Make .bc en/decoding of AttrKind stable

The bitcode representation attribute kinds are encoded into / decoded from
should be independent of the current set of LLVM attributes and their position
in the AttrKind enum. This patch explicitly encodes attributes to fixed bitcode
values.

With this patch applied, LLVM does not silently misread attributes written by
LLVM 3.3. We also enhance the decoding slightly such that an error message is
printed if an unknown AttrKind encoding was dected.

Bonus: Dropping bitcode attributes from AttrKind is now easy, as old AttrKinds
       do not need to be kept to support the Bitcode reader.
llvm-svn: 187186

2 files changed, 236 insertions, 0 deletions

diff --git a/llvm/test/Bitcode/attributes-3.3.ll b/llvm/test/Bitcode/attributes-3.3.ll
new file mode 100644
index 00000000000..cd70ba1a749
--- /dev/null
+++ b/llvm/test/Bitcode/attributes-3.3.ll
@@ -0,0 +1,236 @@
+; RUN:  llvm-dis < %s.bc| FileCheck %s
+
+; attributes-3.3.ll.bc was generated by passing this file to llvm-as-3.3.
+; The test checks that LLVM does not silently misread attributes of
+; older bitcode files.
+
+define void @f1(i8 zeroext)
+; CHECK: define void @f1(i8 zeroext)
+{
+        ret void;
+}
+
+define void @f2(i8 signext)
+; CHECK: define void @f2(i8 signext)
+{
+        ret void;
+}
+
+define void @f3() noreturn
+; CHECK: define void @f3() #0
+{
+        ret void;
+}
+
+define void @f4(i8 inreg)
+; CHECK: define void @f4(i8 inreg)
+{
+        ret void;
+}
+
+define void @f5(i8* sret)
+; CHECK: define void @f5(i8* sret)
+{
+        ret void;
+}
+
+define void @f6() nounwind
+; CHECK: define void @f6() #1
+{
+        ret void;
+}
+
+define void @f7(i8* noalias)
+; CHECK: define void @f7(i8* noalias)
+{
+        ret void;
+}
+
+define void @f8(i8* byval)
+; CHECK: define void @f8(i8* byval)
+{
+        ret void;
+}
+
+define void @f9(i8* nest)
+; CHECK: define void @f9(i8* nest)
+{
+        ret void;
+}
+
+define void @f10() readnone
+; CHECK: define void @f10() #2
+{
+        ret void;
+}
+
+define void @f11() readonly
+; CHECK: define void @f11() #3
+{
+        ret void;
+}
+
+define void @f12() noinline
+; CHECK: define void @f12() #4
+{
+        ret void;
+}
+
+define void @f13() alwaysinline
+; CHECK: define void @f13() #5
+{
+        ret void;
+}
+
+define void @f14() optsize
+; CHECK: define void @f14() #6
+{
+        ret void;
+}
+
+define void @f15() ssp
+; CHECK: define void @f15() #7
+{
+        ret void;
+}
+
+define void @f16() sspreq
+; CHECK: define void @f16() #8
+{
+        ret void;
+}
+
+define void @f17(i8 align 4)
+; CHECK: define void @f17(i8 align 4)
+{
+        ret void;
+}
+
+define void @f18(i8* nocapture)
+; CHECK: define void @f18(i8* nocapture)
+{
+        ret void;
+}
+
+define void @f19() noredzone
+; CHECK: define void @f19() #9
+{
+        ret void;
+}
+
+define void @f20() noimplicitfloat
+; CHECK: define void @f20() #10
+{
+        ret void;
+}
+
+define void @f21() naked
+; CHECK: define void @f21() #11
+{
+        ret void;
+}
+
+define void @f22() inlinehint
+; CHECK: define void @f22() #12
+{
+        ret void;
+}
+
+define void @f23() alignstack(4)
+; CHECK: define void @f23() #13
+{
+        ret void;
+}
+
+define void @f24() returns_twice
+; CHECK: define void @f24() #14
+{
+        ret void;
+}
+
+define void @f25() uwtable
+; CHECK: define void @f25() #15
+{
+        ret void;
+}
+
+define void @f26() nonlazybind
+; CHECK: define void @f26() #16
+{
+        ret void;
+}
+
+define void @f27() sanitize_address
+; CHECK: define void @f27() #17
+{
+        ret void;
+}
+define void @f28() sanitize_thread
+; CHECK: define void @f28() #18
+{
+        ret void;
+}
+define void @f29() sanitize_memory
+; CHECK: define void @f29() #19
+{
+        ret void;
+}
+
+define void @f30() "cpu"="cortex-a8"
+; CHECK: define void @f30() #20
+{
+        ret void;
+}
+
+define i8 @f31(i8 returned %A)
+; CHECK: define i8 @f31(i8 returned %A)
+{
+        ret i8 %A;
+}
+
+define void @f32() sspstrong
+; CHECK: define void @f32() #21
+{
+        ret void;
+}
+
+define void @f33() minsize
+; CHECK: define void @f33() #22
+{
+        ret void;
+}
+
+declare void @nobuiltin()
+
+define void @f34()
+; CHECK: define void @f34()
+{
+        call void @nobuiltin() nobuiltin
+; CHECK: call void @nobuiltin() #23
+        ret void;
+}
+
+; CHECK: attributes #0 = { noreturn }
+; CHECK: attributes #1 = { nounwind }
+; CHECK: attributes #2 = { readnone }
+; CHECK: attributes #3 = { readonly }
+; CHECK: attributes #4 = { noinline }
+; CHECK: attributes #5 = { alwaysinline }
+; CHECK: attributes #6 = { optsize }
+; CHECK: attributes #7 = { ssp }
+; CHECK: attributes #8 = { sspreq }
+; CHECK: attributes #9 = { noredzone }
+; CHECK: attributes #10 = { noimplicitfloat }
+; CHECK: attributes #11 = { naked }
+; CHECK: attributes #12 = { inlinehint }
+; CHECK: attributes #13 = { alignstack=4 }
+; CHECK: attributes #14 = { returns_twice }
+; CHECK: attributes #15 = { uwtable }
+; CHECK: attributes #16 = { nonlazybind }
+; CHECK: attributes #17 = { sanitize_address }
+; CHECK: attributes #18 = { sanitize_thread }
+; CHECK: attributes #19 = { sanitize_memory }
+; CHECK: attributes #20 = { "cpu"="cortex-a8" }
+; CHECK: attributes #21 = { sspstrong }
+; CHECK: attributes #22 = { minsize }
+; CHECK: attributes #23 = { nobuiltin }
diff --git a/llvm/test/Bitcode/attributes-3.3.ll.bc b/llvm/test/Bitcode/attributes-3.3.ll.bc
new file mode 100644
index 00000000000..5dd71864ea4
--- /dev/null
+++ b/llvm/test/Bitcode/attributes-3.3.ll.bc