Handle transitive replacements in Triton kernel mutation analysis

[aakhundov]

Stack from ghstack (oldest at bottom):

• -> Handle transitive replacements in Triton kernel mutation analysis #121867

Summary: Previously, we didn't handle transitive replacements in MLIR walk-based function info mining in the Triton kernel mutation analysis pass. As a result, for the TTIR below:

tt.func private @cumsum__fp32S1_16S__1cconstexpr_1__2cconstexpr_False_(%arg0: tensor<1x16xf32> loc("...":296:0)) -> tensor<1x16xf32> attributes {noinline = false} {
    %0 = "tt.scan"(%arg0) <{axis = 1 : i32, reverse = false}> ({
    ^bb0(%arg1: f32 loc(unknown), %arg2: f32 loc(unknown)):
      %1 = tt.call @_sum_combine__fp32_fp32__(%arg1, %arg2) : (f32, f32) -> f32 loc(#loc16)
      tt.scan.return %1 : f32 loc(#loc16)
    }) : (tensor<1x16xf32>) -> tensor<1x16xf32> loc(#loc16)
    tt.return %0 : tensor<1x16xf32> loc(#loc18)
  } loc(#loc15)

the mined function dict looked like this:

{Intermediate(idx=25): [Op(name='tt.call',
                           fn_call_name='_sum_combine__fp32_fp32__',
                           args=[Intermediate(idx=26),
                                 Intermediate(idx=26)])],
 Intermediate(idx=27): [Op(name='tt.scan.return',
                           fn_call_name=None,
                           args=[Intermediate(idx=25)])],
 Intermediate(idx=-4): [Op(name='tt.return',
                           fn_call_name=None,
                           args=[Intermediate(idx=27)])]}

whereas it should look like this (not the Param(idx=0) arguments of the tt.call):

{Intermediate(idx=25): [Op(name='tt.call',
                           fn_call_name='_sum_combine__fp32_fp32__',
                           args=[Param(idx=0),
                                 Param(idx=0)])],
 Intermediate(idx=27): [Op(name='tt.scan.return',
                           fn_call_name=None,
                           args=[Intermediate(idx=25)])],
 Intermediate(idx=-4): [Op(name='tt.return',
                           fn_call_name=None,
                           args=[Intermediate(idx=27)])]}

This is fixed in the PR.

Test Plan:

$ python test/inductor/test_triton_kernels.py -k test_cumsum
.
----------------------------------------------------------------------
Ran 1 test in 1.771s

OK

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✅ You can merge normally! (2 Unrelated Failures)

As of commit ca91d54 with merge base 70c6f54 ():

FLAKY - The following job failed but was likely due to flakiness present on trunk:

• pull / linux-focal-py3.11-clang10 / test (default, 3, 3, linux.2xlarge) (gh)
  Process completed with exit code 1.

BROKEN TRUNK - The following job failed but was present on the merge base:

👉 Rebase onto the `viable/strict` branch to avoid these failures

• pull / linux-docs / build-docs-python-false (gh)
  Process completed with exit code 1.

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[aakhundov]

@pytorchbot merge

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