[OpenMP] Show error if VLAs are not supported

Some target devices (e.g. Nvidia GPUs) don't support dynamic stack
allocation and hence no VLAs. Print errors with description instead
of failing in the backend or generating code that doesn't work.

This patch handles explicit uses of VLAs (local variable in target
or declare target region) or implicitly generated (private) VLAs
for reductions on VLAs or on array sections with non-constant size.

Differential Revision: https://reviews.llvm.org/D39505

llvm-svn: 318601

2 files changed, 2 insertions, 0 deletions

diff --git a/clang/lib/Basic/Targets/NVPTX.cpp b/clang/lib/Basic/Targets/NVPTX.cpp
index 3889f097350..add3b318aeb 100644
--- a/clang/lib/Basic/Targets/NVPTX.cpp
+++ b/clang/lib/Basic/Targets/NVPTX.cpp
@@ -41,6 +41,7 @@ NVPTXTargetInfo::NVPTXTargetInfo(const llvm::Triple &Triple,
          "NVPTX only supports 32- and 64-bit modes.");
 
   TLSSupported = false;
+  VLASupported = false;
   AddrSpaceMap = &NVPTXAddrSpaceMap;
   UseAddrSpaceMapMangling = true;
 
diff --git a/clang/lib/Basic/Targets/SPIR.h b/clang/lib/Basic/Targets/SPIR.h
index e64ad548290..c384d4260ca 100644
--- a/clang/lib/Basic/Targets/SPIR.h
+++ b/clang/lib/Basic/Targets/SPIR.h
@@ -43,6 +43,7 @@ public:
     assert(getTriple().getEnvironment() == llvm::Triple::UnknownEnvironment &&
            "SPIR target must use unknown environment type");
     TLSSupported = false;
+    VLASupported = false;
     LongWidth = LongAlign = 64;
     AddrSpaceMap = &SPIRAddrSpaceMap;
     UseAddrSpaceMapMangling = true;