LLVM Cookbook

Other optimization passes

In this recipe, we will look at some more transformational passes, which are more like of utility passes. We will look at the strip-debug-symbols pass and the prune-eh pass.

Getting ready…

The opt tool must be installed.

How to do it…

1. Write a test case for checking the strip-debug pass, which strips off the debug symbols from the test code:

   $ cat teststripdebug.ll
   @x = common global i32 0                          ; <i32*> [#uses=0]
   
   define void @foo() nounwind readnone optsize ssp {
   entry:
     tail call void @llvm.dbg.value(metadata i32 0, i64 0, metadata !5, metadata !{}), !dbg !10
     ret void, !dbg !11
   }
   
   declare void @llvm.dbg.value(metadata, i64, metadata, metadata) nounwind readnone
   
   !llvm.dbg.cu = !{!2}
   !llvm.module.flags = !{!13}
   !llvm.dbg.sp = !{!0} ...