[(new) Pass Manager] instantiate SimplifyCFG with the same options as the old PM

The old PM sets the options of what used to be known as "latesimplifycfg" on the 
instantiation after the vectorizers have run, so that's what we'redoing here.

FWIW, there's a later SimplifyCFGPass instantiation in both PMs where we do not 
set the "late" options. I'm not sure if that's intentional or not.

Differential Revision: https://reviews.llvm.org/D39407


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@316869 91177308-0d34-0410-b5e6-96231b3b80d8

Author: rotateright

include/llvm/Transforms/Scalar/SimplifyCFG.h

@@ -31,16 +31,16 @@ class SimplifyCFGPass : public PassInfoMixin<SimplifyCFGPass> {
   SimplifyCFGOptions Options;
 
 public:
-  /// The default constructor sets the pass options to create optimal IR,
-  /// rather than canonical IR. That is, by default we do transformations that
-  /// are likely to improve performance but make analysis more difficult.
-  /// FIXME: This is inverted from what most instantiations of the pass should
-  /// be.
+  /// The default constructor sets the pass options to create canonical IR,
+  /// rather than optimal IR. That is, by default we bypass transformations that
+  /// are likely to improve performance but make analysis for other passes more
+  /// difficult.
   SimplifyCFGPass()
       : SimplifyCFGPass(SimplifyCFGOptions()
-                            .forwardSwitchCondToPhi(true)
-                            .convertSwitchToLookupTable(true)
-                            .needCanonicalLoops(false)) {}
+                            .forwardSwitchCondToPhi(false)
+                            .convertSwitchToLookupTable(false)
+                            .needCanonicalLoops(true)) {}
+
 
   /// Construct a pass with optional optimizations.
   SimplifyCFGPass(const SimplifyCFGOptions &PassOptions);

lib/Passes/PassBuilder.cpp

@@ -751,8 +751,13 @@ PassBuilder::buildModuleOptimizationPipeline(OptimizationLevel Level,
   // Optimize parallel scalar instruction chains into SIMD instructions.
   OptimizePM.addPass(SLPVectorizerPass());
 
-  // Cleanup after all of the vectorizers.
-  OptimizePM.addPass(SimplifyCFGPass());
+  // Cleanup after all of the vectorizers. Simplification passes like CVP and
+  // GVN, loop transforms, and others have already run, so it's now better to
+  // convert to more optimized IR using more aggressive simplify CFG options.
+  OptimizePM.addPass(SimplifyCFGPass(SimplifyCFGOptions().
+                                         forwardSwitchCondToPhi(true).
+                                         convertSwitchToLookupTable(true).
+                                         needCanonicalLoops(false)));
   OptimizePM.addPass(InstCombinePass());
 
   // Unroll small loops to hide loop backedge latency and saturate any parallel

test/Transforms/PhaseOrdering/simplifycfg-options.ll

@@ -1,63 +1,34 @@
 ; NOTE: Assertions have been autogenerated by utils/update_test_checks.py
-; RUN: opt -O1 -S < %s                    | FileCheck %s --check-prefix=OLDPM
-; RUN: opt -passes='default<O1>' -S < %s  | FileCheck %s --check-prefix=NEWPM
+; RUN: opt -O1 -S < %s                    | FileCheck %s --check-prefix=ALL --check-prefix=OLDPM
+; RUN: opt -passes='default<O1>' -S < %s  | FileCheck %s --check-prefix=ALL --check-prefix=NEWPM
 
 ; Don't simplify unconditional branches from empty blocks in simplifyCFG
 ; until late in the pipeline because it can destroy canonical loop structure.
 
