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[AMDGPU] Base getSubRegFromChannel on TableGen data
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Generate (at runtime) the table used to drive getSubRegFromChannel,
base on AMDGPUSubRegIdxRanges from TableGen data.
The is a step closer to it being staticly generated by TableGen and
allows getSubRegFromChannel handle all bitwidths in the mean time.

Reviewed By: rampitec, arsenm, foad

Differential Revision: https://reviews.llvm.org/D89217
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@perlfu
perlfu committed Oct 14, 2020
1 parent 9b3c2a7 commit 01549dd
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Showing 2 changed files with 37 additions and 63 deletions.
95 changes: 32 additions & 63 deletions llvm/lib/Target/AMDGPU/SIRegisterInfo.cpp
View file
Expand Up @@ -40,6 +40,14 @@ static cl::opt<bool> EnableSpillSGPRToVGPR(
cl::init(true));

std::array<std::vector<int16_t>, 16> SIRegisterInfo::RegSplitParts;
std::array<std::array<uint16_t, 32>, 9> SIRegisterInfo::SubRegFromChannelTable;

// Map numbers of DWORDs to indexes in SubRegFromChannelTable.
// Valid indexes are shifted 1, such that a 0 mapping means unsupported.
// e.g. for 8 DWORDs (256-bit), SubRegFromChannelTableWidthMap[8] = 8,
// meaning index 7 in SubRegFromChannelTable.
static const std::array<unsigned, 17> SubRegFromChannelTableWidthMap = {
0, 1, 2, 3, 4, 5, 6, 7, 8, 0, 0, 0, 0, 0, 0, 0, 9};

SIRegisterInfo::SIRegisterInfo(const GCNSubtarget &ST)
: AMDGPUGenRegisterInfo(AMDGPU::PC_REG, ST.getAMDGPUDwarfFlavour()), ST(ST),
Expand Down Expand Up @@ -78,8 +86,27 @@ SIRegisterInfo::SIRegisterInfo(const GCNSubtarget &ST)
}
};

static llvm::once_flag InitializeSubRegFromChannelTableFlag;

static auto InitializeSubRegFromChannelTableOnce = [this]() {
for (auto &Row : SubRegFromChannelTable)
Row.fill(AMDGPU::NoSubRegister);
for (uint16_t Idx = 1; Idx < getNumSubRegIndices(); ++Idx) {
unsigned Width = AMDGPUSubRegIdxRanges[Idx].Size / 32;
unsigned Offset = AMDGPUSubRegIdxRanges[Idx].Offset / 32;
assert(Width < SubRegFromChannelTableWidthMap.size());
Width = SubRegFromChannelTableWidthMap[Width];
if (Width == 0)
continue;
assert((Width - 1) < SubRegFromChannelTable.size());
assert(Offset < SubRegFromChannelTable[Width].size());
SubRegFromChannelTable[Width - 1][Offset] = Idx;
}
};

llvm::call_once(InitializeRegSplitPartsFlag, InitializeRegSplitPartsOnce);
llvm::call_once(InitializeSubRegFromChannelTableFlag,
InitializeSubRegFromChannelTableOnce);
}

void SIRegisterInfo::reserveRegisterTuples(BitVector &Reserved,
Expand Down Expand Up @@ -156,71 +183,13 @@ const uint32_t *SIRegisterInfo::getAllAllocatableSRegMask() const {
return CSR_AMDGPU_AllAllocatableSRegs_RegMask;
}

