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⚡ Avoid redundant target-compilation liveness analysis #2180

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Merged
simon1hofmann merged 1 commit into from
Sep 2, 2026
Merged

⚡ Avoid redundant target-compilation liveness analysis #2180

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1 change: 0 additions & 1 deletion mlir/lib/Compiler/TargetCompilation.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -34,7 +34,6 @@ void populateTargetCompilationPipeline(OpPassManager& pm,
populateQCOCleanupPipeline(pm);
pm.addPass(qco::createTargetNativeSynthesis(target));
pm.addPass(createCSEPass());
pm.addPass(createRemoveDeadValuesPass());
pm.addPass(qco::createVerifyTargetConformance(target));
}

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62 changes: 62 additions & 0 deletions mlir/unittests/Compiler/test_compiler_pipeline.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -57,6 +57,7 @@
#include <mlir/Parser/Parser.h>
#include <mlir/Pass/PassManager.h>
#include <mlir/Support/LLVM.h>
#include <mlir/Transforms/Passes.h>

#include <cctype>
#include <cstddef>
Expand Down Expand Up @@ -1382,6 +1383,67 @@ TEST_F(CompilerPipelineTest, QCOProgramCompilesForTarget) {
EXPECT_FALSE(unsupportedQCO->compileForTarget(makeSparseUCZTarget(false)));
}

/// Test that target compilation leaves dead-value cleanup at a fixed point.
TEST_F(CompilerPipelineTest,
TargetCompilationLeavesDeadValueCleanupAtFixedPoint) {
constexpr llvm::StringLiteral source = R"mlir(
module {
func.func private @forward(%condition: i1) -> i1 {
return %condition : i1
}
func.func @main(%condition: i1)
attributes {mqt.entry_point} {
%q0 = qco.alloc : !qco.qubit
%q1 = qco.alloc : !qco.qubit
%forwarded = func.call @forward(%condition) : (i1) -> i1
%q2, %q3 = qco.if %forwarded
args(%control = %q0, %target = %q1)
-> (!qco.qubit, !qco.qubit) {
%controlOut, %targetOut = qco.ctrl(%control)
targets(%targetArg = %target) {
%x = qco.x %targetArg : !qco.qubit -> !qco.qubit
qco.yield %x : !qco.qubit
} : ({!qco.qubit}, {!qco.qubit})
-> ({!qco.qubit}, {!qco.qubit})
%h = qco.h %controlOut : !qco.qubit -> !qco.qubit
qco.yield %h, %targetOut : !qco.qubit, !qco.qubit
} else args(%control = %q0, %target = %q1) {
%x0 = qco.x %control : !qco.qubit -> !qco.qubit
%x1 = qco.x %target : !qco.qubit -> !qco.qubit
qco.yield %x0, %x1 : !qco.qubit, !qco.qubit
}
qco.sink %q2 : !qco.qubit
qco.sink %q3 : !qco.qubit
return
}
}
)mlir";

auto program = QCOProgram::fromMLIRString(source.str());
ASSERT_TRUE(program);
using TargetOperation = CompilerTarget::Operation;
std::vector operations{llvm::cantFail(TargetOperation::create("u", 1, 3)),
llvm::cantFail(TargetOperation::create("cz", 2, 0))};
auto target = llvm::cantFail(CompilerTarget::create(
2, std::vector<CompilerTarget::Coupling>{{0, 1}}, std::move(operations)));

ASSERT_TRUE(program->compileForTarget(target));
const std::string before = program->str();
EXPECT_NE(before.find("func.func private @forward"), std::string::npos);
EXPECT_NE(before.find("call @forward"), std::string::npos);
EXPECT_NE(before.find("qco.if"), std::string::npos);
EXPECT_NE(before.find("qco.u"), std::string::npos);
EXPECT_NE(before.find("qco.ctrl"), std::string::npos);
EXPECT_NE(before.find("qco.z"), std::string::npos);
EXPECT_EQ(before.find("qco.h"), std::string::npos);
EXPECT_EQ(before.find("qco.x"), std::string::npos);

PassManager pm(program->module().getContext());
pm.addPass(createRemoveDeadValuesPass());
ASSERT_TRUE(pm.run(program->module()).succeeded());
EXPECT_EQ(program->str(), before);
}

TEST_F(CompilerPipelineTest, QCOProgramCompilesDynamicRunForSupportedTargets) {
constexpr llvm::StringLiteral source = R"mlir(module {
func.func @main(%theta: f64 {mqt.input_name = "theta"}) attributes {mqt.entry_point} {
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