AMDGPU: Use inbounds when calculating workitem offset

[arsenm]

Summary

When promoting allocas to LDS, we know we are indexing
into a specific area just created, and the calculation
will also never overflow.

Also emit some of the muls as nsw nuw, because instcombine
infers this already from the range metadata. I think
putting this on the other adds and muls might be OK too,
but I'm not 100% sure.

[arsenm]

Squash with patch that changes vector use to array

[• tstellarAMD]

LGTM.

[arsenm]

r259545

lib/Target/AMDGPU/AMDGPUPromoteAlloca.cpp

void AMDGPUPromoteAlloca::visitAlloca(AllocaInst &I) {
 
   Value *TCntY, *TCntZ;
 
   std::tie(TCntY, TCntZ) = getLocalSizeYZ(Builder);
   Value *TIdX = getWorkitemID(Builder, 0);
   Value *TIdY = getWorkitemID(Builder, 1);
   Value *TIdZ = getWorkitemID(Builder, 2);
 
-  Value *Tmp0 = Builder.CreateMul(TCntY, TCntZ);
+  Value *Tmp0 = Builder.CreateMul(TCntY, TCntZ, "", true, true);
   Tmp0 = Builder.CreateMul(Tmp0, TIdX);
-  Value *Tmp1 = Builder.CreateMul(TIdY, TCntZ);
+  Value *Tmp1 = Builder.CreateMul(TIdY, TCntZ, "", true, true);
   Value *TID = Builder.CreateAdd(Tmp0, Tmp1);
   TID = Builder.CreateAdd(TID, TIdZ);
 
-  std::vector<Value*> Indices;
-  Indices.push_back(Constant::getNullValue(Type::getInt32Ty(Mod->getContext())));
-  Indices.push_back(TID);
+  Value *Indices[] = {
+    Constant::getNullValue(Type::getInt32Ty(Mod->getContext())),
+    TID
+  };
 
-  Value *Offset = Builder.CreateGEP(GVTy, GV, Indices);
+  Value *Offset = Builder.CreateInBoundsGEP(GVTy, GV, Indices);
   I.mutateType(Offset->getType());
   I.replaceAllUsesWith(Offset);
   I.eraseFromParent();
 
   for (std::vector<Value*>::iterator i = WorkList.begin(),
                                      e = WorkList.end(); i != e; ++i) {
     Value *V = *i;
     CallInst *Call = dyn_cast<CallInst>(V);

test/CodeGen/AMDGPU/private-memory.ll

 ; HSAOPT: [[DISPATCH_PTR:%[0-9]+]] = call noalias nonnull dereferenceable(64) i8 addrspace(2)* @llvm.amdgcn.dispatch.ptr()
 ; HSAOPT: [[CAST_DISPATCH_PTR:%[0-9]+]] = bitcast i8 addrspace(2)* [[DISPATCH_PTR]] to i32 addrspace(2)*
 ; HSAOPT: [[GEP0:%[0-9]+]] = getelementptr inbounds i32, i32 addrspace(2)* [[CAST_DISPATCH_PTR]], i64 1
 ; HSAOPT: [[LDXY:%[0-9]+]] = load i32, i32 addrspace(2)* [[GEP0]], align 4, !invariant.load !0
 ; HSAOPT: [[GEP1:%[0-9]+]] = getelementptr inbounds i32, i32 addrspace(2)* [[CAST_DISPATCH_PTR]], i64 2
 ; HSAOPT: [[LDZU:%[0-9]+]] = load i32, i32 addrspace(2)* [[GEP1]], align 4, !range !1, !invariant.load !0
 ; HSAOPT: [[EXTRACTY:%[0-9]+]] = lshr i32 [[LDXY]], 16
 
-; HSAOPT: call i32 @llvm.amdgcn.workitem.id.x(), !range !1
-; HSAOPT: call i32 @llvm.amdgcn.workitem.id.y(), !range !1
-; HSAOPT: call i32 @llvm.amdgcn.workitem.id.z(), !range !1
+; HSAOPT: [[WORKITEM_ID_X:%[0-9]+]] = call i32 @llvm.amdgcn.workitem.id.x(), !range !1
+; HSAOPT: [[WORKITEM_ID_Y:%[0-9]+]] = call i32 @llvm.amdgcn.workitem.id.y(), !range !1
+; HSAOPT: [[WORKITEM_ID_Z:%[0-9]+]] = call i32 @llvm.amdgcn.workitem.id.z(), !range !1
+
+; HSAOPT: [[Y_SIZE_X_Z_SIZE:%[0-9]+]] = mul nuw nsw i32 [[EXTRACTY]], [[LDZU]]
+; HSAOPT: [[YZ_X_XID:%[0-9]+]] = mul i32 [[Y_SIZE_X_Z_SIZE]], [[WORKITEM_ID_X]]
+; HSAOPT: [[Y_X_Z_SIZE:%[0-9]+]] = mul nuw nsw i32 [[WORKITEM_ID_Y]], [[LDZU]]
+; HSAOPT: [[ADD_YZ_X_X_YZ_SIZE:%[0-9]+]] = add i32 [[YZ_X_XID]], [[Y_X_Z_SIZE]]
+; HSAOPT: [[ADD_ZID:%[0-9]+]] = add i32 [[ADD_YZ_X_X_YZ_SIZE]], [[WORKITEM_ID_Z]]
+
+; HSAOPT: [[LOCAL_GEP:%[0-9]+]] = getelementptr inbounds [256 x [5 x i32]], [256 x [5 x i32]] addrspace(3)* @stack, i32 0, i32 [[ADD_ZID]]
+; HSAOPT: %arrayidx1 = getelementptr inbounds [5 x i32], [5 x i32] addrspace(3)* [[LOCAL_GEP]], i32 0, i32 {{%[0-9]+}}
+; HSAOPT: %arrayidx3 = getelementptr inbounds [5 x i32], [5 x i32] addrspace(3)* [[LOCAL_GEP]], i32 0, i32 {{%[0-9]+}}
+; HSAOPT: %arrayidx10 = getelementptr inbounds [5 x i32], [5 x i32] addrspace(3)* [[LOCAL_GEP]], i32 0, i32 0
+; HSAOPT: %arrayidx12 = getelementptr inbounds [5 x i32], [5 x i32] addrspace(3)* [[LOCAL_GEP]], i32 0, i32 1
+
 
 ; NOHSAOPT: call i32 @llvm.r600.read.local.size.y(), !range !0
 ; NOHSAOPT: call i32 @llvm.r600.read.local.size.z(), !range !0
 ; NOHSAOPT: call i32 @llvm.amdgcn.workitem.id.x(), !range !0
 ; NOHSAOPT: call i32 @llvm.amdgcn.workitem.id.y(), !range !0
 ; NOHSAOPT: call i32 @llvm.amdgcn.workitem.id.z(), !range !0
 define void @mova_same_clause(i32 addrspace(1)* nocapture %out, i32 addrspace(1)* nocapture %in) {
 entry: