[Statepoints] Support for "patchable" statepoints.

Summary:
This change adds two new parameters to the statepoint intrinsic, `i64 id`
and `i32 num_patch_bytes`.  `id` gets propagated to the ID field
in the generated StackMap section.  If the `num_patch_bytes` is
non-zero then the statepoint is lowered to `num_patch_bytes` bytes of
nops instead of a call (the spill and reload code remains unchanged).
A non-zero `num_patch_bytes` is useful in situations where a language
runtime requires complete control over how a call is lowered.

This change brings statepoints one step closer to patchpoints.  With
some additional work (that is not part of this patch) it should be
possible to get rid of `TargetOpcode::STATEPOINT` altogether.

PlaceSafepoints generates `statepoint` wrappers with `id` set to
`0xABCDEF00` (the old default value for the ID reported in the stackmap)
and `num_patch_bytes` set to `0`.  This can be made more sophisticated
later.

Reviewers: reames, pgavlin, swaroop.sridhar, AndyAyers

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D9546

llvm-svn: 237214
diff --git a/llvm/test/Transforms/InstCombine/statepoint.ll b/llvm/test/Transforms/InstCombine/statepoint.ll
index 67f6e91..f904f207 100644
--- a/llvm/test/Transforms/InstCombine/statepoint.ll
+++ b/llvm/test/Transforms/InstCombine/statepoint.ll
@@ -7,8 +7,8 @@
 
 define i1 @test_negative(i32 addrspace(1)* %p) gc "statepoint-example" {
 entry:
-  %safepoint_token = tail call i32 (void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0, i32 0, i32 addrspace(1)* %p)
-  %pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token,  i32 5, i32 5)
+  %safepoint_token = tail call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @func, i32 0, i32 0, i32 0, i32 0, i32 addrspace(1)* %p)
+  %pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token,  i32 7, i32 7)
   %cmp = icmp eq i32 addrspace(1)* %pnew, null
   ret i1 %cmp
 ; CHECK-LABEL: test_negative
@@ -18,8 +18,8 @@
 
 define i1 @test_nonnull(i32 addrspace(1)* nonnull %p) gc "statepoint-example" {
 entry:
-  %safepoint_token = tail call i32 (void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0, i32 0, i32 addrspace(1)* %p)
-  %pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token,  i32 5, i32 5)
+  %safepoint_token = tail call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @func, i32 0, i32 0, i32 0, i32 0, i32 addrspace(1)* %p)
+  %pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token,  i32 7, i32 7)
   %cmp = icmp eq i32 addrspace(1)* %pnew, null
   ret i1 %cmp
 ; CHECK-LABEL: test_nonnull
@@ -28,8 +28,8 @@
 
 define i1 @test_null() gc "statepoint-example" {
 entry:
-  %safepoint_token = tail call i32 (void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0, i32 0, i32 addrspace(1)* null)
-  %pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token,  i32 5, i32 5)
+  %safepoint_token = tail call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @func, i32 0, i32 0, i32 0, i32 0, i32 addrspace(1)* null)
+  %pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token,  i32 7, i32 7)
   %cmp = icmp eq i32 addrspace(1)* %pnew, null
   ret i1 %cmp
 ; CHECK-LABEL: test_null
@@ -39,8 +39,8 @@
 
 define i1 @test_undef() gc "statepoint-example" {
 entry:
-  %safepoint_token = tail call i32 (void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @func, i32 0, i32 0, i32 0, i32 0, i32 addrspace(1)* undef)
-  %pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token,  i32 5, i32 5)
+  %safepoint_token = tail call i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @func, i32 0, i32 0, i32 0, i32 0, i32 addrspace(1)* undef)
+  %pnew = call i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32 %safepoint_token,  i32 7, i32 7)
   %cmp = icmp eq i32 addrspace(1)* %pnew, null
   ret i1 %cmp
 ; CHECK-LABEL: test_undef
@@ -48,5 +48,5 @@
 ; CHECK: ret i1 undef
 }
 
-declare i32 @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()*, i32, i32, ...)
+declare i32 @llvm.experimental.gc.statepoint.p0f_isVoidf(i64, i32, void ()*, i32, i32, ...)
 declare i32 addrspace(1)* @llvm.experimental.gc.relocate.p1i32(i32, i32, i32) #3