diff options
Diffstat (limited to 'llvm/lib/Target/AArch64/AArch64MIPeepholeOpt.cpp')
| -rw-r--r-- | llvm/lib/Target/AArch64/AArch64MIPeepholeOpt.cpp | 64 |
1 files changed, 57 insertions, 7 deletions
diff --git a/llvm/lib/Target/AArch64/AArch64MIPeepholeOpt.cpp b/llvm/lib/Target/AArch64/AArch64MIPeepholeOpt.cpp index b97d622..fd4ef2a 100644 --- a/llvm/lib/Target/AArch64/AArch64MIPeepholeOpt.cpp +++ b/llvm/lib/Target/AArch64/AArch64MIPeepholeOpt.cpp @@ -8,8 +8,8 @@ // // This pass performs below peephole optimizations on MIR level. // -// 1. MOVi32imm + ANDS?Wrr ==> ANDWri + ANDS?Wri -// MOVi64imm + ANDS?Xrr ==> ANDXri + ANDS?Xri +// 1. MOVi32imm + (ANDS?|EOR|ORR)Wrr ==> (AND|EOR|ORR)Wri + (ANDS?|EOR|ORR)Wri +// MOVi64imm + (ANDS?|EOR|ORR)Xrr ==> (AND|EOR|ORR)Xri + (ANDS?|EOR|ORR)Xri // // 2. MOVi32imm + ADDWrr ==> ADDWRi + ADDWRi // MOVi64imm + ADDXrr ==> ADDXri + ADDXri @@ -128,6 +128,7 @@ struct AArch64MIPeepholeOpt : public MachineFunctionPass { // Strategy used to split logical immediate bitmasks. enum class SplitStrategy { Intersect, + Disjoint, }; template <typename T> bool trySplitLogicalImm(unsigned Opc, MachineInstr &MI, @@ -163,6 +164,7 @@ INITIALIZE_PASS(AArch64MIPeepholeOpt, "aarch64-mi-peephole-opt", template <typename T> static bool splitBitmaskImm(T Imm, unsigned RegSize, T &Imm1Enc, T &Imm2Enc) { T UImm = static_cast<T>(Imm); + assert(UImm && (UImm != ~static_cast<T>(0)) && "Invalid immediate!"); // The bitmask immediate consists of consecutive ones. Let's say there is // constant 0b00000000001000000000010000000000 which does not consist of @@ -191,18 +193,47 @@ static bool splitBitmaskImm(T Imm, unsigned RegSize, T &Imm1Enc, T &Imm2Enc) { } template <typename T> +static bool splitDisjointBitmaskImm(T Imm, unsigned RegSize, T &Imm1Enc, + T &Imm2Enc) { + assert(Imm && (Imm != ~static_cast<T>(0)) && "Invalid immediate!"); + + // Try to split a bitmask of the form 0b00000000011000000000011110000000 into + // two disjoint masks such as 0b00000000011000000000000000000000 and + // 0b00000000000000000000011110000000 where the inclusive/exclusive OR of the + // new masks match the original mask. + unsigned LowestBitSet = llvm::countr_zero(Imm); + unsigned LowestGapBitUnset = + LowestBitSet + llvm::countr_one(Imm >> LowestBitSet); + + // Create a mask for the least significant group of consecutive ones. + assert(LowestGapBitUnset < sizeof(T) * CHAR_BIT && "Undefined behaviour!"); + T NewImm1 = (static_cast<T>(1) << LowestGapBitUnset) - + (static_cast<T>(1) << LowestBitSet); + // Create a disjoint mask for the remaining ones. + T NewImm2 = Imm & ~NewImm1; + + // Do not split if NewImm2 is not a valid bitmask immediate. + if (!AArch64_AM::isLogicalImmediate(NewImm2, RegSize)) + return false; + + Imm1Enc = AArch64_AM::encodeLogicalImmediate(NewImm1, RegSize); + Imm2Enc = AArch64_AM::encodeLogicalImmediate(NewImm2, RegSize); + return true; +} + +template <typename T> bool AArch64MIPeepholeOpt::trySplitLogicalImm(unsigned Opc, MachineInstr &MI, SplitStrategy Strategy, unsigned OtherOpc) { - // Try below transformation. + // Try below transformations. // - // MOVi32imm + ANDS?Wrr ==> ANDWri + ANDS?Wri - // MOVi64imm + ANDS?Xrr ==> ANDXri + ANDS?Xri + // MOVi32imm + (ANDS?|EOR|ORR)Wrr ==> (AND|EOR|ORR)Wri + (ANDS?|EOR|ORR)Wri + // MOVi64imm + (ANDS?|EOR|ORR)Xrr ==> (AND|EOR|ORR)Xri + (ANDS?|EOR|ORR)Xri // // The mov pseudo instruction could be expanded to multiple mov instructions // later. Let's try to split the constant operand of mov instruction into two - // bitmask immediates. It makes only two AND instructions instead of multiple - // mov + and instructions. + // bitmask immediates based on the given split strategy. It makes only two + // logical instructions instead of multiple mov + logic instructions. return splitTwoPartImm<T>( MI, @@ -224,6 +255,9 @@ bool AArch64MIPeepholeOpt::trySplitLogicalImm(unsigned Opc, MachineInstr &MI, case SplitStrategy::Intersect: SplitSucc = splitBitmaskImm(Imm, RegSize, Imm0, Imm1); break; + case SplitStrategy::Disjoint: + SplitSucc = splitDisjointBitmaskImm(Imm, RegSize, Imm0, Imm1); + break; } if (SplitSucc) return std::make_pair(Opc, !OtherOpc ? Opc : OtherOpc); @@ -889,6 +923,22 @@ bool AArch64MIPeepholeOpt::runOnMachineFunction(MachineFunction &MF) { Changed |= trySplitLogicalImm<uint64_t>( AArch64::ANDXri, MI, SplitStrategy::Intersect, AArch64::ANDSXri); break; + case AArch64::EORWrr: + Changed |= trySplitLogicalImm<uint32_t>(AArch64::EORWri, MI, + SplitStrategy::Disjoint); + break; + case AArch64::EORXrr: + Changed |= trySplitLogicalImm<uint64_t>(AArch64::EORXri, MI, + SplitStrategy::Disjoint); + break; + case AArch64::ORRWrr: + Changed |= trySplitLogicalImm<uint32_t>(AArch64::ORRWri, MI, + SplitStrategy::Disjoint); + break; + case AArch64::ORRXrr: + Changed |= trySplitLogicalImm<uint64_t>(AArch64::ORRXri, MI, + SplitStrategy::Disjoint); + break; case AArch64::ORRWrs: Changed |= visitORR(MI); break; |