From 02e33b70b1cc05671714bf27e5a2661eaa77840f Mon Sep 17 00:00:00 2001 From: Nate Begeman Date: Sun, 12 Jun 2005 23:50:33 +0000 Subject: [PATCH] Fix a memory smasher caught by Mac OS X's debug malloc library. We were incorrectly using an iterator after it was invalid. llvm-svn: 22207 --- .../Target/PowerPC/PowerPCBranchSelector.cpp | 27 +++++++++++++------ 1 file changed, 19 insertions(+), 8 deletions(-) diff --git a/llvm/lib/Target/PowerPC/PowerPCBranchSelector.cpp b/llvm/lib/Target/PowerPC/PowerPCBranchSelector.cpp index 5eaf38f01886..c6e874102861 100644 --- a/llvm/lib/Target/PowerPC/PowerPCBranchSelector.cpp +++ b/llvm/lib/Target/PowerPC/PowerPCBranchSelector.cpp @@ -86,7 +86,14 @@ namespace { for (MachineBasicBlock::iterator MBBI = MBB->begin(), EE = MBB->end(); MBBI != EE; ++MBBI) { - if (MBBI->getOpcode() == PPC::COND_BRANCH) { + // We may end up deleting the MachineInstr that MBBI points to, so + // remember its opcode now so we can refer to it after calling erase() + unsigned OpcodeToReplace = MBBI->getOpcode(); + + if (OpcodeToReplace == PPC::COND_BRANCH) { + MachineBasicBlock::iterator MBBJ = MBBI; + ++MBBJ; + // condbranch operands: // 0. CR0 register // 1. bc opcode @@ -101,17 +108,21 @@ namespace { unsigned Opcode = MBBI->getOperand(1).getImmedValue(); unsigned Inverted = PPC32InstrInfo::invertPPCBranchOpcode(Opcode); - MachineInstr *MI = MBBI; if (Displacement >= -32768 && Displacement <= 32767) { - BuildMI(*MBB, MBBI, Opcode, 2).addReg(PPC::CR0).addMBB(trueMBB); + BuildMI(*MBB, MBBJ, Opcode, 2).addReg(PPC::CR0).addMBB(trueMBB); } else { - BuildMI(*MBB, MBBI, Inverted, 2).addReg(PPC::CR0).addSImm(8); - BuildMI(*MBB, MBBI, PPC::B, 1).addMBB(trueMBB); - BuildMI(*MBB, MBBI, PPC::B, 1).addMBB(falseMBB); + BuildMI(*MBB, MBBJ, Inverted, 2).addReg(PPC::CR0).addSImm(8); + BuildMI(*MBB, MBBJ, PPC::B, 1).addMBB(trueMBB); + BuildMI(*MBB, MBBJ, PPC::B, 1).addMBB(falseMBB); } - MBB->erase(MI); + + // Erase the psuedo COND_BRANCH instruction, and then back up the + // iterator so that when the for loop increments it, we end up in + // the correct place rather than iterating off the end. + MBB->erase(MBBI); + MBBI = --MBBJ; } - ByteCount += bytesForOpcode(MBBI->getOpcode()); + ByteCount += bytesForOpcode(OpcodeToReplace); } }