neonene <[email protected]> added the comment:
With msvc 16.10.3 and 16.11.2 (latest),
PR25244 told me the amount of code in _PyEval_EvalFrameDefault() is over the
limit of PGO.
In the old version of _PyEval_EvalFrameDefault (b98eba5), the same issue can be
caused adding any-code anywhere with more than 20 expressions/statements. For
example, at the top/middle/end of the function, repeating "if (0) {}" 10times,
or "if (0) {19 statements}". As for python3.9.7, more than 800
expressions/statements.
Here is just a workaround for 3.10rc2 on windows.
==================================================
--- Python/ceval.c
+++ Python/ceval.c
@@ -1306,9 +1306 @@
-#define DISPATCH() \
- { \
- if (trace_info.cframe.use_tracing OR_DTRACE_LINE OR_LLTRACE) { \
- goto tracing_dispatch; \
- } \
- f->f_lasti = INSTR_OFFSET(); \
- NEXTOPARG(); \
- DISPATCH_GOTO(); \
- }
+#define DISPATCH() goto tracing_dispatch
@@ -1782,4 +1774,9 @@
tracing_dispatch:
{
+ if (!(trace_info.cframe.use_tracing OR_DTRACE_LINE OR_LLTRACE)) {
+ f->f_lasti = INSTR_OFFSET();
+ NEXTOPARG();
+ DISPATCH_GOTO();
+ }
int instr_prev = f->f_lasti;
f->f_lasti = INSTR_OFFSET();
==================================================
This patch becomes ineffective just adding one expression to DISPATCH macro as
below
#define DISPATCH() {if (1) goto tracing_dispatch;}
And this approach is not sufficient for 3.11 with bigger eval-func.
I don't know a cl/link option to lift such restriction of function size.
3.10rc2 x86 pgo : 1.00
patched : 1.09x faster (slower 5, faster 48, not significant 5)
3.10rc2 x64 pgo : 1.00 (roughly the same speed as official bin)
patched : 1.07x faster (slower 5, faster 47, not significant 6)
patched(/Ob3) : 1.07x faster (slower 7, faster 45, not significant 6)
x64 results are posted.
Fixing inlining rejection also made __forceinline buildable with normal
processing time and memory usage.
----------
Added file: https://bugs.python.org/file50280/310rc2_benchmarks.txt
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<https://bugs.python.org/issue45116>
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