Author: Henrich Lauko Date: 2025-12-23T13:40:56+01:00 New Revision: 60620d08916ff3d362b4a9360b7b5ab818d4badb
URL: https://github.com/llvm/llvm-project/commit/60620d08916ff3d362b4a9360b7b5ab818d4badb DIFF: https://github.com/llvm/llvm-project/commit/60620d08916ff3d362b4a9360b7b5ab818d4badb.diff LOG: [CIR] Canonicalization: leverage MLIR traits and folding (#173305) Replace custom rewrite patterns with dedicated fold implementations for ScopeOp, or rely on DCE in cases of effect-less SwitchOp. Added: Modified: clang/include/clang/CIR/Dialect/IR/CIROps.td clang/lib/CIR/Dialect/IR/CIRDialect.cpp clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp clang/test/CIR/Transforms/canonicalize.cir Removed: ################################################################################ diff --git a/clang/include/clang/CIR/Dialect/IR/CIROps.td b/clang/include/clang/CIR/Dialect/IR/CIROps.td index 86ea5fca75200..8358b076ee7b6 100644 --- a/clang/include/clang/CIR/Dialect/IR/CIROps.td +++ b/clang/include/clang/CIR/Dialect/IR/CIROps.td @@ -842,7 +842,7 @@ defvar CIR_YieldableScopes = [ ]; def CIR_YieldOp : CIR_Op<"yield", [ - ReturnLike, Terminator, ParentOneOf<CIR_YieldableScopes> + ReturnLike, Terminator, ParentOneOf<CIR_YieldableScopes>, NoMemoryEffect ]> { let summary = "Represents the default branching behaviour of a region"; let description = [{ @@ -999,7 +999,8 @@ def CIR_ResumeFlatOp : CIR_Op<"resume.flat", [ def CIR_ScopeOp : CIR_Op<"scope", [ DeclareOpInterfaceMethods<RegionBranchOpInterface>, - RecursivelySpeculatable, AutomaticAllocationScope, NoRegionArguments + RecursivelySpeculatable, AutomaticAllocationScope, NoRegionArguments, + RecursiveMemoryEffects ]> { let summary = "Represents a C/C++ scope"; let description = [{ @@ -1026,6 +1027,7 @@ def CIR_ScopeOp : CIR_Op<"scope", [ let results = (outs Optional<CIR_AnyType>:$results); let regions = (region AnyRegion:$scopeRegion); + let hasFolder = 1; let hasVerifier = 1; let skipDefaultBuilders = 1; let assemblyFormat = [{ @@ -1104,7 +1106,8 @@ def CIR_CaseOp : CIR_Op<"case", [ def CIR_SwitchOp : CIR_Op<"switch", [ SameVariadicOperandSize, DeclareOpInterfaceMethods<RegionBranchOpInterface>, - RecursivelySpeculatable, AutomaticAllocationScope, NoRegionArguments + RecursivelySpeculatable, AutomaticAllocationScope, NoRegionArguments, + RecursiveMemoryEffects ]> { let summary = "Switch operation"; let description = [{ diff --git a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp index cca13a243c419..8f0dc705181e6 100644 --- a/clang/lib/CIR/Dialect/IR/CIRDialect.cpp +++ b/clang/lib/CIR/Dialect/IR/CIRDialect.cpp @@ -1240,6 +1240,27 @@ LogicalResult cir::ScopeOp::verify() { return success(); } +LogicalResult cir::ScopeOp::fold(FoldAdaptor /*adaptor*/, + SmallVectorImpl<OpFoldResult> &results) { + // Only fold "trivial" scopes: a single block containing only a `cir.yield`. + if (!getRegion().hasOneBlock()) + return failure(); + Block &block = getRegion().front(); + if (block.getOperations().size() != 1) + return failure(); + + auto yield = dyn_cast<cir::YieldOp>(block.front()); + if (!yield) + return failure(); + + // Only fold when the scope produces a value. + if (getNumResults() != 1 || yield.getNumOperands() != 1) + return failure(); + + results.push_back(yield.getOperand(0)); + return success(); +} + //===----------------------------------------------------------------------===// // BrOp //===----------------------------------------------------------------------===// diff --git