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Automerge: [TableGen] Pool duplicate code-emitter base encodings (#202619)
Pool duplicate multiword instruction base encodings across the default encoding table and all hardware-mode encoding tables as unique `APInt` rows, then emit a pointer-free fixed-width `uint64_t` row table and one smallest-width opcode-to-row index table per mode. Use the pooled representation only when the combined values and indices are smaller than the original tables. On a Release build, the AMDGPU base-encoding payload shrinks by 440,888 bytes, `llvm-mc` and `llc` each shrink by 445,632 bytes, and the LLVM driver shrinks by 429,120 bytes. All 421 TableGen tests passed. Work towards #202616 AI tool disclosure: Co-authored with OpenAI Codex.
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Lines changed: 232 additions & 76 deletions

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‎llvm/test/TableGen/CodeEmitterBaseEncodingPool.td‎

Lines changed: 45 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,45 @@
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// RUN: llvm-tblgen -gen-emitter -I %p/../../include %s | FileCheck %s
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include "llvm/Target/Target.td"
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def TestInstrInfo : InstrInfo;
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def Test : Target {
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let InstructionSet = TestInstrInfo;
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}
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class TestInst<bits<8> LowEncoding, bit HighEncoding> : Instruction {
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bits<128> Inst;
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let Inst{7...0} = LowEncoding;
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let Inst{64} = HighEncoding;
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let OutOperandList = (outs);
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let InOperandList = (ins);
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}
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def A0 : TestInst<1, 0>;
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def A1 : TestInst<1, 0>;
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def A2 : TestInst<1, 0>;
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def A3 : TestInst<1, 0>;
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def B0 : TestInst<1, 1>;
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def B1 : TestInst<1, 1>;
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def B2 : TestInst<1, 1>;
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def B3 : TestInst<1, 1>;
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// CHECK: static const uint64_t InstBits[][2] = {
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// CHECK-NEXT: {UINT64_C(1), UINT64_C(0)},
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// CHECK-NEXT: {UINT64_C(1), UINT64_C(1)},
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// CHECK-NEXT: };
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// CHECK: static const uint8_t InstBitsIndices[] = {
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// CHECK-NEXT: 0,
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// CHECK-NEXT: 0,
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// CHECK-NEXT: 0,
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// CHECK-NEXT: 0,
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// CHECK-NEXT: 1,
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// CHECK-NEXT: 1,
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// CHECK-NEXT: 1,
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// CHECK-NEXT: 1,
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// CHECK-NEXT: };
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// CHECK: static_assert(sizeof(InstBits) / sizeof(InstBits[0]) <=
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// CHECK-NEXT: (UINT64_C(1) << (sizeof(InstBitsIndices[0]) * 8)));
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// CHECK: unsigned InstBitsIndex = InstBitsIndices[TableIndex];
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// CHECK: Inst = APInt(128, ArrayRef(InstBits[InstBitsIndex]));