-; FIXME: The new pass manager is not limiting simplifycfg at any point in the pipeline,
-; so it performs a transformation before loop optimizations that is avoided in the old PM.
-
 define i1 @PR33605(i32 %a, i32 %b, i32* %c) {
-; OLDPM-LABEL: @PR33605(
-; OLDPM-NEXT:  for.body:
-; OLDPM-NEXT:    [[OR:%.*]] = or i32 [[B:%.*]], [[A:%.*]]
-; OLDPM-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, i32* [[C:%.*]], i64 1
-; OLDPM-NEXT:    [[TMP0:%.*]] = load i32, i32* [[ARRAYIDX]], align 4
-; OLDPM-NEXT:    [[CMP:%.*]] = icmp eq i32 [[OR]], [[TMP0]]
-; OLDPM-NEXT:    br i1 [[CMP]], label [[IF_END:%.*]], label [[IF_THEN:%.*]]
-; OLDPM:       if.then:
-; OLDPM-NEXT:    store i32 [[OR]], i32* [[ARRAYIDX]], align 4
-; OLDPM-NEXT:    tail call void @foo()
-; OLDPM-NEXT:    br label [[IF_END]]
-; OLDPM:       if.end:
-; OLDPM-NEXT:    [[CHANGED_1_OFF0:%.*]] = phi i1 [ true, [[IF_THEN]] ], [ false, [[FOR_BODY:%.*]] ]
-; OLDPM-NEXT:    [[TMP1:%.*]] = load i32, i32* [[C]], align 4
-; OLDPM-NEXT:    [[CMP_1:%.*]] = icmp eq i32 [[OR]], [[TMP1]]
-; OLDPM-NEXT:    br i1 [[CMP_1]], label [[IF_END_1:%.*]], label [[IF_THEN_1:%.*]]
-; OLDPM:       if.then.1:
-; OLDPM-NEXT:    store i32 [[OR]], i32* [[C]], align 4
-; OLDPM-NEXT:    tail call void @foo()
-; OLDPM-NEXT:    br label [[IF_END_1]]
-; OLDPM:       if.end.1:
-; OLDPM-NEXT:    [[CHANGED_1_OFF0_1:%.*]] = phi i1 [ true, [[IF_THEN_1]] ], [ [[CHANGED_1_OFF0]], [[IF_END]] ]
-; OLDPM-NEXT:    ret i1 [[CHANGED_1_OFF0_1]]
-;
-; NEWPM-LABEL: @PR33605(
-; NEWPM-NEXT:  entry:
-; NEWPM-NEXT:    [[OR:%.*]] = or i32 [[B:%.*]], [[A:%.*]]
-; NEWPM-NEXT:    br label [[FOR_COND_OUTER:%.*]]
-; NEWPM:       for.cond.outer:
-; NEWPM-NEXT:    [[I_0_PH:%.*]] = phi i32 [ [[DEC:%.*]], [[IF_THEN:%.*]] ], [ 2, [[ENTRY:%.*]] ]
-; NEWPM-NEXT:    [[CHANGED_0_OFF0_PH:%.*]] = phi i1 [ true, [[IF_THEN]] ], [ false, [[ENTRY]] ]
-; NEWPM-NEXT:    br label [[FOR_COND:%.*]]
-; NEWPM:       for.cond:
-; NEWPM-NEXT:    [[I_0:%.*]] = phi i32 [ [[DEC]], [[FOR_BODY:%.*]] ], [ [[I_0_PH]], [[FOR_COND_OUTER]] ]
-; NEWPM-NEXT:    [[DEC]] = add nsw i32 [[I_0]], -1
-; NEWPM-NEXT:    [[TOBOOL:%.*]] = icmp eq i32 [[I_0]], 0
-; NEWPM-NEXT:    br i1 [[TOBOOL]], label [[FOR_COND_CLEANUP:%.*]], label [[FOR_BODY]]
-; NEWPM:       for.cond.cleanup:
-; NEWPM-NEXT:    ret i1 [[CHANGED_0_OFF0_PH]]
-; NEWPM:       for.body:
-; NEWPM-NEXT:    [[IDXPROM:%.*]] = sext i32 [[DEC]] to i64
-; NEWPM-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, i32* [[C:%.*]], i64 [[IDXPROM]]
-; NEWPM-NEXT:    [[TMP0:%.*]] = load i32, i32* [[ARRAYIDX]], align 4
-; NEWPM-NEXT:    [[CMP:%.*]] = icmp eq i32 [[OR]], [[TMP0]]
-; NEWPM-NEXT:    br i1 [[CMP]], label [[FOR_COND]], label [[IF_THEN]]
-; NEWPM:       if.then:
-; NEWPM-NEXT:    store i32 [[OR]], i32* [[ARRAYIDX]], align 4
-; NEWPM-NEXT:    tail call void @foo()
-; NEWPM-NEXT:    br label [[FOR_COND_OUTER]]
+; ALL-LABEL: @PR33605(
+; ALL-NEXT:  for.body:
+; ALL-NEXT:    [[OR:%.*]] = or i32 [[B:%.*]], [[A:%.*]]
+; ALL-NEXT:    [[ARRAYIDX:%.*]] = getelementptr inbounds i32, i32* [[C:%.*]], i64 1
+; ALL-NEXT:    [[TMP0:%.*]] = load i32, i32* [[ARRAYIDX]], align 4
+; ALL-NEXT:    [[CMP:%.*]] = icmp eq i32 [[OR]], [[TMP0]]
+; ALL-NEXT:    br i1 [[CMP]], label [[IF_END:%.*]], label [[IF_THEN:%.*]]
+; ALL:       if.then:
+; ALL-NEXT:    store i32 [[OR]], i32* [[ARRAYIDX]], align 4
+; ALL-NEXT:    tail call void @foo()
+; ALL-NEXT:    br label [[IF_END]]
+; ALL:       if.end:
+; ALL-NEXT:    [[CHANGED_1_OFF0:%.*]] = phi i1 [ true, [[IF_THEN]] ], [ false, [[FOR_BODY:%.*]] ]
+; ALL-NEXT:    [[TMP1:%.*]] = load i32, i32* [[C]], align 4
+; ALL-NEXT:    [[CMP_1:%.*]] = icmp eq i32 [[OR]], [[TMP1]]
+; ALL-NEXT:    br i1 [[CMP_1]], label [[IF_END_1:%.*]], label [[IF_THEN_1:%.*]]
+; ALL:       if.then.1:
+; ALL-NEXT:    store i32 [[OR]], i32* [[C]], align 4
+; ALL-NEXT:    tail call void @foo()
+; ALL-NEXT:    br label [[IF_END_1]]
+; ALL:       if.end.1:
+; ALL-NEXT:    [[CHANGED_1_OFF0_1:%.*]] = phi i1 [ true, [[IF_THEN_1]] ], [ [[CHANGED_1_OFF0]], [[IF_END]] ]
+; ALL-NEXT:    ret i1 [[CHANGED_1_OFF0_1]]
 ;
 entry:
   br label %for.cond