[llvm] r270924 - [LoopUnrollAnalyzer] Fix a crash in analyzeLoopUnrollCost.

[Michael Zolotukhin via llvm-commits]

Author: mzolotukhin
Date: Thu May 26 16:42:51 2016
New Revision: 270924

URL: http://llvm.org/viewvc/llvm-project?rev=270924&view=rev
Log:
[LoopUnrollAnalyzer] Fix a crash in analyzeLoopUnrollCost.

Condition might be simplified to a Constant, but it doesn't have to be
ConstantInt, so we should dyn_cast, instead of cast.

This fixes PR27886.

Modified:
    llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp
    llvm/trunk/test/Transforms/LoopUnroll/full-unroll-crashers.ll

Modified: llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp?rev=270924&r1=270923&r2=270924&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/LoopUnrollPass.cpp Thu May 26 16:42:51 2016
@@ -464,41 +464,37 @@ analyzeLoopUnrollCost(const Loop *L, uns
 
       // Add in the live successors by first checking whether we have terminator
       // that may be simplified based on the values simplified by this call.
+      BasicBlock *KnownSucc = nullptr;
       if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
         if (BI->isConditional()) {
           if (Constant *SimpleCond =
                   SimplifiedValues.lookup(BI->getCondition())) {
-            BasicBlock *Succ = nullptr;
             // Just take the first successor if condition is undef
             if (isa<UndefValue>(SimpleCond))
-              Succ = BI->getSuccessor(0);
-            else
-              Succ = BI->getSuccessor(
-                  cast<ConstantInt>(SimpleCond)->isZero() ? 1 : 0);
-            if (L->contains(Succ))
-              BBWorklist.insert(Succ);
-            else
-              ExitWorklist.insert({BB, Succ});
-            continue;
+              KnownSucc = BI->getSuccessor(0);
+            else if (ConstantInt *SimpleCondVal =
+                         dyn_cast<ConstantInt>(SimpleCond))
+              KnownSucc = BI->getSuccessor(SimpleCondVal->isZero() ? 1 : 0);
           }
         }
       } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
         if (Constant *SimpleCond =
                 SimplifiedValues.lookup(SI->getCondition())) {
-          BasicBlock *Succ = nullptr;
           // Just take the first successor if condition is undef
           if (isa<UndefValue>(SimpleCond))
-            Succ = SI->getSuccessor(0);
-          else
-            Succ = SI->findCaseValue(cast<ConstantInt>(SimpleCond))
-                       .getCaseSuccessor();
-          if (L->contains(Succ))
-            BBWorklist.insert(Succ);
-          else
-            ExitWorklist.insert({BB, Succ});
-          continue;
+            KnownSucc = SI->getSuccessor(0);
+          else if (ConstantInt *SimpleCondVal =
+                       dyn_cast<ConstantInt>(SimpleCond))
+            KnownSucc = SI->findCaseValue(SimpleCondVal).getCaseSuccessor();
         }
       }
+      if (KnownSucc) {
+        if (L->contains(KnownSucc))
+          BBWorklist.insert(KnownSucc);
+        else
+          ExitWorklist.insert({BB, KnownSucc});
+        continue;
+      }
 
       // Add BB's successors to the worklist.
       for (BasicBlock *Succ : successors(BB))

Modified: llvm/trunk/test/Transforms/LoopUnroll/full-unroll-crashers.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/LoopUnroll/full-unroll-crashers.ll?rev=270924&r1=270923&r2=270924&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/LoopUnroll/full-unroll-crashers.ll (original)
+++ llvm/trunk/test/Transforms/LoopUnroll/full-unroll-crashers.ll Thu May 26 16:42:51 2016
@@ -137,3 +137,33 @@ for.body:
 exit:
   ret void
 }
+
+ at i = external global i32, align 4
+
+define void @folded_not_to_constantint() {
+entry:
+  br label %for.body
+
+for.body:
+  %iv = phi i32 [ 0, %entry ], [ %inc, %for.inc ]
+  %m = phi i32* [ @i, %entry ], [ %m, %for.inc ]
+  br i1 undef, label %if.else, label %if.then
+
+if.then:
+  unreachable
+
+if.else:
+  %cmp = icmp ult i32* %m, null
+  br i1 %cmp, label %cond.false, label %for.inc
+
+cond.false:
+  unreachable
+
+for.inc:
+  %inc = add nuw nsw i32 %iv, 1
+  %cmp2 = icmp ult i32 %inc, 10
+  br i1 %cmp2, label %for.body, label %for.end
+
+for.end:
+  ret void
+}