Fix crash in PRE.

After r203553 overflow intrinsics and their non-intrinsic (normal)
instruction get hashed to the same value. This patch prevents PRE from
moving an instruction into a predecessor block, and trying to add a phi
node that gets two different types (the intrinsic result and the
non-intrinsic result), resulting in a failing assert.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203574 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Transforms/Scalar/GVN.cpp b/lib/Transforms/Scalar/GVN.cpp
index c4a9a5a..53c1205 100644 (file)
--- a/lib/Transforms/Scalar/GVN.cpp
+++ b/lib/Transforms/Scalar/GVN.cpp
@@ -2550,6 +2550,8 @@ bool GVN::performPRE(Function &F) {
           predMap.push_back(std::make_pair(static_cast<Value *>(0), P));
           PREPred = P;
           ++NumWithout;
+        } else if (predV->getType() != CurInst->getType()) {
+          continue;
         } else if (predV == CurInst) {
           /* CurInst dominates this predecessor. */
           NumWithout = 2;

diff --git a/test/Transforms/GVN/overflow.ll b/test/Transforms/GVN/overflow.ll
index 4d5ac66..8c00573 100644 (file)
--- a/test/Transforms/GVN/overflow.ll
+++ b/test/Transforms/GVN/overflow.ll
@@ -39,5 +39,29 @@ if.end:                                           ; preds = %entry
 ; CHECK: ret i32 %sadd3.repl
 }
 
+; Check if PRE does not crash
+define i32 @pre(i32 %a, i32 %b) nounwind ssp uwtable {
+entry:
+  %cmp = icmp sgt i32 %a, 42
+  br i1 %cmp, label %if.then, label %if.end3
+
+if.then:                                          ; preds = %entry
+  %add = call {i32, i1} @llvm.sadd.with.overflow.i32(i32 %a, i32 %b)
+  %add1 = extractvalue {i32, i1} %add, 0
+  %o = extractvalue {i32, i1} %add, 1
+  %o32 = zext i1 %o to i32
+  %add32 = add i32 %add1, %o32
+  %cmp1 = icmp sgt i32 %add1, 42
+  br i1 %cmp1, label %if.then2, label %if.end3
+
+if.then2:                                         ; preds = %if.then
+  call void @abort() noreturn
+  unreachable
+
+if.end3:                                          ; preds = %if.end, %entry
+  %add4 = add i32 %a, %b
+  ret i32 %add4
+}
 
+declare void @abort() noreturn
 declare { i32, i1 } @llvm.sadd.with.overflow.i32(i32, i32) nounwind readnone