[llvm] include GenericLoopInfoImpl for full implementation

[andrurogerz]

MSVC issues a warning when a an extern template instantiation is annotated for DLL export but it does not have the complete template definition. Because the full implementation of LoopBase is in GenericLoopInfoImpl.h rather than GenericLoopInfo.h, MSVC complains whenever LoopInfo.h is included.

S:\llvm\llvm-project\llvm\include\llvm/Support/GenericLoopInfo.h(342): warning C4661: 'BlockT *llvm::LoopBase<BlockT,llvm::Loop>::getLoopLatch(void) const': no suitable definition provided for explicit template instantiation request
        with
        [
            BlockT=llvm::BasicBlock
        ]
S:\llvm\llvm-project\llvm\include\llvm/Support/GenericLoopInfo.h(326): note: see declaration of 'llvm::LoopBase<llvm::BasicBlock,llvm::Loop>::getLoopLatch'

Everything links fine but the warning is very noisy when building LLVM as a Windows DLL. Interestingly, clang-cl does not warn here and is fine with the code as-is.

[llvmbot]

@llvm/pr-subscribers-llvm-analysis

Author: Andrew Rogers (andrurogerz)

Changes

MSVC issues a warning when a an extern template instantiation is annotated for DLL export but it does not have the complete template definition. Because the full implementation of LoopBase is in GenericLoopInfoImpl.h rather than GenericLoopInfo.h, MSVC complains whenever LoopInfo.h is included.

S:\llvm\llvm-project\llvm\include\llvm/Support/GenericLoopInfo.h(342): warning C4661: 'BlockT *llvm::LoopBase<BlockT,llvm::Loop>::getLoopLatch(void) const': no suitable definition provided for explicit template instantiation request
        with
        [
            BlockT=llvm::BasicBlock
        ]
S:\llvm\llvm-project\llvm\include\llvm/Support/GenericLoopInfo.h(326): note: see declaration of 'llvm::LoopBase<llvm::BasicBlock,llvm::Loop>::getLoopLatch'

Everything links fine but the warning is very noisy when building LLVM as a Windows DLL. Interestingly, clang-cl does not warn here and is fine with the code as-is.

---

Full diff: https://github.com/llvm/llvm-project/pull/144621.diff

1 Files Affected:

• (modified) llvm/include/llvm/Analysis/LoopInfo.h (+1-1)

diff --git a/llvm/include/llvm/Analysis/LoopInfo.h b/llvm/include/llvm/Analysis/LoopInfo.h
index 072ddad546bf3..a7a6a2753709c 100644
--- a/llvm/include/llvm/Analysis/LoopInfo.h
+++ b/llvm/include/llvm/Analysis/LoopInfo.h
@@ -18,7 +18,7 @@
 #include "llvm/IR/PassManager.h"
 #include "llvm/Pass.h"
 #include "llvm/Support/Compiler.h"
-#include "llvm/Support/GenericLoopInfo.h"
+#include "llvm/Support/GenericLoopInfoImpl.h"
 #include <optional>
 #include <utility>
 

[andrurogerz]

@compnerd, @vgvassilev another one that should be straight-forward, but I thought it was worth making into its own PR for discussion. Thanks!