From 80c93e7442f89f4a0565258c56dca446e1574f9b Mon Sep 17 00:00:00 2001 From: Dan Gohman Date: Mon, 30 Mar 2009 22:55:17 +0000 Subject: [PATCH] Except in asm-verbose mode, avoid printing labels for blocks that are only reachable via fall-through edges. This dramatically reduces the number of labels printed, and thus also the number of labels the assembler must parse and remember. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@68073 91177308-0d34-0410-b5e6-96231b3b80d8 --- include/llvm/CodeGen/MachineBasicBlock.h | 9 +++++++++ lib/Target/X86/AsmPrinter/X86ATTAsmPrinter.cpp | 7 ++++++- 2 files changed, 15 insertions(+), 1 deletion(-) diff --git a/include/llvm/CodeGen/MachineBasicBlock.h b/include/llvm/CodeGen/MachineBasicBlock.h index 1ba7e798f83..f962273d2be 100644 --- a/include/llvm/CodeGen/MachineBasicBlock.h +++ b/include/llvm/CodeGen/MachineBasicBlock.h @@ -253,6 +253,15 @@ public: /// it returns end() iterator getFirstTerminator(); + /// isOnlyReachableViaFallthough - Return true if this basic block has + /// exactly one predecessor and the control transfer mechanism between + /// the predecessor and this block is a fall-through. + bool isOnlyReachableByFallthrough() const { + return !pred_empty() && + next(pred_begin()) == pred_end() && + (*pred_begin())->getFirstTerminator() == (*pred_begin())->end(); + } + void pop_front() { Insts.pop_front(); } void pop_back() { Insts.pop_back(); } void push_back(MachineInstr *MI) { Insts.push_back(MI); } diff --git a/lib/Target/X86/AsmPrinter/X86ATTAsmPrinter.cpp b/lib/Target/X86/AsmPrinter/X86ATTAsmPrinter.cpp index 3bdcf88365f..d8a33957d5c 100644 --- a/lib/Target/X86/AsmPrinter/X86ATTAsmPrinter.cpp +++ b/lib/Target/X86/AsmPrinter/X86ATTAsmPrinter.cpp @@ -238,7 +238,12 @@ bool X86ATTAsmPrinter::runOnMachineFunction(MachineFunction &MF) { for (MachineFunction::const_iterator I = MF.begin(), E = MF.end(); I != E; ++I) { // Print a label for the basic block. - if (!I->pred_empty()) { + if (!VerboseAsm && (I->pred_empty() || I->isOnlyReachableByFallthrough())) { + // This is an entry block or a block that's only reachable via a + // fallthrough edge. In non-VerboseAsm mode, don't print the label. + assert((I->pred_empty() || (*I->pred_begin())->isLayoutSuccessor(I)) && + "Fall-through predecessor not adjacent to its successor!"); + } else { printBasicBlockLabel(I, true, true, VerboseAsm); O << '\n'; }