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llvm-reduce: Add target-features-attr reduction (llvm#133887)
Try to reduce individual subtarget features in the "target-features" attribute. This attempts a textual removal of the fields in the string, not a semantic removal. Typically there's a lot of redundant feature spam in the feature list implied by the target-cpu (which I really wish clang would stop emitting). If we could parse these out, we could easily drop the fields without testing anything.
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‎llvm/test/tools/llvm-reduce/reduce-target-features-attr.ll

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; RUN: llvm-reduce --abort-on-invalid-reduction --delta-passes=target-features-attr --test FileCheck --test-arg -enable-var-scope --test-arg --check-prefixes=INTERESTING,CHECK --test-arg %s --test-arg --input-file %s -o %t
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; RUN: FileCheck -check-prefixes=RESULT,CHECK %s < %t
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; CHECK: @keep_none_from_one() [[$KEEP_NONE_FROM_ONE:#[0-9]+]]
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define void @keep_none_from_one() #0 {
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ret void
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}
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; CHECK: @keep_one_from_one() [[$KEEP_ONE_FROM_ONE:#[0-9]+]]
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define void @keep_one_from_one() #1 {
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ret void
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}
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; CHECK: @keep_first_from_two() [[$KEEP_FIRST_FROM_TWO:#[0-9]+]]
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define void @keep_first_from_two() #2 {
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ret void
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}
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; CHECK: @keep_second_from_two() [[$KEEP_SECOND_FROM_TWO:#[0-9]+]]
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define void @keep_second_from_two() #3 {
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ret void
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}
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; CHECK: @keep_all_of_two() [[$KEEP_ALL_OF_TWO:#[0-9]+]]
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define void @keep_all_of_two() #4 {
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ret void
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}
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; CHECK: @drop_empty_element() [[$DROP_EMPTY_ELEMENT:#[0-9]+]]
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define void @drop_empty_element() #5 {
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ret void
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}
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; CHECK: @keep_second_from_three() [[$KEEP_SECOND_FROM_THREE:#[0-9]+]]
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define void @keep_second_from_three() #6 {
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ret void
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}
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; RESULT: define void @no_target_features() {
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define void @no_target_features() {
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ret void
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}
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; IR verifier should probably reject this
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; RESULT: define void @no_target_features_value() {
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define void @no_target_features_value() #7 {
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ret void
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}
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attributes #0 = { "target-features"="+foo" "unique-attr-0" }
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attributes #1 = { "target-features"="+foo" "unique-attr-1" }
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attributes #2 = { "target-features"="+first,+second" "unique-attr-2" }
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attributes #3 = { "target-features"="+first,+second" "unique-attr-3" }
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attributes #4 = { "target-features"="+first,+second" "unique-attr-4" }
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attributes #5 = { "target-features"="+dead,,+beef" "unique-attr-5" }
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attributes #6 = { "target-features"="+a,+b,+c" "unique-attr-6" }
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attributes #7 = { "target-features" }
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; INTERESTING-DAG: [[$KEEP_ONE_FROM_ONE]] = { "target-features"="+foo"
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; INTERESTING-DAG: [[$KEEP_FIRST_FROM_TWO]] = { "target-features"="{{.*}}+first
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; INTERESTING-DAG: [[$KEEP_SECOND_FROM_TWO]] = { "target-features"="{{.*}}+second
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; INTERESTING-DAG: [[$KEEP_ALL_OF_TWO]] = { "target-features"="{{.*}}+first,+second
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; INTERESTING-DAG: [[$DROP_EMPTY_ELEMENT]] = { "target-features"="{{.*}}+dead{{.*}}+beef
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; INTERESTING-DAG: [[$KEEP_SECOND_FROM_THREE]] = { "target-features"="{{.*}}+b
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; RESULT-DAG: attributes [[$KEEP_NONE_FROM_ONE]] = { "unique-attr-0" }
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; RESULT-DAG: [[$KEEP_FIRST_FROM_TWO]] = { "target-features"="+first" "unique-attr-2" }
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; RESULT-DAG: [[$KEEP_SECOND_FROM_TWO]] = { "target-features"="+second" "unique-attr-3" }
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; RESULT-DAG: [[$KEEP_ALL_OF_TWO]] = { "target-features"="+first,+second" "unique-attr-4" }
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; RESULT-DAG: [[$DROP_EMPTY_ELEMENT]] = { "target-features"="+dead,+beef" "unique-attr-5" }
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; RESULT-DAG: [[$KEEP_SECOND_FROM_THREE]] = { "target-features"="+b" "unique-attr-6" }

