Handle big index in getelementptr instruction

CodeGen incorrectly ignores (assert from APInt) constant index bigger
than 2^64 in getelementptr instruction. This is a test and fix for that.

Patch by Paweł Bylica!

Reviewed By: rnk

Subscribers: majnemer, rnk, mcrosier, resistor, llvm-commits

Differential Revision: http://reviews.llvm.org/D8219

llvm-svn: 231984

2 files changed, 12 insertions, 21 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
index faa36b038e7..16724b0af7e 100644
--- a/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/FastISel.cpp
@@ -497,7 +497,7 @@ bool FastISel::selectGetElementPtr(const User *I) {
        OI != E; ++OI) {
     const Value *Idx = *OI;
     if (auto *StTy = dyn_cast<StructType>(Ty)) {
-      unsigned Field = cast<ConstantInt>(Idx)->getZExtValue();
+      uint64_t Field = cast<ConstantInt>(Idx)->getZExtValue();
       if (Field) {
         // N = N + Offset
         TotalOffs += DL.getStructLayout(StTy)->getElementOffset(Field);
@@ -518,8 +518,8 @@ bool FastISel::selectGetElementPtr(const User *I) {
         if (CI->isZero())
           continue;
         // N = N + Offset
-        TotalOffs +=
-            DL.getTypeAllocSize(Ty) * cast<ConstantInt>(CI)->getSExtValue();
+        uint64_t IdxN = CI->getValue().sextOrTrunc(64).getSExtValue();
+        TotalOffs += DL.getTypeAllocSize(Ty) * IdxN;
         if (TotalOffs >= MaxOffs) {
           N = fastEmit_ri_(VT, ISD::ADD, N, NIsKill, TotalOffs, VT);
           if (!N) // Unhandled operand. Halt "fast" selection and bail.
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
index 6fc6eb174e0..5a5827375b8 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp
@@ -3448,30 +3448,21 @@ void SelectionDAGBuilder::visitGetElementPtr(const User &I) {
       Ty = StTy->getElementType(Field);
     } else {
       Ty = cast<SequentialType>(Ty)->getElementType();
+      MVT PtrTy = DAG.getTargetLoweringInfo().getPointerTy(AS);
+      unsigned PtrSize = PtrTy.getSizeInBits();
+      APInt ElementSize(PtrSize, DL->getTypeAllocSize(Ty));
 
       // If this is a constant subscript, handle it quickly.
-      const TargetLowering &TLI = DAG.getTargetLoweringInfo();
-      if (const ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) {
-        if (CI->isZero()) continue;
-        uint64_t Offs =
-            DL->getTypeAllocSize(Ty)*cast<ConstantInt>(CI)->getSExtValue();
-        SDValue OffsVal;
-        EVT PTy = TLI.getPointerTy(AS);
-        unsigned PtrBits = PTy.getSizeInBits();
-        if (PtrBits < 64)
-          OffsVal = DAG.getNode(ISD::TRUNCATE, getCurSDLoc(), PTy,
-                                DAG.getConstant(Offs, MVT::i64));
-        else
-          OffsVal = DAG.getConstant(Offs, PTy);
-
-        N = DAG.getNode(ISD::ADD, getCurSDLoc(), N.getValueType(), N,
-                        OffsVal);
+      if (const auto *CI = dyn_cast<ConstantInt>(Idx)) {
+        if (CI->isZero())
+          continue;
+        APInt Offs = ElementSize * CI->getValue().sextOrTrunc(PtrSize);
+        SDValue OffsVal = DAG.getConstant(Offs, PtrTy);
+        N = DAG.getNode(ISD::ADD, getCurSDLoc(), N.getValueType(), N, OffsVal);
         continue;
       }
 
       // N = N + Idx * ElementSize;
-      APInt ElementSize =
-          APInt(TLI.getPointerSizeInBits(AS), DL->getTypeAllocSize(Ty));
       SDValue IdxN = getValue(Idx);
 
       // If the index is smaller or larger than intptr_t, truncate or extend