[MLIR][ExecutionEngine] Restore internal _mlir_{*} builtins

[cbalint13]

During clang-tidy fixes, _mlir_{alloc,aligned_alloc,free,aligned_free} were lost, see the commit: c599650

• Current mlir{Alloc,AlignedAlloc,Free,AlignedFree} are dangling declarations.
• This PR restores the previous behaviour and utility but also keep clang-tidy happy.

---

Issue details

• Prior to this, using mlir-runner-testcase.py.gz reveals the following missing symbols:

-> pm.add("finalize-memref-to-llvm{use-generic-functions=false}")
$ ./mlir-runner-testcase.py
Could not compile malloc:
  Symbols not found: [ _mlir_malloc ]
Generated object file 'obj.o' for inspection.

-> pm.add("finalize-memref-to-llvm{use-generic-functions=false use-aligned-alloc=1}")
$ ./mlir-runner-testcase.py
Could not compile aligned_alloc:
  Symbols not found: [ _mlir_aligned_alloc ]
Generated object file 'obj.o' for inspection.

• Using this PR, symbols resolves and are picked up properly:

$ ./mlir-runner-testcase.py 
Generated object file 'obj.o' for inspection.

$ readelf -Ws obj.o 
Symbol table '.symtab' contains 7 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND 
     1: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS LLVMDialectModule
     2: 0000000000000000    98 FUNC    GLOBAL DEFAULT    3 main
     3: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND aligned_alloc
     4: 0000000000000070   101 FUNC    GLOBAL DEFAULT    3 _mlir_ciface_main
     5: 00000000000000e0   108 FUNC    GLOBAL DEFAULT    3 _mlir_main
     6: 0000000000000150   111 FUNC    GLOBAL DEFAULT    3 _mlir__mlir_ciface_main

Note: Of course one can still use use-generic-functions=true with his own custom shared library, but the scope of this PR is to restore the functionality back to simply what libmlir_c_runner_utils.so already ships as builtins.

[llvmbot]

@llvm/pr-subscribers-mlir

@llvm/pr-subscribers-mlir-execution-engine

Author: Balint Cristian (cbalint13)

Changes

During clang-tidy fixes, _mlir_{alloc,aligned_alloc,free,aligned_free} were lost, see the commit: c599650

• Current mlir{Alloc,AlignedAlloc,Free,AlignedFree} are dangling declarations.
• This PR restores the previous behaviour and utility but also keep clang-tidy happy.

---

Issue details

• Prior to this, using mlir-runner-testcase.py.gz reveals the following missing symbols:

-> pm.add("finalize-memref-to-llvm{use-generic-functions=false}")
$ mlir-runner-testcase.py
Could not compile malloc:
  Symbols not found: [ _mlir_malloc ]
Generated object file 'obj.o' for inspection.
[cbalint@<!-- -->yoda work]$ mcedit mlir-runner-testcase.py 

-> pm.add("finalize-memref-to-llvm{use-generic-functions=false use-aligned-alloc=1}")
$ mlir-runner-testcase.py
Could not compile aligned_alloc:
  Symbols not found: [ _mlir_aligned_alloc ]
Generated object file 'obj.o' for inspection.

• Using this PR, symbols resolves and are picked up properly:

$ ./mlir-runner-testcase.py 
Generated object file 'obj.o' for inspection.

$ readelf -Ws obj.o 
Symbol table '.symtab' contains 7 entries:
   Num:    Value          Size Type    Bind   Vis      Ndx Name
     0: 0000000000000000     0 NOTYPE  LOCAL  DEFAULT  UND 
     1: 0000000000000000     0 FILE    LOCAL  DEFAULT  ABS LLVMDialectModule
     2: 0000000000000000    98 FUNC    GLOBAL DEFAULT    3 main
     3: 0000000000000000     0 NOTYPE  GLOBAL DEFAULT  UND aligned_alloc
     4: 0000000000000070   101 FUNC    GLOBAL DEFAULT    3 _mlir_ciface_main
     5: 00000000000000e0   108 FUNC    GLOBAL DEFAULT    3 _mlir_main
     6: 0000000000000150   111 FUNC    GLOBAL DEFAULT    3 _mlir__mlir_ciface_main

Note: Of course one can still use use-generic-functions=true with his own custom shared library, but the scope of this PR is to restore a the functionality back to simply what libmlir_c_runner_utils.so already ships as builtins.

---

Full diff: https://github.com/llvm/llvm-project/pull/159941.diff

1 Files Affected:

• (modified) mlir/lib/ExecutionEngine/ExecutionEngine.cpp (+20)

diff --git a/mlir/lib/ExecutionEngine/ExecutionEngine.cpp b/mlir/lib/ExecutionEngine/ExecutionEngine.cpp
index 52162a43aeae3..85775aefd1a02 100644
--- a/mlir/lib/ExecutionEngine/ExecutionEngine.cpp
+++ b/mlir/lib/ExecutionEngine/ExecutionEngine.cpp
@@ -134,7 +134,27 @@ void ExecutionEngine::setupTargetTripleAndDataLayout(Module *llvmModule,
   llvmModule->setTargetTriple(tm->getTargetTriple());
 }
 
+static StringRef lookupBuiltinCRunnerNames(StringRef name) {
+  static const llvm::StringMap<StringRef> nameMap = {
+      {"alloc", "mlirAlloc"},
+      {"aligned_alloc", "mlirAlignedAlloc"},
+      {"malloc", "mlirAlloc"},
+      {"free", "mlirFree"},
+      {"aligned_free", "mlirAlignedFree"}};
+
+  auto it = nameMap.find(name);
+  if (it != nameMap.end()) {
+    return it->second;
+  }
+
+  return {};
+}
+
 static std::string makePackedFunctionName(StringRef name) {
+  auto cfuncName = lookupBuiltinCRunnerNames(name);
+  if (!cfuncName.empty())
+    return cfuncName.str();
+
   return "_mlir_" + name.str();
 }
 

[cbalint13]

Cc @joker-eph , @ftynse (authors / code blame list)

[ftynse]

Hmm, this sort of dynamic renaming makes the overall behavior of a system harder to follow, all just to keep the linter happy... Can we rather revert the offending commit + add configuration that prevents it from complaining about these names?

[joker-eph]

+1 to revert + a test using the symbols otherwise this is dead.

[cbalint13]

@ftynse , @joker-eph

As per review requests:

• Reverted c599650
• Protected relevant section against clang-tidy
• Extended actual testDumpToObjectFile, so it would catch failures like:

   TEST: testDumpToObjectFile
   {..}
   Could not compile malloc:
     Symbols not found: [ _mlir_malloc ]
   {..}
  

[cbalint13]

Not sure it is worth, the issue would persist across (too) many older versions.
This works fine with custom libraries.