Eliminate a major performance problem with chained PCH, where we were
causing the deserialization of a large number of declarations when
writing the visible-updates record for the translation unit in C. This
takes us from:
*** AST File Statistics:
2 stat cache hits
6 stat cache misses
1/64463 source location entries read (0.001551%)
15606/16956 types read (92.038216%)
59266/89334 declarations read (66.342041%)
38952/61393 identifiers read (63.446976%)
0/7778 selectors read (0.000000%)
24192/34644 statements read (69.830276%)
388/8809 macros read (4.404586%)
2095/5189 lexical declcontexts read (40.373867%)
0/4587 visible declcontexts read (0.000000%)
0/7716 method pool entries read (0.000000%)
0 method pool misses
to
*** AST File Statistics:
2 stat cache hits
6 stat cache misses
1/64463 source location entries read (0.001551%)
26/16956 types read (0.153338%)
18/89334 declarations read (0.020149%)
145/61393 identifiers read (0.236183%)
0/7778 selectors read (0.000000%)
21/34644 statements read (0.060617%)
0/8809 macros read (0.000000%)
0/5189 lexical declcontexts read (0.000000%)
0/4587 visible declcontexts read (0.000000%)
0/7716 method pool entries read (0.000000%)
0 method pool misses
when generating a chained PCH for a header that #includes Cocoa.h
(from a PCH file) and adds one simple function declaration. The
generated PCH file is now only 9580 bytes (down from > 2MB).
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@125326 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed