[Orc] add C-API for transform layer

[vchuravy]

Summary

Exposes the IRTransformLayer to allow customization of the pass pipeline for Oorcv2

[lhames]

Apart from those two comments, this looks great!

Do you have commit access? If so, land away (with suggested changes), otherwise let me know and I can commit it.

llvm/include/llvm-c/LLJIT.h

51–59

This isn't LLJIT specific -- It should go in Orc.h.

234–240

This should go in Orc.h too.

[lhames]

Committed in 80f30a6b855.

llvm/examples/OrcV2Examples/OrcV2CBindingsBasicUsage/OrcV2CBindingsBasicUsage.c

LLVMOrcThreadSafeModuleRef createDemoModule() {
   // Dispose of our local ThreadSafeContext value. The underlying LLVMContext
   // will be kept alive by our ThreadSafeModule, TSM.
   LLVMOrcDisposeThreadSafeContext(TSCtx);
 
   // Return the result.
   return TSM;
 }
 
+void transform(void *Ctx, LLVMModuleRef Mod, LLVMOrcMaterializationResponsibilityRef MR) {
+  LLVMPassManagerRef PM = LLVMCreatePassManager();
+  // Question @lhames: Do we need to run
+  // - LLVMAddAnalysisPass(TM, PM)
+  // - PM->createTargetInfoTransformInfoWrapperPass
+  // - LLVMAddTargetLibraryInfoByTriple(triple, PM)
+  LLVMAddInstructionCombiningPass(PM);
+  LLVMRunPassManager(PM, Mod);
+  LLVMDisposePassManager(PM);
+}
+
 int main(int argc, char *argv[]) {
 
   int MainResult = 0;
 
   // Parse command line arguments and initialize LLVM Core.
   LLVMParseCommandLineOptions(argc, (const char **)argv, "");
   LLVMInitializeCore(LLVMGetGlobalPassRegistry());
 
   // Initialize native target codegen and asm printer.
   LLVMInitializeNativeTarget();
   LLVMInitializeNativeAsmPrinter();
 
   // Create the JIT instance.
   LLVMOrcLLJITRef J;
   {
     LLVMErrorRef Err;
     if ((Err = LLVMOrcCreateLLJIT(&J, 0))) {
       MainResult = handleError(Err);
       goto llvm_shutdown;
     }
   }
 
+  // add TransformLayer
+  {
+    LLVMOrcIRTransformLayerRef TL = LLVMOrcLLJITGetIRTransformLayer(J);
+    LLVMOrcLLJITIRTransformLayerSetTransform(TL, *transform, NULL);
+  }
+
   // Create our demo module.
   LLVMOrcThreadSafeModuleRef TSM = createDemoModule();
 
   // Add our demo module to the JIT.
   {
     LLVMOrcJITDylibRef MainJD = LLVMOrcLLJITGetMainJITDylib(J);
     LLVMErrorRef Err;
     if ((Err = LLVMOrcLLJITAddLLVMIRModule(J, MainJD, TSM))) {

llvm/include/llvm-c/LLJIT.h

  * Object linking layers returned by this function will become owned by the
  * LLJIT instance. The client is not responsible for managing their lifetimes
  * after the function returns.
  */
 typedef LLVMOrcObjectLayerRef (
     *LLVMOrcLLJITBuilderObjectLinkingLayerCreatorFunction)(
     void *Ctx, LLVMOrcExecutionSessionRef ES, const char *Triple);
 
 /**
+ * A function for applying transformations as part of an transform layer.
+ *
+ * Clients can call LLVMOrcLLJITGetIRTransformLayer to obtain the transform
+ * layer of a LLJIT instance, and use LLVMOrcLLJITIRTransformLayerSetTransform
+ * to set the function. This can be used to override the default transform layer.
+ */
+typedef void (*LLVMOrcIRTransformLayerTransformFunction)(
+    void *Ctx, LLVMModuleRef Mod, LLVMOrcMaterializationResponsibilityRef MR);
+
+/**
  * A reference to an orc::LLJITBuilder instance.
  */
 typedef struct LLVMOrcOpaqueLLJITBuilder *LLVMOrcLLJITBuilderRef;
 
 /**
  * A reference to an orc::LLJIT instance.
  */
 typedef struct LLVMOrcOpaqueLLJIT *LLVMOrcLLJITRef;
LLVMErrorRef LLVMOrcLLJITLookup(LLVMOrcLLJITRef J,
                                 LLVMOrcJITTargetAddress *Result,
                                 const char *Name);
 
