From 14580ce2fdd1898d130b20d9eb21bc4281868e7c Mon Sep 17 00:00:00 2001
From: "Paul C. Anagnostopoulos" <paul@windfall.com>
Date: Mon, 5 Apr 2021 09:13:25 -0400
Subject: [PATCH] [TableGen] Make behavior of list slice suffix consistent
 across all values

Differential Revision: https://reviews.llvm.org/D99883
---
 llvm/lib/TableGen/Record.cpp     |   3 +
 llvm/test/TableGen/ListSlices.td | 114 +++++++++++++++++++++++++++----
 2 files changed, 104 insertions(+), 13 deletions(-)

diff --git a/llvm/lib/TableGen/Record.cpp b/llvm/lib/TableGen/Record.cpp
index eeec9cafcc0d..2c8234da8431 100644
--- a/llvm/lib/TableGen/Record.cpp
+++ b/llvm/lib/TableGen/Record.cpp
@@ -615,6 +615,9 @@ Init *ListInit::convertInitializerTo(RecTy *Ty) const {
 }
 
 Init *ListInit::convertInitListSlice(ArrayRef<unsigned> Elements) const {
+  if (Elements.size() == 1)
+    return getElement(0);
+
   SmallVector<Init*, 8> Vals;
   Vals.reserve(Elements.size());
   for (unsigned Element : Elements) {
diff --git a/llvm/test/TableGen/ListSlices.td b/llvm/test/TableGen/ListSlices.td
index 2f40334798b2..82eeb28541ab 100644
--- a/llvm/test/TableGen/ListSlices.td
+++ b/llvm/test/TableGen/ListSlices.td
@@ -1,19 +1,107 @@
-// RUN: llvm-tblgen %s
+// RUN: llvm-tblgen %s | FileCheck %s
 // XFAIL: vg_leak
 
-def A {
-  list<int> B = [10, 20, 30, 4, 1, 1231, 20];
+// This file has tests for the list slice suffix.
+
+// Test defvars and literal lists.
+
+// CHECK: def Rec00
+// CHECK:   list<int> ShowVar1 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+// CHECK:   int ShowVar2 = 0
+// CHECK:   list<int> ShowVar3 = [2, 3, 4, 5]
+// CHECK:   int ShowVar4 = 0
+// CHECK:   list<int> ShowVar5 = [2, 3, 4, 5]
+
+defvar Var1 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9];
+defvar Var2 = Var1[0];
+defvar Var3 = Var1[2...5];
+
+defvar Var4 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9][0];
+defvar Var5 = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9][2...5];
+
+def Rec00 { // Display the defvars.
+  list<int> ShowVar1 = Var1;
+  int       ShowVar2 = Var2;
+  list<int> ShowVar3 = Var3;
+  int       ShowVar4 = Var4;
+  list<int> ShowVar5 = Var5;
 }
 
-def B {
-  list<int> X = [10, 20, 30, 4, 1, 1231, 20] [2...4,2,2,0...6];
+// CHECK: def Rec01
+// CHECK:   int Zero = 0
+// CHECK:   list<int> TwoFive = [2, 3, 4, 5]
 
-  list<int> Y = X[4,5];
-  int Z = X[4];
-
-  list<int> C = A.B[1...4];
-
-  list<list<int>> AA = [X, Y];
-
-  int BB = AA[0][1];
+def Rec01 {
+  int Zero = Var1[0];
+  list<int> TwoFive = Var1[2...5];
+}
+
+// Test class template arguments.
+
+// CHECK: def Rec02
+// CHECK:   int Zero = 10
+// CHECK:   list<int> TwoFive = [12, 13, 14, 15]
+
+class Class1<list<int> ids> {
+  int Zero = ids[0];
+  list<int> TwoFive = ids[2...5];
+}
+
+def Rec02 : Class1<[10, 11, 12, 13, 14, 15, 16, 17]>;
+
+// Test anonymous record fetches.
+
+// CHECK: def Rec03
+// CHECK:   int Zero = 20
+// CHECK:   list<int> TwoFive = [22, 23, 24, 25]
+
+def Rec03 {
+  int Zero = Class1<[20, 21, 22, 23, 24, 25, 26]>.Zero;
+  list<int> TwoFive = Class1<[20, 21, 22, 23, 24, 25, 26]>.TwoFive;
+}
+
+// Test multiclass template arguments.
+
+// CHECK: def Rec04_MC1
+// CHECK:   int Zero = 30
+// CHECK:   list<int> TwoFive = [32, 33, 34, 35]
+// CHECK: def Rec05_MC1
+// CHECK:   int Zero = 30
+// CHECK:   list<int> TwoFive = [32, 33, 34, 35]
+
+multiclass MC1<list<int> ids> {
+  def _MC1 {
+    int Zero = ids[0];
+    list<int> TwoFive = ids[2...5];
+  }
+}
+
+defm Rec04 : MC1<[30, 31, 32, 33, 34, 35, 36]>;
+defm Rec05 : MC1<[30, 31, 32, 33, 34, 35]>;
+
+// Test taking a complex subset of the list items from another record.
+
+// CHECK: def Rec07
+// CHECK:   list<int> SomeValues = [40, 43, 44, 45, 40, 47, 49, 48, 47, 46, 40]
+
+def Rec06 {
+  list<int> Values = [40, 41, 42, 43, 44, 45, 46, 47, 48, 49];
+}
+
+def Rec07 {
+  list<int> SomeValues = Rec06.Values[0, 3...5, 0, 7, 9...6, 0];
+}
+
+// Test a double subscript.
+
+// CHECK: def Rec08
+// CHECK:   list<list<string>> Array = {{.*}}"foo", "bar", "snork"], ["zoo", "quux", "flarp"]]
+// CHECK:   string Snork = "snork"
+// CHECK:   list<string> ZooQuux = ["zoo", "quux"]
+
+def Rec08 {
+  list<list<string>> Array = [["foo", "bar", "snork"],
+                              ["zoo", "quux", "flarp"]];
+  string Snork = Array[0][2];
+  list<string> ZooQuux = Array[1][0...1];
 }