llvm-reduce: call simplifyCFG on individual basic blocks

[regehr]

Summary

this pass calls simplifyCFG on individual basic blocks; we want this
so that we can reduce away incidental parts of the CFG in cases where
the full simplifyCFG pass would make the test case uninteresting

[aeubanks]

looks like the landed commit 2f1fa6242a1fff0743f74b67f9ea6c08259acfa1 didn't contain phab's summary in its commit message

llvm/test/tools/llvm-reduce/simplify-cfg.ll

4

this broke a buildbot with "x6" in the buildbot path :)

https://lab.llvm.org/buildbot#builders/123/builds/12276

fixed in 5a1f864e89ab4a8e43fd12c9ee590b6c4558deb7

[regehr]

In D131920#3724694, @aeubanks wrote:

looks like the landed commit 2f1fa6242a1fff0743f74b67f9ea6c08259acfa1 didn't contain phab's summary in its commit message

Argh, thank you!!

llvm/test/tools/llvm-reduce/simplify-cfg.ll

+; RUN: llvm-reduce --delta-passes=simplify-cfg --test %python --test-arg %p/Inputs/remove-bbs.py -abort-on-invalid-reduction %s -o %t
+
+; RUN: FileCheck --check-prefix=CHECK-FINAL %s --input-file=%t
+; CHECK-FINAL-NOT: x6
+; CHECK-FINAL-NOT: x10
+
+define void @f1(ptr %interesting3, i32 %interesting2) {
+  %x3 = alloca ptr, i32 0, align 8
+  store ptr %interesting3, ptr %interesting3, align 8
+  switch i32 %interesting2, label %interesting1 [
+    i32 0, label %x6
+    i32 1, label %x11
+  ]
+
+x4:
+  %x5 = call ptr @f2()
+  br label %x10
+
+x10:
+  br label %interesting1
+
+x6:
+  br label %x11
+
+x11:
+  br label %interesting1
+
+interesting1:
+  ret void
+}
+
+declare ptr @f2()

llvm/tools/llvm-reduce/CMakeLists.txt

add_llvm_tool(llvm-reduce
   deltas/ReduceOperandsToArgs.cpp
   deltas/ReduceInstructionsMIR.cpp
   deltas/ReduceInstructionFlagsMIR.cpp
   deltas/ReduceIRReferences.cpp
   deltas/ReduceVirtualRegisters.cpp
   deltas/ReduceRegisterMasks.cpp
   deltas/ReduceRegisterDefs.cpp
   deltas/ReduceRegisterUses.cpp
+  deltas/ReduceUsingSimplifyCFG.cpp
   deltas/RunIRPasses.cpp
   deltas/SimplifyInstructions.cpp
   llvm-reduce.cpp
 
   DEPENDS
   intrinsics_gen
   )

llvm/tools/llvm-reduce/DeltaManager.cpp

 #include "deltas/ReduceOperandBundles.h"
 #include "deltas/ReduceOperands.h"
 #include "deltas/ReduceOperandsSkip.h"
 #include "deltas/ReduceOperandsToArgs.h"
 #include "deltas/ReduceRegisterDefs.h"
 #include "deltas/ReduceRegisterMasks.h"
 #include "deltas/ReduceRegisterUses.h"
 #include "deltas/ReduceSpecialGlobals.h"
+#include "deltas/ReduceUsingSimplifyCFG.h"
 #include "deltas/ReduceVirtualRegisters.h"
 #include "deltas/RunIRPasses.h"
 #include "deltas/SimplifyInstructions.h"
 #include "llvm/Support/CommandLine.h"
 
 using namespace llvm;
 
 extern cl::OptionCategory LLVMReduceOptions;
do {                                                                         \
     DELTA_PASS("simplify-instructions", simplifyInstructionsDeltaPass)         \
     DELTA_PASS("ir-passes", runIRPassesDeltaPass)                              \
     DELTA_PASS("operands-zero", reduceOperandsZeroDeltaPass)                   \
     DELTA_PASS("operands-one", reduceOperandsOneDeltaPass)                     \
     DELTA_PASS("operands-nan", reduceOperandsNaNDeltaPass)                     \
     DELTA_PASS("operands-to-args", reduceOperandsToArgsDeltaPass)              \
     DELTA_PASS("operands-skip", reduceOperandsSkipDeltaPass)                   \
     DELTA_PASS("operand-bundles", reduceOperandBundesDeltaPass)                \
+    DELTA_PASS("simplify-cfg", reduceUsingSimplifyCFGDeltaPass)                \
     DELTA_PASS("attributes", reduceAttributesDeltaPass)                        \
     DELTA_PASS("module-data", reduceModuleDataDeltaPass)                       \
   } while (false)
 
 #define DELTA_PASSES_MIR                                                       \
   do {                                                                         \
     DELTA_PASS("instructions", reduceInstructionsMIRDeltaPass)                 \
     DELTA_PASS("ir-instruction-references",                                    \

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

+//===- ReduceUsingSimplifyCFG.h - Specialized Delta Pass ------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a function which calls the Generic Delta pass in order
+// to call SimplifyCFG on individual basic blocks.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_TOOLS_LLVM_REDUCE_DELTAS_SIMPLIFYCFG_H
+#define LLVM_TOOLS_LLVM_REDUCE_DELTAS_SIMPLIFYCFG_H
+
+#include "Delta.h"
+
+namespace llvm {
+void reduceUsingSimplifyCFGDeltaPass(TestRunner &Test);
+} // namespace llvm
+
+#endif

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

+//===- ReduceUsingSimplifyCFG.h - Specialized Delta Pass ------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements a function which calls the Generic Delta pass in order
+// to call SimplifyCFG on individual basic blocks.
+//
+//===----------------------------------------------------------------------===//
+
+#include "ReduceUsingSimplifyCFG.h"
+#include "llvm/Analysis/TargetTransformInfo.h"
+#include "llvm/Transforms/Utils/Local.h"
+
+using namespace llvm;
+
+static void reduceUsingSimplifyCFG(Oracle &O, Module &Program) {
+  SmallVector<BasicBlock *, 16> ToSimplify;
+  for (auto &F : Program)
+    for (auto &BB : F)
+      if (!O.shouldKeep())
+        ToSimplify.push_back(&BB);
+  TargetTransformInfo TTI(Program.getDataLayout());
+  for (auto *BB : ToSimplify)
+    simplifyCFG(BB, TTI);
+}
+
+void llvm::reduceUsingSimplifyCFGDeltaPass(TestRunner &Test) {
+  outs() << "*** Reducing using SimplifyCFG...\n";
+  runDeltaPass(Test, reduceUsingSimplifyCFG);
+}