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Posted to commits@tvm.apache.org by ar...@apache.org on 2021/10/04 23:50:08 UTC

[tvm-rfcs] branch main updated: [RFC] TVM Unified Static Memory Planning (#9)

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areusch pushed a commit to branch main
in repository https://gitbox.apache.org/repos/asf/tvm-rfcs.git


The following commit(s) were added to refs/heads/main by this push:
     new 3834d72  [RFC] TVM Unified Static Memory Planning (#9)
3834d72 is described below

commit 3834d721762d3cba1634e04c790867a0b7de6a82
Author: Manupa Karunaratne <ma...@arm.com>
AuthorDate: Tue Oct 5 00:50:03 2021 +0100

    [RFC] TVM Unified Static Memory Planning (#9)
    
    * [RFC] TVM Unified Static Memory Planning
    
    This commits adds the RFC (.md) for USMP
    
    * [RFC] TVM Unified Static Memory Planning
    
    *Updating the RFC with PR number
    
    * [RFC] TVM Unified Static Memory Planning
    
    * addressing tristan's comments.
    
    Change-Id: Ieb64ae6fc1de12374836c7f754a70b735fe5d379
    
    * [RFC] TVM Unified Static Memory Planning
    
    *Addressing further tristan's comments
    
    Change-Id: I5eabfda362fa85fa4c377d20043f938ffc6de456
    
    * [RFC] TVM Unified Static Memory Planning
    
    * addressed comments
    
    Change-Id: I12fa85e5ea10eee328be4c5d51c9a481a90dedb5
    
    * [RFC] TVM Unified Static Memory Planning
    
    *reflecting the partial changes for tir pinned memory representation
    *addressing Andrew's comments
    
    Change-Id: I40019ecb8e75ba46b1bf415ea70718bbeab3d26b
    
    * [RFC] TVM Unified Static Memory Planning
    
    *explaining the fallback and candidate_memory_pools
    
    Change-Id: Iab59de953bd931fe44ae77004f8c014e25b126f8
    
    * [RFC] TVM Unified Static Memory Planning
    
    * Improving text
    * Adding more specifics to how to handle fallback pool
    * Renamed TVMC arugments to be pools instead of buffer
---
 rfcs/0009_Unified_Static_Memory_Planning.md | 518 ++++++++++++++++++++++++++++
 1 file changed, 518 insertions(+)

