[SYCL] Add Intel FPGA force_pow2_depth attribute (#1284)

This attribute provides explicit control over the geometry of memory
blocks used in a given memory system.

Signed-off-by: Mikhail Lychkov <mikhail.lychkov@intel.com>

Author: mlychkov

clang/include/clang/Basic/Attr.td

@@ -1852,6 +1852,23 @@ def IntelFPGABankBits : Attr {
   }];
 }
 
+def IntelFPGAForcePow2Depth : Attr {
+  let Spellings = [CXX11<"intelfpga","force_pow2_depth">];
+  let Args = [ExprArgument<"Value">];
+  let Subjects = SubjectList<[IntelFPGAConstVar, IntelFPGALocalStaticSlaveMemVar,
+                              Field], ErrorDiag>;
+  let LangOpts = [SYCLIsDevice, SYCLIsHost];
+  let Documentation = [IntelFPGAForcePow2DepthAttrDocs];
+  let AdditionalMembers = [{
+    static unsigned getMinValue() {
+      return 0;
+    }
+    static unsigned getMaxValue() {
+      return 1;
+    }
+  }];
+}
+
 def Naked : InheritableAttr {
   let Spellings = [GCC<"naked">, Declspec<"naked">];
   let Subjects = SubjectList<[Function]>;

clang/include/clang/Basic/AttrDocs.td

@@ -1935,6 +1935,26 @@ pointer address bits to bank on.
   }];
 }
 
+def IntelFPGAForcePow2DepthAttrDocs : Documentation {
+  let Category = DocCatVariable;
+  let Heading = "force_pow2_depth (IntelFPGA)";
+  let Content = [{
+This attribute may be attached to a variable or struct member declaration and
+provides explicit control over the geometry of memory blocks used in a given
+memory system.
+
+In the presence of this attribute, the compiler:
+
+1. Will automatically size the memory depth to the next largest power of 2 if
+force_pow2_depth is set to 1, and will prefer width-stitching of RAM blocks
+over depth-stitching.
+
+2. Will not size the memory to the next largest power of 2 if force_pow2_depth
+is set to 0, and will prefer depth-stitching over width-stitching if RAM usage
+can be lowered.
+  }];
+}
+
 def SYCLIntelKernelArgsRestrictDocs : Documentation {
   let Category = DocCatVariable;
   let Heading = "kernel_args_restrict";

clang/lib/CodeGen/CodeGenModule.cpp

@@ -4072,6 +4072,11 @@ void CodeGenModule::generateIntelFPGAAnnotation(
   }
   if (D->hasAttr<IntelFPGASimpleDualPortAttr>())
     Out << "{simple_dual_port:1}";
+  if (const auto *FP2D = D->getAttr<IntelFPGAForcePow2DepthAttr>()) {
+    llvm::APSInt FP2DInt =
+        FP2D->getValue()->EvaluateKnownConstInt(getContext());
+    Out << '{' << FP2D->getSpelling() << ':' << FP2DInt << '}';
+  }
 }
 
 void CodeGenModule::addGlobalIntelFPGAAnnotation(const VarDecl *VD,

clang/lib/Sema/SemaDeclAttr.cpp

@@ -5221,6 +5221,8 @@ static bool checkIntelFPGARegisterAttrCompatibility(Sema &S, Decl *D,
     InCompat = true;
   if (checkAttrMutualExclusion<IntelFPGABankBitsAttr>(S, D, Attr))
     InCompat = true;
+  if (checkAttrMutualExclusion<IntelFPGAForcePow2DepthAttr>(S, D, Attr))
+    InCompat = true;
 
   return InCompat;
 }
@@ -5425,6 +5427,24 @@ static void handleIntelFPGAPrivateCopiesAttr(Sema &S, Decl *D,
       D, Attr, Attr.getArgAsExpr(0));
 }
 
+static void handleIntelFPGAForcePow2DepthAttr(Sema &S, Decl *D,
+                                              const ParsedAttr &Attr) {
+  if (S.LangOpts.SYCLIsHost)
+    return;
+
+  checkForDuplicateAttribute<IntelFPGAForcePow2DepthAttr>(S, D, Attr);
+
+  if (checkAttrMutualExclusion<IntelFPGARegisterAttr>(S, D, Attr))
+    return;
+
+  if (!D->hasAttr<IntelFPGAMemoryAttr>())
+    D->addAttr(IntelFPGAMemoryAttr::CreateImplicit(
+        S.Context, IntelFPGAMemoryAttr::Default));
+
+  S.AddOneConstantValueAttr<IntelFPGAForcePow2DepthAttr>(D, Attr,
+                                                         Attr.getArgAsExpr(0));
+}
+
 static void handleXRayLogArgsAttr(Sema &S, Decl *D, const ParsedAttr &AL) {
   ParamIdx ArgCount;
 