 /**
  * Returns a non-owning reference to the LLJIT instance's object linking layer.
  */
 LLVMOrcObjectLayerRef LLVMOrcLLJITGetObjLinkingLayer(LLVMOrcLLJITRef J);
 
+/**
+ * Returns a non-owning reference to the LLJIT instance's IR transform layer.
+ */
+LLVMOrcIRTransformLayerRef LLVMOrcLLJITGetIRTransformLayer(LLVMOrcLLJITRef J);
+
+/**
+ * Set the transform function of the provided transform layer, passing through a
+ * pointer to user provided context.
+ */
+void LLVMOrcLLJITIRTransformLayerSetTransform(
+    LLVMOrcIRTransformLayerRef TransformLayer,
+    LLVMOrcIRTransformLayerTransformFunction F, void *Ctx);
+
 LLVM_C_EXTERN_C_END
 
 #endif /* LLVM_C_LLJIT_H */

llvm/include/llvm-c/Orc.h

 typedef struct LLVMOrcOpaqueObjectLayer *LLVMOrcObjectLayerRef;
 
 /**
  * A reference to an orc::ObjectLinkingLayer instance.
  */
 typedef struct LLVMOrcOpaqueObjectLinkingLayer *LLVMOrcObjectLinkingLayerRef;
 
 /**
+ * A reference to an orc::IRTransformLayer instance.
+ */
+typedef struct LLVMOrcOpaqueIRTransformLayer *LLVMOrcIRTransformLayerRef;
+
+/**
  * Attach a custom error reporter function to the ExecutionSession.
  *
  * The error reporter will be called to deliver failure notices that can not be
  * directly reported to a caller. For example, failure to resolve symbols in
  * the JIT linker is typically reported via the error reporter (callers
  * requesting definitions from the JIT will typically be delivered a
  * FailureToMaterialize error instead).
  */

llvm/lib/ExecutionEngine/Orc/OrcV2CBindings.cpp

DEFINE_SIMPLE_CONVERSION_FUNCTIONS(DefinitionGenerator,
                                    LLVMOrcDefinitionGeneratorRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(InProgressLookupState, LLVMOrcLookupStateRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ThreadSafeContext,
                                    LLVMOrcThreadSafeContextRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ThreadSafeModule, LLVMOrcThreadSafeModuleRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(JITTargetMachineBuilder,
                                    LLVMOrcJITTargetMachineBuilderRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(ObjectLayer, LLVMOrcObjectLayerRef)
+DEFINE_SIMPLE_CONVERSION_FUNCTIONS(IRTransformLayer, LLVMOrcIRTransformLayerRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(LLJITBuilder, LLVMOrcLLJITBuilderRef)
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(LLJIT, LLVMOrcLLJITRef)
 
 DEFINE_SIMPLE_CONVERSION_FUNCTIONS(TargetMachine, LLVMTargetMachineRef)
 
 namespace llvm {
 namespace orc {
 

 void LLVMOrcRTDyldObjectLinkingLayerRegisterJITEventListener(
     LLVMOrcObjectLayerRef RTDyldObjLinkingLayer,
     LLVMJITEventListenerRef Listener) {
   assert(RTDyldObjLinkingLayer && "RTDyldObjLinkingLayer must not be null");
   assert(Listener && "Listener must not be null");
   reinterpret_cast<RTDyldObjectLinkingLayer *>(unwrap(RTDyldObjLinkingLayer))
       ->registerJITEventListener(*unwrap(Listener));
 }
+
+LLVMOrcIRTransformLayerRef LLVMOrcLLJITGetIRTransformLayer(LLVMOrcLLJITRef J) {
+  return wrap(&unwrap(J)->getIRTransformLayer());
+}
+
+void LLVMOrcLLJITIRTransformLayerSetTransform(
+    LLVMOrcIRTransformLayerRef TransformLayer,
+    LLVMOrcIRTransformLayerTransformFunction F, void *Ctx) {
+  unwrap(TransformLayer)->setTransform(
+      [=](ThreadSafeModule TSM,
+          const MaterializationResponsibility &R) -> Expected<ThreadSafeModule> {
+        TSM.withModuleDo(
+          [=, &R](Module &M) {
+            F(Ctx, wrap(&M), wrap(&R));
+          });
+        return std::move(TSM); // Not a redundant move: fix build on gcc-7.5
+      });
+}