[IR] Add token types

This introduces the basic functionality to support "token types".
The motivation stems from the need to perform operations on a Value
whose provenance cannot be obscured.

There are several applications for such a type but my immediate
motivation stems from WinEH.  Our personality routine enforces a
single-entry - single-exit regime for cleanups.  After several rounds of
optimizations, we may be left with a terminator whose "cleanup-entry
block" is not entirely clear because control flow has merged two
cleanups together.  We have experimented with using labels as operands
inside of instructions which are not terminators to indicate where we
came from but found that LLVM does not expect such exotic uses of
BasicBlocks.

Instead, we can use this new type to clearly associate the "entry point"
and "exit point" of our cleanup.  This is done by having the cleanuppad
yield a Token and consuming it at the cleanupret.
The token type makes it impossible to obscure or otherwise hide the
Value, making it trivial to track the relationship between the two
points.

What is the burden to the optimizer?  Well, it turns out we have already
paid down this cost by accepting that there are certain calls that we
are not permitted to duplicate, optimizations have to watch out for
such instructions anyway.  There are additional places in the optimizer
that we will probably have to update but early examination has given me
the impression that this will not be heroic.

Differential Revision: http://reviews.llvm.org/D11861

llvm-svn: 245029

9 files changed, 65 insertions, 0 deletions

diff --git a/llvm/test/Assembler/token.ll b/llvm/test/Assembler/token.ll
new file mode 100644
index 00000000000..22d71b0b730
--- /dev/null
+++ b/llvm/test/Assembler/token.ll
@@ -0,0 +1,6 @@
+; RUN: llvm-as < %s | llvm-dis | FileCheck %s
+; RUN: verify-uselistorder %s
+; Basic smoke test for token type.
+
+; CHECK: declare void @llvm.token.foobar(token)
+declare void @llvm.token.foobar(token)
diff --git a/llvm/test/Bitcode/compatibility.ll b/llvm/test/Bitcode/compatibility.ll
index 585d51b73d4..8763fd4cad1 100644
--- a/llvm/test/Bitcode/compatibility.ll
+++ b/llvm/test/Bitcode/compatibility.ll
@@ -1212,6 +1212,9 @@ define void @misc.metadata() {
   ret void
 }
 
+declare void @llvm.tokenfoo(token)
+; CHECK: declare void @llvm.tokenfoo(token)
+
 ; CHECK: attributes #0 = { alignstack=4 }
 ; CHECK: attributes #1 = { alignstack=8 }
 ; CHECK: attributes #2 = { alwaysinline }
diff --git a/llvm/test/Verifier/token1.ll b/llvm/test/Verifier/token1.ll
new file mode 100644
index 00000000000..ac7ff30948e
--- /dev/null
+++ b/llvm/test/Verifier/token1.ll
@@ -0,0 +1,11 @@
+; RUN: not llvm-as %s -o /dev/null 2>&1 | FileCheck %s
+
+define void @f(token %A, token %B) {
+entry:
+  br label %bb
+
+bb:
+  %phi = phi token [ %A, %bb ], [ %B, %entry]
+; CHECK: PHI nodes cannot have token type!
+  br label %bb
+}
diff --git a/llvm/test/Verifier/token2.ll b/llvm/test/Verifier/token2.ll
new file mode 100644
index 00000000000..b58079de770
--- /dev/null
+++ b/llvm/test/Verifier/token2.ll
@@ -0,0 +1,11 @@
+; RUN: not llvm-as %s -o /dev/null 2>&1 | FileCheck %s
+
+define void @f(token %A, token %B) {
+entry:
+  br label %bb
+
+bb:
+  %sel = select i1 undef, token %A, token %B
+; CHECK: select values cannot have token type
+  br label %bb
+}
diff --git a/llvm/test/Verifier/token3.ll b/llvm/test/Verifier/token3.ll
new file mode 100644
index 00000000000..2cce6b83e7f
--- /dev/null
+++ b/llvm/test/Verifier/token3.ll
@@ -0,0 +1,8 @@
+; RUN: not llvm-as %s -o /dev/null 2>&1 | FileCheck %s
+
+define void @f(token %A, token %B) {
+entry:
+  alloca token
+; CHECK: invalid type for alloca
+  ret void
+}
diff --git a/llvm/test/Verifier/token4.ll b/llvm/test/Verifier/token4.ll
new file mode 100644
index 00000000000..87a8b14efa0
--- /dev/null
+++ b/llvm/test/Verifier/token4.ll
@@ -0,0 +1,4 @@
+; RUN: not llvm-as %s -o /dev/null 2>&1 | FileCheck %s
+
+@GV = external global token
+; CHECK: invalid type for global variable
diff --git a/llvm/test/Verifier/token5.ll b/llvm/test/Verifier/token5.ll
new file mode 100644
index 00000000000..6fc1b045375
--- /dev/null
+++ b/llvm/test/Verifier/token5.ll
@@ -0,0 +1,7 @@
+; RUN: not llvm-as %s -o /dev/null 2>&1 | FileCheck %s
+
+define void @f(token %A) {
+entry:
+  ret void
+}
+; CHECK: Function takes token but isn't an intrinsic
diff --git a/llvm/test/Verifier/token6.ll b/llvm/test/Verifier/token6.ll
new file mode 100644
index 00000000000..9614b91db73
--- /dev/null
+++ b/llvm/test/Verifier/token6.ll
@@ -0,0 +1,7 @@
+; RUN: not llvm-as %s -o /dev/null 2>&1 | FileCheck %s
+
+define token @f() {
+entry:
+  ret token undef
+}
+; CHECK: Functions returns a token but isn't an intrinsic
diff --git a/llvm/test/Verifier/token7.ll b/llvm/test/Verifier/token7.ll
new file mode 100644
index 00000000000..939878cc427
--- /dev/null
+++ b/llvm/test/Verifier/token7.ll
@@ -0,0 +1,8 @@
+; RUN: not llvm-as %s -o /dev/null 2>&1 | FileCheck %s
+
+define void @f() {
+entry:
+  call token () undef ()
+  ret void
+}
+; CHECK: Return type cannot be token for indirect call!