[PredicateInfo] Do not process unreachable operands.

Summary: We should excluded unreachable operands from processing as their DFS visitation order is undefined. When `renameUses` function sorts `OpsToRename` (https://fburl.com/d2wubn60), the comparator assumes that the parent block of the operand has a corresponding dominator tree node. This is not the case for unreachable operands and crashes the compiler.

Reviewers: dberlin, mgrang, davide

Subscribers: efriedma, hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61154

llvm-svn: 360796

llvm/lib/Transforms/Utils/PredicateInfo.cpp

@@ -473,7 +473,8 @@ void PredicateInfo::buildPredicateInfo() {
   }
   for (auto &Assume : AC.assumptions()) {
     if (auto *II = dyn_cast_or_null<IntrinsicInst>(Assume))
-      processAssume(II, II->getParent(), OpsToRename);
+      if (DT.isReachableFromEntry(II->getParent()))
+        processAssume(II, II->getParent(), OpsToRename);
   }
   // Now rename all our operations.
   renameUses(OpsToRename);

llvm/test/Transforms/Util/PredicateInfo/unreachable.ll

@@ -0,0 +1,25 @@
+; RUN: opt -print-predicateinfo < %s 2>&1 | FileCheck %s
+
+declare void @foo()
+declare void @llvm.assume(i1)
+
+define void @bar(i32* %p) {
+entry:
+; CHECK-LABEL: @bar
+  br label %end
+
+unreachable1:
+  %v1 = load i32, i32* %p, align 4
+  %c1 = icmp eq i32 %v1, 0
+  call void @llvm.assume(i1 %c1)
+  br label %unreachable2
+
+unreachable2:
+  %v2 = load i32, i32* %p, align 4
+  %c2 = icmp eq i32 %v2, 0
+  call void @llvm.assume(i1 %c2)
+  br label %end
+
+end:
+  ret void
+}