[flang-commits] [flang] 9b1915c - [flang] Allow compiler directives for collapsed loops in OpenACC

[Daniil Dudkin via flang-commits]

Author: Daniil Dudkin
Date: 2022-08-29T18:17:56+03:00
New Revision: 9b1915cd0a52e785b29021dc3329265345d2b068

URL: https://github.com/llvm/llvm-project/commit/9b1915cd0a52e785b29021dc3329265345d2b068
DIFF: https://github.com/llvm/llvm-project/commit/9b1915cd0a52e785b29021dc3329265345d2b068.diff

LOG: [flang] Allow compiler directives for collapsed loops in OpenACC

If one tries to compile the attached test case code with flan,
the one will get an internal compiler error on `CHECK(level == 0)`
at the end of `PrivatizeAssociatedLoopIndex` function.
Other compilers (gfortran and nvfortran) build this code just fine.
This change fixes the ICE.

Reviewed By: clementval

Differential Revision: https://reviews.llvm.org/D132846

Added: 
    flang/test/Semantics/OpenACC/acc-resolve03.f90

Modified: 
    flang/lib/Semantics/resolve-directives.cpp

Removed: 
    


################################################################################
diff  --git a/flang/lib/Semantics/resolve-directives.cpp b/flang/lib/Semantics/resolve-directives.cpp
index 5926dd0c5d149..5f34061e9a3b6 100644
--- a/flang/lib/Semantics/resolve-directives.cpp
+++ b/flang/lib/Semantics/resolve-directives.cpp
@@ -868,6 +868,21 @@ void AccAttributeVisitor::PrivatizeAssociatedLoopIndex(
   }
   Symbol::Flag ivDSA{Symbol::Flag::AccPrivate};
 
+  const auto getNextDoConstruct =
+      [this](const parser::Block &block) -> const parser::DoConstruct * {
+    for (const auto &entry : block) {
+      if (const auto *doConstruct = GetDoConstructIf(entry)) {
+        return doConstruct;
+      } else if (parser::Unwrap<parser::CompilerDirective>(entry)) {
+        // It is allowed to have a compiler directive associated with the loop.
+        continue;
+      } else {
+        break;
+      }
+    }
+    return nullptr;
+  };
+
   const auto &outer{std::get<std::optional<parser::DoConstruct>>(x.t)};
   for (const parser::DoConstruct *loop{&*outer}; loop && level > 0; --level) {
     // go through all the nested do-loops and resolve index variables
@@ -879,8 +894,7 @@ void AccAttributeVisitor::PrivatizeAssociatedLoopIndex(
     }
 
     const auto &block{std::get<parser::Block>(loop->t)};
-    const auto it{block.begin()};
-    loop = it != block.end() ? GetDoConstructIf(*it) : nullptr;
+    loop = getNextDoConstruct(block);
   }
   CHECK(level == 0);
 }

diff  --git a/flang/test/Semantics/OpenACC/acc-resolve03.f90 b/flang/test/Semantics/OpenACC/acc-resolve03.f90
new file mode 100644
index 0000000000000..341e9d2ce68b2
--- /dev/null
+++ b/flang/test/Semantics/OpenACC/acc-resolve03.f90
@@ -0,0 +1,21 @@
+! RUN: %flang_fc1 -fopenacc %s
+! A regression test to check that
+! arbitrary compiler directives do not generate errors
+! inside OpenACC collapsed loops
+subroutine foo
+  integer, parameter :: loop_bound = 42
+  integer :: a
+  integer :: b
+  integer :: c
+
+  !$acc parallel
+  do a = 0, loop_bound
+    !$acc loop collapse(2)
+    do b = 0, loop_bound
+      !dir$ ivdep
+      do c = 0, loop_bound
+      enddo
+    enddo
+  enddo
+  !$acc end parallel
+end subroutine foo