diff --git a/rfcs/0009_Unified_Static_Memory_Planning.md b/rfcs/0009_Unified_Static_Memory_Planning.md
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+    Feature Name: Unified Static Memory Planner
+    Start Date: 2021 June 1
+    RFC PR: #0009
+    GitHub Issue: https://github.com/apache/tvm/issues/8404
+
+# Background
+
+Currently, given a ML model primarily TVM will generate two main artifacts :
+
+* A1 : A compilation artifact that describes a sequence of calls to the operators
+  1. If building for graph executor, this would be a JSON
+  2. If building for AoT executor, this would be a main function describing call graph of operators
+  3. If building for VM executor, this would be a series of VM bytecode instructions
+* A2 : library of operators (in the form of runtime.Module)
+* A3 : compiled parameters of the model
+
+A1 is generally created out of lowering the "main" relay function and A2 is created lowering fused relay primitive functions → TIR PrimFuncs → C or LLVM artifacts of the operator library.
+
+### Is there some sort of memory planning already being performed ?
+
+Yes, there is.
+
+For A1, the inter-(fused) operator tensors are visible in the "main" relay function. There exists currently a Relay level pass known as "GraphPlanMemory" that works on the Relay IR to share the space used by tensors which are not live simultaneously and are visible between (fused) operators . Currently, the said pass will use Shared Memory Buffer Object memory planning scheme (See https://blog.tensorflow.org/2020/10/optimizing-tensorflow-lite-runtime.html) to perform the planning.
+
+For A2, the operators are lowered to TIR PrimFuncs. There exist a pass called StorageRewrite that more or less does the same thing as "GraphPlanMemory" but on TIR for the tensors visible within (fused) operators and are not live simultaneously.
+
+# Motivation
+
+For embedded use-cases, its widely accepted that aggressive memory optimizations are vital. Intially we are looking at enabling memory planning for embedded use-cases using the AoT executor.
+
+Therefore, there exist two main shortcomings of the current approach :
+
+* The memory used by intermediary tensors within operators are not shared between memory used by inter-operator tensors.
+
+Example TIR :
+```
+    primfn(placeholder_3: handle, placeholder_4: handle, placeholder_5: handle, T_cast_1: handle) -> ()
+      attr = { "global_symbol" :  "fused_nn_conv2d_add_fixed_point_multiply_clip_cast_cast_21" ,  "tir.noalias" : True}
+      buffers = {T_cast: Buffer(T_cast_2: Pointer(int16), int16, [ 1 ,  56 ,  56 ,  128 ], []),
+      placeholder_2: Buffer(placeholder_6: Pointer(int32), int32, [ 1 ,  1 ,  1 ,  128 ], []),
+      placeholder: Buffer(placeholder_7: Pointer(int16), int16, [ 1 ,  56 ,  56 , 128 ], []),
+      placeholder_1: Buffer(placeholder_8: Pointer(int16), int16, [ 3 ,  3 ,  128 ,  1 ], [])}
+
+       buffer_map = {placeholder_3: placeholder, placeholder_4: placeholder_1, placeholder_5: placeholder_2, T_cast_1: T_cast} {
+       attr [PaddedInput: Pointer(int16)]  "storage_scope" =  "global" ;
+       allocate(PaddedInput, int16, [ 430592 ]);
+       attr [DepthwiseConv2d: Pointer(int32)]  "storage_scope" =  "global" ;
+
+       allocate(DepthwiseConv2d, int32, [ 401408 ]) {
+         for (i1: int32,  0 ,  58 ) {
+           for (i2: int32,  0 ,  58 ) {
+            for(i3: int32,0,128) {
+               PaddedInput[(((i1*7424) + (i2*128)) + i3)] = @tir.if_then_else(((((1<= i1) && (i1 < 57)) && (1<= i2)) && (i2 < 57)), (int16*)placeholder_7[((((i1*7168) + (i2* 128 )) + i3) - 7296)], 0i16, dtype=int16)
+             }
+```
+
+The above TIR snippet shows that two intra operator buffers PaddedInput, DepthwiseConv2d are not visible for optimization by the Relay-level GraphPlanMemory approach.
+
+* Assumption of local optimization : performing sharing inside the operator first and subsequently sharing that workspace with inter-operator tensors, would be sub-optimal.
+
+Thus, for the embedded use-cases, we'd need a unified static memory planner that performs memory planning of all tensors holistically to achieve best memory utilization.
