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[TableGen] Don't elide bitconverts in PatFrag fragments.
Summary: In the DAG pattern backend, `SimplifyTree` simplifies a pattern by removing bitconverts between two identical types. But that function is also run on the fragments list in instances of `PatFrags`, in which the types haven't been specified yet. So the input and output of the bitconvert always evaluate to the empty set of types, which makes them compare equal. So the test always passes, and bitconverts are unconditionally removed from the PatFrag RHS. Fixed by spotting the empty type set and using it to inhibit the optimization. Reviewers: nhaehnle, hfinkel Reviewed By: nhaehnle Subscribers: llvm-commits Tags: #llvm Differential Revision: https://reviews.llvm.org/D74627
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// RUN: llvm-tblgen -gen-dag-isel -I %p/../../include %s 2>&1 | FileCheck %s | ||
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include "llvm/Target/Target.td" | ||
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// Minimal Target definition | ||
def DemoInstrInfo : InstrInfo; | ||
def Demo : Target { | ||
let InstructionSet = DemoInstrInfo; | ||
} | ||
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// Some registers which can hold ints or floats | ||
foreach i = 0-7 in | ||
def "R" # i: Register<"r" # i>; | ||
def GPR : RegisterClass<"Demo", [i32, f32], 32, (sequence "R%u", 0, 7)>; | ||
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// Instruction to convert an int to a float | ||
def i2f : Instruction { | ||
let Size = 2; | ||
let OutOperandList = (outs GPR:$dst); | ||
let InOperandList = (ins GPR:$src); | ||
let AsmString = "i2f $dst, $src"; | ||
} | ||
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// Some kind of special type-conversion node supported by this target | ||
def specialconvert : SDNode<"TEST_TARGET_ISD::SPECIAL_CONVERT", SDTUnaryOp>; | ||
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// A PatFrags that matches either bitconvert or the special version | ||
def anyconvert : PatFrags<(ops node:$src), | ||
[(bitconvert node:$src), | ||
(specialconvert node:$src)]>; | ||
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// And a rule that matches that PatFrag and turns it into i2f | ||
def : Pat<(f32 (anyconvert (i32 GPR:$val))), (i2f GPR:$val)>; | ||
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// CHECK: SwitchOpcode{{.*}}ISD::BITCAST | ||
// CHECK: MorphNodeTo1{{.*}}i2f | ||
// CHECK: SwitchOpcode{{.*}}TEST_TARGET_ISD::SPECIAL_CONVERT | ||
// CHECK: MorphNodeTo1{{.*}}i2f |
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