From 2d4c98d79b5526aaf94b87d21a7d672f35b183a9 Mon Sep 17 00:00:00 2001
From: Nate Begeman <natebegeman@mac.com>
Date: Sat, 16 Oct 2004 20:43:38 +0000
Subject: [PATCH] Finally fix one of the oldest FIXMEs in the PowerPC backend:
 correctly flag rotate left word immediate then mask insert (rlwimi) as a
 two-address instruction, and update the ISel usage of the instruction
 accordingly.

This will allow us to properly schedule rlwimi, and use it to efficiently
codegen bitfield operations.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@17068 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Target/PowerPC/PPC32ISelSimple.cpp | 18 ++++++++----------
 lib/Target/PowerPC/PPCInstrInfo.td     |  6 ++++--
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/lib/Target/PowerPC/PPC32ISelSimple.cpp b/lib/Target/PowerPC/PPC32ISelSimple.cpp
index 247da627aae..6ee47e04d37 100644
--- a/lib/Target/PowerPC/PPC32ISelSimple.cpp
+++ b/lib/Target/PowerPC/PPC32ISelSimple.cpp
@@ -2550,25 +2550,23 @@ void PPC32ISel::emitShiftOperation(MachineBasicBlock *MBB,
   // Longs, as usual, are handled specially...
   if (Class == cLong) {
     // If we have a constant shift, we can generate much more efficient code
-    // than otherwise...
-    //
+    // than for a variable shift by using the rlwimi instruction.
     if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(ShiftAmount)) {
       unsigned Amount = CUI->getValue();
       if (Amount < 32) {
+        unsigned TempReg = makeAnotherReg(ResultTy);
         if (isLeftShift) {
-          // FIXME: RLWIMI is a use-and-def of DestReg+1, but that violates SSA
-          BuildMI(*MBB, IP, PPC::RLWINM, 4, DestReg).addReg(SrcReg)
+          BuildMI(*MBB, IP, PPC::RLWINM, 4, TempReg).addReg(SrcReg)
             .addImm(Amount).addImm(0).addImm(31-Amount);
-          BuildMI(*MBB, IP, PPC::RLWIMI, 5).addReg(DestReg).addReg(SrcReg+1)
-            .addImm(Amount).addImm(32-Amount).addImm(31);
+          BuildMI(*MBB, IP, PPC::RLWIMI, 5, DestReg).addReg(TempReg)
+            .addReg(SrcReg+1).addImm(Amount).addImm(32-Amount).addImm(31);
           BuildMI(*MBB, IP, PPC::RLWINM, 4, DestReg+1).addReg(SrcReg+1)
             .addImm(Amount).addImm(0).addImm(31-Amount);
         } else {
-          // FIXME: RLWIMI is a use-and-def of DestReg, but that violates SSA
-          BuildMI(*MBB, IP, PPC::RLWINM, 4, DestReg+1).addReg(SrcReg+1)
+          BuildMI(*MBB, IP, PPC::RLWINM, 4, TempReg).addReg(SrcReg+1)
             .addImm(32-Amount).addImm(Amount).addImm(31);
-          BuildMI(*MBB, IP, PPC::RLWIMI, 5).addReg(DestReg+1).addReg(SrcReg)
-            .addImm(32-Amount).addImm(0).addImm(Amount-1);
+          BuildMI(*MBB, IP, PPC::RLWIMI, 5, DestReg+1).addReg(TempReg)
+            .addReg(SrcReg).addImm(32-Amount).addImm(0).addImm(Amount-1);
           BuildMI(*MBB, IP, PPC::RLWINM, 4, DestReg).addReg(SrcReg)
             .addImm(32-Amount).addImm(Amount).addImm(31);
         }
diff --git a/lib/Target/PowerPC/PPCInstrInfo.td b/lib/Target/PowerPC/PPCInstrInfo.td
index d09636a7354..7009af2a5bc 100644
--- a/lib/Target/PowerPC/PPCInstrInfo.td
+++ b/lib/Target/PowerPC/PPCInstrInfo.td
@@ -412,9 +412,11 @@ def FSUBS : AForm_2<59, 20, 0, 0, 0,
 
 // M-Form instructions.  rotate and mask instructions.
 //
+let isTwoAddress = 1 in {
 def RLWIMI : MForm_2<20, 0, 0, 0,
-                     (ops GPRC:$rA, GPRC:$rS, u5imm:$SH, u5imm:$MB, u5imm:$ME),
-                     "rlwimi $rA, $rS, $SH, $MB, $ME">;
+                     (ops GPRC:$rA, GPRC:$rSi, GPRC:$rS, u5imm:$SH, u5imm:$MB, 
+                      u5imm:$ME), "rlwimi $rA, $rS, $SH, $MB, $ME">;
+}
 def RLWINM : MForm_2<21, 0, 0, 0,
                      (ops GPRC:$rA, GPRC:$rS, u5imm:$SH, u5imm:$MB, u5imm:$ME),
                      "rlwinm $rA, $rS, $SH, $MB, $ME">;