我有一个包含许多目标的C ++项目，其中包含许多boost头文件和其他行密集头文件。大多数目标都包含相同的标题。 因此，我认为这可能是使用预编译头文件（pch）的理想选择。 所以我创建了一个包含最多标题的头文件并对其进行了预编译。
这将编译单元的代码行从350k减少到120k（我将-save-temps标志传递给gcc来检查）。我检查它是否与-H参数一起使用，并且pch前面有一个感叹号。
预编译的头文件有550MB。
尽管如此，编译时间仅从23秒减少到20秒。
预编译头文件有哪些改进？ 如果没有，我做错了什么？ 什么加速了预编译头文件的编译时间？
编辑： 这是gcc命令：
的/ usr / bin中/ C ++
-fPIC -I / projectDir / build / source -I / projectDir / source -I / usr / include / eigen3 -include /projectDir/build/source/Core/core/cotire/Core_ORIGINAL_CXX_prefix.hxx -Winvalid-pch -g -Wall -Wextra -Wno-long-long -Wno-unused-parameter -std = c ++ 0x -DBOOST_ENABLE_ASSERT_HANDLER -D_REENTRANT -o CMakeFiles / SubProject.dir / cotire / SubProject_ORIGINAL_CXX_unity.cxx.o -c /projectDir/build/source/ArmarXCore/statechart/cotire/SubProject_ORIGINAL_CXX_unity.cxx
传递-ftime-report的输出给了我（启用了PCH）：
Execution times (seconds)
phase setup : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 1321 kB ( 0%) ggc
phase parsing : 7.29 (32%) usr 1.69 (51%) sys 8.99 (35%) wall 1135793 kB (54%) ggc
phase lang. deferred : 2.75 (12%) usr 0.40 (12%) sys 3.15 (12%) wall 317920 kB (15%) ggc
phase opt and generate : 12.03 (53%) usr 1.17 (36%) sys 13.22 (51%) wall 622545 kB (30%) ggc
phase check & debug info: 0.01 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 440 kB ( 0%) ggc
phase last asm : 0.63 ( 3%) usr 0.02 ( 1%) sys 0.64 ( 2%) wall 26440 kB ( 1%) ggc
phase finalize : 0.00 ( 0%) usr 0.01 ( 0%) sys 0.02 ( 0%) wall 0 kB ( 0%) ggc
|name lookup : 1.30 ( 6%) usr 0.29 ( 9%) sys 1.42 ( 5%) wall 153617 kB ( 7%) ggc
|overload resolution : 3.37 (15%) usr 0.59 (18%) sys 3.30 (13%) wall 360551 kB (17%) ggc
garbage collection : 1.80 ( 8%) usr 0.01 ( 0%) sys 1.82 ( 7%) wall 0 kB ( 0%) ggc
dump files : 0.11 ( 0%) usr 0.05 ( 2%) sys 0.18 ( 1%) wall 0 kB ( 0%) ggc
callgraph construction : 0.44 ( 2%) usr 0.10 ( 3%) sys 0.59 ( 2%) wall 26388 kB ( 1%) ggc
callgraph optimization : 0.21 ( 1%) usr 0.11 ( 3%) sys 0.23 ( 1%) wall 16131 kB ( 1%) ggc
ipa free inline summary : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 0 kB ( 0%) ggc
cfg construction : 0.03 ( 0%) usr 0.00 ( 0%) sys 0.03 ( 0%) wall 2119 kB ( 0%) ggc
cfg cleanup : 0.08 ( 0%) usr 0.00 ( 0%) sys 0.11 ( 0%) wall 169 kB ( 0%) ggc
trivially dead code : 0.05 ( 0%) usr 0.02 ( 1%) sys 0.13 ( 0%) wall 0 kB ( 0%) ggc
df scan insns : 0.30 ( 1%) usr 0.02 ( 1%) sys 0.38 ( 1%) wall 1126 kB ( 0%) ggc
df live regs : 0.07 ( 0%) usr 0.00 ( 0%) sys 0.10 ( 0%) wall 0 kB ( 0%) ggc
df reg dead/unused notes: 0.10 ( 0%) usr 0.03 ( 1%) sys 0.12 ( 0%) wall 7774 kB ( 0%) ggc
register information : 0.03 ( 0%) usr 0.00 ( 0%) sys 0.04 ( 0%) wall 0 kB ( 0%) ggc
alias analysis : 0.02 ( 0%) usr 0.02 ( 1%) sys 0.08 ( 0%) wall 2621 kB ( 0%) ggc
rebuild jump labels : 0.05 ( 0%) usr 0.01 ( 0%) sys 0.03 ( 0%) wall 0 kB ( 0%) ggc
preprocessing : 1.16 ( 5%) usr 0.45 (14%) sys 1.61 ( 6%) wall 209848 kB (10%) ggc
parser (global) : 0.43 ( 2%) usr 0.29 ( 9%) sys 0.83 ( 3%) wall 193966 kB ( 9%) ggc
parser struct body : 1.03 ( 5%) usr 0.20 ( 6%) sys 1.37 ( 5%) wall 199825 kB ( 9%) ggc
parser enumerator list : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 574 kB ( 0%) ggc
