vendor/llvm/llvm-trunk-r303197

1 files changed, 26 insertions, 1 deletions

diff --git a/lib/Target/AArch64/AArch64RegisterBankInfo.cpp b/lib/Target/AArch64/AArch64RegisterBankInfo.cpp
index 5f895903da6f..789270c2a34b 100644
--- a/lib/Target/AArch64/AArch64RegisterBankInfo.cpp
+++ b/lib/Target/AArch64/AArch64RegisterBankInfo.cpp
@@ -529,9 +529,34 @@ AArch64RegisterBankInfo::getInstrMapping(const MachineInstr &MI) const {
     // for the greedy mode the cost of the cross bank copy will
     // offset this number.
     // FIXME: Should be derived from the scheduling model.
-    if (OpRegBankIdx[0] >= PMI_FirstFPR)
+    if (OpRegBankIdx[0] != PMI_FirstGPR)
       Cost = 2;
+    else
+      // Check if that load feeds fp instructions.
+      // In that case, we want the default mapping to be on FPR
+      // instead of blind map every scalar to GPR.
+      for (const MachineInstr &UseMI :
+           MRI.use_instructions(MI.getOperand(0).getReg()))
+        // If we have at least one direct use in a FP instruction,
+        // assume this was a floating point load in the IR.
+        // If it was not, we would have had a bitcast before
+        // reaching that instruction.
+        if (isPreISelGenericFloatingPointOpcode(UseMI.getOpcode())) {
+          OpRegBankIdx[0] = PMI_FirstFPR;
+          break;
+        }
     break;
+  case TargetOpcode::G_STORE:
+    // Check if that store is fed by fp instructions.
+    if (OpRegBankIdx[0] == PMI_FirstGPR) {
+      unsigned VReg = MI.getOperand(0).getReg();
+      if (!VReg)
+        break;
+      MachineInstr *DefMI = MRI.getVRegDef(VReg);
+      if (isPreISelGenericFloatingPointOpcode(DefMI->getOpcode()))
+        OpRegBankIdx[0] = PMI_FirstFPR;
+      break;
+    }
   }
 
   // Finally construct the computed mapping.