[Mlir-commits] [mlir] 8735b7d - [mlir] do not inject malloc/free in to-LLVM translation (#73224)

[llvmlistbot at llvm.org]

Author: Oleksandr "Alex" Zinenko
Date: 2023-11-23T13:38:25+01:00
New Revision: 8735b7dcc9ebcfd00f478660656f75432af38ed3

URL: https://github.com/llvm/llvm-project/commit/8735b7dcc9ebcfd00f478660656f75432af38ed3
DIFF: https://github.com/llvm/llvm-project/commit/8735b7dcc9ebcfd00f478660656f75432af38ed3.diff

LOG: [mlir] do not inject malloc/free in to-LLVM translation (#73224)

In the early days of MLIR-to-LLVM IR translation, it had to forcefully
inject declarations of `malloc` and `free` functions as then-standard
(now `memref`) dialect ops were unconditionally lowering to libc calls.
This is no longer the case. Even when they do lower to libc calls, the
signatures of those methods are injected at lowering since calls must
target declared functions in valid IR. Don't inject those declarations
anymore.

Added: 
    

Modified: 
    mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
    mlir/test/Target/LLVMIR/llvmir.mlir

Removed: 
    


################################################################################
diff  --git a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
index 245048ef0b93939..322843e65627603 100644
--- a/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
+++ b/mlir/lib/Target/LLVMIR/ModuleTranslation.cpp
@@ -1369,14 +1369,6 @@ prepareLLVMModule(Operation *m, llvm::LLVMContext &llvmContext,
           m->getDiscardableAttr(LLVM::LLVMDialect::getTargetTripleAttrName()))
     llvmModule->setTargetTriple(cast<StringAttr>(targetTripleAttr).getValue());
 
-  // Inject declarations for `malloc` and `free` functions that can be used in
-  // memref allocation/deallocation coming from standard ops lowering.
-  llvm::IRBuilder<> builder(llvmContext);
-  llvmModule->getOrInsertFunction("malloc", builder.getInt8PtrTy(),
-                                  builder.getInt64Ty());
-  llvmModule->getOrInsertFunction("free", builder.getVoidTy(),
-                                  builder.getInt8PtrTy());
-
   return llvmModule;
 }
 

diff  --git a/mlir/test/Target/LLVMIR/llvmir.mlir b/mlir/test/Target/LLVMIR/llvmir.mlir
index 73fcee0dd2e70bd..ab8506ff163efe6 100644
--- a/mlir/test/Target/LLVMIR/llvmir.mlir
+++ b/mlir/test/Target/LLVMIR/llvmir.mlir
@@ -179,7 +179,7 @@ llvm.mlir.global internal constant @sectionvar("teststring")  {section = ".mysec
 // CHECK: declare ptr @malloc(i64)
 llvm.func @malloc(i64) -> !llvm.ptr
 // CHECK: declare void @free(ptr)
-
+llvm.func @free(!llvm.ptr)
 
 //
 // Basic functionality: function and block conversion, function calls,