From: Duncan Sands <baldrick@free.fr>
Date: Fri, 12 Mar 2010 17:55:20 +0000 (+0000)
Subject: When constant folding GEP of GEP, do not crash if an index of
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=890edda7c22dd8525f9fe44085cfd7080e67dfee;p=oota-llvm.git

When constant folding GEP of GEP, do not crash if an index of
the inner GEP is not a ConstantInt.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@98359 91177308-0d34-0410-b5e6-96231b3b80d8
---

diff --git a/lib/Analysis/ConstantFolding.cpp b/lib/Analysis/ConstantFolding.cpp
index 62020afb723..96bb02714a0 100644
--- a/lib/Analysis/ConstantFolding.cpp
+++ b/lib/Analysis/ConstantFolding.cpp
@@ -589,15 +589,28 @@ static Constant *SymbolicallyEvaluateGEP(Constant *const *Ops, unsigned NumOps,
   APInt Offset = APInt(BitWidth,
                        TD->getIndexedOffset(Ptr->getType(),
                                             (Value**)Ops+1, NumOps-1));
+  Ptr = cast<Constant>(Ptr->stripPointerCasts());
 
   // If this is a GEP of a GEP, fold it all into a single GEP.
   while (GEPOperator *GEP = dyn_cast<GEPOperator>(Ptr)) {
     SmallVector<Value *, 4> NestedOps(GEP->op_begin()+1, GEP->op_end());
+
+    // Do not try the incorporate the sub-GEP if some index is not a number.
+    bool AllConstantInt = true;
+    for (unsigned i = 0, e = NestedOps.size(); i != e; ++i)
+      if (!isa<ConstantInt>(NestedOps[i])) {
+        AllConstantInt = false;
+        break;
+      }
+    if (!AllConstantInt)
+      break;
+
     Ptr = cast<Constant>(GEP->getOperand(0));
     Offset += APInt(BitWidth,
                     TD->getIndexedOffset(Ptr->getType(),
                                          (Value**)NestedOps.data(),
                                          NestedOps.size()));
+    Ptr = cast<Constant>(Ptr->stripPointerCasts());
   }
 
   // If the base value for this address is a literal integer value, fold the
@@ -611,7 +624,6 @@ static Constant *SymbolicallyEvaluateGEP(Constant *const *Ops, unsigned NumOps,
   // we eliminate over-indexing of the notional static type array bounds.
   // This makes it easy to determine if the getelementptr is "inbounds".
   // Also, this helps GlobalOpt do SROA on GlobalVariables.
-  Ptr = cast<Constant>(Ptr->stripPointerCasts());
   const Type *Ty = Ptr->getType();
   SmallVector<Constant*, 32> NewIdxs;
   do {
diff --git a/test/Transforms/InstCombine/gepgep.ll b/test/Transforms/InstCombine/gepgep.ll
new file mode 100644
index 00000000000..9e681d28c42
--- /dev/null
+++ b/test/Transforms/InstCombine/gepgep.ll
@@ -0,0 +1,13 @@
+; RUN: opt < %s -instcombine -disable-output
+
+target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64"
+target triple = "x86_64-unknown-linux-gnu"
+
+@buffer = external global [64 x float]
+
+declare void @use(i8*)
+
+define void @f() {
+  call void @use(i8* getelementptr (i8* getelementptr (i8* bitcast ([64 x float]* @buffer to i8*), i64 and (i64 sub (i64 0, i64 ptrtoint ([64 x float]* @buffer to i64)), i64 63)), i64 64))
+  ret void
+}