+
+# Goals
+
+G1. There would be no TVMBackendAlloc(/Free)Workspace calls generated for tir.allocates that could be evaluated at compile time.
+
+Currently, the TVM codegen and the AoT executor relies on TVMB(A/F)W calls to increment/decrement a pointer of user provided workspace buffer. By the end of this set of work, if the backend uses Unified Static Memory Planning, there should not be TVMB(A/F)W calls rather correct offset in to the user provided buffer should be codegen'd for allocates for which the size argument could be evaluated at compile time. The dynamically sized allocates will remain untouched, thus will be lowered a [...]
+
+G2. The static memory planning algorithm should be changeable.
+
+There are a variety of memory planning algorithms in discussion with different tradeoffs (See https://discuss.tvm.apache.org/t/discussion-alignment-memory-planning/9730 and https://blog.tensorflow.org/2020/10/optimizing-tensorflow-lite-runtime.html). Depending on the topology and schedules of intermediary buffers, the memory planning algorithm should easily be able to be change able. However, the current design ties the algorithm intimately to the IR constructs – making it harder to modu [...]
+
+G3. Multiple pool support (including constants)
+
+Ideally, the user would expect to provide these buffers in the granularity of the memories they'd want to pin them to. E.g., if there are two RW memories : DRAM and SRAM, the buffers need to be identified and pooled by the compiler. Similiarly for constant data, we need to have a mechanism to allow users to pin them to appropriate memories and addresses. In the IR, they would simply be offsets into the constant buffer(s) provided by the user
+
+
+# Guide-level explanation
+
+NOTE : the embedded runtime interface used in the example are for demonstration purposes and the actual runtime API is defined and discussed [here.](https://discuss.tvm.apache.org/t/rfc-utvm-embedded-c-runtime-interface/9951)
+
+## U1: Most simple use case
+
+### TVMC
+
+
+```
+tvmc compile my_model.tflite --executor=aot --output-format=mlf --target=c
+```
+
+ ### Codegen'd artifacts
+
+
+```
+    `//Codegen'd artifacts in metadata.c (lib0.c)`
+    const TVMModel my_model = {
+       ...
+       .entrypoint = &entrypoint,
+    }
+
+    static uint8_t workspace_buffer[WORKSPACE_BUFFER_SIZE];
+    static const uint8_t parameters_buffer[PARAMETERS_BUFFER_SIZE] = <compiler_generated_constant_data>;
+
+    static int32_t entrypoint(TVMInputs_my_model* inputs, 
+                              TVMOutputs_my_model* outputs,
+                               TVMContext* context){
+        return my_model_main(inputs.input0, 
+                             outputs.output0,
+                             &workspace_buffer,
+                             parameters_buffer,
+                             context.resource_handle);
+    }
+```
+```
+// metadata.h
+
+    typedef struct {
+       uint8_t* input0;
+    }  TVMInputs_my_model;
+
+    typedef struct {
+       uint8_t* output0;
+    }  TVMOutputs_my_model;
+```
+
+### User Application
+```
+
+    // The User Application 
+        extern  const TVMModel my_model;
+           int main(...) {
+                ...
+                TVMInputs_my_model inputs = {my_data};
+                TVMOutputs_my_model outputs = {output_space};
+                TVMExecute(&my_model,
+                           &inputs,
+                           &outputs,  
+                           NULL);
+            }
+```
+## U2: User wants to share workspaces
+
+### TVMC
+```
+    tvmc compile my_model_1.tflite
+    --executor=aot 
+    --output-format=mlf
+    --target=accel,c
+    --usmp-workspace-pools=sram
+    --usmp-workspace-pool-sram= "target=c:rw,accel:rw"
+
+    tvmc compile my_model_2.tflite 
+    --executor=aot
+    --output-format=mlf 
+    --target=accel,c
+    --usmp-workspace-pools=sram
+    --usmp-workspace-pool-sram= "target=c:rw,accel:rw"
+```
+### Codegen'd Artifacts
+```
+    //Codegen'd artifacts in metadata.c (lib0.c)
+    const TVMModel my_model_1 = {