‎llvm/tools/llvm-reduce/CMakeLists.txt

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deltas/ReduceRegisterMasks.cpp
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deltas/ReduceRegisterDefs.cpp
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deltas/ReduceRegisterUses.cpp
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deltas/ReduceTargetFeaturesAttr.cpp
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deltas/ReduceUsingSimplifyCFG.cpp
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deltas/RunIRPasses.cpp
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deltas/SimplifyInstructions.cpp

‎llvm/tools/llvm-reduce/DeltaManager.cpp

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#include "deltas/ReduceRegisterMasks.h"
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#include "deltas/ReduceRegisterUses.h"
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#include "deltas/ReduceSpecialGlobals.h"
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#include "deltas/ReduceTargetFeaturesAttr.h"
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#include "deltas/ReduceUsingSimplifyCFG.h"
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#include "deltas/ReduceVirtualRegisters.h"
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#include "deltas/RunIRPasses.h"

‎llvm/tools/llvm-reduce/DeltaPasses.def

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DELTA_PASS_IR("operands-skip", reduceOperandsSkipDeltaPass, "Reducing operands by skipping over instructions")
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DELTA_PASS_IR("operand-bundles", reduceOperandBundesDeltaPass, "Reducing Operand Bundles")
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DELTA_PASS_IR("attributes", reduceAttributesDeltaPass, "Reducing Attributes")
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DELTA_PASS_IR("target-features-attr", reduceTargetFeaturesAttrDeltaPass, "Reducing target-features")
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DELTA_PASS_IR("module-data", reduceModuleDataDeltaPass, "Reducing Module Data")
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DELTA_PASS_IR("opcodes", reduceOpcodesDeltaPass, "Reducing Opcodes")
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DELTA_PASS_IR("volatile", reduceVolatileInstructionsDeltaPass, "Reducing Volatile Instructions")

‎llvm/tools/llvm-reduce/deltas/ReduceTargetFeaturesAttr.cpp

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//===- ReduceTargetFeaturesAttr.cpp - Specialized Delta Pass --------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// Attempt to remove individual elements of the "target-features" attribute on
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// functions.
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//
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//===----------------------------------------------------------------------===//
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#include "ReduceTargetFeaturesAttr.h"
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#include "llvm/ADT/SmallString.h"
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#include "llvm/ADT/StringExtras.h"
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#include "llvm/IR/Function.h"
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// TODO: We could maybe do better if we did a semantic parse of the attributes
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// through MCSubtargetInfo. Features can be flipped on and off in the string,
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// some are implied by target-cpu and can't be meaningfully re-added.
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void llvm::reduceTargetFeaturesAttrDeltaPass(Oracle &O,
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ReducerWorkItem &WorkItem) {
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Module &M = WorkItem.getModule();
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SmallString<256> NewValueString;
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SmallVector<StringRef, 32> SplitFeatures;
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for (Function &F : M) {
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Attribute TargetFeaturesAttr = F.getFnAttribute("target-features");
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if (!TargetFeaturesAttr.isValid())
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continue;
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StringRef TargetFeatures = TargetFeaturesAttr.getValueAsString();
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TargetFeatures.split(SplitFeatures, ',', /*MaxSplit=*/-1,
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/*KeepEmpty=*/false);
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ListSeparator LS(",");
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{
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raw_svector_ostream OS(NewValueString);
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for (StringRef Feature : SplitFeatures) {
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if (O.shouldKeep())
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OS << LS << Feature;
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}
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}
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if (NewValueString.empty())
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F.removeFnAttr("target-features");
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else
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F.addFnAttr("target-features", NewValueString);
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SplitFeatures.clear();
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NewValueString.clear();
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}
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}

‎llvm/tools/llvm-reduce/deltas/ReduceTargetFeaturesAttr.h

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//===- ReduceTargetFeaturesAttr.h - Specialized Delta Pass ------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// This file implements a function which calls the Generic Delta pass in order
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// to reduce uninteresting attributes.
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TOOLS_LLVM_REDUCE_DELTAS_REDUCETARGETFEATURESATTR_H
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#define LLVM_TOOLS_LLVM_REDUCE_DELTAS_REDUCETARGETFEATURESATTR_H
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#include "Delta.h"
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namespace llvm {
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void reduceTargetFeaturesAttrDeltaPass(Oracle &O, ReducerWorkItem &WorkItem);
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} // namespace llvm
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#endif

‎llvm/utils/gn/secondary/llvm/tools/llvm-reduce/BUILD.gn

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"deltas/ReduceRegisterDefs.cpp",
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"deltas/ReduceRegisterMasks.cpp",
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"deltas/ReduceRegisterUses.cpp",
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"deltas/ReduceTargetFeaturesAttr.cpp",
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"deltas/ReduceSpecialGlobals.cpp",
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"deltas/ReduceUsingSimplifyCFG.cpp",
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"deltas/ReduceVirtualRegisters.cpp",

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