From 64a334da36da748426904701bfc56c3bf5d064fe Mon Sep 17 00:00:00 2001
From: Pete Cooper <peter_cooper@apple.com>
Date: Thu, 7 Aug 2014 05:47:07 +0000
Subject: [PATCH] Change the { } expression in tablegen to accept sized binary
 literals which are not just 0 and 1.

It also allows nested { } expressions, as now that they are sized, we can merge pull bits from the nested value.

In the current behaviour, everything in { } must have been convertible to a single bit.
However, now that binary literals are sized, its useful to be able to initialize a range of bits.

So, for example, its now possible to do

bits<8> x = { 0, 1, { 0b1001 }, 0, 0b0 }

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@215086 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/TableGen/TGParser.cpp | 15 +++++++++++++--
 test/TableGen/BitsInit.td | 24 ++++++++++++++++++++++++
 2 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/lib/TableGen/TGParser.cpp b/lib/TableGen/TGParser.cpp
index 709c7a52b9f..072e3ef5909 100644
--- a/lib/TableGen/TGParser.cpp
+++ b/lib/TableGen/TGParser.cpp
@@ -1302,17 +1302,28 @@ Init *TGParser::ParseSimpleValue(Record *CurRec, RecTy *ItemType,
     }
     Lex.Lex();  // eat the '}'
 
-    SmallVector<Init *, 16> NewBits(Vals.size());
+    SmallVector<Init *, 16> NewBits;
 
+    // As we parse { a, b, ... }, 'a' is the highest bit, but we parse it
+    // first.  We'll first read everything in to a vector, then we can reverse
+    // it to get the bits in the correct order for the BitsInit value.
     for (unsigned i = 0, e = Vals.size(); i != e; ++i) {
+      // bits<n> values are allowed to initialize n bits.
+      if (BitsInit *BI = dyn_cast<BitsInit>(Vals[i])) {
+        for (unsigned i = 0, e = BI->getNumBits(); i != e; ++i)
+          NewBits.push_back(BI->getBit((e - i) - 1));
+        continue;
+      }
+      // All other values must be convertible to just a single bit.
       Init *Bit = Vals[i]->convertInitializerTo(BitRecTy::get());
       if (!Bit) {
         Error(BraceLoc, "Element #" + utostr(i) + " (" + Vals[i]->getAsString()+
               ") is not convertable to a bit");
         return nullptr;
       }
-      NewBits[Vals.size()-i-1] = Bit;
+      NewBits.push_back(Bit);
     }
+    std::reverse(NewBits.begin(), NewBits.end());
     return BitsInit::get(NewBits);
   }
   case tgtok::l_square: {          // Value ::= '[' ValueList ']'
diff --git a/test/TableGen/BitsInit.td b/test/TableGen/BitsInit.td
index c3d5113ebdb..81cf77baa45 100644
--- a/test/TableGen/BitsInit.td
+++ b/test/TableGen/BitsInit.td
@@ -40,6 +40,21 @@ def {
   bits<8> E;
   let E{7-0} = {0,0,1,?,?,?,?,?};
   let E{3-0} = 0b0010;
+
+  bits<8> F1 = { 0, 1, 0b1001, 0, 0b0 }; // ok
+  bits<7> F2 = { 0, 1, 0b1001, 0, 0b0 }; // LHS doesn't have enough bits
+  bits<9> F3 = { 0, 1, 0b1001, 0, 0b0 }; // RHS doesn't have enough bits
+
+  bits<8> G1 = { 0, { 1, 0b1001, 0 }, 0b0 }; // ok
+  bits<8> G2 = { 0, { 1, 0b1001 }, 0, 0b0 }; // ok
+  bits<8> G3 = { 0, 1, { 0b1001 }, 0, 0b0 }; // ok
+
+  bits<16> H;
+  let H{15-0} = { { 0b11001100 }, 0b00110011 };
+
+  // Make sure we can initialise ints with bits<> values.
+  int J = H;
+  int K = { 0, 1 };
 }
 
 // CHECK: def {{.*}} {
@@ -56,4 +71,13 @@ def {
 // CHECK: bits<1> D7 = { ? };
 // CHECK: bits<2> D8;
 // CHECK: bits<8> E = { 0, 0, 1, ?, 0, 0, 1, 0 };
+// CHECK: bits<8> F1 = { 0, 1, 1, 0, 0, 1, 0, 0 };
+// CHECK: bits<7> F2;
+// CHECK: bits<9> F3;
+// CHECK: bits<8> G1 = { 0, 1, 1, 0, 0, 1, 0, 0 };
+// CHECK: bits<8> G2 = { 0, 1, 1, 0, 0, 1, 0, 0 };
+// CHECK: bits<8> G3 = { 0, 1, 1, 0, 0, 1, 0, 0 };
+// CHECK: bits<16> H = { 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1 };
+// CHECK: int J = 52275;
+// CHECK: int K = 1;
 // CHECK: }
-- 
2.11.0