@@ -8059,6 +8079,9 @@ static void ProcessDeclAttribute(Sema &S, Scope *scope, Decl *D,
   case ParsedAttr::AT_IntelFPGABankBits:
     handleIntelFPGABankBitsAttr(S, D, AL);
     break;
+  case ParsedAttr::AT_IntelFPGAForcePow2Depth:
+    handleIntelFPGAForcePow2DepthAttr(S, D, AL);
+    break;
   case ParsedAttr::AT_SYCLIntelPipeIO:
     handleSYCLIntelPipeIOAttr(S, D, AL);
     break;

clang/lib/Sema/SemaTemplateInstantiateDecl.cpp

@@ -556,6 +556,17 @@ static void instantiateIntelFPGABankBitsAttr(
   S.AddIntelFPGABankBitsAttr(New, *Attr, Args.data(), Args.size());
 }
 
+static void instantiateIntelFPGAForcePow2DepthAttr(
+    Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
+    const IntelFPGAForcePow2DepthAttr *Attr, Decl *New) {
+  EnterExpressionEvaluationContext Unevaluated(
+      S, Sema::ExpressionEvaluationContext::ConstantEvaluated);
+  ExprResult Result = S.SubstExpr(Attr->getValue(), TemplateArgs);
+  if (!Result.isInvalid())
+    S.AddOneConstantValueAttr<IntelFPGAForcePow2DepthAttr>(
+        New, *Attr, Result.getAs<Expr>());
+}
+
 static void instantiateSYCLIntelPipeIOAttr(
     Sema &S, const MultiLevelTemplateArgumentList &TemplateArgs,
     const SYCLIntelPipeIOAttr *Attr, Decl *New) {
@@ -700,6 +711,11 @@ void Sema::InstantiateAttrs(const MultiLevelTemplateArgumentList &TemplateArgs,
       instantiateIntelFPGABankBitsAttr(*this, TemplateArgs, IntelFPGABankBits,
                                        New);
     }
+    if (const auto *IntelFPGAForcePow2Depth =
+            dyn_cast<IntelFPGAForcePow2DepthAttr>(TmplAttr)) {
+      instantiateIntelFPGAForcePow2DepthAttr(*this, TemplateArgs,
+                                             IntelFPGAForcePow2Depth, New);
+    }
     if (const auto *SYCLIntelPipeIO = dyn_cast<SYCLIntelPipeIOAttr>(TmplAttr)) {
       instantiateSYCLIntelPipeIOAttr(*this, TemplateArgs, SYCLIntelPipeIO, New);
       continue;

clang/test/CodeGenSYCL/intel-fpga-local.cpp

@@ -5,6 +5,8 @@
 // CHECK-DEVICE:  [[ANN_numbanks_4:@.str]] = {{.*}}{memory:DEFAULT}{sizeinfo:4}{numbanks:4}
 // CHECK-BOTH: @_ZZ15attrs_on_staticvE15static_annotate = internal{{.*}}constant i32 30, align 4
 // CHECK-BOTH:    [[ANN_annotate:@.str[.0-9]*]] = {{.*}}foobar
+// CHECK-BOTH: @_ZZ15attrs_on_staticvE16static_force_p2d = internal{{.*}}constant i32 40, align 4
+// CHECK-DEVICE:  [[ANN_force_pow2_depth_0:@.str[.0-9]*]] = {{.*}}{memory:DEFAULT}{sizeinfo:4}{force_pow2_depth:0}
 // CHECK-DEVICE:  [[ANN_register:@.str.[0-9]*]] = {{.*}}{register:1}
 // CHECK-DEVICE:  [[ANN_memory_default:@.str.[0-9]*]] = {{.*}}{memory:DEFAULT}{sizeinfo:4}
 // CHECK-DEVICE:  [[ANN_mlab_sizeinfo_500:@.str.[0-9]*]] = {{.*}}{memory:MLAB}{sizeinfo:4,500}
@@ -22,22 +24,25 @@
 // CHECK-DEVICE:  [[ANN_bankbits_bankwidth:@.str.[0-9]*]] = {{.*}}{memory:DEFAULT}{sizeinfo:4,10,2}{bankwidth:16}{numbanks:2}{bank_bits:0}
 // CHECK-DEVICE:  [[ANN_memory_blockram:@.str.[0-9]*]] = {{.*}}{memory:BLOCK_RAM}{sizeinfo:4}
 // CHECK-DEVICE:  [[ANN_memory_mlab:@.str.[0-9]*]] = {{.*}}{memory:MLAB}{sizeinfo:4}
+// CHECK-DEVICE:  [[ANN_force_pow2_depth_1:@.str.[0-9]*]] = {{.*}}{memory:DEFAULT}{sizeinfo:4}{force_pow2_depth:1}
 // CHECK-DEVICE:  [[ANN_private_copies_4:@.str.[0-9]*]] = {{.*}}{memory:DEFAULT}{sizeinfo:4}{private_copies:4}
 // CHECK-DEVICE:  [[ANN_max_replicates_4:@.str.[0-9]*]] = {{.*}}{max_replicates:4}
 
