[llvm][MIRVRegNamerUtils] Add support for hashing MachineOperand FrameIndices.

[plotfi]

Summary

This patch makes it so that cases where multiple instructions that differ only in their frame-index MachineOperand values no longer collide. For instance:

%1:_(p0) = G_FRAME_INDEX %stack.0
%2:_(p0) = G_FRAME_INDEX %stack.1
%3:gr32 = MOV32rm %fixed-stack.0, 1, _, 0, _
%4:gr32 = MOV32rm %fixed-stack.1, 1, _, 0,

Prior to this patch the first two instructions would collide together. Also, the last two instructions would also collide. Now they will no longer collide.

[plotfi]

ping

llvm/lib/CodeGen/MIRVRegNamerUtils.cpp

auto GetHashableMO = [this](const MachineOperand &MO) -> unsigned {
     case MachineOperand::MO_Register:
       if (Register::isVirtualRegister(MO.getReg()))
         return MRI.getVRegDef(MO.getReg())->getOpcode();
       return MO.getReg();
     case MachineOperand::MO_Immediate:
       return MO.getImm();
     case MachineOperand::MO_TargetIndex:
       return MO.getOffset() | (MO.getTargetFlags() << 16);
+    case MachineOperand::MO_FrameIndex:
+      return llvm::hash_value(MO);
 
     // We could explicitly handle all the types of the MachineOperand,
     // here but we can just return a common number until we find a
     // compelling test case where this is bad. The only side effect here
     // is contributing to a hash collision but there's enough information
     // (Opcodes,other registers etc) that this will likely not be a problem.
 
     // TODO: Handle the following Index/ID/Predicate cases. They can
     // be hashed on in a stable manner.
-    case MachineOperand::MO_FrameIndex:
     case MachineOperand::MO_ConstantPoolIndex:
     case MachineOperand::MO_JumpTableIndex:
     case MachineOperand::MO_CFIIndex:
     case MachineOperand::MO_IntrinsicID:
     case MachineOperand::MO_Predicate:
 
     // In the cases below we havn't found a way to produce an artifact that will
     // result in a stable hash, in most cases because they are pointers. We want

llvm/test/CodeGen/MIR/X86/mir-namer-hash-frameindex.mir

+# RUN: llc -mtriple x86_64-linux-gnu -run-pass mir-canonicalizer -verify-machineinstrs %s -o - | FileCheck %s
+
+...
+---
+name: f
+stack:
+  - { id: 0, size: 4 }
+  - { id: 1, size: 4 }
+fixedStack:
+  - { id: 0, offset: 0, size: 4 }
+  - { id: 1, offset: 0, size: 4 }
+body: |
+  bb.1:
+    ; CHECK: _1:_(p0) = G_FRAME_INDEX %stack.{{[0-1]}}
+    ; CHECK: _1:_(p0) = G_FRAME_INDEX %stack.{{[0-1]}}
+    ; CHECK: _1:gr32 = MOV32rm %fixed-stack.{{[0-1]}}
+    ; CHECK: _1:gr32 = MOV32rm %fixed-stack.{{[0-1]}}
+    %1:_(p0) = G_FRAME_INDEX %stack.0
+    %2:_(p0) = G_FRAME_INDEX %stack.1
+    %3:gr32 = MOV32rm %fixed-stack.0, 1, _, 0, _
+    %4:gr32 = MOV32rm %fixed-stack.1, 1, _, 0, _
+
+...