[llvm-branch-commits] [clang] [llvm] [openmp] [Clang][OpenMP] Add reverse directive (PR #92916)
via llvm-branch-commits
llvm-branch-commits at lists.llvm.org
Tue May 21 06:46:55 PDT 2024
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Michael Kruse (Meinersbur)
<details>
<summary>Changes</summary>
Add the reverse directive which will be introduced in the upcoming OpenMP 6.0 specification. A preview has been published in [Technical Report 12](https://www.openmp.org/wp-content/uploads/openmp-TR12.pdf).
This is the reverse directive part extracted out of #<!-- -->92030 which included reverse and interchange.
---
Patch is 144.58 KiB, truncated to 20.00 KiB below, full version: https://github.com/llvm/llvm-project/pull/92916.diff
30 Files Affected:
- (modified) clang/include/clang-c/Index.h (+4)
- (modified) clang/include/clang/AST/RecursiveASTVisitor.h (+3)
- (modified) clang/include/clang/AST/StmtOpenMP.h (+70-2)
- (modified) clang/include/clang/Basic/StmtNodes.td (+1)
- (modified) clang/include/clang/Sema/SemaOpenMP.h (+5)
- (modified) clang/include/clang/Serialization/ASTBitCodes.h (+1)
- (modified) clang/lib/AST/StmtOpenMP.cpp (+19)
- (modified) clang/lib/AST/StmtPrinter.cpp (+5)
- (modified) clang/lib/AST/StmtProfile.cpp (+4)
- (modified) clang/lib/Basic/OpenMPKinds.cpp (+2-1)
- (modified) clang/lib/CodeGen/CGStmt.cpp (+3)
- (modified) clang/lib/CodeGen/CGStmtOpenMP.cpp (+8)
- (modified) clang/lib/CodeGen/CodeGenFunction.h (+1)
- (modified) clang/lib/Parse/ParseOpenMP.cpp (+2)
- (modified) clang/lib/Sema/SemaExceptionSpec.cpp (+1)
- (modified) clang/lib/Sema/SemaOpenMP.cpp (+190)
- (modified) clang/lib/Sema/TreeTransform.h (+11)
- (modified) clang/lib/Serialization/ASTReaderStmt.cpp (+12)
- (modified) clang/lib/Serialization/ASTWriterStmt.cpp (+5)
- (added) clang/test/OpenMP/reverse_ast_print.cpp (+159)
- (added) clang/test/OpenMP/reverse_codegen.cpp (+1554)
- (added) clang/test/OpenMP/reverse_messages.cpp (+40)
- (modified) clang/tools/libclang/CIndex.cpp (+7)
- (modified) clang/tools/libclang/CXCursor.cpp (+3)
- (modified) llvm/include/llvm/Frontend/OpenMP/OMP.td (+3)
- (added) openmp/runtime/test/transform/reverse/foreach.cpp (+162)
- (added) openmp/runtime/test/transform/reverse/intfor.c (+25)
- (added) openmp/runtime/test/transform/reverse/iterfor.cpp (+164)
- (added) openmp/runtime/test/transform/reverse/parallel-wsloop-collapse-foreach.cpp (+285)
- (added) openmp/runtime/test/transform/reverse/parallel-wsloop-collapse-intfor.cpp (+51)
``````````diff
diff --git a/clang/include/clang-c/Index.h b/clang/include/clang-c/Index.h
index 365b607c74117..c7d63818ece23 100644
--- a/clang/include/clang-c/Index.h
+++ b/clang/include/clang-c/Index.h
@@ -2146,6 +2146,10 @@ enum CXCursorKind {
*/
CXCursor_OMPScopeDirective = 306,
+ /** OpenMP reverse directive.
+ */
+ CXCursor_OMPReverseDirective = 307,
+
/** OpenACC Compute Construct.
