From ca93f5e60515081f0314ef4e7f376af9af4eb2a7 Mon Sep 17 00:00:00 2001 From: Krzysztof Parzyszek Date: Fri, 23 Mar 2018 19:47:13 +0000 Subject: [PATCH] [Hexagon] Assume all extendable branches to be of size 8 in relaxation The branch relaxation pass collects sizes of all instructions at the beginning, before any changes have been made. It then performs one pass over all branches to see which ones need to be extended. It does not account for the case when a previously valid branch becomes out-of-range due to relaxing other branches. This approach fixes this problem by assuming from the beginning that all extendable branches have been extended. This may cause unneeded relaxation in some cases, but avoids iteration and recomputing instruction sizes. llvm-svn: 328360 --- llvm/lib/Target/Hexagon/HexagonBranchRelaxation.cpp | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-) diff --git a/llvm/lib/Target/Hexagon/HexagonBranchRelaxation.cpp b/llvm/lib/Target/Hexagon/HexagonBranchRelaxation.cpp index 84af4b14b9f7..3e6420c671f9 100644 --- a/llvm/lib/Target/Hexagon/HexagonBranchRelaxation.cpp +++ b/llvm/lib/Target/Hexagon/HexagonBranchRelaxation.cpp @@ -114,8 +114,12 @@ void HexagonBranchRelaxation::computeOffset(MachineFunction &MF, InstOffset = (InstOffset + ByteAlign) & ~(ByteAlign); } OffsetMap[&B] = InstOffset; - for (auto &MI : B.instrs()) + for (auto &MI : B.instrs()) { InstOffset += HII->getSize(MI); + // Assume that all extendable branches will be extended. + if (MI.isBranch() && HII->isExtendable(MI)) + InstOffset += HEXAGON_INSTR_SIZE; + } } } @@ -145,6 +149,9 @@ bool HexagonBranchRelaxation::isJumpOutOfRange(MachineInstr &MI, if (FirstTerm == B.instr_end()) return false; + if (HII->isExtended(MI)) + return false; + unsigned InstOffset = BlockToInstOffset[&B]; unsigned Distance = 0;