+       ...
+       .entrypoint = &entrypoint,
+    }
+
+    static const uint8_t parameters_buffer[PARAMETERS_BUFFER_SIZE] = <compiler_generated_constant_data>;
+
+     static int32_t entrypoint(TVMInputs_my_model_1* inputs, 
+                               TVMOutputs_my_model_1* outputs, 
+                               TVMContext* context){
+        return my_model_1_main(inputs.input0,
+                               outputs.output0,
+                               parameters_buffer,
+                               context.workspaces.sram, 
+                               context.resource_handle);
+    }
+```
+```
+// metadata.h
+
+    #define TVM_MY_MODEL_1_SRAM_WORKSPACE_BUFFER_SIZE xxxx
+
+    typedef struct {
+       uint8_t* sram;
+    }  TVMWorkspaces_my_model_1;
+
+    typedef struct {
+       uint8_t* input0;
+    }  TVMInputs_my_model_1;
+
+    typedef struct {
+       uint8_t* output0;
+    }  TVMOutputs_my_model_1;
+
+`//Codegen'd artifacts in metadata.c (lib0.c)`
+
+    const TVMModel my_model_2 = {
+       ...
+       .entrypoint = &entrypoint,
+    }
+```
+```
+    static const uint8_t parameters_buffer[PARAMETERS_BUFFER_SIZE] = <compiler_generated_constant_data>;
+
+    static int32_t entrypoint(TVMInputs_my_model_2* inputs, 
+                              TVMOutputs_my_model_2* outputs, 
+                              TVMContext* context){
+        return my_model_2_main(inputs.input0,
+        outputs.output0,
+                              parameters_buffer,
+                              context.workspaces.sram, 
+                              context.resource_handle);
+    }
+```
+```
+// metadata.h
+
+    #define TVM_MY_MODEL_2_SRAM_WORKSPACE_BUFFER_SIZE xxxx
+
+    typedef struct {
+       uint8_t* sram;
+    }  TVMWorkspaces_my_model_2;
+
+    typedef struct {
+       uint8_t* input0;
+    }  TVMInputs_my_model_2;
+
+    typedef struct {
+       uint8_t* output0;
+    }  TVMOutputs_my_model_2;
+```
+### User Application
+```
+    // The User Application    
+        extern  const TVMModel my_model_1;
+        extern  const TVMModel my_model_2;
+
+        // Please calculate the maximum of TVM_MY_MODEL_1_SRAM_WORKSPACE_BUFFER_SIZE and TVM_MY_MODEL_2_SRAM_WORKSPACE_BUFFER_SIZE and define it as TVM_MY_MODELS_COMMON_WORKSPACE_BUFFER_SIZE
+        // Alternatively, user could use a malloc (if permitted and desired) for runtime calculation of the max
+        static uint8_t workspace_buffer[TVM_MY_MODELS_COMMON_WORKSPACE_BUFFER_SIZE];
+
+            int main(...) {
+                ...
+                TVMContext context;
+                TVMInputs_my_model_1 inputs = {my_data_1};
+                TVMOutputs_my_model_1 outputs = {output_space_1};
+                TVMWorkspaces_my_model_1 workspaces1 = {
+                    .sram = &workspace_buffer,
+                };
+                TVMSetWorkspaces(&context, &workspaces1);
+                TVMExecute(&my_model_1, &inputs_1, &outputs_1, &context);
+                ...
+                TVMInputs_my_model_2 inputs = {my_data_2};
+                TVMOutputs_my_model_2 outputs = {output_space_2};
+                TVMWorkspaces_my_model_2 workspaces2 = {
+                    .sram = &workspace_buffer,
+                };
+                TVMSetWorkspaces(&context, &workspaces2);
+                TVMExecute(&my_model_2, &inputs_2, &outputs_2, &context);
+                ...
+            }
+```
+## U3 : User wants to pin buffers to different memories
+
+### TVMC
+```
+    tvmc compile my_model.tflite 
+    --executor=aot 
+    --target=accel,c
+    --usmp-workspace-pools=dtcm,sram
+    --usmp-parameter-pools=itcm,flash
+    --usmp-workspace-pool-dtcm= "target=c;size=1000" # Here the size is more of a hint/guide provided to USMP
+    --usmp-workspace-pool-sram= "target=c,accel"
+    --usmp-parameter-pool-itcm= "target=c;size=5000" # Here the size is more of a hint/guide provided to USMP
+    --usmp-parameter-pool-flash= "target=c,accel"
+```
+### Codegen'd Artifacts
+```
+    //Codegen'd artifacts in metadata.c (lib0.c)
+    const TVMModel my_model = {
+       ...