*/
CXCursor_OpenACCComputeConstruct = 320,
diff --git a/clang/include/clang/AST/RecursiveASTVisitor.h b/clang/include/clang/AST/RecursiveASTVisitor.h
index f5cefedb07e0e..06b29d59785f6 100644
--- a/clang/include/clang/AST/RecursiveASTVisitor.h
+++ b/clang/include/clang/AST/RecursiveASTVisitor.h
@@ -3021,6 +3021,9 @@ DEF_TRAVERSE_STMT(OMPTileDirective,
DEF_TRAVERSE_STMT(OMPUnrollDirective,
{ TRY_TO(TraverseOMPExecutableDirective(S)); })
+DEF_TRAVERSE_STMT(OMPReverseDirective,
+ { TRY_TO(TraverseOMPExecutableDirective(S)); })
+
DEF_TRAVERSE_STMT(OMPForDirective,
{ TRY_TO(TraverseOMPExecutableDirective(S)); })
diff --git a/clang/include/clang/AST/StmtOpenMP.h b/clang/include/clang/AST/StmtOpenMP.h
index f735fa5643aec..4be2e2d3a4605 100644
--- a/clang/include/clang/AST/StmtOpenMP.h
+++ b/clang/include/clang/AST/StmtOpenMP.h
@@ -1007,8 +1007,9 @@ class OMPLoopTransformationDirective : public OMPLoopBasedDirective {
Stmt *getPreInits() const;
static bool classof(const Stmt *T) {
- return T->getStmtClass() == OMPTileDirectiveClass ||
- T->getStmtClass() == OMPUnrollDirectiveClass;
+ Stmt::StmtClass C = T->getStmtClass();
+ return C == OMPTileDirectiveClass || C == OMPUnrollDirectiveClass ||
+ C == OMPReverseDirectiveClass;
}
};
@@ -5711,6 +5712,73 @@ class OMPUnrollDirective final : public OMPLoopTransformationDirective {
}
};
+/// Represents the '#pragma omp reverse' loop transformation directive.
+///
+/// \code
+/// #pragma omp reverse
+/// for (int i = 0; i < n; ++i)
+/// ...
+/// \endcode
+class OMPReverseDirective final : public OMPLoopTransformationDirective {
+ friend class ASTStmtReader;
+ friend class OMPExecutableDirective;
+
+ /// Offsets of child members.
+ enum {
+ PreInitsOffset = 0,
+ TransformedStmtOffset,
+ };
+
+ explicit OMPReverseDirective(SourceLocation StartLoc, SourceLocation EndLoc)
+ : OMPLoopTransformationDirective(OMPReverseDirectiveClass,
+ llvm::omp::OMPD_reverse, StartLoc,
+ EndLoc, 1) {}
+
+ void setPreInits(Stmt *PreInits) {
+ Data->getChildren()[PreInitsOffset] = PreInits;
+ }
+
+ void setTransformedStmt(Stmt *S) {
+ Data->getChildren()[TransformedStmtOffset] = S;
+ }
+
+public:
+ /// Create a new AST node representation for '#pragma omp reverse'.
+ ///
+ /// \param C Context of the AST.
+ /// \param StartLoc Location of the introducer (e.g. the 'omp' token).
+ /// \param EndLoc Location of the directive's end (e.g. the tok::eod).
+ /// \param Clauses The directive's clauses.
+ /// \param AssociatedStmt The outermost associated loop.
+ /// \param TransformedStmt The loop nest after tiling, or nullptr in
+ /// dependent contexts.
+ /// \param PreInits Helper preinits statements for the loop nest.
+ static OMPReverseDirective *
+ Create(const ASTContext &C, SourceLocation StartLoc, SourceLocation EndLoc,
+ ArrayRef<OMPClause *> Clauses, Stmt *AssociatedStmt,
+ Stmt *TransformedStmt, Stmt *PreInits);
+
+ /// Build an empty '#pragma omp reverse' AST node for deserialization.
+ ///
+ /// \param C Context of the AST.
+ /// \param NumClauses Number of clauses to allocate.
+ static OMPReverseDirective *CreateEmpty(const ASTContext &C,
+ unsigned NumClauses);
+
+ /// Gets/sets the associated loops after the transformation, i.e. after
+ /// de-sugaring.
+ Stmt *getTransformedStmt() const {
+ return Data->getChildren()[TransformedStmtOffset];
+ }
+
+ /// Return preinits statement.
+ Stmt *getPreInits() const { return Data->getChildren()[PreInitsOffset]; }
+
+ static bool classof(const Stmt *T) {
+ return T->getStmtClass() == OMPReverseDirectiveClass;
+ }
+};
+
/// This represents '#pragma omp scan' directive.
///
/// \code
diff --git a/clang/include/clang/Basic/StmtNodes.td b/clang/include/clang/Basic/StmtNodes.td
index 305f19daa4a92..b2e2be5c998bb 100644
--- a/clang/include/clang/Basic/StmtNodes.td
+++ b/clang/include/clang/Basic/StmtNodes.td
@@ -229,6 +229,7 @@ def OMPSimdDirective : StmtNode<OMPLoopDirective>;
def OMPLoopTransformationDirective : StmtNode<OMPLoopBasedDirective, 1>;
def OMPTileDirective : StmtNode<OMPLoopTransformationDirective>;
def OMPUnrollDirective : StmtNode<OMPLoopTransformationDirective>;
+def OMPReverseDirective : StmtNode<OMPLoopTransformationDirective>;
def OMPForDirective : StmtNode<OMPLoopDirective>;
def OMPForSimdDirective : StmtNode<OMPLoopDirective>;
def OMPSectionsDirective : StmtNode<OMPExecutableDirective>;
diff --git a/clang/include/clang/Sema/SemaOpenMP.h b/clang/include/clang/Sema/SemaOpenMP.h
index 51981e1c9a8b9..e36a90ba4e1b9 100644
--- a/clang/include/clang/Sema/SemaOpenMP.h
+++ b/clang/include/clang/Sema/SemaOpenMP.h
@@ -422,6 +422,11 @@ class SemaOpenMP : public SemaBase {
StmtResult ActOnOpenMPUnrollDirective(ArrayRef<OMPClause *> Clauses,
Stmt *AStmt, SourceLocation StartLoc,
SourceLocation EndLoc);
+ /// Called on well-formed '#pragma omp reverse' after parsing of its clauses
+ /// and the associated statement.
+ StmtResult ActOnOpenMPReverseDirective(ArrayRef<OMPClause *> Clauses,
+ Stmt *AStmt, SourceLocation StartLoc,
+ SourceLocation EndLoc);
/// Called on well-formed '\#pragma omp for' after parsing
/// of the associated statement.
StmtResult
diff --git a/clang/include/clang/Serialization/ASTBitCodes.h b/clang/include/clang/Serialization/ASTBitCodes.h
index fe1bd47348be1..dee0d073557cc 100644
--- a/clang/include/clang/Serialization/ASTBitCodes.h
+++ b/clang/include/clang/Serialization/ASTBitCodes.h
@@ -1856,6 +1856,7 @@ enum StmtCode {
STMT_OMP_SIMD_DIRECTIVE,
STMT_OMP_TILE_DIRECTIVE,
STMT_OMP_UNROLL_DIRECTIVE,
+ STMT_OMP_REVERSE_DIRECTIVE,
STMT_OMP_FOR_DIRECTIVE,
STMT_OMP_FOR_SIMD_DIRECTIVE,
STMT_OMP_SECTIONS_DIRECTIVE,
diff --git a/clang/lib/AST/StmtOpenMP.cpp b/clang/lib/AST/StmtOpenMP.cpp
index d8519b2071e6d..0be0d9d2cfa94 100644
--- a/clang/lib/AST/StmtOpenMP.cpp
+++ b/clang/lib/AST/StmtOpenMP.cpp
@@ -449,6 +449,25 @@ OMPUnrollDirective *OMPUnrollDirective::CreateEmpty(const ASTContext &C,
SourceLocation(), SourceLocation());
}
+OMPReverseDirective *
+OMPReverseDirective::Create(const ASTContext &C, SourceLocation StartLoc,
+ SourceLocation EndLoc,
+ ArrayRef<OMPClause *> Clauses, Stmt *AssociatedStmt,
+ Stmt *TransformedStmt, Stmt *PreInits) {
+ OMPReverseDirective *Dir = createDirective<OMPReverseDirective>(
+ C, Clauses, AssociatedStmt, TransformedStmtOffset + 1, StartLoc, EndLoc);
+ Dir->setTransformedStmt(TransformedStmt);
+ Dir->setPreInits(PreInits);
+ return Dir;
+}
+
+OMPReverseDirective *OMPReverseDirective::CreateEmpty(const ASTContext &C,
+ unsigned NumClauses) {
+ return createEmptyDirective<OMPReverseDirective>(
+ C, NumClauses, /*HasAssociatedStmt=*/true, TransformedStmtOffset + 1,
+ SourceLocation(), SourceLocation());
+}
+
OMPForSimdDirective *
OMPForSimdDirective::Create(const ASTContext &C, SourceLocation StartLoc,
SourceLocation EndLoc, unsigned CollapsedNum,
diff --git a/clang/lib/AST/StmtPrinter.cpp b/clang/lib/AST/StmtPrinter.cpp
index be2d5a2eb6b46..64b481f680311 100644
--- a/clang/lib/AST/StmtPrinter.cpp
+++ b/clang/lib/AST/StmtPrinter.cpp
@@ -763,6 +763,11 @@ void StmtPrinter::VisitOMPUnrollDirective(OMPUnrollDirective *Node) {
PrintOMPExecutableDirective(Node);
}
+void StmtPrinter::VisitOMPReverseDirective(OMPReverseDirective *Node) {
+ Indent() << "#pragma omp reverse";
+ PrintOMPExecutableDirective(Node);
+}
+
void StmtPrinter::VisitOMPForDirective(OMPForDirective *Node) {
Indent() << "#pragma omp for";
PrintOMPExecutableDirective(Node);
diff --git a/clang/lib/AST/StmtProfile.cpp b/clang/lib/AST/StmtProfile.cpp
index caab4ab0ef160..f0e1c9548de72 100644
--- a/clang/lib/AST/StmtProfile.cpp
+++ b/clang/lib/AST/StmtProfile.cpp
@@ -985,6 +985,10 @@ void StmtProfiler::VisitOMPUnrollDirective(const OMPUnrollDirective *S) {
VisitOMPLoopTransformationDirective(S);
}
+void StmtProfiler::VisitOMPReverseDirective(const OMPReverseDirective *S) {
+ VisitOMPLoopTransformationDirective(S);
+}
+
void StmtProfiler::VisitOMPForDirective(const OMPForDirective *S) {
VisitOMPLoopDirective(S);
}
diff --git a/clang/lib/Basic/OpenMPKinds.cpp b/clang/lib/Basic/OpenMPKinds.cpp
index b3e9affbb3e58..803808c38e2fe 100644
--- a/clang/lib/Basic/OpenMPKinds.cpp
+++ b/clang/lib/Basic/OpenMPKinds.cpp
@@ -684,7 +684,7 @@ bool clang::isOpenMPLoopBoundSharingDirective(OpenMPDirectiveKind Kind) {
}
bool clang::isOpenMPLoopTransformationDirective(OpenMPDirectiveKind DKind) {
- return DKind == OMPD_tile || DKind == OMPD_unroll;
+ return DKind == OMPD_tile || DKind == OMPD_unroll || DKind == OMPD_reverse;
}
bool clang::isOpenMPCombinedParallelADirective(OpenMPDirectiveKind DKind) {
@@ -808,6 +808,7 @@ void clang::getOpenMPCaptureRegions(
break;
case OMPD_tile:
case OMPD_unroll:
+ case OMPD_reverse:
// loop transformations do not introduce captures.
break;
case OMPD_threadprivate:
diff --git a/clang/lib/CodeGen/CGStmt.cpp b/clang/lib/CodeGen/CGStmt.cpp
index 99daaa14cf3fe..93c2f8900dd12 100644
--- a/clang/lib/CodeGen/CGStmt.cpp
+++ b/clang/lib/CodeGen/CGStmt.cpp
@@ -222,6 +222,9 @@ void CodeGenFunction::EmitStmt(const Stmt *S, ArrayRef<const Attr *> Attrs) {
case Stmt::OMPUnrollDirectiveClass:
EmitOMPUnrollDirective(cast<OMPUnrollDirective>(*S));
break;
+ case Stmt::OMPReverseDirectiveClass:
+ EmitOMPReverseDirective(cast<OMPReverseDirective>(*S));
+ break;
case Stmt::OMPForDirectiveClass:
EmitOMPForDirective(cast<OMPForDirective>(*S));
break;
diff --git a/clang/lib/CodeGen/CGStmtOpenMP.cpp b/clang/lib/CodeGen/CGStmtOpenMP.cpp
index 6410f9e102c90..ad6c044aa483b 100644
--- a/clang/lib/CodeGen/CGStmtOpenMP.cpp
+++ b/clang/lib/CodeGen/CGStmtOpenMP.cpp
@@ -187,6 +187,8 @@ class OMPLoopScope : public CodeGenFunction::RunCleanupsScope {
PreInits = Tile->getPreInits();
} else if (const auto *Unroll = dyn_cast<OMPUnrollDirective>(&S)) {
PreInits = Unroll->getPreInits();
+ } else if (const auto *Reverse = dyn_cast<OMPReverseDirective>(&S)) {
+ PreInits = Reverse->getPreInits();
} else {
llvm_unreachable("Unknown loop-based directive kind.");
}
@@ -2762,6 +2764,12 @@ void CodeGenFunction::EmitOMPTileDirective(const OMPTileDirective &S) {
EmitStmt(S.getTransformedStmt());
}
+void CodeGenFunction::EmitOMPReverseDirective(const OMPReverseDirective &S) {
+ // Emit the de-sugared statement.
+ OMPTransformDirectiveScopeRAII ReverseScope(*this, &S);
+ EmitStmt(S.getTransformedStmt());
+}
+
void CodeGenFunction::EmitOMPUnrollDirective(const OMPUnrollDirective &S) {
bool UseOMPIRBuilder = CGM.getLangOpts().OpenMPIRBuilder;
diff --git a/clang/lib/CodeGen/CodeGenFunction.h b/clang/lib/CodeGen/CodeGenFunction.h
index 5f3ee7eb943f9..ac738e1e82886 100644
--- a/clang/lib/CodeGen/CodeGenFunction.h
+++ b/clang/lib/CodeGen/CodeGenFunction.h
@@ -3807,6 +3807,7 @@ class CodeGenFunction : public CodeGenTypeCache {
void EmitOMPSimdDirective(const OMPSimdDirective &S);
void EmitOMPTileDirective(const OMPTileDirective &S);
void EmitOMPUnrollDirective(const OMPUnrollDirective &S);
+ void EmitOMPReverseDirective(const OMPReverseDirective &S);
void EmitOMPForDirective(const OMPForDirective &S);
void EmitOMPForSimdDirective(const OMPForSimdDirective &S);
void EmitOMPSectionsDirective(const OMPSectionsDirective &S);
diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index e959dd6378f46..57fcf6ce520ac 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -2384,6 +2384,7 @@ Parser::DeclGroupPtrTy Parser::ParseOpenMPDeclarativeDirectiveWithExtDecl(
case OMPD_simd:
case OMPD_tile:
case OMPD_unroll:
+ case OMPD_reverse:
case OMPD_task:
case OMPD_taskyield:
case OMPD_barrier:
@@ -2802,6 +2803,7 @@ StmtResult Parser::ParseOpenMPDeclarativeOrExecutableDirective(
case OMPD_simd:
case OMPD_tile:
case OMPD_unroll:
+ case OMPD_reverse:
case OMPD_for:
case OMPD_for_simd:
case OMPD_sections:
diff --git a/clang/lib/Sema/SemaExceptionSpec.cpp b/clang/lib/Sema/SemaExceptionSpec.cpp
index 41bf273d12f2f..4de7183cde281 100644
--- a/clang/lib/Sema/SemaExceptionSpec.cpp
+++ b/clang/lib/Sema/SemaExceptionSpec.cpp
@@ -1486,6 +1486,7 @@ CanThrowResult Sema::canThrow(const Stmt *S) {
case Stmt::OMPSimdDirectiveClass:
case Stmt::OMPTileDirectiveClass:
case Stmt::OMPUnrollDirectiveClass:
+ case Stmt::OMPReverseDirectiveClass:
case Stmt::OMPSingleDirectiveClass:
case Stmt::OMPTargetDataDirectiveClass:
case Stmt::OMPTargetDirectiveClass:
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index 663dbb927250e..7b9898704eb1c 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -4334,6 +4334,7 @@ void SemaOpenMP::ActOnOpenMPRegionStart(OpenMPDirectiveKind DKind,
case OMPD_masked:
case OMPD_tile:
case OMPD_unroll:
+ case OMPD_reverse:
break;
case OMPD_loop:
// TODO: 'loop' may require additional parameters depending on the binding.
