Bugfix: Hetero-C++ launching graph with no inputs

hpvm/projects/hetero-c++/lib/HPVMCGen.cpp

@@ -178,10 +178,22 @@ CallInst* HPVMCGenBase::insertCallUnchecked(Instruction* insertBefore,
 }
 
 AllocaInst* HPVMCGenBase::insertAlloca(Instruction* insertBefore, std::vector<Value *>& args) {
+
+    // If trying to launch a graph which takes no 
+    // input, return an empty alloca
+    if(args.empty()){
+        LLVM_DEBUG(errs() << "Warning: Attempting to launch a graph which takes 0 inputs ... "<< "\n");
+        Type* voidTy = Type::getInt8Ty(theContext.getLLVMContext());
+        getIRB().SetInsertPoint(insertBefore);
+        return getIRB().CreateAlloca(voidTy);
+    }
+
     std::vector<Type *> argTypesVec;
     for(auto *argument : args) {
         argTypesVec.push_back(argument->getType());
     }
+
+
     ArrayRef<Type *> argTypes(argTypesVec);
     StructType *StructTy = StructType::create(argTypes, "DFGArgs", true);
 

hpvm/projects/hetero-c++/test/unit/hetero-host/happy/empty_launch.cc

+#include "heterocc.h"
+#include <stdlib.h>
+#include <stdio.h>
+
+
+
+
+void RootFn()
+{
+    auto s = __hetero_section_begin();
+
+    for(int i = 0 ; i < 100; i++){
+        __hetero_parallel_loop(1, 0, 0, "empty_loop");
+        printf("Hello World!\n");
+    }
+
+    __hetero_section_end(s);
+
+}
+
+
+int main(){
+
+
+    void* DFG = __hetero_launch((void*) RootFn, 
+            0, 0);
+
+
+    __hetero_wait(DFG);
+
+
+
+
+    return 0;
+}

hpvm/projects/hetero-c++/test/unit/hetero_pass/hetero-host/empty_launch.ll

+; RUN: hcc  -declsfile ../tools/hpvm/projects/hetero-c++/lib/HPVMCFunctionDeclarations/HPVMCFunctionDeclarations.bc  -control-only -S  < %s | FileCheck %s  
+; ModuleID = 'happy/empty_launch.cc'
+source_filename = "happy/empty_launch.cc"
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+@.str = private unnamed_addr constant [11 x i8] c"empty_loop\00", align 1
+@str = private unnamed_addr constant [13 x i8] c"Hello World!\00", align 1
+
+; CHECK-LABEL: i32 @main(
+; CHECK: call void @__hpvm__init()
+; CHECK: %0 = alloca i8, align 1
+; CHECK: %__hpvm__launch = call i8* (i32, ...) @__hpvm__launch(i32 0, void ()* @_Z6RootFnv, i8* %0)
+; CHECK: call void @__hpvm__wait(i8* %__hpvm__launch)
+; CHECK: call void @__hpvm__cleanup()
+
+; Function Attrs: mustprogress uwtable
+define dso_local void @_Z6RootFnv() #0 {
+entry:
+  %call = call i8* @__hetero_section_begin()
+  br label %for.body
+
+for.cond.cleanup:                                 ; preds = %for.body
+  call void @__hetero_section_end(i8* %call)
+  ret void
+
+for.body:                                         ; preds = %entry, %for.body
+  %i.05 = phi i32 [ 0, %entry ], [ %inc, %for.body ]
+  call void (i32, ...) @__hetero_parallel_loop(i32 1, i32 0, i32 0, i8* getelementptr inbounds ([11 x i8], [11 x i8]* @.str, i64 0, i64 0))
+  %puts = call i32 @puts(i8* nonnull dereferenceable(1) getelementptr inbounds ([13 x i8], [13 x i8]* @str, i64 0, i64 0))
+  %inc = add nuw nsw i32 %i.05, 1
+  %exitcond.not = icmp eq i32 %inc, 100
+  br i1 %exitcond.not, label %for.cond.cleanup, label %for.body, !llvm.loop !3
+}
+
+declare dso_local i8* @__hetero_section_begin() local_unnamed_addr #1
+
+declare dso_local void @__hetero_parallel_loop(i32, ...) local_unnamed_addr #1
+
+declare dso_local void @__hetero_section_end(i8*) local_unnamed_addr #1
+
+
+
+; Function Attrs: mustprogress norecurse uwtable
+define dso_local i32 @main() local_unnamed_addr #2 {
+entry:
+  %call = call i8* (i8*, ...) @__hetero_launch(i8* bitcast (void ()* @_Z6RootFnv to i8*), i32 0, i32 0)
+  call void @__hetero_wait(i8* %call)
+  ret i32 0
+}
+
+declare dso_local i8* @__hetero_launch(i8*, ...) local_unnamed_addr #1
+
+declare dso_local void @__hetero_wait(i8*) local_unnamed_addr #1
+
+; Function Attrs: nofree nounwind
+declare noundef i32 @puts(i8* nocapture noundef readonly) local_unnamed_addr #3
+
+attributes #0 = { mustprogress uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+attributes #1 = { "frame-pointer"="none" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+attributes #2 = { mustprogress norecurse uwtable "frame-pointer"="none" "min-legal-vector-width"="0" "no-trapping-math"="true" "stack-protector-buffer-size"="8" "target-cpu"="x86-64" "target-features"="+cx8,+fxsr,+mmx,+sse,+sse2,+x87" "tune-cpu"="generic" }
+attributes #3 = { nofree nounwind }
+
+!llvm.module.flags = !{!0, !1}
+!llvm.ident = !{!2}
+
+!0 = !{i32 1, !"wchar_size", i32 4}
+!1 = !{i32 7, !"uwtable", i32 1}
+!2 = !{!"clang version 13.0.0 (https://gitlab.engr.illinois.edu/llvm/hpvm.git 19bf92289531ec07aff279c436faf9c5821e1f66)"}
+!3 = distinct !{!3, !4, !5}
+!4 = !{!"llvm.loop.mustprogress"}
+!5 = !{!"llvm.loop.unroll.disable"}