DPDK backend: Add support for tuple expressions in transition select statement #2836

usha1830 · 2021-07-02T19:16:33Z

This PR adds support for the tuple expressions in transition select statement.
The changes include:

New function for handling the tuple expressions.
New helpers functions to refactor some of existing code.

Added new tests and reference outputs

The tuple expressions are evaluated as exact match of each element in the tuple and is
translated to dpdk assembly by short-circuiting the conditions where beginning of each keyset
starts with a unique case label.

   transition select(a,b) {      
          (a1, b1) : state1;
          (a2, b2) : state2;        
          (a3, b3) : state3;        
          }                         
      is evaluated as               
      if (a == a1 && b == b1)       
          goto state1               
      else (a == a2 && b == b2)     
          goto state2               
      .....
      
   Equivalent dpdk assembly:                            
    
   jmpneq case1 a, a1
   jmpneq case1 b, b1
   jmp state1
   case1:   jmpneq case2 a, a2
   jmpneq case2 b, b2
   jmp state2
   case2:    jmpneq case a, a3
   jmpneq case2 b, b3
   jmp state3
   ....

1) Add missing regarray declarations 2) Fix read() method implementation

…n objects and methods in/from control blocks only

- Disabled Midend predication pass to allow conditional operator to be splitted into if-else statement - Added a new test and reference output for conditional operator

…ce output

…830/p4c into ushag_conditional_operator

…ement. Fixed few typos

hesingh · 2021-07-02T21:40:02Z

Why don't you first use the SingleArgumentSelect midend pass in dpdk midend.cpp and then change the dpdk backend like #2827 has done?

mihaibudiu · 2021-07-03T01:38:23Z

If dpdk is limited to 64 bits per value this implementation is more general

…statement

mihaibudiu · 2021-07-04T06:24:16Z

backends/dpdk/dpdkProgram.cpp

+        auto left = maskexpr->left;
+        auto right = maskexpr->right;
+        /* Dpdk architecture requires that both operands of &&& be constants */
+        if (!left->is<IR::Constant>() || !left->is<IR::Constant>()) {


You are using the same expression twice.

Thanks for catching this. When I tried hitting this error with a testcase, I see this condition is already checked by midend in DoSimplifySelectCases pass. So will remove this error check altogether.

backends/dpdk/dpdkProgram.cpp

usha1830 · 2021-07-05T14:17:54Z

Why don't you first use the SingleArgumentSelect midend pass in dpdk midend.cpp and then change the dpdk backend like #2827 has done?

I don't see any benefit in using the SingleArgumentSelect pass as there is no corresponding assembly instruction for concat operator and we will have to ultimately convert the case value into series of jmpneqs.

mihaibudiu

I will approve, but please consider using a name generator. Maybe you want to file an issue about it.

mihaibudiu · 2021-07-10T04:51:43Z

backends/dpdk/dpdkProgram.cpp

+void ConvertToDpdkParser::getCondVars(const IR::Expression *sv, const IR::Expression *ce,
+                                      IR::Expression **leftExpr, IR::Expression **rightExpr) {
+    if (sv->is<IR::Constant>() && sv->type->width_bits() > 32) {
+        ::error(ErrorType::ERR_UNEXPECTED,


This is a back end constraint so perhaps you should use one of the unsupported errors.

mihaibudiu · 2021-07-10T04:55:52Z

backends/dpdk/dpdkProgram.cpp

+                    /* For each select case, emit the block start label and then a series of
+                       jmp instructions. */
+                    for (auto sc : caseList) {
+                        cstring labelName = state->name + "_" + std::to_string(count++);


This looks like it could generate collisions if some states already have such names. I would always recommend using a name generator, but you have to use it everywhere so it keeps track of all used symbols.

I have updated the code to use refmap->newName() for generating the case label.

… few errors

usha1830 · 2021-07-14T10:45:15Z

@mbudiu-vmw I have updated the code as per your comments. If there are no further comments, could you please merge this PR?