+       .entrypoint = &entrypoint,
+    }
+
+    static int32_t entrypoint(TVMInputs_my_model* inputs, 
+                               TVMOutputs_my_model* outputs, 
+                               TVMContext* context){
+
+         return my_model_main(inputs.input0,
+                              outputs.output0,
+                              context.workspaces.dtcm,
+                              context.workspaces.sram,
+                              context.parameters.itcm,
+                              context.parameters.flash, 
+                              context.resource_handle);
+    }
+```
+```
+// metadata.h
+
+    #define TVM_MY_MODEL_DTCM_WORKSPACE_BUFFER_SIZE xxxx
+    #define TVM_MY_MODEL_SRAM_WORKSPACE_BUFFER_SIZE xxxx
+    #define TVM_MY_MODEL_ITCM_PARAMETER_BUFFER_SIZE xxxx
+    #define TVM_MY_MODEL_FLASH_PARAMETER_BUFFER_SIZE xxxx
+
+    typedef struct {
+       uint8_t* dtcm;
+       uint8_t* sram;
+    }  TVMWorkspaces_my_model;
+
+    typedef struct {
+       uint8_t* itcm;
+       uint8_t* flash;
+    }  TVMParameters_my_model;
+
+    typedef struct {
+       uint8_t* input0;
+    }  TVMInputs_my_model;
+
+    typedef struct {
+       uint8_t* output0;
+    }  TVMOutputs_my_model;
+```
+### User Application
+```
+    // The User Application 
+        extern  const TVMModel my_model;
+        __attribute__((section( "ITCM" )  const uint8_t   my_model_params_1[TVM_MY_MODEL_ITCM_PARAMETER_BUFFER_SIZE] = <param_1_data>;
+        __attribute__((section( "FLASH" ), aligned( 16 )))  const uint8_t my_model_params_2[TVM_MY_MODEL_FLASH_PARAMETER_BUFFER_SIZE] = <param_2_data>;
+        __attribute__((section( "DTCM" )  static uint8_t workspace_buffer_1[TVM_MY_MODEL_DTCM_WORKSPACE_BUFFER_SIZE];
+        __attribute__((section( "SRAM" ), aligned( 16 )))  static uint8_t workspace_buffer_2[TVM_MY_MODEL_SRAM_WORKSPACE_BUFFER_SIZE];
+
+    int main(...) {
+         ...
+         TVMContext context;
+         TVMInputs_my_model_1 inputs = {input};
+         TVMOutputs_my_model_1 outputs = {output};
+         TVMWorkspaces_my_model workspaces = {
+             .sram = &workspace_buffer_1,
+             .dtcm = &workspace_buffer_2,
+         };
+         TVMParameters_my_model parameters = {
+             .flash = &my_model_params_1,
+             .itcm = &my_model_params_2
+         };
+         TVMSetWorkspaces(&context, &workspaces);
+         TVMSetParameters(&context, parameters);
+         TVMExecute(&my_model, &inputs, &outputs, &context);
+    }
+```
+# Reference-level explanation
+
+## Overview
+
+This should be a IRModule (TIR) → IRModule (TIR) pass.
+
+Inputs :
+* IRModule containing 
+    * AoT TIR PrimFunc (the control function describing the call graph to operators)
+    * All Operator Functions
+    * Each tir.allocate in the IRModule annotated with candidate pools ([Using the annotation field of tir.allocate](https://github.com/apache/tvm-rfcs/blob/c447cbfbd5abceaa7623a0f90cc492784e6f0c0b/rfcs/0023-adding-annotation-field-to-tir.allocate.md))
+
+
+        ```
+        struct PoolInfoNode : public Object {
+        String  pool_name;
+        Integer size_bytes;
+        Integer alignment;
+        Integer pool_offset;
+        Map<Target,String> target_access; // 'rw' or 'ro'
+        }
+        ```
+        The input IRModule is expected to have "candidate_memory_pools" annotation populated with a orderered list of PoolInfo objects. The ordering will indicate to the planner the order of preference each allocate will be pinned to each Pool. The core compiler will run a pass to assign each tir.allocate with candidate_memory_pools based on the target each PrimFunc is executed, prior to invoking the USMP.
+
+
+The idea is USMP will try to pool them using the preferred "candidate_memory_pools" and fallback whenever the size is exceeding the user provided max size for each pool (if any). The fallback only happens if the tir.allocate is annotated with more than one candidate memory pool. Initially, it will take the ordering provided to the TVMC interface.
+
+If the fallback is not desired, the user need not to provide multiple candidate_memory_pools with size constraints to TVMC interface.
