From 85ee72f7ba48a1657b4443f3326267c7544b3468 Mon Sep 17 00:00:00 2001 From: Dale Johannesen Date: Thu, 12 Jul 2007 16:45:35 +0000 Subject: ARM: make branch folder remove unconditional branches following jump tables that it earlier inserted. This would be OK on other targets but is needed for correctness only on ARM (constant islands needs to find jump tables). llvm-svn: 39782 --- llvm/lib/Target/ARM/ARMConstantIslandPass.cpp | 7 ++----- llvm/lib/Target/ARM/ARMInstrInfo.cpp | 15 +++++++++++++-- 2 files changed, 15 insertions(+), 7 deletions(-) (limited to 'llvm/lib') diff --git a/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp b/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp index 13b812ca1ae..1b936312c0a 100644 --- a/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp +++ b/llvm/lib/Target/ARM/ARMConstantIslandPass.cpp @@ -740,14 +740,11 @@ void ARMConstantIslands::AdjustBBOffsetsAfter(MachineBasicBlock *BB, delta -= 2; } } - // Thumb jump tables require padding. They can be at the end, or - // followed by an unconditional branch. + // Thumb jump tables require padding. They should be at the end; + // following unconditional branches are removed by AnalyzeBranch. MachineInstr *ThumbJTMI = NULL; if (prior(MBB->end())->getOpcode() == ARM::tBR_JTr) ThumbJTMI = prior(MBB->end()); - else if (prior(MBB->end()) != MBB->begin() && - prior(prior(MBB->end()))->getOpcode() == ARM::tBR_JTr) - ThumbJTMI = prior(prior(MBB->end())); if (ThumbJTMI) { unsigned newMIOffset = GetOffsetOf(ThumbJTMI); unsigned oldMIOffset = newMIOffset - delta; diff --git a/llvm/lib/Target/ARM/ARMInstrInfo.cpp b/llvm/lib/Target/ARM/ARMInstrInfo.cpp index f4b4dbe2e3a..b404ec078e5 100644 --- a/llvm/lib/Target/ARM/ARMInstrInfo.cpp +++ b/llvm/lib/Target/ARM/ARMInstrInfo.cpp @@ -350,8 +350,8 @@ bool ARMInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB, return false; } - // If the block ends with two B's or tB's, handle it. The second one is not - // executed, so remove it. + // If the block ends with two unconditional branches, handle it. The second + // one is not executed, so remove it. if ((SecondLastOpc == ARM::B || SecondLastOpc==ARM::tB) && (LastOpc == ARM::B || LastOpc == ARM::tB)) { TBB = SecondLastInst->getOperand(0).getMachineBasicBlock(); @@ -360,6 +360,17 @@ bool ARMInstrInfo::AnalyzeBranch(MachineBasicBlock &MBB,MachineBasicBlock *&TBB, return false; } + // Likewise if it ends with a branch table followed by an unconditional branch. + // The branch folder can create these, and we must get rid of them for + // correctness of Thumb constant islands. + if ((SecondLastOpc == ARM::BR_JTr || SecondLastOpc==ARM::BR_JTm || + SecondLastOpc == ARM::BR_JTadd || SecondLastOpc==ARM::tBR_JTr) && + (LastOpc == ARM::B || LastOpc == ARM::tB)) { + I = LastInst; + I->eraseFromParent(); + return true; + } + // Otherwise, can't handle this. return true; } -- cgit v1.2.3