[PowerPC] Add DFP compare instructions.

[stefanp]

Summary

This patch adds the DFP compare instructions:
dcmpu, dcmpuq, dcmpo, dcmpoq

[amyk]

I think this patch looks OK to me, but I had one question regarding it.

llvm/lib/Target/PowerPC/PPCInstrDFP.td

46

I noticed some other compare instructions set hasSideEffects to 0 accordingly, but I was wondering if we need to do that here?

[stefanp]

Missed a few flags for the instructions. Added them now.

llvm/lib/Target/PowerPC/PPCInstrDFP.td

46

Actually, I seem to have missed a few flags here and not just that one. I'll add the flags for this now.

[amyk]

Thanks for addressing my comment, Stefan.
I do not have any further comments/questions, so I'm going to approve this. LGTM.

llvm/lib/Target/PowerPC/PPCInstrDFP.td

 //===-- PPCInstrDFP.td - PowerPC Decimal Floating Point ----*- tablegen -*-===//
 //
 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
 // See https://llvm.org/LICENSE.txt for license information.
 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
 //
 //===----------------------------------------------------------------------===//
 //
 // This file describes the PowerPC Decimal Floating Point (DFP) instructions.
 //
 //===----------------------------------------------------------------------===//
 
 // We provide no scheduling info for the DFP instructions.
 // While they are not pseudo instructions we don't intend on scheduling them.
 let hasNoSchedulingInfo = 1 in {
+let mayRaiseFPException = 1, hasSideEffects = 0 in {
+
+let isCommutable = 1 in {
 defm DADD : XForm_28r<59, 2, (outs f8rc:$RST), (ins f8rc:$RA, f8rc:$RB),
                       "dadd",  "$RST, $RA, $RB", IIC_FPGeneral, []>;
 
 defm DADDQ : XForm_28r<63, 2, (outs fpairrc:$RST), (ins fpairrc:$RA, fpairrc:$RB),
                        "daddq",  "$RST, $RA, $RB", IIC_FPGeneral, []>;
+}
 
 defm DSUB : XForm_28r<59, 514, (outs f8rc:$RST), (ins f8rc:$RA, f8rc:$RB),
                       "dsub",  "$RST, $RA, $RB", IIC_FPGeneral, []>;
 
 defm DSUBQ : XForm_28r<63, 514, (outs fpairrc:$RST), (ins fpairrc:$RA, fpairrc:$RB),
                        "dsubq",  "$RST, $RA, $RB", IIC_FPGeneral, []>;
 
+let isCommutable = 1 in {
 defm DMUL : XForm_28r<59, 34, (outs f8rc:$RST), (ins f8rc:$RA, f8rc:$RB),
                       "dmul",  "$RST, $RA, $RB", IIC_FPGeneral, []>;
 
 defm DMULQ : XForm_28r<63, 34, (outs fpairrc:$RST), (ins fpairrc:$RA, fpairrc:$RB),
                        "dmulq",  "$RST, $RA, $RB", IIC_FPGeneral, []>;
+}
 
 defm DDIV : XForm_28r<59, 546, (outs f8rc:$RST), (ins f8rc:$RA, f8rc:$RB),
                       "ddiv",  "$RST, $RA, $RB", IIC_FPGeneral, []>;
 
 defm DDIVQ : XForm_28r<63, 546, (outs fpairrc:$RST), (ins fpairrc:$RA, fpairrc:$RB),
                        "ddivq",  "$RST, $RA, $RB", IIC_FPGeneral, []>;
+
+let isCompare = 1 in {
+  def DCMPU : XForm_17<59, 642, (outs crrc:$BF), (ins f8rc:$RA, f8rc:$RB),
+                       "dcmpu $BF, $RA, $RB", IIC_FPCompare>;
+
+  def DCMPUQ : XForm_17<63, 642, (outs crrc:$BF), (ins fpairrc:$RA, fpairrc:$RB),
+                        "dcmpuq $BF, $RA, $RB", IIC_FPCompare>;
+
+  def DCMPO : XForm_17<59, 130, (outs crrc:$BF), (ins f8rc:$RA, f8rc:$RB),
+                       "dcmpo $BF, $RA, $RB", IIC_FPCompare>;
+
+  def DCMPOQ : XForm_17<63, 130, (outs crrc:$BF), (ins fpairrc:$RA, fpairrc:$RB),
+                        "dcmpoq $BF, $RA, $RB", IIC_FPCompare>;
+}
+}
 }
 

llvm/test/MC/Disassembler/PowerPC/ppc64-encoding-dfp.txt

 # CHECK: ddiv. 2, 3, 4
 0xec 0x43 0x24 0x45
 
 # CHECK: ddivq 2, 6, 4
 0xfc 0x46 0x24 0x44
 
 # CHECK: ddivq. 2, 6, 4
 0xfc 0x46 0x24 0x45
+
+# CHECK: dcmpu 2, 6, 4
+0xed 0x06 0x25 0x04
+
+# CHECK: dcmpuq 2, 6, 4
+0xfd 0x06 0x25 0x04
+
+# CHECK: dcmpo 2, 6, 4
+0xed 0x06 0x21 0x04
+
+# CHECK: dcmpoq 2, 6, 4
+0xfd 0x06 0x21 0x04

llvm/test/MC/PowerPC/ppc64-encoding-dfp.s

 # CHECK-LE: ddiv. 2, 3, 4                  # encoding: [0x45,0x24,0x43,0xec]
             ddiv. 2, 3, 4
 # CHECK-BE: ddivq 2, 6, 4                  # encoding: [0xfc,0x46,0x24,0x44]
 # CHECK-LE: ddivq 2, 6, 4                  # encoding: [0x44,0x24,0x46,0xfc]
             ddivq 2, 6, 4
 # CHECK-BE: ddivq. 2, 6, 4                 # encoding: [0xfc,0x46,0x24,0x45]
 # CHECK-LE: ddivq. 2, 6, 4                 # encoding: [0x45,0x24,0x46,0xfc]
             ddivq. 2, 6, 4
+# CHECK-BE: dcmpu 2, 6, 4                  # encoding: [0xed,0x06,0x25,0x04]
+# CHECK-LE: dcmpu 2, 6, 4                  # encoding: [0x04,0x25,0x06,0xed]
+            dcmpu 2, 6, 4
+# CHECK-BE: dcmpuq 2, 6, 4                 # encoding: [0xfd,0x06,0x25,0x04]
+# CHECK-LE: dcmpuq 2, 6, 4                 # encoding: [0x04,0x25,0x06,0xfd]
+            dcmpuq 2, 6, 4
+# CHECK-BE: dcmpo 2, 6, 4                  # encoding: [0xed,0x06,0x21,0x04]
+# CHECK-LE: dcmpo 2, 6, 4                  # encoding: [0x04,0x21,0x06,0xed]
+            dcmpo 2, 6, 4
+# CHECK-BE: dcmpoq 2, 6, 4                 # encoding: [0xfd,0x06,0x21,0x04]
+# CHECK-LE: dcmpoq 2, 6, 4                 # encoding: [0x04,0x21,0x06,0xfd]
+            dcmpoq 2, 6, 4