This patch series improves the coverage and correctness of data type
annotations in the perf tools.
Here's a breakdown of the patches:
Patches 1-4 improve variable type matching:
- Skip redundant check_variable for die_find_variable_by_reg since
match_var_offset already performs sufficient checking
- Add die_get_pointer_type() to properly handle typedef'd pointer types
- Preserve typedefs in match_var_offset for consistent type handling
- Improve type comparison when variables are found in different scopes
Patch 5 handles array types in die_get_member_type, allowing proper
resolution of struct members that are arrays.
Patches 6-7 improve global variable handling:
- Allow collecting global variables without symbol names (DWARF provides
the address directly via DW_OP_addr)
- Handle global variable access when a register holds a const value
with negative offset
Patches 8-9 improve caller-saved register handling:
- Add invalidate_reg_state() helper for consistent register invalidation
- Always invalidate caller-saved registers for call instructions per ABI
requirements, even when the call target is unknown
Patches 10-11 use DWARF location ranges to improve type tracking:
- Track DWARF location lifetime to preserve register state across calls
when the debug info indicates the value is still valid
- Collect all variable location entries instead of just the first one
Tested with the Linux kernel vmlinux with sampled functions and five
programs from binutils (as, ld, nm, objdump, readelf) with all
functions. Coverage rate includes all memory assess instructions,
excluding stack memory accesses.
`lost` means coverage loss (only including annotated -> none);
`chg` means type name change. Net coverage gain is new_rate - prev_rate.
-------- vmlinux -------- ------- binutils -------
Patch rate lost chg rate lost chg
----------------------------------------------------------------
base 88.78% - - 72.55% - -
1 72.95% 15.63% .71% 65.01% 8.59% 22.89%
2 72.95% 0% 0% 65.16% 0% 0%
3 88.88% 0% .73% 74.73% 0% 23.72%
4 88.88% 0% .83% 74.73% 0% .17%
5 89.09% .01% .08% 74.75% 0% .01%
6 89.10% 0% .02% 75.67% 0% 1.62%
7 89.16% 0% 0% 75.67% 0% 0%
8 89.16% 0% 0% 75.64% .02% 0%
9 89.07% .08% 0% 75.59% .05% 0%
10 89.02% .08% .09% 75.85% .03% .03%
11 89.95% 0% .10% 76.94% .26% .07%
Total: vmlinux 88.78% -> 89.95% (+1.17%)
binutils 72.55% -> 76.94% (+4.39%)
Note: Patches 1-3 are designed to work together. Patch 1 causes a
temporary regression that patch 3 resolves while adding typedef support.
Zecheng Li (11):
perf dwarf-aux: Skip check_variable for die_find_variable_by_reg
perf dwarf-aux: Add die_get_pointer_type to get pointer types
perf dwarf-aux: Preserve typedefs in match_var_offset
perf annotate-data: Improve type comparison from different scopes
perf dwarf-aux: Handle array types in die_get_member_type
perf annotate-data: Collect global variables without name
perf annotate-data: Handle global variable access with const register
perf annotate-data: Add invalidate_reg_state() helper for x86
perf annotate-data: Invalidate caller-saved regs for all calls
perf annotate-data: Use DWARF location ranges to preserve reg state
perf dwarf-aux: Collect all variable locations for insn tracking
tools/perf/arch/x86/annotate/instructions.c | 69 +++++++---
tools/perf/util/annotate-data.c | 86 ++++++++----
tools/perf/util/annotate-data.h | 3 +
tools/perf/util/dwarf-aux.c | 139 ++++++++++++++------
tools/perf/util/dwarf-aux.h | 6 +-
5 files changed, 211 insertions(+), 92 deletions(-)
--
2.52.0