================
@@ -1224,6 +1225,9 @@ Parser::DeclGroupPtrTy
Parser::ParseDeclOrFunctionDefInternal(
Parser::DeclGroupPtrTy Parser::ParseDeclarationOrFunctionDefinition(
ParsedAttributes &Attrs, ParsedAttributes &DeclSpecAttrs,
ParsingDeclSpec *DS, AccessSpecifier AS) {
+ // Add an enclosing time trace scope for a bunch of small scopes with
+ // "EvaluateAsConstExpr".
+ llvm::TimeTraceScope TimeScope("ParseDeclarationOrFunctionDefinition");
----------------
MaggieYingYi wrote:
Hi @AaronBallman ,
Many thanks for your suggestions.
> Should we supply a second argument to the ctor here so that we can include
> the function name as part of the time trace output?
Good point. I cannot add `function name` as a second argument in the
`Parser::ParseDeclarationOrFunctionDefinition()` since the function
definition/declaration is not parsed yet. However, as you suggested, I have
added a new time trace variable to `Parser::ParseFunctionDefinition()` and
included the function name as a part of the time trace output in the commit
https://github.com/llvm/llvm-project/pull/65268/commits/deecf8c2.
> Also, I wonder if we want more or less granularity here. This will fire for
> function declarations and function definitions, so we could add it to
> `Parser::ParseFunctionDefinition()` instead to only time function definition
> parsing, or we could split it up so that we time parsing function signatures
> separately from parsing the function body so we can more easily see how much
> time is spent in which activity.
As mentioned above, I have added a new time trace variable of
`ParseFunctionDefinition`. However, I cannot remove the time trace variable of
"ParseDeclarationOrFunctionDefinition" since `ParseFunctionDefinition` doesn't
enclose small time scopes (named EvaluateAsConstExpr) in the function
declarations. The initial issue is shown in the function declarations (not
function definitions).
I will use a simple test to show the issue.
1. Source file test.cpp:
```
$ cat test.cpp
consteval double slow_func() {
double d = 0.0;
for (int i = 0; i < 100; ++i) {
d += i;
}
return d;
}
void slow_test() {
constexpr auto slow_value = slow_func();
}
int slow_arr[12 + 34 * 56 + static_cast<int>(slow_func())];
```
2. Compile test.cpp using the clang which is built using the repo of
yingyi/main/time-trace:
```
$ clang.exe -ftime-trace -ftime-trace-granularity=0 -std=c++20 test.cpp -c -o
test.o
```
3. View the generated time-trace file of test.json using `chrome://tracing/`.
For `slow_arr`, it uses the `slow_func()` declaration. `EvaluateAsConstantExpr`
is under the time scope of `ParseDeclarationOrFunctionDefinition` but not under
the time scope of `ParseFunctionDefinition`.
Therefore, I think we need both time scope variables of
`ParseDeclarationOrFunctionDefinition` and
`ParseFunctionDefinition`.
https://github.com/llvm/llvm-project/pull/65268
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