From 63a622b768b3ba7c9d8dfe148aea0b9cd2b094f3 Mon Sep 17 00:00:00 2001
From: Jakob Stoklund Olesen <stoklund@2pi.dk>
Date: Thu, 8 Jul 2010 19:46:30 +0000
Subject: [PATCH] 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
---
 llvm/lib/Target/X86/X86FloatingPoint.cpp | 37 +++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/llvm/lib/Target/X86/X86FloatingPoint.cpp b/llvm/lib/Target/X86/X86FloatingPoint.cpp
index b5c6aa6b9c77..0e135f3a4962 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;
+}