 // CHECK-BOTH: @llvm.global.annotations
 // CHECK-DEVICE-SAME: { i8* addrspacecast (i8 addrspace(1)* bitcast (i32 addrspace(1)* @_ZZ15attrs_on_staticvE15static_numbanks to i8 addrspace(1)*) to i8*)
-// CHECK-DEVICE-SAME: [[ANN_numbanks_4]]{{.*}} i32 39
+// CHECK-DEVICE-SAME: [[ANN_numbanks_4]]{{.*}} i32 43
 // CHECK-DEVICE-SAME: { i8* addrspacecast (i8 addrspace(1)* bitcast (i32 addrspace(1)* @_ZZ15attrs_on_staticvE15static_annotate to i8 addrspace(1)*) to i8*)
 // CHECK-HOST-SAME: { i8* bitcast (i32* @_ZZ15attrs_on_staticvE15static_annotate to i8*)
-// CHECK-BOTH-SAME: [[ANN_annotate]]{{.*}} i32 40
-
+// CHECK-BOTH-SAME: [[ANN_annotate]]{{.*}} i32 44
+// CHECK-DEVICE-SAME: { i8* addrspacecast (i8 addrspace(1)* bitcast (i32 addrspace(1)* @_ZZ15attrs_on_staticvE16static_force_p2d to i8 addrspace(1)*) to i8*)
+// CHECK-DEVICE-SAME: [[ANN_force_pow2_depth_0]]{{.*}} i32 45
 // CHECK-HOST-NOT: llvm.var.annotation
 // CHECK-HOST-NOT: llvm.ptr.annotation
 
 void attrs_on_static() {
   const static int static_numbanks [[intelfpga::numbanks(4)]] = 20;
   const static int static_annotate [[clang::annotate("foobar")]] = 30;
+  const static int static_force_p2d [[intelfpga::force_pow2_depth(0)]] = 40;
 }
 
 void attrs_on_var() {
@@ -105,6 +110,10 @@ void attrs_on_var() {
   // CHECK-DEVICE: %[[VAR_BANK_BITS_WIDTH1:bank_bits_width[0-9]+]] = bitcast{{.*}}%bank_bits_width
   // CHECK-DEVICE: @llvm.var.annotation{{.*}}%[[VAR_BANK_BITS_WIDTH1]],{{.*}}[[ANN_bankbits_bankwidth]]
   [[intelfpga::bank_bits(0), intelfpga::bankwidth(16)]] int bank_bits_width[10][2];
+  // CHECK-DEVICE: %[[VAR_FP2D:[0-9]+]] = bitcast{{.*}}%force_p2d
+  // CHECK-DEVICE: %[[VAR_FP2D1:force_p2d[0-9]+]] = bitcast{{.*}}%force_p2d
+  // CHECK-DEVICE: llvm.var.annotation{{.*}}%[[VAR_FP2D1]],{{.*}}[[ANN_force_pow2_depth_0]]
+  int force_p2d [[intelfpga::force_pow2_depth(0)]];
 }
 
 void attrs_on_struct() {
@@ -123,6 +132,7 @@ void attrs_on_struct() {
     int maxreplicates [[intelfpga::max_replicates(2)]];
     int dualport [[intelfpga::simple_dual_port]];
     int bankbits [[intelfpga::bank_bits(4, 5)]];
+    int force_p2d [[intelfpga::force_pow2_depth(1)]];
   } s;
 
