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Propagate attributes from the llvm dialect during cf canonicalization #2

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Propagate attributes from the llvm dialect during cf canonicalization #2

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19 changes: 16 additions & 3 deletions mlir/lib/Dialect/ControlFlow/IR/ControlFlowOps.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -12,6 +12,8 @@
#include "mlir/Dialect/Arith/IR/Arith.h"
#include "mlir/Dialect/Bufferization/IR/BufferDeallocationOpInterface.h"
#include "mlir/Dialect/Bufferization/IR/BufferizableOpInterface.h"
#include "mlir/Dialect/LLVMIR/LLVMAttrs.h"
#include "mlir/Dialect/LLVMIR/LLVMDialect.h"
#include "mlir/IR/AffineExpr.h"
#include "mlir/IR/AffineMap.h"
#include "mlir/IR/Builders.h"
Expand Down Expand Up @@ -265,9 +267,20 @@ struct SimplifyPassThroughCondBranch : public OpRewritePattern<CondBranchOp> {
return failure();

// Create a new branch with the collapsed successors.
rewriter.replaceOpWithNewOp<CondBranchOp>(condbr, condbr.getCondition(),
trueDest, trueDestOperands,
falseDest, falseDestOperands);
auto newCondbr = rewriter.replaceOpWithNewOp<CondBranchOp>(
condbr, condbr.getCondition(), trueDest, trueDestOperands, falseDest,
falseDestOperands);

// Ensure loop metadata is copied into the new op
rewriter.modifyOpInPlace(newCondbr, [&]() {
SmallVector<NamedAttribute> llvmAttrs;
llvm::copy_if(
condbr->getAttrs(), std::back_inserter(llvmAttrs), [](auto attr) {
return isa<mlir::LLVM::LLVMDialect>(attr.getValue().getDialect());
});
newCondbr->setDiscardableAttrs(llvmAttrs);
});

return success();
}
};
Expand Down
25 changes: 25 additions & 0 deletions mlir/test/Dialect/ControlFlow/canonicalize.mlir
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Original file line number Diff line number Diff line change
Expand Up @@ -118,6 +118,31 @@ func.func @cond_br_passthrough(%arg0 : i32, %arg1 : i32, %arg2 : i32, %cond : i1
return %arg4, %arg5 : i32, i32
}

/// Test that pass-through simplification does not lose metadata
#loop_unroll = #llvm.loop_unroll<disable = false, full = true>
#loop_annotation = #llvm.loop_annotation<unroll = #loop_unroll>
func.func @cond_br_preserve_loop_md(%arg0 : i32, %arg1 : i32, %arg2 : i32, %cond : i1) {
// CHECK-LABEL: @cond_br_preserve_loop_md(
// CHECK: cf.cond_br
// CHECK-SAME: loop_annotation = #loop_annotation
cf.cond_br %cond, ^bb1, ^bb2 {loop_annotation = #loop_annotation}

// CHECK-NEXT: ^bb1:
// CHECK-NEXT: foo.op
// CHECK-NEXT: cf.br
// CHECK-NEXT: ^bb2:
// CHECK-NEXT: return
^bb1:
cf.br ^bb3

^bb2:
"foo.op"() : () -> ()
cf.br ^bb3

^bb3:
return
}

/// Test the failure modes of collapsing CondBranchOp pass-throughs successors.

// CHECK-LABEL: func @cond_br_pass_through_fail(
Expand Down