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[clang][CodeGen] Keep processing the rest of AST after encountering unsupported MC/DC expressions (#82464)

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Currently, upon seeing unsupported decisions (more than 6 conditions, or
split nesting), the post-visitor hook dataTraverseStmtPost() returns a
false. As a result, in the rest of tree even supported decisions will
be skipped as well. Like in the below code:

{ // CompoundStmt
  a && b;           // 1: BinaryOperator (supported)
  a && foo(b && c); // 2: BinaryOperator (not yet supported due to split
                    //                    nesting)
  a && b;           // 3: BinaryOperator (supported)
}

Decision 3 will not be processed at all. And only one "Decision" region
will be emitted. Compiler explorer example:
https://godbolt.org/z/Px61sesoo

We hope to process such cases and emit two "Decision" regions (1 and 3)
in the above example.

(cherry picked from commit d4bfca3b2e673789f7c278d46a199ae8910ddd37)
This commit is contained in:
Wentao Zhang 2024-02-22 16:04:25 -06:00 committed by Tom Stellard
parent c8b11e9300
commit 9274829eb6
1 changed files with 7 additions and 4 deletions
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11
clang/lib/CodeGen/CodeGenPGO.cpp
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@ -240,9 +240,12 @@ struct MapRegionCounters : public RecursiveASTVisitor<MapRegionCounters> {
if (MCDCMaxCond == 0)
return true;
/// At the top of the logical operator nest, reset the number of conditions.
if (LogOpStack.empty())
/// At the top of the logical operator nest, reset the number of conditions,
/// also forget previously seen split nesting cases.
if (LogOpStack.empty()) {
NumCond = 0;
SplitNestedLogicalOp = false;
}
if (const Expr *E = dyn_cast<Expr>(S)) {
const BinaryOperator *BinOp = dyn_cast<BinaryOperator>(E->IgnoreParens());
@ -293,7 +296,7 @@ struct MapRegionCounters : public RecursiveASTVisitor<MapRegionCounters> {
"contains an operation with a nested boolean expression. "
"Expression will not be covered");
Diag.Report(S->getBeginLoc(), DiagID);
return false;
return true;
}
/// Was the maximum number of conditions encountered?
@ -304,7 +307,7 @@ struct MapRegionCounters : public RecursiveASTVisitor<MapRegionCounters> {
"number of conditions (%0) exceeds max (%1). "
"Expression will not be covered");
Diag.Report(S->getBeginLoc(), DiagID) << NumCond << MCDCMaxCond;
return false;
return true;
}
// Otherwise, allocate the number of bytes required for the bitmap