+
+If the fallback is not desired by the scheduler, the scheduling passes could remove the memory pools from the candidate_memory_pools.
+
+* How is the fallback pool decided ?
+
+Currently, the pool ordering the user provides to TVMC interface will be used as a priority order for determining pools for tir.allocate/tir.allocate_const nodes (i.e. USMP will try to use highest priority pool for each allocate). Each pool specifies the information on whether it could be acessed by a given set of targets. Therefore, the ordered list of pools will be further filtered by for each allocate node that belongs to different targets.
+
+It is important to note that scheduling stage could remove pools from candidate pools for performance reasons.
+
+
+Outputs : 
+* AoT TIR PrimFunc accepting pool buffers from the user.
+* All Operator functions accepting pool buffers.
+  * Each operator function should address using the correct offset in the correct pool buffer
+
+Special Parametric Inputs : 
+* function : The algorithm to be used for planning From a component PoV, the algorithm is a special input with a defined interface.
+
+The current proposal for the interface of the memory planning algorithm is as follows :
+```
+    struct BufferInfo {
+        String name_hint; // this is the tir.buffer name
+        Integer size_bytes;
+        Integer alignment;
+        Array<BufferInfo> conflicts; //the conflicting bufferinfo objs
+        Array<PoolInfo> pool_candidates;
+    }
+```
+
+```
+    struct PoolAllocation {
+        PoolInfo pool;
+        Integer offset;
+    }
+```
+
+
+```
+Map<BufferInfo, PoolAllocation> (*foo)(Array<BufferInfo> buffers, Map<String, Integer> pool_sizes)
+```
+The memory planning algorithm is expected to return a Map of BufferInfo to PoolAllocation with the planned offsets into respective pool.
+### Special Considerations :
+
+* tir.constants : TIR does not have the ability to represent constants – which is limiting and often leads to having side-channels to carry constants between TIR compiler passes including this one.
+Therefore, in this work as a pre-requisite we should aim to fix this by supporting tir.constants (similiar to relay.constants). Please refer to the [TIR non-scalar constants RFC](https://github.com/apache/tvm-rfcs/pull/22).
+
+* Currently "with" or "let" scopes are tree structured and carry transitive property. E.g, if tensor A is live with tensor B && tensor B is live with tensor C → tensor A is live with tensor C – which may not be true always.
+Thus current "let" or "with" scopes are unable to express liveness information. Therefore, we'd need a side-channel to express this information.
+
+### How the input TIR to USMP should be lowered ?
+
+##### Step 1 : The bound relay.const in Relay IR should be lowered via TE → TIR as tir.constants
+After Step 1 (introducing tir.constants to hold constant data) : the TIR code should like as follows :
+```
+# This snippet shows the format of pre-USMP pseudo TIR code.
+
+    def main(input1: ty.handle, output1: ty.handle):
+       my_model_fused_op1 = tir.allocate(...) # attrs.candidate_memory_pools = ["dtcm", "sram"]
+       my_model_fused_op2 = tir.allocate(...) # attrs.candidate_memory_pools = ["dtcm", "sram"]
+       tir.call("my_model_fused_op1", input1, my_model_fused_op1, fused_op1_weights, fused_op1_biases)
+       tir.call( "my_model_fused_op2" , my_model_fused_op1, my_model_fused_op2, fused_op2_weights, fused_op2_biases)
+
+    def my_model_fused_op1(input : ty.handle, output : ty.handle):
+       tir.func_attr({"global_symbol":"my_model_fused_op1","tir.noalias": True})
+       intermediate_tensor_1 = tir.allocate(...) # attrs.candidate_memory_pools = ["dtcm", "sram"] 
+       intermediate_tensor_2 = tir.allocate(...) # attrs.candidate_memory_pools = ["dtcm", "sram"] 
+       weights = tir.allocate_const(...) # attrs.candidate_memory_pools = ["itcm", "flash"]
+       biases = tir.allocate_const(...) # attrs.candidate_memory_pools = ["itcm", "flash"]
+       ...
+       <compute>
+       ...
+
