Merge r100936 from mainline to fix PR6760.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/branches/release_27@101137 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Transforms/IPO/GlobalOpt.cpp

@@ -955,7 +955,8 @@ static bool ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Instruction *V,
       continue; // Otherwise, storing through it, or storing into GV... fine.
     }
     
-    if (isa<GetElementPtrInst>(Inst)) {
+    // Must index into the array and into the struct.
+    if (isa<GetElementPtrInst>(Inst) && Inst->getNumOperands() >= 3) {
       if (!ValueIsOnlyUsedLocallyOrStoredToOneGlobal(Inst, GV, PHIs))
         return false;
       continue;

test/Transforms/GlobalOpt/crash.ll

@@ -14,3 +14,29 @@ entry:
   store float 1.0, float* getelementptr inbounds (%struct.btSimdScalar* @_ZL6vTwist, i32 0, i32 0, i32 0, i32 3), align 4
   ret void
 }
+
+
+; PR6760
+%T = type { [5 x i32] }
+
+@switch_inf = internal global %T* null
+
+define void @test(i8* %arch_file, i32 %route_type) {
+entry:
+  %A = sext i32 1 to i64
+  %B = mul i64 %A, 20
+  %C = call noalias i8* @malloc(i64 %B) nounwind
+  %D = bitcast i8* %C to %T*
+  store %T* %D, %T** @switch_inf, align 8
+  unreachable
+
+bb.nph.i: 
+  %scevgep.i539 = getelementptr i8* %C, i64 4
+  unreachable
+
+xx:
+  %E = load %T** @switch_inf, align 8 
+  unreachable
+}
+
+declare noalias i8* @malloc(i64) nounwind