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Allow the second opcode info table to be 8, 16, or 32-bits as needed to represent additional fragments. This recovers some space on ATT X86 syntax and PowerPC which only need 40-bits instead of 48-bits. This also increases ARM to 64-bits to fully encode all of its operands.
llvm-svn: 163880
This commit is contained in:
Craig Topper
parent
5cd6b912e7
commit
0320f5eded
@ -315,7 +315,7 @@ void AsmWriterEmitter::EmitPrintInstruction(raw_ostream &O) {
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/// chunk of the output as well as indices used for operand printing.
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/// To reduce the number of unhandled cases, we expand the size from 32-bit
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/// to 32+16 = 48-bit.
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std::vector<std::pair<unsigned, uint16_t> > OpcodeInfo;
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std::vector<uint64_t> OpcodeInfo;
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// Add all strings to the string table upfront so it can generate an optimized
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// representation.
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@ -356,7 +356,7 @@ void AsmWriterEmitter::EmitPrintInstruction(raw_ostream &O) {
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}
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// Bias offset by one since we want 0 as a sentinel.
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OpcodeInfo.push_back(std::make_pair(Idx+1, 0));
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OpcodeInfo.push_back(Idx+1);
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}
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// Figure out how many bits we used for the string index.
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@ -364,7 +364,7 @@ void AsmWriterEmitter::EmitPrintInstruction(raw_ostream &O) {
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// To reduce code size, we compactify common instructions into a few bits
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// in the opcode-indexed table.
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unsigned BitsLeft = 32+16-AsmStrBits;
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unsigned BitsLeft = 64-AsmStrBits;
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std::vector<std::vector<std::string> > TableDrivenOperandPrinters;
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@ -382,13 +382,6 @@ void AsmWriterEmitter::EmitPrintInstruction(raw_ostream &O) {
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// ceil(log2(numentries)).
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unsigned NumBits = Log2_32_Ceil(UniqueOperandCommands.size());
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// Check whether these Bits will fit in the first 32 bits.
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if (BitsLeft > 16 && NumBits > BitsLeft - 16)
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// We don't have enough bits in the first 32 bits, and we skip the
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// left-over bits.
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BitsLeft = 16;
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bool UseSecond = (BitsLeft <= 16);
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// If we don't have enough bits for this operand, don't include it.
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if (NumBits > BitsLeft) {
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DEBUG(errs() << "Not enough bits to densely encode " << NumBits
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@ -397,15 +390,11 @@ void AsmWriterEmitter::EmitPrintInstruction(raw_ostream &O) {
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}
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// Otherwise, we can include this in the initial lookup table. Add it in.
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BitsLeft -= NumBits;
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for (unsigned i = 0, e = InstIdxs.size(); i != e; ++i)
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// Update the first 32 bits or the second 16 bits.
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if (InstIdxs[i] != ~0U) {
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if (UseSecond)
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OpcodeInfo[i].second |= InstIdxs[i] << BitsLeft;
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else
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OpcodeInfo[i].first |= InstIdxs[i] << (BitsLeft-16+AsmStrBits);
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OpcodeInfo[i] |= (uint64_t)InstIdxs[i] << (64-BitsLeft);
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}
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BitsLeft -= NumBits;
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// Remove the info about this operand.
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for (unsigned i = 0, e = NumberedInstructions.size(); i != e; ++i) {
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@ -424,21 +413,25 @@ void AsmWriterEmitter::EmitPrintInstruction(raw_ostream &O) {
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}
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O<<" static const unsigned OpInfo[] = {\n";
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// We always emit at least one 32-bit table. A second table is emitted if
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// more bits are needed.
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O<<" static const uint32_t OpInfo[] = {\n";
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for (unsigned i = 0, e = NumberedInstructions.size(); i != e; ++i) {
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O << " " << OpcodeInfo[i].first << "U,\t// "
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O << " " << (OpcodeInfo[i] & 0xffffffff) << "U,\t// "
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<< NumberedInstructions[i]->TheDef->getName() << "\n";
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}
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// Add a dummy entry so the array init doesn't end with a comma.
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O << " 0U\n";
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O << " };\n\n";
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if (BitsLeft < 16) {
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if (BitsLeft < 32) {
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// Add a second OpInfo table only when it is necessary.
