[clang] [llvm] [OpenMP] Missing implicit otherwise clause in metadirective. (PR #127113)
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Fri Feb 14 04:30:52 PST 2025
llvmbot wrote:
<!--LLVM PR SUMMARY COMMENT-->
@llvm/pr-subscribers-clang
Author: Zahira Ammarguellat (zahiraam)
<details>
<summary>Changes</summary>
Compiling this:
`int main() {`
` #pragma omp metadirective when(use r= {condition(0)}`
`: parallel for)`
`for (int i=0; i<10; i++)`
;
}`
is generating an error:
`error: expected expression`
The compiler is interpreting this as if it's compiling a `#pragma omp metadirective` with no `otherwise` clause.
In the OMP5.2 specs chapter 7.4 it's mentioned that:
`If no otherwise clause is specified the effect is as if one was specified without an associated directive variant.`
This patch fixes the issue.
---
Full diff: https://github.com/llvm/llvm-project/pull/127113.diff
4 Files Affected:
- (modified) clang/lib/Parse/ParseOpenMP.cpp (+6)
- (modified) clang/test/OpenMP/metadirective_ast_print.c (+18)
- (added) clang/test/OpenMP/metadirective_otherwise.cpp (+72)
- (modified) llvm/include/llvm/Frontend/OpenMP/OMPContext.h (+1-1)
``````````diff
diff --git a/clang/lib/Parse/ParseOpenMP.cpp b/clang/lib/Parse/ParseOpenMP.cpp
index a455659ca8f2c..0f68d4002ad8e 100644
--- a/clang/lib/Parse/ParseOpenMP.cpp
+++ b/clang/lib/Parse/ParseOpenMP.cpp
@@ -2882,6 +2882,12 @@ StmtResult Parser::ParseOpenMPDeclarativeOrExecutableDirective(
/*ReadDirectiveWithinMetadirective=*/true);
break;
}
+ // If no match is found and no otherwise clause is present, skip
+ // OMP5.2 Chapter 7.4: If no otherwise clause is specified the effect is as
+ // if one was specified without an associated directive variant.
+ if (BestIdx == -1 && Idx == 1) {
+ SkipUntil(tok::annot_pragma_openmp_end);
+ }
break;
}
case OMPD_threadprivate: {
diff --git a/clang/test/OpenMP/metadirective_ast_print.c b/clang/test/OpenMP/metadirective_ast_print.c
index d9ff7e7645216..06991c6f06a02 100644
--- a/clang/test/OpenMP/metadirective_ast_print.c
+++ b/clang/test/OpenMP/metadirective_ast_print.c
@@ -77,6 +77,24 @@ void foo(void) {
: parallel) default(nothing)
for (int i = 0; i < 16; i++)
;
+
+#pragma omp metadirective when(user = {condition(0)} \
+ : parallel for) otherwise()
+ for (int i=0; i<10; i++)
+ ;
+#pragma omp metadirective when(user = {condition(0)} \
+ : parallel for)
+ for (int i=0; i<10; i++)
+ ;
+
+#pragma omp metadirective when(user = {condition(1)} \
+ : parallel for) otherwise()
+ for (int i=0; i<10; i++)
+ ;
+#pragma omp metadirective when(user = {condition(1)} \
+ : parallel for)
+ for (int i=0; i<10; i++)
+ ;
}
// CHECK: void bar(void);
diff --git a/clang/test/OpenMP/metadirective_otherwise.cpp b/clang/test/OpenMP/metadirective_otherwise.cpp
new file mode 100644
index 0000000000000..50c9fe8a2b0e7
--- /dev/null
+++ b/clang/test/OpenMP/metadirective_otherwise.cpp
@@ -0,0 +1,72 @@
+// RUN: %clang_cc1 -verify -fopenmp -x c++ -triple x86_64-unknown-linux -emit-llvm %s -o - | FileCheck %s
+// expected-no-diagnostics
+
+#ifndef HEADER
+#define HEADER
+
+void func1() {
+#pragma omp metadirective when(user = {condition(0)} \
+ : parallel for) otherwise()
+ for (int i = 0; i < 100; i++)
+ ;
+
+#pragma omp metadirective when(user = {condition(0)} \
+ : parallel for)
+ for (int i = 0; i < 100; i++)
+ ;
+}
+
+// CHECK-LABEL: define dso_local void @_Z5func1v()
+// CHECK: entry
+// CHECK-NEXT: [[I:%.*]] = alloca i32, align 4
+// CHECK-NEXT: [[I1:%.*]] = alloca i32, align 4
+// CHECK-NEXT: store i32 0, ptr [[I]], align 4
+// CHECK-NEXT: br label %[[FOR_COND:.*]]
+// CHECK: [[FOR_COND]]:
+// CHECK-NEXT: [[TMP0:%.*]] = load i32, ptr [[I]], align 4
+// CHECK-NEXT: [[CMP:%.*]] = icmp slt i32 [[TMP0]], 100
+// CHECK-NEXT: br i1 [[CMP]], label %[[FOR_BODY:.*]], label %[[FOR_END:.*]]
+// CHECK: [[FOR_BODY]]:
+// CHECK-NEXT: br label %[[FOR_INC:.*]]
+// CHECK: [[FOR_INC]]:
+// CHECK-NEXT: [[TMP1:%.*]] = load i32, ptr [[I]], align 4
+// CHECK-NEXT: [[INC:%.*]] = add nsw i32 [[TMP1]], 1
+// CHECK-NEXT: store i32 [[INC]], ptr [[I]], align 4
+// CHECK-NEXT: br label %[[FOR_COND]], !llvm.loop [[LOOP3:![0-9]+]]
+// CHECK: [[FOR_END]]:
+// CHECK-NEXT: store i32 0, ptr [[I1]], align 4
+// CHECK-NEXT: br label %[[FOR_COND2:.*]]
+// CHECK: [[FOR_COND2]]:
+// CHECK-NEXT: [[TMP2:%.*]] = load i32, ptr [[I1]], align 4
+// CHECK-NEXT: [[CMP3:%.*]] = icmp slt i32 [[TMP2]], 100
+// CHECK-NEXT: br i1 [[CMP3]], label %[[FOR_BODY4:.*]], label %[[FOR_END7:.*]]
+// CHECK: [[FOR_BODY4]]:
+// CHECK-NEXT: br label %[[FOR_INC5:.*]]
+// CHECK: [[FOR_INC5]]:
+// CHECK-NEXT: [[TMP3:%.*]] = load i32, ptr [[I1]], align 4
+// CHECK-NEXT: [[INC6:%.*]] = add nsw i32 [[TMP3]], 1
+// CHECK-NEXT: store i32 [[INC6]], ptr [[I1]], align 4
+// CHECK-NEXT: br label %[[FOR_COND2]], !llvm.loop [[LOOP5:![0-9]+]]
+// CHECK: [[FOR_END7]]:
+// CHECK-NEXT: ret void
+
+void func2() {
+#pragma omp metadirective when(user = {condition(1)} \
+ : parallel for) otherwise()
+ for (int i = 0; i < 100; i++)
+ ;
+
+#pragma omp metadirective when(user = {condition(1)} \
+ : parallel for)
+ for (int i = 0; i < 100; i++)
+ ;
+}
+
+// CHECK-LABEL: define dso_local void @_Z5func2v()
+// CHECK: entry
+// CHECK-NEXT: call void (ptr, i32, ptr, ...) @__kmpc_fork_call(ptr @[[GLOB2:[0-9]+]], i32 0, ptr @_Z5func2v.omp_outlined)
+// CHECK-NEXT: call void (ptr, i32, ptr, ...) @__kmpc_fork_call(ptr @[[GLOB2]], i32 0, ptr @_Z5func2v.omp_outlined.1)
+// CHECK-NEXT: ret void
+
+
+#endif
diff --git a/llvm/include/llvm/Frontend/OpenMP/OMPContext.h b/llvm/include/llvm/Frontend/OpenMP/OMPContext.h
index a501eaf2356ff..26163fdb4b63d 100644
--- a/llvm/include/llvm/Frontend/OpenMP/OMPContext.h
+++ b/llvm/include/llvm/Frontend/OpenMP/OMPContext.h
@@ -188,7 +188,7 @@ bool isVariantApplicableInContext(const VariantMatchInfo &VMI,
bool DeviceSetOnly = false);
/// Return the index (into \p VMIs) of the variant with the highest score
-/// from the ones applicble in \p Ctx. See llvm::isVariantApplicableInContext.
+/// from the ones applicable in \p Ctx. See llvm::isVariantApplicableInContext.
int getBestVariantMatchForContext(const SmallVectorImpl<VariantMatchInfo> &VMIs,
const OMPContext &Ctx);
``````````
</details>
https://github.com/llvm/llvm-project/pull/127113
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