[LoopSimplifyCFG] Fix inconsistency in blocks in loop markup

2nd part of D57095 with the same reason, just in another place. We never
fold branches that are not immediately in the current loop, but this check
is missing in `IsEdgeLive` As result, it may think that the edge in subloop is
dead while it's live. It's a pessimization in the current stance.

Differential Revision: https://reviews.llvm.org/D57147
Reviewed By: rupprecht

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@352170 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/LoopSimplifyCFG.cpp b/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
index 669faf5aa18db678fe07bb02ec9e6bfc400411ec..85b6444d33d63990ca4eadbde4eec1669d09082e 100644 (file)
--- a/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
+++ b/lib/Transforms/Scalar/LoopSimplifyCFG.cpp
@@ -239,7 +239,7 @@ private:
       if (!LiveLoopBlocks.count(From))
         return false;
       BasicBlock *TheOnlySucc = getOnlyLiveSuccessor(From);
-      return !TheOnlySucc || TheOnlySucc == To;
+      return !TheOnlySucc || TheOnlySucc == To || LI.getLoopFor(From) != &L;
     };
 
     // The loop will not be destroyed if its latch is live.

diff --git a/test/Transforms/LoopSimplifyCFG/live_block_marking.ll b/test/Transforms/LoopSimplifyCFG/live_block_marking.ll
index f15f626d5d3b3949e7fda72d4e60f3fdc7db1941..344871c79ae913e77b3379585abbb6f0aacd3beb 100644 (file)
--- a/test/Transforms/LoopSimplifyCFG/live_block_marking.ll
+++ b/test/Transforms/LoopSimplifyCFG/live_block_marking.ll
@@ -4,11 +4,13 @@
 ; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -passes='require<domtree>,loop(indvars,simplify-cfg)' -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
 ; RUN: opt -S -enable-loop-simplifycfg-term-folding=true -indvars -loop-simplifycfg -enable-mssa-loop-dependency=true -verify-memoryssa -debug-only=loop-simplifycfg -verify-loop-info -verify-dom-info -verify-loop-lcssa 2>&1 < %s | FileCheck %s
 
-; This test demonstrates a bug in live blocks markup that is only catchable in
-; inter-pass interaction.
 define void @test(i1 %c) {
 ; CHECK-LABEL: @test(
 ; CHECK-NEXT:  entry:
+; CHECK-NEXT:    switch i32 0, label [[ENTRY_SPLIT:%.*]] [
+; CHECK-NEXT:    i32 1, label [[DEAD_EXIT:%.*]]
+; CHECK-NEXT:    ]
+; CHECK:       entry-split:
 ; CHECK-NEXT:    br label [[OUTER:%.*]]
 ; CHECK:       outer:
 ; CHECK-NEXT:    br i1 [[C:%.*]], label [[TO_FOLD:%.*]], label [[LATCH:%.*]]
@@ -25,7 +27,7 @@ define void @test(i1 %c) {
 ; CHECK:       latch.loopexit:
 ; CHECK-NEXT:    br label [[LATCH]]
 ; CHECK:       latch:
-; CHECK-NEXT:    br i1 true, label [[OUTER]], label [[DEAD_EXIT:%.*]]
+; CHECK-NEXT:    br label [[OUTER]]
 ; CHECK:       dead_exit:
 ; CHECK-NEXT:    ret void
 ;