// FIXME: TableGen should generate something to make this manageable for all
// register classes. At a minimum we could use the opposite of
// composeSubRegIndices and go up from the base 32-bit subreg.
unsigned SIRegisterInfo::getSubRegFromChannel(unsigned Channel,
unsigned NumRegs) {
// Table of NumRegs sized pieces at every 32-bit offset.
static const uint16_t SubRegFromChannelTable[][32] = {
{AMDGPU::sub0, AMDGPU::sub1, AMDGPU::sub2, AMDGPU::sub3,
AMDGPU::sub4, AMDGPU::sub5, AMDGPU::sub6, AMDGPU::sub7,
AMDGPU::sub8, AMDGPU::sub9, AMDGPU::sub10, AMDGPU::sub11,
AMDGPU::sub12, AMDGPU::sub13, AMDGPU::sub14, AMDGPU::sub15,
AMDGPU::sub16, AMDGPU::sub17, AMDGPU::sub18, AMDGPU::sub19,
AMDGPU::sub20, AMDGPU::sub21, AMDGPU::sub22, AMDGPU::sub23,
AMDGPU::sub24, AMDGPU::sub25, AMDGPU::sub26, AMDGPU::sub27,
AMDGPU::sub28, AMDGPU::sub29, AMDGPU::sub30, AMDGPU::sub31},
{AMDGPU::sub0_sub1, AMDGPU::sub1_sub2, AMDGPU::sub2_sub3,
AMDGPU::sub3_sub4, AMDGPU::sub4_sub5, AMDGPU::sub5_sub6,
AMDGPU::sub6_sub7, AMDGPU::sub7_sub8, AMDGPU::sub8_sub9,
AMDGPU::sub9_sub10, AMDGPU::sub10_sub11, AMDGPU::sub11_sub12,
AMDGPU::sub12_sub13, AMDGPU::sub13_sub14, AMDGPU::sub14_sub15,
AMDGPU::sub15_sub16, AMDGPU::sub16_sub17, AMDGPU::sub17_sub18,
AMDGPU::sub18_sub19, AMDGPU::sub19_sub20, AMDGPU::sub20_sub21,
AMDGPU::sub21_sub22, AMDGPU::sub22_sub23, AMDGPU::sub23_sub24,
AMDGPU::sub24_sub25, AMDGPU::sub25_sub26, AMDGPU::sub26_sub27,
AMDGPU::sub27_sub28, AMDGPU::sub28_sub29, AMDGPU::sub29_sub30,
AMDGPU::sub30_sub31, AMDGPU::NoSubRegister},
{AMDGPU::sub0_sub1_sub2, AMDGPU::sub1_sub2_sub3,
AMDGPU::sub2_sub3_sub4, AMDGPU::sub3_sub4_sub5,
AMDGPU::sub4_sub5_sub6, AMDGPU::sub5_sub6_sub7,
AMDGPU::sub6_sub7_sub8, AMDGPU::sub7_sub8_sub9,
AMDGPU::sub8_sub9_sub10, AMDGPU::sub9_sub10_sub11,
AMDGPU::sub10_sub11_sub12, AMDGPU::sub11_sub12_sub13,
AMDGPU::sub12_sub13_sub14, AMDGPU::sub13_sub14_sub15,
AMDGPU::sub14_sub15_sub16, AMDGPU::sub15_sub16_sub17,
AMDGPU::sub16_sub17_sub18, AMDGPU::sub17_sub18_sub19,
AMDGPU::sub18_sub19_sub20, AMDGPU::sub19_sub20_sub21,
AMDGPU::sub20_sub21_sub22, AMDGPU::sub21_sub22_sub23,
AMDGPU::sub22_sub23_sub24, AMDGPU::sub23_sub24_sub25,
AMDGPU::sub24_sub25_sub26, AMDGPU::sub25_sub26_sub27,
AMDGPU::sub26_sub27_sub28, AMDGPU::sub27_sub28_sub29,
AMDGPU::sub28_sub29_sub30, AMDGPU::sub29_sub30_sub31,
AMDGPU::NoSubRegister, AMDGPU::NoSubRegister},
{AMDGPU::sub0_sub1_sub2_sub3, AMDGPU::sub1_sub2_sub3_sub4,
AMDGPU::sub2_sub3_sub4_sub5, AMDGPU::sub3_sub4_sub5_sub6,
AMDGPU::sub4_sub5_sub6_sub7, AMDGPU::sub5_sub6_sub7_sub8,
AMDGPU::sub6_sub7_sub8_sub9, AMDGPU::sub7_sub8_sub9_sub10,
AMDGPU::sub8_sub9_sub10_sub11, AMDGPU::sub9_sub10_sub11_sub12,
AMDGPU::sub10_sub11_sub12_sub13, AMDGPU::sub11_sub12_sub13_sub14,
AMDGPU::sub12_sub13_sub14_sub15, AMDGPU::sub13_sub14_sub15_sub16,
AMDGPU::sub14_sub15_sub16_sub17, AMDGPU::sub15_sub16_sub17_sub18,
AMDGPU::sub16_sub17_sub18_sub19, AMDGPU::sub17_sub18_sub19_sub20,
AMDGPU::sub18_sub19_sub20_sub21, AMDGPU::sub19_sub20_sub21_sub22,
AMDGPU::sub20_sub21_sub22_sub23, AMDGPU::sub21_sub22_sub23_sub24,
AMDGPU::sub22_sub23_sub24_sub25, AMDGPU::sub23_sub24_sub25_sub26,
AMDGPU::sub24_sub25_sub26_sub27, AMDGPU::sub25_sub26_sub27_sub28,
AMDGPU::sub26_sub27_sub28_sub29, AMDGPU::sub27_sub28_sub29_sub30,
AMDGPU::sub28_sub29_sub30_sub31, AMDGPU::NoSubRegister,
AMDGPU::NoSubRegister, AMDGPU::NoSubRegister}};

const unsigned NumRegIndex = NumRegs - 1;

assert(NumRegIndex < array_lengthof(SubRegFromChannelTable) &&
"Not implemented");
assert(Channel < array_lengthof(SubRegFromChannelTable[0]));
return SubRegFromChannelTable[NumRegIndex][Channel];
assert(NumRegs < SubRegFromChannelTableWidthMap.size());
unsigned NumRegIndex = SubRegFromChannelTableWidthMap[NumRegs];
assert(NumRegIndex && "Not implemented");
assert(Channel < SubRegFromChannelTable[NumRegIndex - 1].size());
return SubRegFromChannelTable[NumRegIndex - 1][Channel];
}

MCRegister SIRegisterInfo::reservedPrivateSegmentBufferReg(
Expand Down
5 changes: 5 additions & 0 deletions llvm/lib/Target/AMDGPU/SIRegisterInfo.h
View file
Expand Up @@ -40,6 +40,11 @@ class SIRegisterInfo final : public AMDGPUGenRegisterInfo {
/// all elements of the inner vector combined give a full lane mask.
static std::array<std::vector<int16_t>, 16> RegSplitParts;

// Table representing sub reg of given width and offset.
// First index is subreg size: 32, 64, 96, 128, 160, 192, 256, 512.
// Second index is 32 different dword offsets.
static std::array<std::array<uint16_t, 32>, 9> SubRegFromChannelTable;

void reserveRegisterTuples(BitVector &, MCRegister Reg) const;

public:
Expand Down

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