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[stackprotector] Allow for copies from vreg -> vreg to be in a terminator sequence.

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Sometimes a copy from a vreg -> vreg sneaks into the middle of a terminator
sequence. It is safe to slice this into the stack protector success bb.

This fixes PR16979.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@191260 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Michael Gottesman
2013-09-24 01:50:26 +00:00
parent 17f013265f
commit eed779ff68
2 changed files with 89 additions and 6 deletions
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32
lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
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@ -1165,13 +1165,33 @@ static bool MIIsInTerminatorSequence(const MachineInstr *MI) {
// sequence, so we return true in that case.
return MI->isDebugValue();
// If we are not defining a register that is a physical register via a copy or
// are defining a register via an implicit def, we have left the terminator
// sequence.
MachineInstr::const_mop_iterator OPI = MI->operands_begin();
if (!OPI->isReg() || !OPI->isDef() ||
// We have left the terminator sequence if we are not doing one of the
// following:
//
// 1. Copying a vreg into a physical register.
// 2. Copying a vreg into a vreg.
// 3. Defining a register via an implicit def.
// OPI should always be a register definition...
MachineInstr::const_mop_iterator OPI = MI->operands_begin();
if (!OPI->isReg() || !OPI->isDef())
return false;
// Defining any register via an implicit def is always ok.
if (MI->isImplicitDef())
return true;
// Grab the copy source...
MachineInstr::const_mop_iterator OPI2 = OPI;
++OPI2;
assert(OPI2 != MI->operands_end()
&& "Should have a copy implying we should have 2 arguments.");
// Make sure that the copy dest is not a vreg when the copy source is a
// physical register.
if (!OPI2->isReg() ||
(!TargetRegisterInfo::isPhysicalRegister(OPI->getReg()) &&
!MI->isImplicitDef()))
TargetRegisterInfo::isPhysicalRegister(OPI2->getReg())))
return false;
return true;