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O<<" static const uint16_t OpInfo2[] = {\n";
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// Adjust the type of the second table based on the number of bits needed.
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O << " static const uint"
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<< ((BitsLeft < 16) ? "32" : (BitsLeft < 24) ? "16" : "8")
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<< "_t OpInfo2[] = {\n";
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for (unsigned i = 0, e = NumberedInstructions.size(); i != e; ++i) {
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O << " " << OpcodeInfo[i].second << "U,\t// "
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O << " " << (OpcodeInfo[i] >> 32) << "U,\t// "
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<< NumberedInstructions[i]->TheDef->getName() << "\n";
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}
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// Add a dummy entry so the array init doesn't end with a comma.
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@ -453,15 +446,22 @@ void AsmWriterEmitter::EmitPrintInstruction(raw_ostream &O) {
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O << " O << \"\\t\";\n\n";
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O << " // Emit the opcode for the instruction.\n"
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<< " unsigned Bits = OpInfo[MI->getOpcode()];\n";
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if (BitsLeft < 16)
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O << " unsigned short Bits2 = OpInfo2[MI->getOpcode()];\n";
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O << " // Emit the opcode for the instruction.\n";
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if (BitsLeft < 32) {
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// If we have two tables then we need to perform two lookups and combine
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// the results into a single 64-bit value.
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O << " uint64_t Bits1 = OpInfo[MI->getOpcode()];\n"
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<< " uint64_t Bits2 = OpInfo2[MI->getOpcode()];\n"
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<< " uint64_t Bits = (Bits2 << 32) | Bits1;\n";
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} else {
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// If only one table is used we just need to perform a single lookup.
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O << " uint32_t Bits = OpInfo[MI->getOpcode()];\n";
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}
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O << " assert(Bits != 0 && \"Cannot print this instruction.\");\n"
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<< " O << AsmStrs+(Bits & " << (1 << AsmStrBits)-1 << ")-1;\n\n";
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// Output the table driven operand information.
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BitsLeft = 32+16-AsmStrBits;
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BitsLeft = 64-AsmStrBits;
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for (unsigned i = 0, e = TableDrivenOperandPrinters.size(); i != e; ++i) {
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std::vector<std::string> &Commands = TableDrivenOperandPrinters[i];
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@ -470,21 +470,14 @@ void AsmWriterEmitter::EmitPrintInstruction(raw_ostream &O) {
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unsigned NumBits = Log2_32_Ceil(Commands.size());
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assert(NumBits <= BitsLeft && "consistency error");
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// Check whether these Bits will fit in the first 32 bits.
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if (BitsLeft > 16 && NumBits > BitsLeft - 16)
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BitsLeft = 16;
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bool UseSecond = (BitsLeft <= 16);
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// Emit code to extract this field from Bits.
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BitsLeft -= NumBits;
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O << "\n // Fragment " << i << " encoded into " << NumBits
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<< " bits for " << Commands.size() << " unique commands.\n";
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if (Commands.size() == 2) {
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// Emit two possibilitys with if/else.
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O << (UseSecond ? " if ((Bits2 >> " : " if ((Bits >> ")
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<< (UseSecond ? BitsLeft : (BitsLeft-16+AsmStrBits)) << ") & "
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O << " if ((Bits >> "
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<< (64-BitsLeft) << ") & "
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<< ((1 << NumBits)-1) << ") {\n"
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<< Commands[1]
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<< " } else {\n"
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@ -494,8 +487,8 @@ void AsmWriterEmitter::EmitPrintInstruction(raw_ostream &O) {
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// Emit a single possibility.
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O << Commands[0] << "\n\n";
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} else {
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O << (UseSecond ? " switch ((Bits2 >> " : " switch ((Bits >> ")
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<< (UseSecond ? BitsLeft : (BitsLeft-16+AsmStrBits)) << ") & "
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O << " switch ((Bits >> "
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<< (64-BitsLeft) << ") & "
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<< ((1 << NumBits)-1) << ") {\n"
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<< " default: // unreachable.\n";
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@ -507,6 +500,7 @@ void AsmWriterEmitter::EmitPrintInstruction(raw_ostream &O) {
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}
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O << " }\n\n";
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}
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BitsLeft -= NumBits;
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}
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// Okay, delete instructions with no operand info left.
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