[PATCH] D130791: [clang] Short-circuit trivial constexpr array constructors
Timm Bäder via Phabricator via cfe-commits
cfe-commits at lists.llvm.org
Mon Aug 1 21:57:08 PDT 2022
tbaeder updated this revision to Diff 449182.
CHANGES SINCE LAST ACTION
https://reviews.llvm.org/D130791/new/
https://reviews.llvm.org/D130791
Files:
clang/docs/ReleaseNotes.rst
clang/lib/AST/ExprConstant.cpp
Index: clang/lib/AST/ExprConstant.cpp
===================================================================
--- clang/lib/AST/ExprConstant.cpp
+++ clang/lib/AST/ExprConstant.cpp
@@ -10833,6 +10833,9 @@
if (FinalSize == 0)
return true;
+ bool HasTrivialConstructor = CheckTrivialDefaultConstructor(
+ Info, E->getExprLoc(), E->getConstructor(),
+ E->requiresZeroInitialization());
LValue ArrayElt = Subobject;
ArrayElt.addArray(Info, E, CAT);
// We do the whole initialization in two passes, first for just one element,
@@ -10856,19 +10859,26 @@
for (unsigned I = OldElts; I < N; ++I)
Value->getArrayInitializedElt(I) = Filler;
- // Initialize the elements.
- for (unsigned I = OldElts; I < N; ++I) {
- if (!VisitCXXConstructExpr(E, ArrayElt,
- &Value->getArrayInitializedElt(I),
- CAT->getElementType()) ||
- !HandleLValueArrayAdjustment(Info, E, ArrayElt,
- CAT->getElementType(), 1))
- return false;
- // When checking for const initilization any diagnostic is considered
- // an error.
- if (Info.EvalStatus.Diag && !Info.EvalStatus.Diag->empty() &&
- !Info.keepEvaluatingAfterFailure())
- return false;
+ if (HasTrivialConstructor && N == FinalSize) {
+ // If we have a trivial constructor, only evaluate it once and copy
+ // the result into all the array elements.
+ APValue &FirstResult = Value->getArrayInitializedElt(0);
+ for (unsigned I = OldElts; I < FinalSize; ++I)
+ Value->getArrayInitializedElt(I) = FirstResult;
+ } else {
+ for (unsigned I = OldElts; I < N; ++I) {
+ if (!VisitCXXConstructExpr(E, ArrayElt,
+ &Value->getArrayInitializedElt(I),
+ CAT->getElementType()) ||
+ !HandleLValueArrayAdjustment(Info, E, ArrayElt,
+ CAT->getElementType(), 1))
+ return false;
+ // When checking for const initilization any diagnostic is considered
+ // an error.
+ if (Info.EvalStatus.Diag && !Info.EvalStatus.Diag->empty() &&
+ !Info.keepEvaluatingAfterFailure())
+ return false;
+ }
}
}
Index: clang/docs/ReleaseNotes.rst
===================================================================
--- clang/docs/ReleaseNotes.rst
+++ clang/docs/ReleaseNotes.rst
@@ -55,6 +55,9 @@
- Fixes an accepts-invalid bug in C when using a ``_Noreturn`` function
specifier on something other than a function declaration. This fixes
`Issue 56800 <https://github.com/llvm/llvm-project/issues/56800>`_.
+- Improve compile-times with large dynamic array allocations with trivial
+ constructors. This fixes
+ `Issue 56774<https://github.com/llvm/llvm-project/issues/56774>`_.
Improvements to Clang's diagnostics
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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