From fea914288b48bc8dc173e43d85f8dc194a8674c7 Mon Sep 17 00:00:00 2001
From: Simon Pilgrim <llvm-dev@redking.me.uk>
Date: Thu, 20 Jun 2019 17:36:23 +0000
Subject: [PATCH] [DAGCombiner] Use getAPIntValue() instead of getZExtValue()
 where possible.

Better handling of out-of-i64-range values due to large integer types or from fuzz tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363955 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 41 ++++++++++++------------
 1 file changed, 20 insertions(+), 21 deletions(-)

diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 8959ac92c1f..9c67c3e948c 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -3190,7 +3190,8 @@ SDValue DAGCombiner::visitSUB(SDNode *N) {
   if (!LegalOperations && N1.getOpcode() == ISD::SRL && N1.hasOneUse()) {
     SDValue ShAmt = N1.getOperand(1);
     ConstantSDNode *ShAmtC = isConstOrConstSplat(ShAmt);
-    if (ShAmtC && ShAmtC->getZExtValue() == N1.getScalarValueSizeInBits() - 1) {
+    if (ShAmtC &&
+        ShAmtC->getAPIntValue() == (N1.getScalarValueSizeInBits() - 1)) {
       SDValue SRA = DAG.getNode(ISD::SRA, DL, VT, N1.getOperand(0), ShAmt);
       return DAG.getNode(ISD::ADD, DL, VT, N0, SRA);
     }
@@ -7492,6 +7493,7 @@ SDValue DAGCombiner::visitSRA(SDNode *N) {
       return DAG.getNode(ISD::SRA, SDLoc(N), VT, N0, NewOp1);
   }
 
+  // fold (sra (trunc (sra x, c1)), c2) -> (trunc (sra x, c1 + c2))
   // fold (sra (trunc (srl x, c1)), c2) -> (trunc (sra x, c1 + c2))
   //      if c1 is equal to the number of bits the trunc removes
   // TODO - support non-uniform vector shift amounts.
@@ -7499,20 +7501,17 @@ SDValue DAGCombiner::visitSRA(SDNode *N) {
       (N0.getOperand(0).getOpcode() == ISD::SRL ||
        N0.getOperand(0).getOpcode() == ISD::SRA) &&
       N0.getOperand(0).hasOneUse() &&
-      N0.getOperand(0).getOperand(1).hasOneUse() &&
-      N1C) {
+      N0.getOperand(0).getOperand(1).hasOneUse() && N1C) {
     SDValue N0Op0 = N0.getOperand(0);
     if (ConstantSDNode *LargeShift = isConstOrConstSplat(N0Op0.getOperand(1))) {
-      unsigned LargeShiftVal = LargeShift->getZExtValue();
       EVT LargeVT = N0Op0.getValueType();
-
-      if (LargeVT.getScalarSizeInBits() - OpSizeInBits == LargeShiftVal) {
+      unsigned TruncBits = LargeVT.getScalarSizeInBits() - OpSizeInBits;
+      if (LargeShift->getAPIntValue() == TruncBits) {
         SDLoc DL(N);
-        SDValue Amt =
-          DAG.getConstant(LargeShiftVal + N1C->getZExtValue(), DL,
-                          getShiftAmountTy(N0Op0.getOperand(0).getValueType()));
-        SDValue SRA = DAG.getNode(ISD::SRA, DL, LargeVT,
-                                  N0Op0.getOperand(0), Amt);
+        SDValue Amt = DAG.getConstant(N1C->getZExtValue() + TruncBits, DL,
+                                      getShiftAmountTy(LargeVT));
+        SDValue SRA =
+            DAG.getNode(ISD::SRA, DL, LargeVT, N0Op0.getOperand(0), Amt);
         return DAG.getNode(ISD::TRUNCATE, DL, VT, SRA);
       }
     }
@@ -7632,7 +7631,7 @@ SDValue DAGCombiner::visitSRL(SDNode *N) {
     // Shifting in all undef bits?
     EVT SmallVT = N0.getOperand(0).getValueType();
     unsigned BitSize = SmallVT.getScalarSizeInBits();
-    if (N1C->getZExtValue() >= BitSize)
+    if (N1C->getAPIntValue().uge(BitSize))
       return DAG.getUNDEF(VT);
 
     if (!LegalTypes || TLI.isTypeDesirableForOp(ISD::SRL, SmallVT)) {
@@ -7653,7 +7652,7 @@ SDValue DAGCombiner::visitSRL(SDNode *N) {
 
   // fold (srl (sra X, Y), 31) -> (srl X, 31).  This srl only looks at the sign
   // bit, which is unmodified by sra.
-  if (N1C && N1C->getZExtValue() + 1 == OpSizeInBits) {
+  if (N1C && N1C->getAPIntValue() == (OpSizeInBits - 1)) {
     if (N0.getOpcode() == ISD::SRA)
       return DAG.getNode(ISD::SRL, SDLoc(N), VT, N0.getOperand(0), N1);
   }
@@ -10370,14 +10369,14 @@ SDValue DAGCombiner::visitSIGN_EXTEND_INREG(SDNode *N) {
   // fold (sext_in_reg (srl X, 23), i8) -> (sra X, 23) iff possible.
   // We already fold "(sext_in_reg (srl X, 25), i8) -> srl X, 25" above.
   if (N0.getOpcode() == ISD::SRL) {
-    if (ConstantSDNode *ShAmt = dyn_cast<ConstantSDNode>(N0.getOperand(1)))
-      if (ShAmt->getZExtValue()+EVTBits <= VTBits) {
+    if (auto *ShAmt = dyn_cast<ConstantSDNode>(N0.getOperand(1)))
+      if (ShAmt->getAPIntValue().ule(VTBits - EVTBits)) {
         // We can turn this into an SRA iff the input to the SRL is already sign
         // extended enough.
         unsigned InSignBits = DAG.ComputeNumSignBits(N0.getOperand(0));
-        if (VTBits-(ShAmt->getZExtValue()+EVTBits) < InSignBits)
-          return DAG.getNode(ISD::SRA, SDLoc(N), VT,
-                             N0.getOperand(0), N0.getOperand(1));
+        if (((VTBits - EVTBits) - ShAmt->getZExtValue()) < InSignBits)
+          return DAG.getNode(ISD::SRA, SDLoc(N), VT, N0.getOperand(0),
+                             N0.getOperand(1));
       }
   }
 
@@ -17869,14 +17868,14 @@ SDValue DAGCombiner::visitCONCAT_VECTORS(SDNode *N) {
         return SDValue();
     }
 
-    unsigned IdentityIndex = i * PartNumElem;
-    ConstantSDNode *CS = dyn_cast<ConstantSDNode>(Op.getOperand(1));
+    auto *CS = dyn_cast<ConstantSDNode>(Op.getOperand(1));
     // The extract index must be constant.
     if (!CS)
       return SDValue();
 
     // Check that we are reading from the identity index.
-    if (CS->getZExtValue() != IdentityIndex)
+    unsigned IdentityIndex = i * PartNumElem;
+    if (CS->getAPIntValue() != IdentityIndex)
       return SDValue();
   }
 
-- 
2.50.1