[PATCH] D97101: [Coverage] Emit zero count gap region between statements if first statements contains return, throw, goto, co_return

[Zequan Wu via Phabricator via cfe-commits]

zequanwu added inline comments.


================
Comment at: clang/lib/CodeGen/CoverageMappingGen.cpp:942
     pushRegion(Counter::getZero());
-    auto &ZeroRegion = getRegion();
-    ZeroRegion.setDeferred(true);
-    LastTerminatedRegion = {EndLoc, RegionStack.size()};
+    if (!HasTerminateStmt) {
+      auto &ZeroRegion = getRegion();
----------------
vsk wrote:
> zequanwu wrote:
> > vsk wrote:
> > > What's supposed to be the difference between the zero region pushed after a `return;` vs. after a `break;`?
> > What I think is `DeferredRegion` is only used for `break;` and `continue`. Other terminate statements like `return;`, `throw` etc will use the logic in `VisitStmt` to emit gap region. So, I added this condition to separate the two cases.
> What do you think of the notion of using the gaps inserted in VisitStmt to replace the whole deferred region system? Is it something that might be feasible (if perhaps out of scope for this patch), or do you see a fundamental reason it can't/shouldn't be done?
I think it is feasible. For break and continue, they only affect the statements after them in the same block. For other terminate statements, they affect all the statements after them even outside the block, see example below. Also instead of emitting a zero gap region in VisitStmt, we need emit gap region with (previous counter - current statement counter).

```
while (cond) {
...
break; // This affects statements' count until the end of the while body.
...
}

while (cond) {
...
return; // This affects statements' count until the end of the function body.
...
}
```



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  https://reviews.llvm.org/D97101/new/

https://reviews.llvm.org/D97101