[SwitchToIf] support multi-result scf.index_switch + add regression test #9245
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@cowardsa could you review it ? thanks. |
cowardsa
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Nov 21, 2025
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| // CHECK: %[[CDEF:.*]] = arith.constant 30 : i32 | ||
| // CHECK: %[[FDEF:.*]] = arith.constant 3.000000e+00 : f32 | ||
| // CHECK: scf.yield %[[CDEF]], %[[FDEF]] : i32, f32 |
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Amusing observation - C default -> CDEF (just thought you'd written a string of letters)
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Just realizing that, Constant of the default case in my mind..
lib/Transforms/IndexSwitchToIf.cpp
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| Value switchOperand = adaptor.getArg(); | ||
| if (!switchOperand) | ||
| switchOperand = switchOp.getOperand(); |
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If getArg fails I would have thought this should be a failure? I.e. return failure(); as then the operator is not satisfying its definition?
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Good catch, I addressed that the simplest possible way @cowardsa
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Changes look good to me - will merge once actions have run |
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Motivation
Many of CIRCT’s hardware lowering paths (HW/Handshake, HLS) emit
scf.index_switchoperations whose cases drive more than one signal (e.g., a mux returning both data
and a valid flag). The existing
switch-to-ifpass only threaded the first resultthrough the nested
scf.ifchain, so multi-result switches either lost data orcrashed during conversion.
Summary of changes
lib/Transforms/IndexSwitchToIf.cppso the conversion pattern threadsthe entire result tuple through each nested
scf.if(using the adaptor’sswitch operand when available) and replaces the original switch with every
result value.
test/Transforms/switch-to-if.mlircoverage for a switch that yields(i32,f32)to ensure every result survives the transformation.