   // CHECK-DEVICE: %[[FIELD_NUMBANKS:.*]] = getelementptr inbounds %struct.{{.*}}.attrs_on_struct{{.*}}
@@ -167,12 +177,15 @@ void attrs_on_struct() {
   // CHECK-DEVICE: %[[FIELD_BANKBITS:.*]] = getelementptr inbounds %struct.{{.*}}.attrs_on_struct{{.*}}
   // CHECK-DEVICE: call i32* @llvm.ptr.annotation.p0i32{{.*}}%[[FIELD_BANKBITS]]{{.*}}[[ANN_bankbits_4_5]]
   s.bankbits = 0;
+  // CHECK-DEVICE: %[[FIELD_FP2D:.*]] = getelementptr inbounds %struct.{{.*}}.attrs_on_struct{{.*}}
+  // CHECK-DEVICE: call i32* @llvm.ptr.annotation.p0i32{{.*}}%[[FIELD_FP2D]]{{.*}}[[ANN_force_pow2_depth_1]]
+  s.force_p2d = 0;
 }
 
 // CHECK-HOST-NOT: llvm.var.annotation
 // CHECK-HOST-NOT: llvm.ptr.annotation
 
-template <int A, int B>
+template <int A, int B, int C>
 void attrs_with_template_param() {
   // CHECK-DEVICE: %[[TEMPL_NUMBANKS:numbanks[0-9]+]] = bitcast{{.*}}%numbanks
   // CHECK-DEVICE: @llvm.var.annotation{{.*}}%[[TEMPL_NUMBANKS]],{{.*}}[[ANN_numbanks_4]]
@@ -189,13 +202,17 @@ void attrs_with_template_param() {
   // CHECK-DEVICE: %[[TEMPL_BANKBITS:bankbits[0-9]+]] = bitcast{{.*}}%bankbits
   // CHECK-DEVICE: @llvm.var.annotation{{.*}}%[[TEMPL_BANKBITS]],{{.*}}[[ANN_bankbits_4_5]]
   int bankbits [[intelfpga::bank_bits(A, B)]];
+  // CHECK-DEVICE: %[[TEMPL_FP2D:force_p2d[0-9]+]] = bitcast{{.*}}%force_p2d
+  // CHECK-DEVICE: @llvm.var.annotation{{.*}}%[[TEMPL_FP2D]]{{.*}}[[ANN_force_pow2_depth_1]]
+  int force_p2d [[intelfpga::force_pow2_depth(C)]];
 
   struct templ_on_struct_fields {
     int numbanks [[intelfpga::numbanks(A)]] ;
     int bankwidth [[intelfpga::bankwidth(A)]];
     int privatecopies [[intelfpga::private_copies(A)]];
     int maxreplicates [[intelfpga::max_replicates(A)]];
     int bankbits [[intelfpga::bank_bits(A, B)]];
+    int force_p2d [[intelfpga::force_pow2_depth(C)]];
   } s;
 
   // CHECK-DEVICE: %[[FIELD_NUMBANKS:.*]] = getelementptr inbounds %struct.{{.*}}.templ_on_struct_fields{{.*}}
@@ -213,6 +230,9 @@ void attrs_with_template_param() {
   // CHECK-DEVICE: %[[FIELD_BANKBITS:.*]] = getelementptr inbounds %struct.{{.*}}.templ_on_struct_fields{{.*}}
   // CHECK-DEVICE: call i32* @llvm.ptr.annotation.p0i32{{.*}}%[[FIELD_BANKBITS]]{{.*}}[[ANN_bankbits_4_5]]
   s.bankbits = 0;
+  // CHECK-DEVICE: %[[FIELD_FP2D:.*]] = getelementptr inbounds %struct.{{.*}}.templ_on_struct_fields{{.*}}
+  // CHECK-DEVICE: call i32* @llvm.ptr.annotation.p0i32{{.*}}%[[FIELD_FP2D]]{{.*}}[[ANN_force_pow2_depth_1]]
+  s.force_p2d = 0;
 }
 
 void field_addrspace_cast() {
@@ -246,7 +266,7 @@ int main() {
     attrs_on_var();
     attrs_on_struct();
     field_addrspace_cast();
-    attrs_with_template_param<4,5>();
+    attrs_with_template_param<4, 5, 1>();
   });
   return 0;
 }