From 4b8af31f63464e5433c8c8f3f9941ea5d38f4341 Mon Sep 17 00:00:00 2001
From: Puyan Lotfi <puyan@puyan.org>
Date: Tue, 10 Mar 2020 00:31:01 -0400
Subject: [PATCH] [llvm][MIRVRegNamer] Avoid collisions across constant pool
 indices.

When hashing on MachineOperand::MO_ConstantPoolIndex, now MIR-Canon and
MIRVRegNamer will no longer result in a hash collision.

Differential Revision: https://reviews.llvm.org/D74449
---
 llvm/lib/CodeGen/MIRVRegNamerUtils.cpp        |  2 +-
 .../AArch64/mir-canon-constant-pool-hash.mir  | 20 +++++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)
 create mode 100644 llvm/test/CodeGen/MIR/AArch64/mir-canon-constant-pool-hash.mir

diff --git a/llvm/lib/CodeGen/MIRVRegNamerUtils.cpp b/llvm/lib/CodeGen/MIRVRegNamerUtils.cpp
index fcc40b26c527..47e712aaccf3 100644
--- a/llvm/lib/CodeGen/MIRVRegNamerUtils.cpp
+++ b/llvm/lib/CodeGen/MIRVRegNamerUtils.cpp
@@ -69,6 +69,7 @@ std::string VRegRenamer::getInstructionOpcodeHash(MachineInstr &MI) {
     case MachineOperand::MO_TargetIndex:
       return MO.getOffset() | (MO.getTargetFlags() << 16);
     case MachineOperand::MO_FrameIndex:
+    case MachineOperand::MO_ConstantPoolIndex:
       return llvm::hash_value(MO);
 
     // We could explicitly handle all the types of the MachineOperand,
@@ -79,7 +80,6 @@ std::string VRegRenamer::getInstructionOpcodeHash(MachineInstr &MI) {
 
     // TODO: Handle the following Index/ID/Predicate cases. They can
     // be hashed on in a stable manner.
-    case MachineOperand::MO_ConstantPoolIndex:
     case MachineOperand::MO_JumpTableIndex:
     case MachineOperand::MO_CFIIndex:
     case MachineOperand::MO_IntrinsicID:
diff --git a/llvm/test/CodeGen/MIR/AArch64/mir-canon-constant-pool-hash.mir b/llvm/test/CodeGen/MIR/AArch64/mir-canon-constant-pool-hash.mir
new file mode 100644
index 000000000000..7ece521bedbf
--- /dev/null
+++ b/llvm/test/CodeGen/MIR/AArch64/mir-canon-constant-pool-hash.mir
@@ -0,0 +1,20 @@
+# RUN: llc -o - -run-pass mir-canonicalizer -verify-machineinstrs %s | FileCheck %s
+--- |
+  target triple = "aarch64-unknown-unknown"
+  define void @f() { unreachable }
+...
+---
+name: f
+constants:
+  - id:              0
+    value:           '<1 x i8> <i8 0>'
+  - id:              1
+    value:           '<1 x i8> <i8 1>'
+body: |
+  bb.0:
+    ; Test that we no longer have hash collisions between two different consts:
+    ;CHECK: %bb{{[0-9]+}}_{{[0-9]+}}__1:gpr64common = ADR
+    ;CHECK: %bb{{[0-9]+}}_{{[0-9]+}}__1:gpr64common = ADR
+    %vreg0:gpr64common = ADRP target-flags(aarch64-page) %const.0
+    %vreg1:gpr64common = ADRP target-flags(aarch64-page) %const.1
+...