[SYCL][ESIMD] Mark ESIMD kernel callgraph with sycl_explicit_simd.

Traverse callgraph from ESIMD kernels and mark all functions
with sycl_explicit_simd along the way. ESIMD code generation depends
on presence of this attribute, which will be used to distinguish
normal from ESIMD code.

Author: Denis Bakhvalov <denis.bakhvalov@intel.com>.

Signed-off-by: Konstantin S Bobrovsky <konstantin.s.bobrovsky@intel.com>

Author: kbobrovs

clang/include/clang/Sema/Sema.h

@@ -12696,6 +12696,7 @@ class Sema final {
   void checkSYCLDeviceVarDecl(VarDecl *Var);
   void ConstructOpenCLKernel(FunctionDecl *KernelCallerFunc, MangleContext &MC);
   void MarkDevice();
+  void MarkSyclSimd();
 
   /// Creates a DeviceDiagBuilder that emits the diagnostic if the current
   /// context is "used as device code".

clang/lib/Sema/Sema.cpp

@@ -990,6 +990,8 @@ void Sema::ActOnEndOfTranslationUnitFragment(TUFragmentKind Kind) {
       SyclIntHeader->emit(getLangOpts().SYCLIntHeader);
     MarkDevice();
   }
+  if (getLangOpts().SYCLExplicitSIMD)
+    MarkSyclSimd();
 
   emitDeferredDiags();
 

clang/lib/Sema/SemaSYCL.cpp

@@ -1900,6 +1900,27 @@ void Sema::ConstructOpenCLKernel(FunctionDecl *KernelCallerFunc,
   ConstructingOpenCLKernel = false;
 }
 
+// This function marks all the callees of explicit SIMD kernel
+// with !sycl_explicit_simd. We want to have different semantics
+// for functions that are called from SYCL and E-SIMD contexts.
+// Later, functions marked with !sycl_explicit_simd will be cloned
+// to maintain two different semantics.
+void Sema::MarkSyclSimd() {
+  for (Decl *D : syclDeviceDecls())
+    if (auto SYCLKernel = dyn_cast<FunctionDecl>(D))
+      if (SYCLKernel->hasAttr<SYCLSimdAttr>()) {
+        MarkDeviceFunction Marker(*this);
+        Marker.SYCLCG.addToCallGraph(getASTContext().getTranslationUnitDecl());
+        llvm::SmallPtrSet<FunctionDecl *, 10> VisitedSet;
+        Marker.CollectKernelSet(SYCLKernel, SYCLKernel, VisitedSet);
+        for (const auto &elt : Marker.KernelSet) {
+          if (FunctionDecl *Def = elt->getDefinition())
+            if (!Def->hasAttr<SYCLSimdAttr>())
+              Def->addAttr(SYCLSimdAttr::CreateImplicit(getASTContext()));
+        }
+      }
+}
+
 void Sema::MarkDevice(void) {
   // Create the call graph so we can detect recursion and check the validity
   // of new operator overrides. Add the kernel function itself in case
@@ -1910,7 +1931,8 @@ void Sema::MarkDevice(void) {
   // Iterate through SYCL_EXTERNAL functions and add them to the device decls.
   for (const auto &entry : *Marker.SYCLCG.getRoot()) {
     if (auto *FD = dyn_cast<FunctionDecl>(entry.Callee->getDecl())) {
-      if (FD->hasAttr<SYCLDeviceAttr>() && !FD->hasAttr<SYCLKernelAttr>())
+      if (FD->hasAttr<SYCLDeviceAttr>() && !FD->hasAttr<SYCLKernelAttr>() &&
+          FD->hasBody())
         addSyclDeviceDecl(FD);
     }
   }
@@ -1975,7 +1997,7 @@ void Sema::MarkDevice(void) {
         case attr::Kind::SYCLIntelMaxWorkGroupSize:
         case attr::Kind::SYCLIntelNoGlobalWorkOffset:
         case attr::Kind::SYCLSimd: {
-          if ((A->getKind() == attr::Kind::SYCLSimd) &&
+          if ((A->getKind() == attr::Kind::SYCLSimd) && KernelBody &&
               !KernelBody->getAttr<SYCLSimdAttr>()) {
             // Usual kernel can't call ESIMD functions.
             Diag(KernelBody->getLocation(),

