Merging r286998:

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r286998 | chfast | 2016-11-15 19:29:24 +0100 (wto, 15 lis 2016) | 12 lines

Integer legalization: fix MUL expansion

Summary:
This fixes the runtime results produces by the fallback multiplication expansion introduced in r270720.

For tests I created a fuzz tester that compares the results with Boost.Multiprecision.

Reviewers: hfinkel

Subscribers: llvm-commits

Differential Revision: https://reviews.llvm.org/D26628

llvm-svn: 288086

llvm/lib/CodeGen/SelectionDAG/LegalizeIntegerTypes.cpp

@@ -2207,7 +2207,7 @@ void DAGTypeLegalizer::ExpandIntRes_MUL(SDNode *N,
     SDValue RLH = DAG.getNode(ISD::SRL, dl, NVT, RL, Shift);
 
     SDValue U = DAG.getNode(ISD::ADD, dl, NVT,
-                            DAG.getNode(ISD::MUL, dl, NVT, LLH, RLL), TL);
+                            DAG.getNode(ISD::MUL, dl, NVT, LLH, RLL), TH);
     SDValue UL = DAG.getNode(ISD::AND, dl, NVT, U, Mask);
     SDValue UH = DAG.getNode(ISD::SRL, dl, NVT, U, Shift);
 
@@ -2216,14 +2216,14 @@ void DAGTypeLegalizer::ExpandIntRes_MUL(SDNode *N,
     SDValue VH = DAG.getNode(ISD::SRL, dl, NVT, V, Shift);
 
     SDValue W = DAG.getNode(ISD::ADD, dl, NVT,
-                            DAG.getNode(ISD::MUL, dl, NVT, LL, RL),
+                            DAG.getNode(ISD::MUL, dl, NVT, LLH, RLH),
                             DAG.getNode(ISD::ADD, dl, NVT, UH, VH));
-    Lo = DAG.getNode(ISD::ADD, dl, NVT, TH,
+    Lo = DAG.getNode(ISD::ADD, dl, NVT, TL,
                      DAG.getNode(ISD::SHL, dl, NVT, V, Shift));
 
     Hi = DAG.getNode(ISD::ADD, dl, NVT, W,
                      DAG.getNode(ISD::ADD, dl, NVT,
-                                 DAG.getNode(ISD::MUL, dl, NVT, RH, LL), 
+                                 DAG.getNode(ISD::MUL, dl, NVT, RH, LL),
                                  DAG.getNode(ISD::MUL, dl, NVT, RL, LH)));
     return;
   }