diff options
Diffstat (limited to 'llvm')
| -rw-r--r-- | llvm/lib/CodeGen/MachineBlockPlacement.cpp | 25 | ||||
| -rw-r--r-- | llvm/test/CodeGen/PowerPC/block-placement-1.mir | 10 | ||||
| -rw-r--r-- | llvm/test/CodeGen/PowerPC/block-placement.mir | 12 |
3 files changed, 31 insertions, 16 deletions
diff --git a/llvm/lib/CodeGen/MachineBlockPlacement.cpp b/llvm/lib/CodeGen/MachineBlockPlacement.cpp index 639b588766a..a469f893ce1 100644 --- a/llvm/lib/CodeGen/MachineBlockPlacement.cpp +++ b/llvm/lib/CodeGen/MachineBlockPlacement.cpp @@ -2730,6 +2730,31 @@ void MachineBlockPlacement::optimizeBranches() { TII->removeBranch(*ChainBB); TII->insertBranch(*ChainBB, FBB, TBB, Cond, dl); ChainBB->updateTerminator(); + } else if (Cond.empty() && TBB && ChainBB != TBB && + !TBB->canFallThrough()) { + // When ChainBB is unconditional branch to the TBB, and TBB has no + // fallthrough predecessor and fallthrough successor, try to merge + // ChainBB and TBB. This is legal under the one of following conditions: + // 1. ChainBB is empty except for an unconditional branch. + // 2. TBB has only one predecessor. + MachineFunction::iterator I(TBB); + if (((TBB == &*F->begin()) || !std::prev(I)->canFallThrough()) && + (TailDup.isSimpleBB(ChainBB) || (TBB->pred_size() == 1))) { + TII->removeBranch(*ChainBB); + ChainBB->removeSuccessor(TBB); + + // Update the CFG. + for (MachineBasicBlock::pred_iterator PI = TBB->pred_begin(), + PE = TBB->pred_end(); PI != PE; PI++) + (*PI)->ReplaceUsesOfBlockWith(TBB, ChainBB); + + for (MachineBasicBlock *Succ : TBB->successors()) + ChainBB->addSuccessor(Succ, MBPI->getEdgeProbability(TBB, Succ)); + + // Move all the instructions of TBB to ChainBB. + ChainBB->splice(ChainBB->end(), TBB, TBB->begin(), TBB->end()); + F->remove(TBB); + } } } } diff --git a/llvm/test/CodeGen/PowerPC/block-placement-1.mir b/llvm/test/CodeGen/PowerPC/block-placement-1.mir index 01967e46da9..fdd57cd4061 100644 --- a/llvm/test/CodeGen/PowerPC/block-placement-1.mir +++ b/llvm/test/CodeGen/PowerPC/block-placement-1.mir @@ -299,14 +299,8 @@ body: | bb.11.unreachable: ; CHECK: bb.1.for.body: - ; CHECK: successors: %bb.2(0x7ffff800), %bb.3(0x00000800) - ; CHECK: B %bb.2 + ; CHECK-NEXT: successors: %bb.3(0x00000800) ; CHECK: bb.4.catch4: - ; CHECK: successors: %bb.11(0x7ffff800), %bb.6(0x00000800) - ; CHECK: B %bb.11 - - ; CHECK: bb.2..noexc: - - ; CHECK: bb.11.unreachable: + ; CHECK-NEXT: %bb.6(0x00000800) ... diff --git a/llvm/test/CodeGen/PowerPC/block-placement.mir b/llvm/test/CodeGen/PowerPC/block-placement.mir index 9406e13b354..e413e3db2d5 100644 --- a/llvm/test/CodeGen/PowerPC/block-placement.mir +++ b/llvm/test/CodeGen/PowerPC/block-placement.mir @@ -209,14 +209,10 @@ body: | BLR8 implicit $lr8, implicit $rm, implicit killed $x3 ; CHECK: bb.5.if.else.i: - ; CHECK: successors: %bb.11(0x80000000) - ; CHECK: B %bb.11 + ; CHECK-NEXT: renamable $x3 = LI8 1 + ; CHECK-NEXT: BLR8 implicit $lr8, implicit $rm, implicit killed $x3 ; CHECK: bb.8.while.body.i (align 4): - ; CHECK: successors: %bb.11(0x04000000), %bb.9(0x7c000000) - ; CHECK: BCC 76, killed renamable $cr0, %bb.11 - - ; CHECK: bb.11: - ; CHECK: renamable $x3 = LI8 1 - ; CHECK-NEXT: BLR8 implicit $lr8, implicit $rm, implicit killed $x3 + ; CHECK: successors: %bb.5(0x04000000), %bb.9(0x7c000000) + ; CHECK: BCC 76, killed renamable $cr0, %bb.5 ... |
