[PATCH] D27154: [CodeGen] Fix result type for SMULO/UMULO legalization

[Vadzim Dambrouski via Phabricator via llvm-commits]

pftbest updated this revision to Diff 79413.
pftbest added a comment.

Check if types are different before truncate


https://reviews.llvm.org/D27154

Files:
  lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
  test/CodeGen/MSP430/umulo-16.ll


Index: test/CodeGen/MSP430/umulo-16.ll
===================================================================
--- /dev/null
+++ test/CodeGen/MSP430/umulo-16.ll
@@ -0,0 +1,32 @@
+; RUN: llc < %s -march=msp430 | FileCheck %s
+target datalayout = "e-m:e-p:16:16-i32:16:32-a:16-n8:16"
+target triple = "msp430"
+
+define void @foo(i16 %arg) unnamed_addr {
+entry-block:
+  br i1 undef, label %bb2, label %bb3
+
+bb2:                                              ; preds = %entry-block
+  unreachable
+
+bb3:                                              ; preds = %entry-block
+  %0 = call { i16, i1 } @llvm.umul.with.overflow.i16(i16 undef, i16 %arg)
+; CHECK: call
+  %1 = extractvalue { i16, i1 } %0, 1
+  %2 = call i1 @llvm.expect.i1(i1 %1, i1 false)
+  br i1 %2, label %panic, label %bb5
+
+bb5:                                              ; preds = %bb3
+  unreachable
+
+panic:                                            ; preds = %bb3
+  unreachable
+}
+
+; Function Attrs: nounwind readnone
+declare i1 @llvm.expect.i1(i1, i1) #0
+
+; Function Attrs: nounwind readnone
+declare { i16, i1 } @llvm.umul.with.overflow.i16(i16, i16) #0
+
+attributes #0 = { nounwind readnone }
Index: lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
===================================================================
--- lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
+++ lib/CodeGen/SelectionDAG/LegalizeDAG.cpp
@@ -3515,6 +3515,13 @@
       TopHalf = DAG.getSetCC(dl, getSetCCResultType(VT), TopHalf,
                              DAG.getConstant(0, dl, VT), ISD::SETNE);
     }
+
+    // Truncate the result if SetCC returns a larger type than needed.
+    EVT RType = Node->getValueType(1);
+    EVT OType = getSetCCResultType(VT);
+    if (RType.getSizeInBits() < OType.getSizeInBits())
+      TopHalf = DAG.getNode(ISD::TRUNCATE, dl, RType, TopHalf);
+
     Results.push_back(BottomHalf);
     Results.push_back(TopHalf);
     break;


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