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RedundantPhiElimination: exclude allocation instructions. #31066

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Merged
merged 1 commit into from
Apr 16, 2020
Merged

RedundantPhiElimination: exclude allocation instructions. #31066

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6 changes: 6 additions & 0 deletions lib/SILOptimizer/Transforms/RedundantPhiElimination.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -175,6 +175,12 @@ bool RedundantPhiEliminationPass::valuesAreEqual(SILValue val1, SILValue val2) {
if (inst1->getMemoryBehavior() != SILInstruction::MemoryBehavior::None)
return false;

// Allocation instructions are defined to have no side-effects.
// Two allocations (even if the instruction look the same) don't define
// the same value.
if (isa<AllocationInst>(inst1))
return false;

auto *inst2 = cast<SingleValueInstruction>(val2);

// Compare the operands by putting them on the worklist.
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20 changes: 20 additions & 0 deletions test/SILOptimizer/redundant_phi_elimination.sil
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Expand Up @@ -5,6 +5,8 @@ sil_stage canonical
import Builtin
import Swift

class X {}

// CHECK-LABEL: sil @test_simple
// CHECK: bb1:
// CHECK: br bb3(%0 : $Builtin.Int64)
Expand Down Expand Up @@ -153,3 +155,21 @@ bb3:
%r = tuple ()
return %r : $()
}

// CHECK-LABEL: sil @test_allocation_inst
// CHECK: alloc_ref
// CHECK: alloc_ref
// CHECK: bb1([[ARG1:%[0-9]+]] : $X, [[ARG2:%[0-9]+]] : $X):
// CHECK: tuple ([[ARG1]] : $X, [[ARG2]] : $X)
// CHECK: } // end sil function 'test_allocation_inst'
sil @test_allocation_inst : $@convention(thin) () -> (X, X) {
bb0:
%1 = alloc_ref $X
%2 = alloc_ref $X
br bb1(%1 : $X, %2 : $X)

bb1(%3 : $X, %4 : $X):
%r = tuple (%3 : $X, %4 : $X)
return %r : $(X, X)
}