@@ -6546,6 +6547,10 @@ StmtResult SemaOpenMP::ActOnOpenMPExecutableDirective(
Res = ActOnOpenMPUnrollDirective(ClausesWithImplicit, AStmt, StartLoc,
EndLoc);
break;
+ case OMPD_reverse:
+ Res = ActOnOpenMPReverseDirective(ClausesWithImplicit, AStmt, StartLoc,
+ EndLoc);
+ break;
case OMPD_for:
Res = ActOnOpenMPForDirective(ClausesWithImplicit, AStmt, StartLoc, EndLoc,
VarsWithInheritedDSA);
@@ -15121,6 +15126,8 @@ bool SemaOpenMP::checkTransformableLoopNest(
DependentPreInits = Dir->getPreInits();
else if (auto *Dir = dyn_cast<OMPUnrollDirective>(Transform))
DependentPreInits = Dir->getPreInits();
+ else if (auto *Dir = dyn_cast<OMPReverseDirective>(Transform))
+ DependentPreInits = Dir->getPreInits();
else
llvm_unreachable("Unhandled loop transformation");
if (!DependentPreInits)
@@ -15746,6 +15753,189 @@ StmtResult SemaOpenMP::ActOnOpenMPUnrollDirective(ArrayRef<OMPClause *> Clauses,
buildPreInits(Context, PreInits));
}
+StmtResult
+SemaOpenMP::ActOnOpenMPReverseDirective(ArrayRef<OMPClause *> Clauses,
+ Stmt *AStmt, SourceLocation StartLoc,
+ SourceLocation EndLoc) {
+ ASTContext &Context = getASTContext();
+ Scope *CurScope = SemaRef.getCurScope();
+ assert(Clauses.empty() && "reverse directive does not accept any clauses; "
+ "must have beed checked before");
+
+ // Empty statement should only be possible if there already was an error.
+ if (!AStmt)
+ return StmtError();
+
+ constexpr unsigned NumLoops = 1;
+ Stmt *Body = nullptr;
+ SmallVector<OMPLoopBasedDirective::HelperExprs, NumLoops> LoopHelpers(
+ NumLoops);
+ SmallVector<SmallVector<Stmt *, 0>, NumLoops + 1> OriginalInits;
+ if (!checkTransformableLoopNest(OMPD_reverse, AStmt, NumLoops, LoopHelpers,
+ Body, OriginalInits))
+ return StmtError();
+
+ // Delay applying the transformation to when template is completely
+ // instantiated.
+ if (SemaRef.CurContext->isDependentContext())
+ return OMPReverseDirective::Create(Context, StartLoc, EndLoc, Clauses,
+ AStmt, nullptr, nullptr);
+
+ assert(LoopHelpers.size() == NumLoops &&
+ "Expecting a single-dimensional loop iteration space");
+ assert(OriginalInits.size() == NumLoops &&
+ "Expecting a single-dimensional loop iteration space");
+ OMPLoopBasedDirective::HelperExprs &LoopHelper = LoopHelpers.front();
+
+ // Find the loop statement.
+ Stmt *LoopStmt = nullptr;
+ collectLoopStmts(AStmt, {LoopStmt});
+
+ // Determine the PreInit declarations.