…statement (p4lang#2836) * Fix dpdk regression failure: Duplicates declaration * Fix cpplint errors * Added checks to ensure parameters exist before accessing them * Fix PSA extern Register's implementation 1) Add missing regarray declarations 2) Fix read() method implementation * Updated spec.cpp as per review comments * Emit a warning if Register instantiation is found outside control block * Fixed a typo * Remove restriction for instantiation and invocation of register extern objects and methods in/from control blocks only * Conditional operator support for P4C-DPDK. - Disabled Midend predication pass to allow conditional operator to be splitted into if-else statement - Added a new test and reference output for conditional operator * Changing ternary match to exact in test program, updating the reference output * Added support for range and mask operations in transition select statement. Fixed few typos * Support mask operations in dpdk backend (#1) * Remove pass for inserting temporary mask variables * update reference output * Address review comments * DPDK backend: Add support for tuple expressions in transition select statement * Address review comments for tuple expression support * Use refmap to create label names, use ERR_UNSUPPORTED_ON_TARGET for a few errors * Update test files to include core.p4

usha1830 added 29 commits April 22, 2021 00:28

Fix dpdk regression failure: Duplicates declaration

a805208

Fix cpplint errors

611261b

Added checks to ensure parameters exist before accessing them

9c8e6d2

Merge branch 'master' into ushag/fix_duplicates_declaration

b184e0b

Merge remote-tracking branch 'upstream/master'

c03e07d

Merging with p4lang/p4c repo main branch

c99d261

Merge branch 'p4lang:main' into main

c6a5c12

Fix PSA extern Register's implementation

4817ea2

1) Add missing regarray declarations 2) Fix read() method implementation

Updated spec.cpp as per review comments

bfb6f02

Emit a warning if Register instantiation is found outside control block

f5cfb35

Fixed a typo

5ca47b1

Remove restriction for instantiation and invocation of register exter…

f0c7f9c

…n objects and methods in/from control blocks only

Merge branch 'p4lang:main' into ushag_conditional_operator

f3ab6ad

Conditional operator support for P4C-DPDK.

778cd74

- Disabled Midend predication pass to allow conditional operator to be splitted into if-else statement - Added a new test and reference output for conditional operator

Merge branch 'p4lang:main' into ushag_conditional_operator

2b992a4

Changing ternary match to exact in test program, updating the referen…

61567fd

…ce output

Merge branch 'ushag_conditional_operator' of https://github.com/usha1…

009fd24

…830/p4c into ushag_conditional_operator

Merge branch 'p4lang:main' into ushag_conditional_operator

afa8764

Added support for range and mask operations in transition select stat…

05a68ba

…ement. Fixed few typos

Merge branch 'p4lang:main' into origin/ushag/mask_range

d43963c

Support mask operations in dpdk backend (#1)

8b9927f

Remove pass for inserting temporary mask variables

3bde5de

Merge branch 'p4lang:main' into origin/ushag/mask_range

f7cb04d

update reference output

a3e6ef6

Merge branch 'p4lang:main' into origin/ushag/mask_range

6b963ce

Address review comments

8cf5882

Merge branch 'p4lang:main' into origin/ushag/mask_range

00ce76f

Merge branch 'p4lang:main' into origin/ushag/mask_range

32d2abe

Merge branch 'p4lang:main' into origin/ushag/mask_range

d89ed0c

DPDK backend: Add support for tuple expressions in transition select …

8301a85

…statement

mihaibudiu requested changes Jul 4, 2021

View reviewed changes

Address review comments for tuple expression support

a849326

usha1830 requested a review from mihaibudiu July 9, 2021 02:04

mihaibudiu approved these changes Jul 10, 2021

View reviewed changes

usha1830 added 2 commits July 11, 2021 07:29

Use refmap to create label names, use ERR_UNSUPPORTED_ON_TARGET for a…

ebac98c

… few errors

Update test files to include core.p4

b117ec9

mihaibudiu merged commit 00796e9 into p4lang:main Jul 14, 2021

usha1830 deleted the ushag/tuple_expression branch August 9, 2021 05:48

usha1830 mentioned this pull request Aug 12, 2021

p4c-dpdk unsupported select expression(s) #2692

Closed

kfcripps mentioned this pull request Apr 16, 2024

[#4614] Unconditionally copy dpdk p4include files to the binary directory #4615

Merged

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DPDK backend: Add support for tuple expressions in transition select statement #2836

DPDK backend: Add support for tuple expressions in transition select statement #2836

usha1830 commented Jul 2, 2021

hesingh commented Jul 2, 2021

mihaibudiu commented Jul 3, 2021

mihaibudiu Jul 4, 2021

usha1830 Jul 5, 2021

usha1830 commented Jul 5, 2021

mihaibudiu left a comment

mihaibudiu Jul 10, 2021

usha1830 Jul 12, 2021

mihaibudiu Jul 10, 2021

usha1830 Jul 12, 2021

usha1830 commented Jul 14, 2021

DPDK backend: Add support for tuple expressions in transition select statement #2836

DPDK backend: Add support for tuple expressions in transition select statement #2836

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usha1830 commented Jul 2, 2021

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usha1830 commented Jul 14, 2021