diff options
Diffstat (limited to 'lib/CodeGen/PrologEpilogInserter.cpp')
-rw-r--r-- | lib/CodeGen/PrologEpilogInserter.cpp | 27 |
1 files changed, 18 insertions, 9 deletions
diff --git a/lib/CodeGen/PrologEpilogInserter.cpp b/lib/CodeGen/PrologEpilogInserter.cpp index 873d237..8388fdb 100644 --- a/lib/CodeGen/PrologEpilogInserter.cpp +++ b/lib/CodeGen/PrologEpilogInserter.cpp @@ -778,6 +778,8 @@ void PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) { // directly. for (MachineBasicBlock::iterator I = BB->begin(); I != BB->end(); ++I) { MachineInstr *MI = I; + bool isDefInsn = false; + bool isKillInsn = false; for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) if (MI->getOperand(i).isReg()) { MachineOperand &MO = MI->getOperand(i); @@ -802,6 +804,12 @@ void PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) { } continue; } + // If this is a def, remember that this insn defines the value. + // This lets us properly consider insns which re-use the scratch + // register, such as r2 = sub r2, #imm, in the middle of the + // scratch range. + if (MO.isDef()) + isDefInsn = true; // Have we already allocated a scratch register for this virtual? if (Reg != CurrentVirtReg) { @@ -866,19 +874,20 @@ void PEI::scavengeFrameVirtualRegs(MachineFunction &Fn) { assert (CurrentScratchReg && "Missing scratch register!"); MI->getOperand(i).setReg(CurrentScratchReg); - // If this is the last use of the register, stop tracking it. if (MI->getOperand(i).isKill()) { - PrevScratchReg = CurrentScratchReg; - PrevLastUseMI = MI; + isKillInsn = true; PrevLastUseOp = i; - CurrentScratchReg = CurrentVirtReg = 0; - havePrevValue = trackingCurrentValue; - // Re-scan the operands of this instruction to catch definitions - // of the scratch register we're using. This is to handle things - // like ldr "r2, [scratch]" where scratch is r2. - i = 0; + PrevLastUseMI = MI; } } + // If this is the last use of the scratch, stop tracking it. The + // last use will be a kill operand in an instruction that does + // not also define the scratch register. + if (isKillInsn && !isDefInsn) { + PrevScratchReg = CurrentScratchReg; + CurrentScratchReg = CurrentVirtReg = 0; + havePrevValue = trackingCurrentValue; + } RS->forward(MI); } } |