[CGP] Fix crash on i96 bit multiply

Issue found by llvm-isel-fuzzer on OSS fuzz, https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=3725

If anyone actually cares about > 64 bit arithmetic, there's a lot more to do in this area.  There's a bunch of obviously wrong code in the same function.  I don't have the time to fix all of them and am just using this to understand what the workflow for fixing fuzzer cases might look like.

llvm-svn: 316967

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
index 47bdac00ae1..57deddc80d9 100644
--- a/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
+++ b/llvm/lib/Analysis/ScalarEvolutionExpander.cpp
@@ -1690,8 +1690,13 @@ SCEVExpander::FindValueInExprValueMap(const SCEV *S,
       // the LCSSA form.
       for (auto const &VOPair : *Set) {
         Value *V = VOPair.first;
+        dbgs() << "found " << *V << "\n";
         ConstantInt *Offset = VOPair.second;
         Instruction *EntInst = nullptr;
+        if (V && isa<Constant>(V))
+          return {V, Offset};
+        if (V && isa<Argument>(V))
+          return {V, Offset};
         if (V && isa<Instruction>(V) && (EntInst = cast<Instruction>(V)) &&
             S->getType() == V->getType() &&
             EntInst->getFunction() == InsertPt->getFunction() &&
@@ -1702,6 +1707,9 @@ SCEVExpander::FindValueInExprValueMap(const SCEV *S,
       }
     }
   }
+  if (auto *C = dyn_cast<SCEVConstant>(S))
+    return {C->getValue(), nullptr};
+  dbgs() << "Reject: " << *S << "\n";
   return {nullptr, nullptr};
 }