Simplify operand folding when rematerializing a load.

We already know how to fold a reload from a frameindex without
analyzing the load instruction. Generalize this to handle any
frameindex load. This streamlines the logic for rematerializing loads
from stack arguments. As a side effect, it allows stackmaps to record
a stack argument location without spilling it.

Verified no effect on codegen for llvm test-suite.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@194497 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 6 insertions, 1 deletions

diff --git a/lib/Target/X86/X86InstrInfo.cpp b/lib/Target/X86/X86InstrInfo.cpp
index eda285b861..75c6c2a755 100644
--- a/lib/Target/X86/X86InstrInfo.cpp
+++ b/lib/Target/X86/X86InstrInfo.cpp
@@ -4292,6 +4292,12 @@ MachineInstr* X86InstrInfo::foldMemoryOperandImpl(MachineFunction &MF,
                                                   MachineInstr *MI,
                                            const SmallVectorImpl<unsigned> &Ops,
                                                   MachineInstr *LoadMI) const {
+  // If loading from a FrameIndex, fold directly from the FrameIndex.
+  unsigned NumOps = LoadMI->getDesc().getNumOperands();
+  int FrameIndex;
+  if (isLoadFromStackSlot(LoadMI, FrameIndex))
+    return foldMemoryOperandImpl(MF, MI, Ops, FrameIndex);
+
   // Check switch flag
   if (NoFusing) return NULL;
 
@@ -4417,7 +4423,6 @@ MachineInstr* X86InstrInfo::foldMemoryOperandImpl(MachineFunction &MF,
       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)
       MOs.push_back(LoadMI->getOperand(i));
     break;