c++ - 了解使用 GCC 时编译时间花在哪里

Question

我有一个大量使用模板的项目。最近编译时间涨的挺猛的。我想知道是否有一种方法可以查看 g++ 编译哪些类/行需要最多的时间。

这是 -ftime-report 的一些输出:

Execution times (seconds)
 TOTAL                 :   0.30             0.05             0.37               9119 kB

Execution times (seconds)
 garbage collection    :   0.91 ( 6%) usr   0.00 ( 0%) sys   0.92 ( 5%) wall       0 kB ( 0%) ggc
 callgraph construction:   0.23 ( 2%) usr   0.11 ( 3%) sys   0.37 ( 2%) wall   10652 kB ( 1%) ggc
 callgraph optimization:   0.18 ( 1%) usr   0.12 ( 3%) sys   0.28 ( 2%) wall   11906 kB ( 2%) ggc
 varpool construction  :   0.04 ( 0%) usr   0.01 ( 0%) sys   0.08 ( 0%) wall    6984 kB ( 1%) ggc
 cfg construction      :   0.03 ( 0%) usr   0.00 ( 0%) sys   0.05 ( 0%) wall     644 kB ( 0%) ggc
 cfg cleanup           :   0.05 ( 0%) usr   0.02 ( 0%) sys   0.05 ( 0%) wall       7 kB ( 0%) ggc
 trivially dead code   :   0.05 ( 0%) usr   0.01 ( 0%) sys   0.12 ( 1%) wall       0 kB ( 0%) ggc
 df scan insns         :   0.37 ( 3%) usr   0.03 ( 1%) sys   0.43 ( 2%) wall     677 kB ( 0%) ggc
 df live regs          :   0.07 ( 0%) usr   0.01 ( 0%) sys   0.02 ( 0%) wall       0 kB ( 0%) ggc
 df reg dead/unused notes:   0.08 ( 1%) usr   0.01 ( 0%) sys   0.08 ( 0%) wall    2755 kB ( 0%) ggc
 register information  :   0.05 ( 0%) usr   0.01 ( 0%) sys   0.05 ( 0%) wall       0 kB ( 0%) ggc
 alias analysis        :   0.01 ( 0%) usr   0.01 ( 0%) sys   0.01 ( 0%) wall     878 kB ( 0%) ggc
 rebuild jump labels   :   0.03 ( 0%) usr   0.01 ( 0%) sys   0.01 ( 0%) wall       0 kB ( 0%) ggc
 preprocessing         :   0.19 ( 1%) usr   0.44 (11%) sys   0.68 ( 4%) wall    5284 kB ( 1%) ggc
 parser                :   3.94 (28%) usr   1.43 (35%) sys   4.94 (27%) wall  355964 kB (48%) ggc
 name lookup           :   1.35 ( 9%) usr   0.88 (21%) sys   2.76 (15%) wall   64919 kB ( 9%) ggc
 inline heuristics     :   0.14 ( 1%) usr   0.03 ( 1%) sys   0.14 ( 1%) wall       0 kB ( 0%) ggc
 integration           :   0.02 ( 0%) usr   0.00 ( 0%) sys   0.02 ( 0%) wall      20 kB ( 0%) ggc
 tree gimplify         :   0.31 ( 2%) usr   0.07 ( 2%) sys   0.28 ( 2%) wall   24598 kB ( 3%) ggc
 tree eh               :   0.07 ( 0%) usr   0.02 ( 0%) sys   0.11 ( 1%) wall    7267 kB ( 1%) ggc
 tree CFG construction :   0.04 ( 0%) usr   0.04 ( 1%) sys   0.11 ( 1%) wall   15754 kB ( 2%) ggc
 tree CFG cleanup      :   0.12 ( 1%) usr   0.00 ( 0%) sys   0.05 ( 0%) wall       3 kB ( 0%) ggc
 tree find ref. vars   :   0.03 ( 0%) usr   0.01 ( 0%) sys   0.02 ( 0%) wall     963 kB ( 0%) ggc
 tree PHI insertion    :   0.00 ( 0%) usr   0.01 ( 0%) sys   0.01 ( 0%) wall     351 kB ( 0%) ggc
 tree SSA rewrite      :   0.03 ( 0%) usr   0.01 ( 0%) sys   0.01 ( 0%) wall    4078 kB ( 1%) ggc
 tree SSA other        :   0.03 ( 0%) usr   0.06 ( 1%) sys   0.12 ( 1%) wall    1504 kB ( 0%) ggc
 tree operand scan     :   0.04 ( 0%) usr   0.02 ( 0%) sys   0.08 ( 0%) wall   10781 kB ( 1%) ggc
 dominance computation :   0.15 ( 1%) usr   0.04 ( 1%) sys   0.15 ( 1%) wall       0 kB ( 0%) ggc
 out of ssa            :   0.09 ( 1%) usr   0.00 ( 0%) sys   0.02 ( 0%) wall       0 kB ( 0%) ggc
 expand vars           :   0.03 ( 0%) usr   0.00 ( 0%) sys   0.03 ( 0%) wall    1840 kB ( 0%) ggc
 expand                :   0.45 ( 3%) usr   0.04 ( 1%) sys   0.59 ( 3%) wall   37695 kB ( 5%) ggc
 post expand cleanups  :   0.08 ( 1%) usr   0.02 ( 0%) sys   0.06 ( 0%) wall    4542 kB ( 1%) ggc
 varconst              :   0.15 ( 1%) usr   0.03 ( 1%) sys   0.12 ( 1%) wall    3595 kB ( 0%) ggc
 jump                  :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.04 ( 0%) wall    1904 kB ( 0%) ggc
 mode switching        :   0.01 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall       0 kB ( 0%) ggc
 integrated RA         :   1.33 ( 9%) usr   0.09 ( 2%) sys   1.49 ( 8%) wall   18163 kB ( 2%) ggc
 reload                :   0.60 ( 4%) usr   0.10 ( 2%) sys   0.62 ( 3%) wall    8668 kB ( 1%) ggc
 thread pro- & epilogue:   0.17 ( 1%) usr   0.00 ( 0%) sys   0.20 ( 1%) wall   11884 kB ( 2%) ggc
 reg stack             :   0.02 ( 0%) usr   0.00 ( 0%) sys   0.00 ( 0%) wall       0 kB ( 0%) ggc
 final                 :   0.71 ( 5%) usr   0.10 ( 2%) sys   0.84 ( 5%) wall    6251 kB ( 1%) ggc
 symout                :   1.10 ( 8%) usr   0.16 ( 4%) sys   1.19 ( 6%) wall  100954 kB (14%) ggc
 uninit var analysis   :   0.03 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall       0 kB ( 0%) ggc
 early local passes    :   0.00 ( 0%) usr   0.00 ( 0%) sys   0.01 ( 0%) wall       0 kB ( 0%) ggc
 rest of compilation   :   0.49 ( 3%) usr   0.06 ( 1%) sys   0.76 ( 4%) wall   19252 kB ( 3%) ggc
 unaccounted todo      :   0.43 ( 3%) usr   0.09 ( 2%) sys   0.55 ( 3%) wall       0 kB ( 0%) ggc
 TOTAL                 :  14.26             4.11            18.52             742072 kB

Answer 1

Steven Watanabe 的模板分析器可以帮助您获得每个类/函数的实例化计数。

参见 Debugging GCC Compile Times 以获得此工具的实际链接。