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Emit .set directives for jump table entries when possible, which reduces
the number of relocations in object files, shrinkifying them. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@29650 91177308-0d34-0410-b5e6-96231b3b80d8
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@ -185,6 +185,10 @@ namespace llvm {
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//===--- Global Variable Emission Directives --------------------------===//
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//===--- Global Variable Emission Directives --------------------------===//
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/// SetDirective - This is the name of a directive that can be used to tell
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/// the assembler to set the value of a variable to some expression.
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const char *SetDirective; // Defaults to null.
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/// LCOMMDirective - This is the name of a directive (if supported) that can
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/// LCOMMDirective - This is the name of a directive (if supported) that can
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/// be used to efficiently declare a local (internal) block of zero
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/// be used to efficiently declare a local (internal) block of zero
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/// initialized data in the .bss/.data section. The syntax expected is:
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/// initialized data in the .bss/.data section. The syntax expected is:
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@ -323,6 +327,10 @@ namespace llvm {
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bool printColon = false,
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bool printColon = false,
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bool printComment = true) const;
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bool printComment = true) const;
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/// printSetLabel - This method prints a set label for the specified
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/// MachineBasicBlock
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void printSetLabel(unsigned uid, const MachineBasicBlock *MBB) const;
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private:
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private:
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void EmitXXStructorList(Constant *List);
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void EmitXXStructorList(Constant *List);
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void EmitConstantPool(unsigned Alignment, const char *Section,
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void EmitConstantPool(unsigned Alignment, const char *Section,
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@ -59,6 +59,7 @@ AsmPrinter::AsmPrinter(std::ostream &o, TargetMachine &tm)
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FourByteConstantSection(0),
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FourByteConstantSection(0),
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EightByteConstantSection(0),
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EightByteConstantSection(0),
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SixteenByteConstantSection(0),
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SixteenByteConstantSection(0),
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SetDirective(0),
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LCOMMDirective(0),
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LCOMMDirective(0),
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COMMDirective("\t.comm\t"),
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COMMDirective("\t.comm\t"),
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COMMDirectiveTakesAlignment(true),
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COMMDirectiveTakesAlignment(true),
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@ -228,15 +229,36 @@ void AsmPrinter::EmitJumpTableInfo(MachineJumpTableInfo *MJTI) {
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EmitAlignment(Log2_32(TD->getPointerAlignment()));
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EmitAlignment(Log2_32(TD->getPointerAlignment()));
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for (unsigned i = 0, e = JT.size(); i != e; ++i) {
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for (unsigned i = 0, e = JT.size(); i != e; ++i) {
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const std::vector<MachineBasicBlock*> &JTBBs = JT[i].MBBs;
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// For PIC codegen, if possible we want to use the SetDirective to reduce
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// the number of relocations the assembler will generate for the jump table.
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// Set directives are all printed before the jump table itself.
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std::set<MachineBasicBlock*> EmittedSets;
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if (SetDirective && TM.getRelocationModel() == Reloc::PIC_)
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for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii)
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if (EmittedSets.insert(JTBBs[ii]).second)
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printSetLabel(i, JTBBs[ii]);
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O << PrivateGlobalPrefix << "JTI" << getFunctionNumber() << '_' << i
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O << PrivateGlobalPrefix << "JTI" << getFunctionNumber() << '_' << i
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<< ":\n";
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<< ":\n";
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const std::vector<MachineBasicBlock*> &JTBBs = JT[i].MBBs;
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for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii) {
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for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii) {
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O << JTEntryDirective << ' ';
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O << JTEntryDirective << ' ';
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// If we have emitted set directives for the jump table entries, print
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// them rather than the entries themselves. If we're emitting PIC, then
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// emit the table entries as differences between two text section labels.
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// If we're emitting non-PIC code, then emit the entries as direct
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// references to the target basic blocks.
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if (!EmittedSets.empty()) {
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O << PrivateGlobalPrefix << getFunctionNumber() << '_' << i << "_set_"
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<< JTBBs[ii]->getNumber();
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} else if (TM.getRelocationModel() == Reloc::PIC_) {
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printBasicBlockLabel(JTBBs[ii], false, false);
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printBasicBlockLabel(JTBBs[ii], false, false);
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if (TM.getRelocationModel() == Reloc::PIC_) {
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O << '-' << PrivateGlobalPrefix << "JTI" << getFunctionNumber()
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O << '-' << PrivateGlobalPrefix << "JTI" << getFunctionNumber()
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<< '_' << i;
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<< '_' << i;
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} else {
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printBasicBlockLabel(JTBBs[ii], false, false);
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}
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}
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O << '\n';
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O << '\n';
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}
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}
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@ -818,3 +840,17 @@ void AsmPrinter::printBasicBlockLabel(const MachineBasicBlock *MBB,
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if (printComment)
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if (printComment)
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O << '\t' << CommentString << MBB->getBasicBlock()->getName();
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O << '\t' << CommentString << MBB->getBasicBlock()->getName();
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}
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}
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/// printSetLabel - This method prints a set label for the specified
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/// MachineBasicBlock
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void AsmPrinter::printSetLabel(unsigned uid,
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const MachineBasicBlock *MBB) const {
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if (!SetDirective)
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return;
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O << SetDirective << ' ' << PrivateGlobalPrefix << getFunctionNumber()
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<< '_' << uid << "_set_" << MBB->getNumber() << ',';
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printBasicBlockLabel(MBB, false, false);
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O << '-' << PrivateGlobalPrefix << "JTI" << getFunctionNumber()
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<< '_' << uid << '\n';
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}
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@ -276,6 +276,7 @@ namespace {
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GlobalPrefix = "_";
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GlobalPrefix = "_";
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PrivateGlobalPrefix = "L"; // Marker for constant pool idxs
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PrivateGlobalPrefix = "L"; // Marker for constant pool idxs
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ZeroDirective = "\t.space\t"; // ".space N" emits N zeros.
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ZeroDirective = "\t.space\t"; // ".space N" emits N zeros.
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SetDirective = "\t.set";
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if (isPPC64)
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if (isPPC64)
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Data64bitsDirective = ".quad\t"; // we can't emit a 64-bit unit
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Data64bitsDirective = ".quad\t"; // we can't emit a 64-bit unit
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else
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else
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@ -72,6 +72,7 @@ bool X86SharedAsmPrinter::doInitialization(Module &M) {
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StaticDtorsSection = ".mod_term_func";
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StaticDtorsSection = ".mod_term_func";
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InlineAsmStart = "# InlineAsm Start";
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InlineAsmStart = "# InlineAsm Start";
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InlineAsmEnd = "# InlineAsm End";
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InlineAsmEnd = "# InlineAsm End";
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SetDirective = "\t.set";
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break;
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break;
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case X86Subtarget::isCygwin:
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case X86Subtarget::isCygwin:
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GlobalPrefix = "_";
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GlobalPrefix = "_";
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