parser function body : 0.53 ( 2%) usr 0.06 ( 2%) sys 0.49 ( 2%) wall 35252 kB ( 2%) ggc
parser inl. func. body : 0.13 ( 1%) usr 0.03 ( 1%) sys 0.14 ( 1%) wall 11720 kB ( 1%) ggc
parser inl. meth. body : 1.14 ( 5%) usr 0.19 ( 6%) sys 1.45 ( 6%) wall 115776 kB ( 6%) ggc
template instantiation : 4.11 (18%) usr 0.82 (25%) sys 4.78 (18%) wall 566245 kB (27%) ggc
inline parameters : 0.05 ( 0%) usr 0.01 ( 0%) sys 0.03 ( 0%) wall 12792 kB ( 1%) ggc
tree gimplify : 0.28 ( 1%) usr 0.03 ( 1%) sys 0.27 ( 1%) wall 55239 kB ( 3%) ggc
tree eh : 0.19 ( 1%) usr 0.00 ( 0%) sys 0.14 ( 1%) wall 20091 kB ( 1%) ggc
tree CFG construction : 0.02 ( 0%) usr 0.00 ( 0%) sys 0.05 ( 0%) wall 34452 kB ( 2%) ggc
tree CFG cleanup : 0.09 ( 0%) usr 0.02 ( 1%) sys 0.15 ( 1%) wall 27 kB ( 0%) ggc
tree PHI insertion : 0.01 ( 0%) usr 0.01 ( 0%) sys 0.01 ( 0%) wall 5960 kB ( 0%) ggc
tree SSA rewrite : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.04 ( 0%) wall 8035 kB ( 0%) ggc
tree SSA other : 0.04 ( 0%) usr 0.03 ( 1%) sys 0.12 ( 0%) wall 1604 kB ( 0%) ggc
tree operand scan : 0.06 ( 0%) usr 0.04 ( 1%) sys 0.08 ( 0%) wall 16681 kB ( 1%) ggc
dominance frontiers : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 0 kB ( 0%) ggc
dominance computation : 0.14 ( 1%) usr 0.04 ( 1%) sys 0.12 ( 0%) wall 0 kB ( 0%) ggc
out of ssa : 0.04 ( 0%) usr 0.03 ( 1%) sys 0.14 ( 1%) wall 8 kB ( 0%) ggc
expand vars : 0.10 ( 0%) usr 0.00 ( 0%) sys 0.14 ( 1%) wall 10387 kB ( 0%) ggc
expand : 0.79 ( 3%) usr 0.05 ( 2%) sys 0.77 ( 3%) wall 89756 kB ( 4%) ggc
post expand cleanups : 0.10 ( 0%) usr 0.00 ( 0%) sys 0.05 ( 0%) wall 14796 kB ( 1%) ggc
varconst : 0.03 ( 0%) usr 0.00 ( 0%) sys 0.03 ( 0%) wall 532 kB ( 0%) ggc
jump : 0.00 ( 0%) usr 0.01 ( 0%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc
integrated RA : 4.92 (22%) usr 0.12 ( 4%) sys 4.54 (17%) wall 167029 kB ( 8%) ggc
LRA non-specific : 0.38 ( 2%) usr 0.01 ( 0%) sys 0.81 ( 3%) wall 776 kB ( 0%) ggc
LRA virtuals elimination: 0.07 ( 0%) usr 0.00 ( 0%) sys 0.07 ( 0%) wall 6530 kB ( 0%) ggc
LRA reload inheritance : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 4 kB ( 0%) ggc
LRA create live ranges : 0.03 ( 0%) usr 0.00 ( 0%) sys 0.02 ( 0%) wall 40 kB ( 0%) ggc
LRA hard reg assignment : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 0 kB ( 0%) ggc
reload : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.03 ( 0%) wall 0 kB ( 0%) ggc
thread pro- & epilogue : 0.16 ( 1%) usr 0.01 ( 0%) sys 0.26 ( 1%) wall 19997 kB ( 1%) ggc
shorten branches : 0.17 ( 1%) usr 0.01 ( 0%) sys 0.16 ( 1%) wall 0 kB ( 0%) ggc
reg stack : 0.01 ( 0%) usr 0.00 ( 0%) sys 0.00 ( 0%) wall 0 kB ( 0%) ggc
final : 0.63 ( 3%) usr 0.04 ( 1%) sys 0.69 ( 3%) wall 29353 kB ( 1%) ggc
symout : 1.28 ( 6%) usr 0.06 ( 2%) sys 1.23 ( 5%) wall 173563 kB ( 8%) ggc
uninit var analysis : 0.00 ( 0%) usr 0.00 ( 0%) sys 0.01 ( 0%) wall 0 kB ( 0%) ggc
rest of compilation : 0.81 ( 4%) usr 0.18 ( 5%) sys 0.93 ( 4%) wall 34415 kB ( 2%) ggc
unaccounted todo : 0.25 ( 1%) usr 0.16 ( 5%) sys 0.39 ( 1%) wall 0 kB ( 0%) ggc
TOTAL : 22.71 3.29 26.03 2104543 kB
感谢veio