‎llvm/test/TableGen/HwModeEncodeAPInt.td‎

Lines changed: 43 additions & 35 deletions
Original file line numberDiff line numberDiff line change
@@ -107,45 +107,51 @@ def unrelated: Instruction {
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let AsmString = "unrelated $factor";
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}
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// For 'bar' and 'unrelated', we didn't assign any HwModes for them,
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// they should keep the same in the following four tables.
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// For 'foo' we assigned four HwModes( includes 'DefaultMode' ),
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// it's encodings should be different in the following four tables.
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// For 'baz' we only assigned ModeB for it, so it will be presented
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// as '0' in the tables of ModeA, ModeC and Default Mode.
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// ENCODER-LABEL: static const uint64_t InstBits[] = {
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// ENCODER-NEXT: UINT64_C(2), UINT64_C(0), // bar
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// ENCODER-NEXT: UINT64_C(0), UINT64_C(0), // baz
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// ENCODER-NEXT: UINT64_C(8), UINT64_C(0), // foo
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// ENCODER-NEXT: UINT64_C(2), UINT64_C(0), // unrelated
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// InstBits contains the unique base encodings from all four HwModes.
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// Each InstBitsIndices table maps opcodes for one hardware mode into InstBits.
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// ENCODER-LABEL: static const uint64_t InstBits[][2] = {
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// ENCODER-NEXT: {UINT64_C(2), UINT64_C(0)},
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// ENCODER-NEXT: {UINT64_C(0), UINT64_C(0)},
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// ENCODER-NEXT: {UINT64_C(8), UINT64_C(0)},
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// ENCODER-NEXT: {UINT64_C(12), UINT64_C(0)},
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// ENCODER-NEXT: {UINT64_C(0), UINT64_C(211106232532992)},
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// ENCODER-NEXT: {UINT64_C(12582915), UINT64_C(0)},
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// ENCODER-NEXT: };
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// ENCODER-LABEL: static const uint64_t InstBits_ModeA[] = {
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// ENCODER-NEXT: UINT64_C(2), UINT64_C(0), // bar
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// ENCODER-NEXT: UINT64_C(0), UINT64_C(0), // baz
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// ENCODER-NEXT: UINT64_C(12), UINT64_C(0), // foo
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// ENCODER-NEXT: UINT64_C(2), UINT64_C(0), // unrelated
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// ENCODER-LABEL: static const uint8_t InstBitsIndices[] = {
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// ENCODER-NEXT: 0,
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// ENCODER-NEXT: 1,
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// ENCODER-NEXT: 2,
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// ENCODER-NEXT: 0,
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// ENCODER-NEXT: };
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// ENCODER-LABEL: static const uint64_t InstBits_ModeB[] = {
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// ENCODER-NEXT: UINT64_C(2), UINT64_C(0), // bar
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// ENCODER-NEXT: UINT64_C(12), UINT64_C(0), // baz
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// ENCODER-NEXT: UINT64_C(0), UINT64_C(211106232532992), // foo
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// ENCODER-NEXT: UINT64_C(2), UINT64_C(0), // unrelated
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// ENCODER-LABEL: static const uint8_t InstBitsIndices_ModeA[] = {
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// ENCODER-NEXT: 0,
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// ENCODER-NEXT: 1,
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// ENCODER-NEXT: 3,
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// ENCODER-NEXT: 0,
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// ENCODER-NEXT: };
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// ENCODER-LABEL: static const uint64_t InstBits_ModeC[] = {
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// ENCODER-NEXT: UINT64_C(2), UINT64_C(0), // bar
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// ENCODER-NEXT: UINT64_C(0), UINT64_C(0), // baz
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// ENCODER-NEXT: UINT64_C(12582915), UINT64_C(0), // foo
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// ENCODER-NEXT: UINT64_C(2), UINT64_C(0), // unrelated
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// ENCODER-LABEL: static const uint8_t InstBitsIndices_ModeB[] = {
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// ENCODER-NEXT: 0,
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// ENCODER-NEXT: 3,
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// ENCODER-NEXT: 4,
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// ENCODER-NEXT: 0,
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// ENCODER-NEXT: };
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// ENCODER-LABEL: static const uint8_t InstBitsIndices_ModeC[] = {
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// ENCODER-NEXT: 0,
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// ENCODER-NEXT: 1,
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// ENCODER-NEXT: 5,
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// ENCODER-NEXT: 0,
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// ENCODER-NEXT: };
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// ENCODER: const uint8_t *InstBitsIndicesByHw;
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141-
// ENCODER: const uint64_t *InstBitsByHw;
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// ENCODER: constexpr unsigned FirstSupportedOpcode
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// ENCODER: const unsigned opcode = MI.getOpcode();
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// ENCODER: if (opcode < FirstSupportedOpcode)
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// ENCODER: unsigned TableIndex = opcode - FirstSupportedOpcode
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// ENCODER: if (Scratch.getBitWidth() != 128)
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// ENCODER: Scratch = Scratch.zext(128);
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// ENCODER: Inst = APInt(128, ArrayRef(InstBits + TableIndex * 2, 2));
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// ENCODER: unsigned InstBitsIndex = InstBitsIndices[TableIndex];
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// ENCODER: Inst = APInt(128, ArrayRef(InstBits[InstBitsIndex]));
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// ENCODER: APInt &Value = Inst;
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// ENCODER: APInt &op = Scratch;
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// ENCODER: switch (opcode) {
@@ -156,12 +162,13 @@ def unrelated: Instruction {
156162
// ENCODER: unsigned HwMode = STI.getHwMode(MCSubtargetInfo::HwMode_EncodingInfo);
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// ENCODER: switch (HwMode) {
158164
// ENCODER: default: llvm_unreachable("Unknown hardware mode!"); break;
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// ENCODER: case 0: InstBitsByHw = InstBits; break;
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// ENCODER: case 1: InstBitsByHw = InstBits_ModeA; break;
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// ENCODER: case 2: InstBitsByHw = InstBits_ModeB; break;
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// ENCODER: case 3: InstBitsByHw = InstBits_ModeC; break;
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// ENCODER: case 0: InstBitsIndicesByHw = InstBitsIndices; break;
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// ENCODER: case 1: InstBitsIndicesByHw = InstBitsIndices_ModeA; break;
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// ENCODER: case 2: InstBitsIndicesByHw = InstBitsIndices_ModeB; break;
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// ENCODER: case 3: InstBitsIndicesByHw = InstBitsIndices_ModeC; break;
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// ENCODER: };
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// ENCODER: Inst = APInt(128, ArrayRef(InstBitsByHw + TableIndex * 2, 2));
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// ENCODER: InstBitsIndex = InstBitsIndicesByHw[TableIndex];
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// ENCODER: Inst = APInt(128, ArrayRef(InstBits[InstBitsIndex]));
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// ENCODER: Value = Inst;
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// ENCODER: switch (HwMode) {
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// ENCODER: default: llvm_unreachable("Unhandled HwMode");
@@ -188,9 +195,10 @@ def unrelated: Instruction {
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// ENCODER: unsigned HwMode = STI.getHwMode(MCSubtargetInfo::HwMode_EncodingInfo);
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// ENCODER: switch (HwMode) {
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// ENCODER: default: llvm_unreachable("Unknown hardware mode!"); break;
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// ENCODER: case 2: InstBitsByHw = InstBits_ModeB; break;
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// ENCODER: case 2: InstBitsIndicesByHw = InstBitsIndices_ModeB; break;
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// ENCODER: };
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// ENCODER: Inst = APInt(128, ArrayRef(InstBitsByHw + TableIndex * 2, 2));
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// ENCODER: InstBitsIndex = InstBitsIndicesByHw[TableIndex];
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// ENCODER: Inst = APInt(128, ArrayRef(InstBits[InstBitsIndex]));
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// ENCODER: Value = Inst;
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// ENCODER: switch (HwMode) {
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// ENCODER: default: llvm_unreachable("Unhandled HwMode");

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