[llvm] r333198 - [LICM] Preserve DT and LoopInfo specifically

[Jun Bum Lim via llvm-commits]

Author: junbuml
Date: Thu May 24 08:58:34 2018
New Revision: 333198

URL: http://llvm.org/viewvc/llvm-project?rev=333198&view=rev
Log:
[LICM] Preserve DT and LoopInfo specifically

Summary:
In LICM, CFG could be changed in splitPredecessorsOfLoopExit(), which update
only DT and LoopInfo. Therefore, we should preserve only DT and LoopInfo specifically,
instead of all analyses that depend on the CFG (setPreservesCFG()).

This change should fix PR37323.

Reviewers: uabelho, davide, dberlin, Ka-Ka

Reviewed By: dberlin

Subscribers: mzolotukhin, bjope, mcrosier, llvm-commits

Differential Revision: https://reviews.llvm.org/D46775

Added:
    llvm/trunk/test/Transforms/LICM/pr37323.ll
Modified:
    llvm/trunk/lib/Transforms/Scalar/LICM.cpp

Modified: llvm/trunk/lib/Transforms/Scalar/LICM.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LICM.cpp?rev=333198&r1=333197&r2=333198&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LICM.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LICM.cpp Thu May 24 08:58:34 2018
@@ -170,7 +170,8 @@ struct LegacyLICMPass : public LoopPass
   /// loop preheaders be inserted into the CFG...
   ///
   void getAnalysisUsage(AnalysisUsage &AU) const override {
-    AU.setPreservesCFG();
+    AU.addPreserved<DominatorTreeWrapperPass>();
+    AU.addPreserved<LoopInfoWrapperPass>();
     AU.addRequired<TargetLibraryInfoWrapperPass>();
     if (EnableMSSALoopDependency)
       AU.addRequired<MemorySSAWrapperPass>();
@@ -220,7 +221,10 @@ PreservedAnalyses LICMPass::run(Loop &L,
     return PreservedAnalyses::all();
 
   auto PA = getLoopPassPreservedAnalyses();
-  PA.preserveSet<CFGAnalyses>();
+
+  PA.preserve<DominatorTreeAnalysis>();
+  PA.preserve<LoopAnalysis>();
+
   return PA;
 }
 

Added: llvm/trunk/test/Transforms/LICM/pr37323.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LICM/pr37323.ll?rev=333198&view=auto
==============================================================================
--- llvm/trunk/test/Transforms/LICM/pr37323.ll (added)
+++ llvm/trunk/test/Transforms/LICM/pr37323.ll Thu May 24 08:58:34 2018
@@ -0,0 +1,31 @@
+;RUN: opt -verify-dom-info -loop-simplify -postdomtree -licm -adce -verify-loop-info -S -o - %s | FileCheck %s
+;RUN: opt -verify-dom-info -passes='loop-simplify,require<postdomtree>,require<opt-remark-emit>,loop(licm),function(adce)' -S -o - %s | FileCheck %s
+
+target triple = "x86_64-unknown-linux-gnu"
+
+ at c = external global i16, align 1
+
+;Make sure this test do not crash while accessing PostDomTree which is not
+;preserved in LICM.
+;
+;CHECK-LABEL: fn1()
+;CHECK-LABEL: for.cond.loopexit.split.loop.exit
+;CHECK-LABEL: for.cond.loopexit.split.loop.exit1
+define void @fn1() {
+entry:
+  br label %for.cond
+
+for.cond:                                         ; preds = %if.end, %for.cond1, %entry
+  %0 = phi i16 [ undef, %entry ], [ ptrtoint (i16* @c to i16), %if.end ], [ %.mux, %for.cond1 ]
+  br i1 undef, label %for.cond1, label %for.end8
+
+for.cond1:                                        ; preds = %if.end, %for.cond
+  %.mux = select i1 undef, i16 undef, i16 ptrtoint (i16* @c to i16)
+  br i1 undef, label %for.cond, label %if.end
+
+if.end:                                           ; preds = %for.cond1
+  br i1 undef, label %for.cond, label %for.cond1
+
+for.end8:                                         ; preds = %for.cond
+  ret void
+}