[BitcodeReader] Fixing bug that caused BitcodeReader to fail to proce…

…ss Tapir sync instructions correctly. This change addresses issue #56.

llvm/lib/Bitcode/Reader/BitcodeReader.cpp

@@ -4680,7 +4680,7 @@ Error BitcodeReader::parseFunctionBody(Function *F) {
       break;
     }
     case bitc::FUNC_CODE_INST_SYNC: { // Sync: [bb#, val]
-      if (Record.size() != 1)
+      if (Record.size() != 2)
         return error("Invalid record");
       BasicBlock *Continue = getBasicBlock(Record[0]);
       if (!Continue)

llvm/test/Bitcode/tapir.ll

@@ -0,0 +1,42 @@
+; Test that bitcode reader and writer can handle Tapir extensions.
+;
+; Thanks to @joshbohde for the code for this test case.
+;;
+; RUN: llvm-as %s -o=- | llvm-dis 
+
+declare token @llvm.syncregion.start() #3
+
+declare void @print(i32)
+
+define void @test (i32 %n) {
+entry:
+    %i = alloca i32
+    store i32 0, i32* %i  ; store it back
+    br label %loop.1.entry
+
+loop.1.entry:
+    %tmp = load i32, i32* %i
+    %cmp = icmp ne i32 %tmp, %n
+    br i1 %cmp, label %loop.1.body, label %loop.1.exit
+
+loop.1.body:
+    %syncreg = call token @llvm.syncregion.start()
+    detach within %syncreg, label %loop.1.body.1, label %loop.1.body.2
+
+loop.1.body.1:
+    %tmp2 = load i32, i32* %i
+    call void @print(i32 %tmp2)
+    reattach within %syncreg, label %loop.1.body.2
+
+loop.1.body.2:
+    %tmp3 = load i32, i32* %i
+    %tmp4 = add i32 %tmp3, 1   ; increment it
+    store i32 %tmp4, i32* %i  ; store it back
+    br label %loop.1.final
+
+loop.1.final:
+    sync within %syncreg, label %loop.1.entry
+
+loop.1.exit:
+    ret void
+}