clang/test/CodeGenSYCL/esimd_metadata2.cpp

@@ -0,0 +1,39 @@
+// RUN: %clang_cc1 -disable-llvm-passes -triple spir64-unknown-unknown-sycldevice -fsycl -fsycl-is-device -fsycl-explicit-simd -S -emit-llvm %s -o - | FileCheck %s --check-prefixes CHECK,CHECK-ESIMD
+
+// In ESIMD mode:
+// 1. Attribute !intel_reqd_sub_group_size !1 is added
+//    for kernels with !sycl_explicit_simd
+// 2. Attribute !sycl_explicit_simd is propagated to all the
+//    callees of ESIMD kernel.
+
+__attribute__((sycl_device)) void shared_func_decl();
+__attribute__((sycl_device)) void shared_func() { shared_func_decl(); }
+
+__attribute__((sycl_device)) __attribute__((sycl_explicit_simd)) void esimd_func() { shared_func(); }
+
+// CHECK-ESIMD-DAG: define spir_kernel void @{{.*}}kernel_cm() #{{[0-9]+}} !sycl_explicit_simd !{{[0-9]+}} {{.*}} !intel_reqd_sub_group_size ![[SGSIZE1:[0-9]+]] {{.*}}{
+// CHECK-ESIMD-DAG: define spir_func void @{{.*}}esimd_funcv() #{{[0-9]+}} !sycl_explicit_simd !{{[0-9]+}} {
+// CHECK-ESIMD-DAG: define spir_func void @{{.*}}shared_funcv() #{{[0-9]+}} !sycl_explicit_simd !{{[0-9]+}} {
+// CHECK-ESIMD-DAG: define linkonce_odr spir_func void @_ZN12ESIMDFunctorclEv({{.*}}) #{{[0-9]+}} {{.*}} !sycl_explicit_simd !{{[0-9]+}} {
+// CHECK-ESIMD-DAG: declare spir_func void @{{.*}}shared_func_declv() #{{[0-9]+}}
+
+class ESIMDFunctor {
+public:
+  void operator()() __attribute__((sycl_explicit_simd)) {
+    esimd_func();
+  }
+};
+
+template <typename name, typename Func>
+__attribute__((sycl_kernel)) void kernel(Func kernelFunc) {
+  kernelFunc();
+}
+
+void bar() {
+  ESIMDFunctor cmf;
+  kernel<class kernel_cm>(cmf);
+}
+
+// CHECK: !spirv.Source = !{[[LANG:![0-9]+]]}
+// CHECK: [[LANG]] = !{i32 6, i32 100000}
+// CHECK-ESIMD: ![[SGSIZE1]] = !{i32 1}

clang/test/CodeGenSYCL/esimd_metadata3.cpp

@@ -0,0 +1,7 @@
+// RUN: %clang_cc1 -disable-llvm-passes -triple spir64-unknown-unknown-sycldevice -fsycl -fsycl-is-device -fsycl-explicit-simd -S -emit-llvm %s -o - | FileCheck %s --check-prefix CHECK-ESIMD
+
+__attribute__((sycl_device)) void funcWithSpirvIntrin() {}
+__attribute__((sycl_device)) __attribute__((sycl_explicit_simd)) void standaloneCmFunc() { funcWithSpirvIntrin(); }
+
+// CHECK-ESIMD-DAG: define spir_func void @{{.*}}funcWithSpirvIntrinv() #{{[0-9]+}} !sycl_explicit_simd !{{[0-9]+}} {
+// CHECK-ESIMD-DAG: define spir_func void @{{.*}}standaloneCmFuncv() #{{[0-9]+}} !sycl_explicit_simd !{{[0-9]+}} {