Changes in directory llvm/lib/CodeGen:
AsmPrinter.cpp updated: 1.88 -> 1.89
---
Log message:
Emit .set directives for jump table entries when possible, which reduces
the number of relocations in object files, shrinkifying them.
---
Diffs of the changes: (+39 -3)
AsmPrinter.cpp | 42 +++++++++++++++++++++++++++++++++++++++---
1 files changed, 39 insertions(+), 3 deletions(-)
Index: llvm/lib/CodeGen/AsmPrinter.cpp
diff -u llvm/lib/CodeGen/AsmPrinter.cpp:1.88
llvm/lib/CodeGen/AsmPrinter.cpp:1.89
--- llvm/lib/CodeGen/AsmPrinter.cpp:1.88 Fri Jul 28 20:57:19 2006
+++ llvm/lib/CodeGen/AsmPrinter.cpp Sat Aug 12 16:29:52 2006
@@ -59,6 +59,7 @@
FourByteConstantSection(0),
EightByteConstantSection(0),
SixteenByteConstantSection(0),
+ SetDirective(0),
LCOMMDirective(0),
COMMDirective("\t.comm\t"),
COMMDirectiveTakesAlignment(true),
@@ -228,15 +229,36 @@
EmitAlignment(Log2_32(TD->getPointerAlignment()));
for (unsigned i = 0, e = JT.size(); i != e; ++i) {
+ const std::vector<MachineBasicBlock*> &JTBBs = JT[i].MBBs;
+
+ // For PIC codegen, if possible we want to use the SetDirective to reduce
+ // the number of relocations the assembler will generate for the jump
table.
+ // Set directives are all printed before the jump table itself.
+ std::set<MachineBasicBlock*> EmittedSets;
+ if (SetDirective && TM.getRelocationModel() == Reloc::PIC_)
+ for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii)
+ if (EmittedSets.insert(JTBBs[ii]).second)
+ printSetLabel(i, JTBBs[ii]);
+
O << PrivateGlobalPrefix << "JTI" << getFunctionNumber() << '_' << i
<< ":\n";
- const std::vector<MachineBasicBlock*> &JTBBs = JT[i].MBBs;
+
for (unsigned ii = 0, ee = JTBBs.size(); ii != ee; ++ii) {
O << JTEntryDirective << ' ';
- printBasicBlockLabel(JTBBs[ii], false, false);
- if (TM.getRelocationModel() == Reloc::PIC_) {
+ // If we have emitted set directives for the jump table entries, print
+ // them rather than the entries themselves. If we're emitting PIC, then
+ // emit the table entries as differences between two text section labels.
+ // If we're emitting non-PIC code, then emit the entries as direct
+ // references to the target basic blocks.
+ if (!EmittedSets.empty()) {
+ O << PrivateGlobalPrefix << getFunctionNumber() << '_' << i << "_set_"
+ << JTBBs[ii]->getNumber();
+ } else if (TM.getRelocationModel() == Reloc::PIC_) {
+ printBasicBlockLabel(JTBBs[ii], false, false);
O << '-' << PrivateGlobalPrefix << "JTI" << getFunctionNumber()
<< '_' << i;
+ } else {
+ printBasicBlockLabel(JTBBs[ii], false, false);
}
O << '\n';
}
@@ -818,3 +840,17 @@
if (printComment)
O << '\t' << CommentString << MBB->getBasicBlock()->getName();
}
+
+/// printSetLabel - This method prints a set label for the specified
+/// MachineBasicBlock
+void AsmPrinter::printSetLabel(unsigned uid,
+ const MachineBasicBlock *MBB) const {
+ if (!SetDirective)
+ return;
+
+ O << SetDirective << ' ' << PrivateGlobalPrefix << getFunctionNumber()
+ << '_' << uid << "_set_" << MBB->getNumber() << ',';
+ printBasicBlockLabel(MBB, false, false);
+ O << '-' << PrivateGlobalPrefix << "JTI" << getFunctionNumber()
+ << '_' << uid << '\n';
+}
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