Modify emission of jump tables on darwin to emit an extra "l" label that

delimits the boundaries of jump tables.  This lets the linker's dead code
stripping optimization do a better job.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@33315 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 7 insertions, 0 deletions

diff --git a/lib/Target/X86/X86TargetAsmInfo.cpp b/lib/Target/X86/X86TargetAsmInfo.cpp
index 1735220ae2..2bb4a6c227 100644
--- a/lib/Target/X86/X86TargetAsmInfo.cpp
+++ b/lib/Target/X86/X86TargetAsmInfo.cpp
@@ -68,6 +68,13 @@ X86TargetAsmInfo::X86TargetAsmInfo(const X86TargetMachine &TM) {
     WeakRefDirective = "\t.weak_reference\t";
     HiddenDirective = "\t.private_extern\t";
     
+    // In non-PIC modes, emit a special label before jump tables so that the
+    // linker can perform more accurate dead code stripping.
+    if (TM.getRelocationModel() != Reloc::PIC_) {
+      // Emit a local label that is preserved until the linker runs.
+      JumpTableSpecialLabelPrefix = "l";
+    }
+    
     NeedsSet = true;
     DwarfAbbrevSection = ".section __DWARF,__debug_abbrev,regular,debug";
     DwarfInfoSection = ".section __DWARF,__debug_info,regular,debug";