+ SmallVector<Stmt *> PreInits;
+ addLoopPreInits(Context, LoopHelper, LoopStmt, OriginalInits[0], PreInits);
+
+ auto *IterationVarRef = cast<DeclRefExpr>(LoopHelper.IterationVarRef);
+ QualType IVTy = IterationVarRef->getType();
+ uint64_t IVWidth = Context.getTypeSize(IVTy);
+ auto *OrigVar = cast<DeclRefExpr>(LoopHelper.Counters.front());
+
+ // Iteration variable SourceLocations.
+ SourceLocation OrigVarLoc = OrigVar->getExprLoc();
+ SourceLocation OrigVarLocBegin = OrigVar->getBeginLoc();
+ SourceLocation OrigVarLocEnd = OrigVar->getEndLoc();
+
+ // Locations pointing to the transformation.
+ SourceLocation TransformLoc = StartLoc;
+ SourceLocation TransformLocBegin = StartLoc;
+ SourceLocation TransformLocEnd = EndLoc;
+
+ // Internal variable names.
+ std::string OrigVarName = OrigVar->getNameInfo().getAsString();
+ std::string TripCountName = (Twine(".tripcount.") + OrigVarName).str();
+ std::string ForwardIVName = (Twine(".forward.iv.") + OrigVarName).str();
+ std::string ReversedIVName = (Twine(".reversed.iv.") + OrigVarName).str();
+
+ // LoopHelper.Updates will read the logical iteration number from
+ // LoopHelper.IterationVarRef, compute the value of the user loop counter of
+ // that logical iteration from it, then assign it to the user loop counter
+ // variable. We cannot directly use LoopHelper.IterationVarRef as the
+ // induction variable of the generated loop because it may cause an underflow:
+ // \code
+ // for (unsigned i = 0; i < n; ++i)
+ // body(i);
+ // \endcode
+ //
+ // Naive reversal:
+ // \code
+ // for (unsigned i = n-1; i >= 0; --i)
+ // body(i);
+ // \endcode
+ //
+ // Instead, we introduce a new iteration variable representing the logical
+ // iteration counter of the original loop, convert it to the logical iteration
+ // number of the reversed loop, then let LoopHelper.Updates compute the user's
+ // loop iteration variable from it.
+ // \code
+ // for (auto .forward.iv = 0; .forward.iv < n; ++.forward.iv) {
+ // auto .reversed.iv = n - .forward.iv - 1;
+ // i = (.reversed.iv + 0) * 1; // LoopHelper.Updates
+ // body(i); // Body
+ // }
+ // \endcode
+
+ // Subexpressions with more than one use. One of the constraints of an AST is
+ // that every node object must appear at most once, hence we define a lambda
+ // that creates a new AST node at every use.
+ CaptureVars CopyTransformer(SemaRef);
+ auto MakeNumIterations = [&CopyTransformer, &LoopHelper]() -> Expr * {
+ return AssertSuccess(
+ CopyTransformer.TransformExpr(LoopHelper.NumIterations));
+ };
+
+ // Create the iteration variable for the forward loop (from 0 to n-1).
+ VarDecl *ForwardIVDecl =
+ buildVarDecl(SemaRef, {}, IVTy, ForwardIVName, nullptr, OrigVar);
+ auto MakeForwardRef = [&SemaRef = this->SemaRef, ForwardIVDecl, IVTy,
+ OrigVarLoc]() {
+ return buildDeclRefExpr(SemaRef, ForwardIVDecl, IVTy, OrigVarLoc);
+ };
+
+ // Iteration variable for the reversed induction variable (from n-1 downto 0):
+ // Reuse the iteration variable created by checkOpenMPLoop.
+ auto *ReversedIVDecl = cast<VarDecl>(IterationVarRef->getDecl());
+ ReversedIVDecl->setDeclName(
+ &SemaRef.PP.getIdentifierTable().get(ReversedIVName));
+
+ // For init-statement:
+ // \code
+ // auto .forward.iv = 0
+ // \endcode
+ IntegerLiteral *Zero =
+ IntegerLiteral::Create(Context, llvm::APInt::getZero(IVWi...
[truncated]
``````````
</details>
https://github.com/llvm/llvm-project/pull/92916
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