+    def my_model_fused_op2(input : ty.handle, output : ty.handle):
+       tir.func_attr({"global_symbol":"my_model_fused_op2", "tir.noalias": True})
+       intermediate_tensor_1 = tir.allocate(...) # attrs.candidate_memory_pools = ["dtcm", "sram"]
+       intermediate_tensor_2 = tir.allocate(...) # attrs.candidate_memory_pools = ["dtcm", "sram"]
+       weights = tir.allocate_const(...) # attrs.candidate_memory_pools = ["itcm", "flash"]
+       biases = tir.allocate_const(...) # attrs.candidate_memory_pools = ["itcm", "flash"]
+       ...
+       <compute>
+       ...
+```
+##### Step 2 : Run an analysis pass to populate a Map<BufferInfo, tir.StmtNode> that contains buffer information as defined above (See the struct BufferInfo).
+
+Note : here tir.StmtNode is treated as a Union[tir.AllocateNode, tir.AllocateConstNode]
+
+This actual pass would traverse full TIR program and construct BufferInfo objects that captures liveness conflicts between allocates that are live together.
+
+##### Step 3 : Use the updated Map<BufferInfo, tir.StmtNode> to generate Array\<BufferInfo>
+
+##### Step 4 : Call the provided/default algorithm (void (*foo)(Array<BufferInfo> buffers) to generate Map<BufferInfo, PoolAllocation>
+
+##### Step 5 : Use the updated Map<BufferInfo, PoolAllocation> and Map<BufferInfo, tir.StmtNode> to mutate the IR that would result as following :
+```
+# This snippet shows the format of post-USMP pseudo TIR code.
+
+    def main(input1: ty.handle, output1: ty.handle, params_1 : ty.handle, params_2 : ty.handle, workspace_1 : ty.handle, workspace_2 : ty.handle):
+       tir.call("my_model_fused_op1", input1, params1, params2, workspace_1, workspace_2)
+       tir.call("my_model_fused_op2", params1, params2, workspace_1, workspace_2)
+
+    def my_model_fused_op1(input, params_1, params_2, workspace_1, workspace_2):
+       tir.func_attr({"global_symbol":"my_model_fused_op1","tir.noalias":True})
+       intermediate_tensor_1=tir.load("uint8", workspace_1.data, <offset>)
+       intermediate_tensor_2=tir.load("uint8", workspace_1.data, <offset>)
+       output=tir.load("uint8", workspace_1.data, <offset>)
+       weights=tir.load("uint8", params_1.data, <offset>)
+       biases=tir.load("uint8", params_1.data, <offset>)
+       ...
+       <compute>
+       ...
+
+    def my_model_fused_op2(params_1, params_2, workspace_1, workspace_2):
+       tir.func_attr({"global_symbol":"my_model_fused_op2","tir.noalias":True})
+       input=tir.load("uint8", workspace_1.data, <offset>)
+       intermediate_tensor_1=tir.load("uint8", workspace_1.data, <offset>)
+       intermediate_tensor_2=tir.load("uint8", workspace_2.data, <offset>)
+       output=tir.load("uint8", workspace_2.data, <offset>)
+       weights=tir.load("uint8", params_1.data, <offset>)
+       biases=tir.load("uint8", params_2.data, <offset>)
+       ...
+       <compute>
+       ...
+```
+# Code Structure
+
+* src/tir/usmp/analysis/ -- this is where analysis passes of USMP will live
+    * python/tir/usmp/analysis/ -- python interface to call analysis passes of USMP
+* src/tir/usmp/transforms/ -- this is where transform passes of USMP will live
+    * python/tir/usmp/transform/ -- python interface to call analysis pases of USMP
+* src/tir/usmp/usmp.cc -- this is main intergration of USMP that exposes the full TIR --> TIR transformation as described.
+    * python/tir/usmp/ -- python interface to call the integrated the USMP
+* tests/python/unittest/test_tir_usmp_*.py -- this where unittests for each of the passes and pass pipeline for USMP as a component will live.
+
+
+NOTE : to support tir.constants generally, we'll be enhancing the bound relay.constants to be lowered down to tir.constants to codegen. Those changes will appear through out the stack accordingly.
+
+# Drawbacks
+
+* The relay "main" function that describes the call order to operator PrimFuncs has to be described in TIR to be able to integrate the USMP into the respective executor codegen. However, we dont view this as a major problem as the relay "main" function could easily be lowered to TIR.
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