[RISCV][GISel] Make G_ICMP of pointers legal.

[reames]

LGTM

llvm/lib/Target/RISCV/GISel/RISCVLegalizerInfo.cpp

 //===-- RISCVLegalizerInfo.cpp ----------------------------------*- C++ -*-===//
 //
 // 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
 //
 //===----------------------------------------------------------------------===//
 /// \file
 /// This file implements the targeting of the Machinelegalizer class for RISC-V.
 /// \todo This should be generated by TableGen.
 //===----------------------------------------------------------------------===//
 
 #include "RISCVLegalizerInfo.h"
 #include "RISCVSubtarget.h"
 #include "llvm/CodeGen/TargetOpcodes.h"
 #include "llvm/CodeGen/ValueTypes.h"
 #include "llvm/IR/DerivedTypes.h"
 #include "llvm/IR/Type.h"
 
 using namespace llvm;
 
 RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST) {
   const unsigned XLen = ST.getXLen();
   const LLT XLenLLT = LLT::scalar(XLen);
+  const LLT p0 = LLT::pointer(0, XLen);
 
   using namespace TargetOpcode;
 
   getActionDefinitionsBuilder({G_ADD, G_SUB, G_AND, G_OR, G_XOR})
       .legalFor({XLenLLT})
       .widenScalarToNextPow2(0)
       .clampScalar(0, XLenLLT, XLenLLT);
 
RISCVLegalizerInfo::RISCVLegalizerInfo(const RISCVSubtarget &ST) {
   }
 
   getActionDefinitionsBuilder({G_CONSTANT, G_IMPLICIT_DEF})
       .legalFor({XLenLLT})
       .widenScalarToNextPow2(0)
       .clampScalar(0, XLenLLT, XLenLLT);
 
   getActionDefinitionsBuilder(G_ICMP)
-      .legalFor({{XLenLLT, XLenLLT}})
+      .legalFor({{XLenLLT, XLenLLT}, {XLenLLT, p0}})
       .widenScalarToNextPow2(1)
       .clampScalar(1, XLenLLT, XLenLLT)
       .clampScalar(0, XLenLLT, XLenLLT);
 
   getActionDefinitionsBuilder(G_SELECT)
       .legalFor({{XLenLLT, XLenLLT}})
       .widenScalarToNextPow2(0)
       .clampScalar(0, XLenLLT, XLenLLT)
       .clampScalar(1, XLenLLT, XLenLLT);
 
   getLegacyLegalizerInfo().computeTables();
 }

llvm/test/CodeGen/RISCV/GlobalISel/legalizer/rv32/legalize-icmp.mir

bb.0.entry:
     %x:_(s64) = G_MERGE_VALUES %xhi(s32), %xlo(s32)
     %y:_(s64) = G_MERGE_VALUES %yhi(s32), %ylo(s32)
     %z:_(s1) = G_ICMP intpred(ne), %x, %y
     %z0:_(s32) = G_ANYEXT %z(s1)
     $x10 = COPY %z0(s32)
     PseudoRET implicit $x10
 
 ...
+---
+name:            cmp_eq_ptr
+body:             |
+  bb.0.entry:
+    ; CHECK-LABEL: name: cmp_eq_ptr
+    ; CHECK: [[COPY:%[0-9]+]]:_(p0) = COPY $x10
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(p0) = COPY $x11
+    ; CHECK-NEXT: [[ICMP:%[0-9]+]]:_(s32) = G_ICMP intpred(eq), [[COPY]](p0), [[COPY1]]
+    ; CHECK-NEXT: $x10 = COPY [[ICMP]](s32)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(p0) = COPY $x10
+    %1:_(p0) = COPY $x11
+    %2:_(s1) = G_ICMP intpred(eq), %0(p0), %1
+    %3:_(s32) = G_ANYEXT %2(s1)
+    $x10 = COPY %3(s32)
+    PseudoRET implicit $x10
+
+...

llvm/test/CodeGen/RISCV/GlobalISel/legalizer/rv64/legalize-icmp.mir

bb.0.entry:
     %x:_(s128) = G_MERGE_VALUES %xhi(s64), %xlo(s64)
     %y:_(s128) = G_MERGE_VALUES %yhi(s64), %ylo(s64)
     %z:_(s1) = G_ICMP intpred(ne), %x, %y
     %z0:_(s64) = G_ANYEXT %z(s1)
     $x10 = COPY %z0(s64)
     PseudoRET implicit $x10
 
 ...
+---
+name:            cmp_ne_ptr
+body:             |
+  bb.0.entry:
+    ; CHECK-LABEL: name: cmp_ne_ptr
+    ; CHECK: [[COPY:%[0-9]+]]:_(p0) = COPY $x10
+    ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(p0) = COPY $x11
+    ; CHECK-NEXT: [[ICMP:%[0-9]+]]:_(s64) = G_ICMP intpred(ne), [[COPY]](p0), [[COPY1]]
+    ; CHECK-NEXT: $x10 = COPY [[ICMP]](s64)
+    ; CHECK-NEXT: PseudoRET implicit $x10
+    %0:_(p0) = COPY $x10
+    %1:_(p0) = COPY $x11
+    %2:_(s1) = G_ICMP intpred(ne), %0(p0), %1
+    %3:_(s64) = G_ANYEXT %2(s1)
+    $x10 = COPY %3(s64)
+    PseudoRET implicit $x10
+
+...