(unsigned Reg, const TargetRegisterInfo &TRI) {
assert(TargetRegisterInfo::isPhysicalRegister(Reg));
if (getSubReg()) {
Reg = TRI.getSubReg(Reg, getSubReg());
assert(Reg && "Invalid SubReg for physical register");
// Note that getSubReg() may return 0 if the sub-register doesn't exist.
// That won't happen in legal code.
setSubReg(0);
}
setReg(Reg);