2009/3/17 Ian Lance Taylor <i...@google.com>: > The local labels used for blocks are normally discarded by the assembler > and thus are never seen by tools like oprofile. Using named symbols for > basic blocks seems like a reasonable option if it will indeed give > better information from oprofile, but it should be an option separate > from -fverbose-asm. The labels in RTL are CODE_LABEL insns, so you > would want to change the way that they are emitted in final_scan_insn. > The fact that there can be several CODE_LABELs in sequence doesn't seem > to matter too much, since only one will be picked up by profiling tools. > To be clear, I would want to see that you really do get better results > from profiling tools before accepting such a patch.
I use -Wa,-L to prevent the assembler to discard the local labels. I hope this will be useful. We can provide an option, say -flong-internal-label, which just change the output of local labels from prefix + labelno to prefix + func_name + labelno The objective of this is to generate a unique label name, so that the oprofile samples will not fall into the different label areas with the same name. But I find It's difficult to change the internal label composition. The target macros/hooks related to the label output all consider that a internal label is composed by "prefix + labelno". Many places need to be changed. So I try to do this by redefine ASM_GENERATE_INTERNAL_LABEL and TARGET_ASM_INTERNAL_LABEL in the back-end. But there's also a problem which is that the user need to consider the length of the function name and length of the label string buff. Best regards, Eric Fisher Mar 17, 2009