a/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp b/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp index 0749c5e79e3ff..6a0c46e546cd5 100644 --- a/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp +++ b/clang/lib/CIR/Dialect/Transforms/CIRCanonicalize.cpp @@ -66,42 +66,6 @@ struct RemoveRedundantBranches : public OpRewritePattern<BrOp> { } }; -struct RemoveEmptyScope : public OpRewritePattern<ScopeOp> { - using OpRewritePattern<ScopeOp>::OpRewritePattern; - - LogicalResult matchAndRewrite(ScopeOp op, - PatternRewriter &rewriter) const final { - // TODO: Remove this logic once CIR uses MLIR infrastructure to remove - // trivially dead operations - if (op.isEmpty()) { - rewriter.eraseOp(op); - return success(); - } - - Region ®ion = op.getScopeRegion(); - if (region.getBlocks().front().getOperations().size() == 1 && - isa<YieldOp>(region.getBlocks().front().front())) { - rewriter.eraseOp(op); - return success(); - } - - return failure(); - } -}; - -struct RemoveEmptySwitch : public OpRewritePattern<SwitchOp> { - using OpRewritePattern<SwitchOp>::OpRewritePattern; - - LogicalResult matchAndRewrite(SwitchOp op, - PatternRewriter &rewriter) const final { - if (!(op.getBody().empty() || isa<YieldOp>(op.getBody().front().front()))) - return failure(); - - rewriter.eraseOp(op); - return success(); - } -}; - //===----------------------------------------------------------------------===// // CIRCanonicalizePass //===----------------------------------------------------------------------===// @@ -124,8 +88,7 @@ struct CIRCanonicalizePass void populateCIRCanonicalizePatterns(RewritePatternSet &patterns) { // clang-format off patterns.add< - RemoveRedundantBranches, - RemoveEmptyScope + RemoveRedundantBranches >(patterns.getContext()); // clang-format on } @@ -138,7 +101,6 @@ void CIRCanonicalizePass::runOnOperation() { // Collect operations to apply patterns. llvm::SmallVector<Operation *, 16> ops; getOperation()->walk([&](Operation *op) { - assert(!cir::MissingFeatures::switchOp()); assert(!cir::MissingFeatures::tryOp()); assert(!cir::MissingFeatures::callOp()); diff --git a/clang/test/CIR/Transforms/canonicalize.cir b/clang/test/CIR/Transforms/canonicalize.cir index 5606f9e16a690..de7c90f716398 100644 --- a/clang/test/CIR/Transforms/canonicalize.cir +++ b/clang/test/CIR/Transforms/canonicalize.cir @@ -22,6 +22,19 @@ module { // CHECK-NEXT: cir.return // CHECK-NEXT: } + cir.func @scope_yield_value_fold() -> !u32i { + %0 = cir.const #cir.int<7> : !u32i + %1 = cir.scope { + cir.yield %0 : !u32i + } : !u32i + cir.return %1 : !u32i + } + // CHECK: cir.func{{.*}} @scope_yield_value_fold() -> !u32i { + // CHECK-NEXT: %[[C:.*]] = cir.const #cir.int<7> : !u32i + // CHECK-NOT: cir.scope + // CHECK: cir.return %[[C]] : !u32i + // CHECK-NEXT: } + cir.func @empty_scope() { cir.scope { } @@ -31,6 +44,19 @@ module { // CHECK-NEXT: cir.return // CHECK-NEXT: } + cir.func @dead_switch() { + %0 = cir.const #cir.int<0> : !s32i + cir.switch (%0 : !s32i) { + cir.yield + } + cir.return + } + // CHECK: cir.func{{.*}} @dead_switch() { + // CHECK-NOT: %[[Z:.*]] = cir.const #cir.int<0> : !s32i + // CHECK-NOT: cir.switch + // CHECK-NEXT: cir.return + // CHECK-NEXT: } + cir.func @unary_not(%arg0: !cir.bool) -> !cir.bool { %0 = cir.unary(not, %arg0) : !cir.bool, !cir.bool %1 = cir.unary(not, %0) : !cir.bool, !cir.bool _______________________________________________ cfe-commits mailing list [email protected] https://lists.llvm.org/cgi-bin/mailman/listinfo/cfe-commits
