* decompositions: fuse (x << n) + c to MULACC
MUL→SHL converts x*(2^n) to x<<n before MULACC can fuse (x*c)+y.
Add pattern to also fuse (x<<n)+c → MULACC(x, 2^n, c) for backends
that support both MULACC and SHL.
* test: add test_mulacc_shl for SHL->MULACC fusion
* test: relax test_mulacc_unrolled to >= 4
SHL->MULACC fusion now also catches power-of-2 address calculations,
increasing MULACC count from 4 to 6 on PTX. the test's intent is that
each unrolled multiply is individually fused (not grouped), so >= 4
is the correct assertion.
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Co-authored-by: Prithvish <[email protected]>
Co-authored-by: Nicolas Pinto <[email protected]>
Co-authored-by: Nicolas Pinto <[email protected]>
