some likely looking GVN bugs

VNpatch2.diff

diff -rpu llvm-6.0.0.src/lib/Transforms/Scalar/GVN.cpp llvm-6.0.0-VNpatch2/lib/Transforms/Scalar/GVN.cpp
--- llvm-6.0.0.src/lib/Transforms/Scalar/GVN.cpp	2017-12-08 19:21:41.000000000 -0500
+++ llvm-6.0.0-VNpatch2/lib/Transforms/Scalar/GVN.cpp	2018-07-19 16:35:26.000000000 -0400
@@ -871,6 +871,10 @@ bool GVN::AnalyzeLoadAvailability(LoadIn
     // read by the load, we can extract the bits we need for the load from the
     // stored value.
     if (StoreInst *DepSI = dyn_cast<StoreInst>(DepInfo.getInst())) {
+        if (DepSI->getValueOperand()->getType() != LI->getType() &&
+            !canCoerceMustAliasedValueToLoad(DepSI->getValueOperand(),
+                                             LI->getType(), DL))
+          return false;
       // Can't forward from non-atomic to atomic without violating memory model.
       if (Address && LI->isAtomic() <= DepSI->isAtomic()) {
         int Offset =
@@ -887,6 +891,9 @@ bool GVN::AnalyzeLoadAvailability(LoadIn
     //    load i8* (P+1)
     // if we have this, replace the later with an extraction from the former.
     if (LoadInst *DepLI = dyn_cast<LoadInst>(DepInfo.getInst())) {
+        if (LD->getType() != DepLI->getType() &&
+            !canCoerceMustAliasedValueToLoad(LD, DepLI->getType(), DL))
+          return false;
       // If this is a clobber and L is the first instruction in its block, then
       // we have the first instruction in the entry block.
       // Can't forward from non-atomic to atomic without violating memory model.
@@ -904,6 +911,8 @@ bool GVN::AnalyzeLoadAvailability(LoadIn
     // If the clobbering value is a memset/memcpy/memmove, see if we can
     // forward a value on from it.
     if (MemIntrinsic *DepMI = dyn_cast<MemIntrinsic>(DepInfo.getInst())) {
+      if (DL.isNonIntegralPointerType(LD->getType())) // check canCoerceMustAliasedValueToLoad(LD, LI->getType(), DL))
+        return false;
       if (Address && !LI->isAtomic()) {
         int Offset = analyzeLoadFromClobberingMemInst(LI->getType(), Address,
                                                       DepMI, DL);