Teach the x86 floating point stackifier to handle COPY instructions.

This pass runs before COPY instructions are passed to copyPhysReg, so we simply
translate COPY to the proper pseudo instruction. Note that copyPhysReg does not
handle floating point stack copies.

Once COPY is used everywhere, this can be cleaned up a bit, and most of the
pseudo instructions can be removed.

llvm-svn: 107899

1 files changed, 36 insertions, 1 deletions

diff --git a/llvm/lib/Target/X86/X86FloatingPoint.cpp b/llvm/lib/Target/X86/X86FloatingPoint.cpp
index b5c6aa6b9c7..0e135f3a496 100644
--- a/llvm/lib/Target/X86/X86FloatingPoint.cpp
+++ b/llvm/lib/Target/X86/X86FloatingPoint.cpp
@@ -164,6 +164,8 @@ namespace {
     void handleCompareFP(MachineBasicBlock::iterator &I);
     void handleCondMovFP(MachineBasicBlock::iterator &I);
     void handleSpecialFP(MachineBasicBlock::iterator &I);
+
+    bool translateCopy(MachineInstr*);
   };
   char FPS::ID = 0;
 }
@@ -237,7 +239,10 @@ bool FPS::processBasicBlock(MachineFunction &MF, MachineBasicBlock &BB) {
     unsigned FPInstClass = Flags & X86II::FPTypeMask;
     if (MI->isInlineAsm())
       FPInstClass = X86II::SpecialFP;
-    
+
+    if (MI->isCopy() && translateCopy(MI))
+      FPInstClass = X86II::SpecialFP;
+
     if (FPInstClass == X86II::NotFP)
       continue;  // Efficiently ignore non-fp insts!
 
@@ -1206,3 +1211,33 @@ void FPS::handleSpecialFP(MachineBasicBlock::iterator &I) {
   I = MBB->erase(I);  // Remove the pseudo instruction
   --I;
 }
+
+// Translate a COPY instruction to a pseudo-op that handleSpecialFP understands.
+bool FPS::translateCopy(MachineInstr *MI) {
+  unsigned DstReg = MI->getOperand(0).getReg();
+  unsigned SrcReg = MI->getOperand(1).getReg();
+
+  if (DstReg == X86::ST0) {
+    MI->setDesc(TII->get(X86::FpSET_ST0_80));
+    MI->RemoveOperand(0);
+    return true;
+  }
+  if (DstReg == X86::ST1) {
+    MI->setDesc(TII->get(X86::FpSET_ST1_80));
+    MI->RemoveOperand(0);
+    return true;
+  }
+  if (SrcReg == X86::ST0) {
+    MI->setDesc(TII->get(X86::FpGET_ST0_80));
+    return true;
+  }
+  if (SrcReg == X86::ST1) {
+    MI->setDesc(TII->get(X86::FpGET_ST1_80));
+    return true;
+  }
+  if (X86::RFP80RegClass.contains(DstReg, SrcReg)) {
+    MI->setDesc(TII->get(X86::MOV_Fp8080));
+    return true;
+  }
+  return false;
+}