r331879 - [OPENMP] Mark global tors/dtors as used.

[Alexey Bataev via cfe-commits]

Author: abataev
Date: Wed May  9 07:15:18 2018
New Revision: 331879

URL: http://llvm.org/viewvc/llvm-project?rev=331879&view=rev
Log:
[OPENMP] Mark global tors/dtors as used.

If the global variables are marked as declare target and they need
ctors/dtors, these ctors/dtors are emitted and then invoked by the
offloading runtime library. They are not explicitly used in the emitted
code and thus can be optimized out. Patch marks these functions as used,
so the optimizer cannot remove these function during the optimization
phase.

Modified:
    cfe/trunk/lib/CodeGen/CGOpenMPRuntime.cpp
    cfe/trunk/test/OpenMP/declare_target_codegen.cpp

Modified: cfe/trunk/lib/CodeGen/CGOpenMPRuntime.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/CGOpenMPRuntime.cpp?rev=331879&r1=331878&r2=331879&view=diff
==============================================================================
--- cfe/trunk/lib/CodeGen/CGOpenMPRuntime.cpp (original)
+++ cfe/trunk/lib/CodeGen/CGOpenMPRuntime.cpp Wed May  9 07:15:18 2018
@@ -2686,6 +2686,7 @@ bool CGOpenMPRuntime::emitDeclareTargetV
       CtorCGF.FinishFunction();
       Ctor = Fn;
       ID = llvm::ConstantExpr::getBitCast(Fn, CGM.Int8PtrTy);
+      CGM.addUsedGlobal(cast<llvm::GlobalValue>(Ctor));
     } else {
       Ctor = new llvm::GlobalVariable(
           CGM.getModule(), CGM.Int8Ty, /*isConstant=*/true,
@@ -2724,6 +2725,7 @@ bool CGOpenMPRuntime::emitDeclareTargetV
       DtorCGF.FinishFunction();
       Dtor = Fn;
       ID = llvm::ConstantExpr::getBitCast(Fn, CGM.Int8PtrTy);
+      CGM.addUsedGlobal(cast<llvm::GlobalValue>(Dtor));
     } else {
       Dtor = new llvm::GlobalVariable(
           CGM.getModule(), CGM.Int8Ty, /*isConstant=*/true,

Modified: cfe/trunk/test/OpenMP/declare_target_codegen.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/OpenMP/declare_target_codegen.cpp?rev=331879&r1=331878&r2=331879&view=diff
==============================================================================
--- cfe/trunk/test/OpenMP/declare_target_codegen.cpp (original)
+++ cfe/trunk/test/OpenMP/declare_target_codegen.cpp Wed May  9 07:15:18 2018
@@ -17,10 +17,13 @@
 // CHECK-DAG: @b = global i32 15,
 // CHECK-DAG: @d = global i32 0,
 // CHECK-DAG: @c = external global i32,
+// CHECK-DAG: @globals = global %struct.S zeroinitializer,
+// CHECK-DAG: @llvm.used = appending global [1 x i8*] [i8* bitcast (void ()* @__omp_offloading__{{.+}}_globals_l[[@LINE+41]]_ctor to i8*)], section "llvm.metadata"
 
 // CHECK-DAG: define {{.*}}i32 @{{.*}}{{foo|bar|baz2|baz3|FA|f_method}}{{.*}}()
 // CHECK-DAG: define {{.*}}void @{{.*}}TemplateClass{{.*}}(%class.TemplateClass* %{{.*}})
 // CHECK-DAG: define {{.*}}i32 @{{.*}}TemplateClass{{.*}}f_method{{.*}}(%class.TemplateClass* %{{.*}})
+// CHECK-DAG: define {{.*}}void @__omp_offloading__{{.*}}_globals_l[[@LINE+36]]_ctor()
 
 #ifndef HEADER
 #define HEADER
@@ -56,6 +59,7 @@ struct S {
 int foo() { return 0; }
 int b = 15;
 int d;
+S globals(d);
 #pragma omp end declare target
 int c;