X86: do not fold load instructions such as [V]MOVS[S|D] to other instructions

[oota-llvm.git] / lib / Target / X86 / X86InstrInfo.cpp

diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index 5a99ff004d4840093509ccd8d7f96ea45c816f0c..4e31af14eb6a30c7d1769ca968b652be00ab4f32 100644 (file)
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -3982,6 +3982,21 @@ MachineInstr* X86InstrInfo::foldMemoryOperandImpl(MachineFunction &MF,
     break;
   }
   default: {
+    if ((LoadMI->getOpcode() == X86::MOVSSrm ||
+         LoadMI->getOpcode() == X86::VMOVSSrm) &&
+        MF.getRegInfo().getRegClass(LoadMI->getOperand(0).getReg())->getSize()
+          > 4)
+      // These instructions only load 32 bits, we can't fold them if the
+      // destination register is wider than 32 bits (4 bytes).
+      return NULL;
+    if ((LoadMI->getOpcode() == X86::MOVSDrm ||
+         LoadMI->getOpcode() == X86::VMOVSDrm) &&
+        MF.getRegInfo().getRegClass(LoadMI->getOperand(0).getReg())->getSize()
+          > 8)
+      // These instructions only load 64 bits, we can't fold them if the
+      // destination register is wider than 64 bits (8 bytes).
+      return NULL;
+
     // Folding a normal load. Just copy the load's address operands.
     unsigned NumOps = LoadMI->getDesc().getNumOperands();
     for (unsigned i = NumOps - X86::AddrNumOperands; i != NumOps; ++i)