2 files changed, 29 insertions, 6 deletions
diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 8921bd44b34..56c6bd9d268 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -30833,14 +30833,19 @@ static SDValue combineBitcast(SDNode *N, SelectionDAG &DAG,
   // it's better to handle them early to be sure we emit efficient code by
   // avoiding store-load conversions.
   if (VT == MVT::x86mmx) {
-    // Detect zero-extended MMX constant vectors.
+    // Detect MMX constant vectors.
     APInt UndefElts;
-    SmallVector<APInt, 2> EltBits;
-    if (getTargetConstantBitsFromNode(N0, 32, UndefElts, EltBits) &&
-        EltBits[1] == 0) {
+    SmallVector<APInt, 1> EltBits;
+    if (getTargetConstantBitsFromNode(N0, 64, UndefElts, EltBits)) {
       SDLoc DL(N0);
-      return DAG.getNode(X86ISD::MMX_MOVW2D, DL, VT,
-                         DAG.getConstant(EltBits[0], DL, MVT::i32));
+      // Handle zero-extension of i32 with MOVD.
+      if (EltBits[0].countLeadingZeros() >= 32)
+        return DAG.getNode(X86ISD::MMX_MOVW2D, DL, VT,
+                           DAG.getConstant(EltBits[0].trunc(32), DL, MVT::i32));
+      // Else, bitcast to a double.
+      // TODO - investigate supporting sext 32-bit immediates on x86_64.
+      APFloat F64(APFloat::IEEEdouble(), EltBits[0]);
+      return DAG.getBitcast(VT, DAG.getConstantFP(F64, DL, MVT::f64));
     }
 
     // Detect bitcasts to x86mmx low word.
diff --git a/llvm/lib/Target/X86/X86MCInstLower.cpp b/llvm/lib/Target/X86/X86MCInstLower.cpp
index 730ba745eb7..f5f87c1fdab 100644
--- a/llvm/lib/Target/X86/X86MCInstLower.cpp
+++ b/llvm/lib/Target/X86/X86MCInstLower.cpp
@@ -1822,6 +1822,24 @@ void X86AsmPrinter::EmitInstruction(const MachineInstr *MI) {
     break;
   }
 
+  case X86::MMX_MOVQ64rm: {
+    if (!OutStreamer->isVerboseAsm())
+      break;
+    if (MI->getNumOperands() <= 4)
+      break;
+    if (auto *C = getConstantFromPool(*MI, MI->getOperand(4))) {
+      std::string Comment;
+      raw_string_ostream CS(Comment);
+      const MachineOperand &DstOp = MI->getOperand(0);
+      CS << X86ATTInstPrinter::getRegisterName(DstOp.getReg()) << " = ";
+      if (auto *CF = dyn_cast<ConstantFP>(C)) {
+        CS << "0x" << CF->getValueAPF().bitcastToAPInt().toString(16, false);
+        OutStreamer->AddComment(CS.str(), !EnablePrintSchedInfo);
+      }
+    }
+    break;
+  }
+
 #define MOV_CASE(Prefix, Suffix)        \
   case X86::Prefix##MOVAPD##Suffix##rm: \
   case X86::Prefix##MOVAPS##Suffix##rm: \