[AMDGPU] Translate reqd_work_group_size into amdgpu_flat_work_group_size

[rampitec]

Summary

These two attributes specify the same info in a different way.
AMGPU BE only checks the latter as a target specific attribute
as opposed to language specific reqd_work_group_size.

This change produces amdgpu_flat_work_group_size out of
reqd_work_group_size if specified.

[yaxunl]

lib/CodeGen/TargetInfo.cpp

7308

should we emit some warning if they both exist and conflict with each other?

[rampitec]

lib/CodeGen/TargetInfo.cpp

7308

I do not see any diagnostics here beyond asserts. I.e. if we need diagnostics we need it everywhere.

[rampitec]

lib/CodeGen/TargetInfo.cpp

7308

I mean, there is assert below which checks if they disagree. The same way as other errors in attributes checked here.

[rampitec]

Only produce amdgpu_flat_work_group_size if user's attribute is not present.

[rampitec]

lib/CodeGen/TargetInfo.cpp

7308

Actually I think an user shall never use both attributes together. Therefor I have inhibited this if user's attribute already present, deferring the resolution to RT.

[yaxunl]

LGTM. Thanks.

lib/CodeGen/TargetInfo.cpp

void AMDGPUTargetCodeGenInfo::setTargetAttributes(
     llvm::GlobalValue *GV,
     CodeGen::CodeGenModule &M) const {
   const FunctionDecl *FD = dyn_cast_or_null<FunctionDecl>(D);
   if (!FD)
     return;
 
   llvm::Function *F = cast<llvm::Function>(GV);
 
-  if (const auto *Attr = FD->getAttr<AMDGPUFlatWorkGroupSizeAttr>()) {
-    unsigned Min = Attr->getMin();
-    unsigned Max = Attr->getMax();
+  const auto *ReqdWGS = M.getLangOpts().OpenCL ?
+    FD->getAttr<ReqdWorkGroupSizeAttr>() : nullptr;
+  const auto *FlatWGS = FD->getAttr<AMDGPUFlatWorkGroupSizeAttr>();
+  if (ReqdWGS || FlatWGS) {
+    unsigned Min = FlatWGS ? FlatWGS->getMin() : 0;
+    unsigned Max = FlatWGS ? FlatWGS->getMax() : 0;
+    if (ReqdWGS && Min == 0 && Max == 0)
+      Min = Max = ReqdWGS->getXDim() * ReqdWGS->getYDim() * ReqdWGS->getZDim();
 
     if (Min != 0) {
       assert(Min <= Max && "Min must be less than or equal Max");
 
       std::string AttrVal = llvm::utostr(Min) + "," + llvm::utostr(Max);
       F->addFnAttr("amdgpu-flat-work-group-size", AttrVal);
     } else
       assert(Max == 0 && "Max must be zero");

test/CodeGenOpenCL/amdgpu-attrs.cl

 kernel void flat_work_group_size_32_64_waves_per_eu_2_num_sgpr_32_num_vgpr_64() {
 // CHECK: define amdgpu_kernel void @flat_work_group_size_32_64_waves_per_eu_2_num_sgpr_32_num_vgpr_64() [[FLAT_WORK_GROUP_SIZE_32_64_WAVES_PER_EU_2_NUM_SGPR_32_NUM_VGPR_64:#[0-9]+]]
 }
 __attribute__((amdgpu_flat_work_group_size(32, 64), amdgpu_waves_per_eu(2, 4), amdgpu_num_sgpr(32), amdgpu_num_vgpr(64))) // expected-no-diagnostics
 kernel void flat_work_group_size_32_64_waves_per_eu_2_4_num_sgpr_32_num_vgpr_64() {
 // CHECK: define amdgpu_kernel void @flat_work_group_size_32_64_waves_per_eu_2_4_num_sgpr_32_num_vgpr_64() [[FLAT_WORK_GROUP_SIZE_32_64_WAVES_PER_EU_2_4_NUM_SGPR_32_NUM_VGPR_64:#[0-9]+]]
 }
 
+__attribute__((reqd_work_group_size(32, 2, 1))) // expected-no-diagnostics
+kernel void reqd_work_group_size_32_2_1() {
+// CHECK: define amdgpu_kernel void @reqd_work_group_size_32_2_1() [[FLAT_WORK_GROUP_SIZE_64_64:#[0-9]+]]
+}
+__attribute__((reqd_work_group_size(32, 2, 1), amdgpu_flat_work_group_size(16, 128))) // expected-no-diagnostics
+kernel void reqd_work_group_size_32_2_1_flat_work_group_size_16_128() {
+// CHECK: define amdgpu_kernel void @reqd_work_group_size_32_2_1_flat_work_group_size_16_128() [[FLAT_WORK_GROUP_SIZE_16_128:#[0-9]+]]
+}
+
+
 // Make sure this is silently accepted on other targets.
 // X86-NOT: "amdgpu-flat-work-group-size"
 // X86-NOT: "amdgpu-waves-per-eu"
 // X86-NOT: "amdgpu-num-vgpr"
 // X86-NOT: "amdgpu-num-sgpr"
 
 // CHECK-NOT: "amdgpu-flat-work-group-size"="0,0"
 // CHECK-NOT: "amdgpu-waves-per-eu"="0"
 // CHECK-NOT: "amdgpu-waves-per-eu"="0,0"
 // CHECK-NOT: "amdgpu-num-sgpr"="0"
 // CHECK-NOT: "amdgpu-num-vgpr"="0"
 
 // CHECK-DAG: attributes [[FLAT_WORK_GROUP_SIZE_32_64]] = { noinline nounwind "amdgpu-flat-work-group-size"="32,64"
+// CHECK-DAG: attributes [[FLAT_WORK_GROUP_SIZE_64_64]] = { noinline nounwind "amdgpu-flat-work-group-size"="64,64"
+// CHECK-DAG: attributes [[FLAT_WORK_GROUP_SIZE_16_128]] = { noinline nounwind "amdgpu-flat-work-group-size"="16,128"
 // CHECK-DAG: attributes [[WAVES_PER_EU_2]] = { noinline nounwind "amdgpu-waves-per-eu"="2"
 // CHECK-DAG: attributes [[WAVES_PER_EU_2_4]] = { noinline nounwind "amdgpu-waves-per-eu"="2,4"
 // CHECK-DAG: attributes [[NUM_SGPR_32]] = { noinline nounwind "amdgpu-num-sgpr"="32"
 // CHECK-DAG: attributes [[NUM_VGPR_64]] = { noinline nounwind "amdgpu-num-vgpr"="64"
 
 // CHECK-DAG: attributes [[FLAT_WORK_GROUP_SIZE_32_64_WAVES_PER_EU_2]] = { noinline nounwind "amdgpu-flat-work-group-size"="32,64" "amdgpu-waves-per-eu"="2"
 // CHECK-DAG: attributes [[FLAT_WORK_GROUP_SIZE_32_64_WAVES_PER_EU_2_4]] = { noinline nounwind "amdgpu-flat-work-group-size"="32,64" "amdgpu-waves-per-eu"="2,4"
 // CHECK-DAG: attributes [[FLAT_WORK_GROUP_SIZE_32_64_NUM_SGPR_32]] = { noinline nounwind "amdgpu-flat-work-group-size"="32,64" "amdgpu-num-sgpr"="32"