[PATCH] [PlaceSafepoints] New attributes for patchable statepoints.

[Sanjoy Das]

Hi reames, pgavlin,

This patch teaches the PlaceSafepoints pass about two `CallSite`
function attributes:

 * "statepoint-id": if the string value of this attribute can be parsed
   as an integer, then it is propagated to the ID parameter of the
   statepoint created.

 * "statepoint-num-patch-bytes": if the string value of this attribute
   can be parsed as an integer, then it is propagated to the `num patch
   bytes` parameter of the statepoint created.

This change intentionally does not assert on a malformed value for these
attributes, given that they're not "official" attributes.

http://reviews.llvm.org/D9735

Files:
  lib/Transforms/Scalar/PlaceSafepoints.cpp
  test/Transforms/PlaceSafepoints/patchable-statepoints.ll

Index: lib/Transforms/Scalar/PlaceSafepoints.cpp
===================================================================
--- lib/Transforms/Scalar/PlaceSafepoints.cpp
+++ lib/Transforms/Scalar/PlaceSafepoints.cpp
@@ -901,11 +901,37 @@
   Instruction *Token = nullptr;
   AttributeSet OriginalAttrs;
 
+  uint64_t ID;
+  uint32_t NumPatchBytes;
+
+  AttributeSet AS = CS.getAttributes();
+  Attribute AttrID =
+      AS.getAttribute(AttributeSet::FunctionIndex, "statepoint-id");
+  Attribute AttrNumPatchBytes = AS.getAttribute(AttributeSet::FunctionIndex,
+                                                "statepoint-num-patch-bytes");
+
+  bool HasID = AttrID.isStringAttribute() &&
+               !AttrID.getValueAsString().getAsInteger(10, ID);
+  if (!HasID)
+    ID = 0xABCDEF00;
+
+  bool HasNumPatchBytes =
+      AttrNumPatchBytes.isStringAttribute() &&
+      !AttrNumPatchBytes.getValueAsString().getAsInteger(10, NumPatchBytes);
+  if (!HasNumPatchBytes)
+    NumPatchBytes = 0;
+
+  Value *StatepointTarget = NumPatchBytes == 0
+                                ? CS.getCalledValue()
+                                : ConstantPointerNull::get(cast<PointerType>(
+                                      CS.getCalledValue()->getType()));
+
   if (CS.isCall()) {
     CallInst *ToReplace = cast<CallInst>(CS.getInstruction());
     CallInst *Call = Builder.CreateGCStatepointCall(
-        0xABCDEF00, 0, CS.getCalledValue(), makeArrayRef(CS.arg_begin(), CS.arg_end()),
-        None, None, "safepoint_token");
+        ID, NumPatchBytes, StatepointTarget,
+        makeArrayRef(CS.arg_begin(), CS.arg_end()), None, None,
+        "safepoint_token");
     Call->setTailCall(ToReplace->isTailCall());
     Call->setCallingConv(ToReplace->getCallingConv());
 
@@ -933,7 +959,7 @@
     // original block.
     Builder.SetInsertPoint(ToReplace->getParent());
     InvokeInst *Invoke = Builder.CreateGCStatepointInvoke(
-        0xABCDEF00, 0, CS.getCalledValue(), ToReplace->getNormalDest(),
+        ID, NumPatchBytes, StatepointTarget, ToReplace->getNormalDest(),
         ToReplace->getUnwindDest(), makeArrayRef(CS.arg_begin(), CS.arg_end()),
         Builder.getInt32(0), None, "safepoint_token");
 
Index: test/Transforms/PlaceSafepoints/patchable-statepoints.ll
===================================================================
--- /dev/null
+++ test/Transforms/PlaceSafepoints/patchable-statepoints.ll
@@ -0,0 +1,41 @@
+; RUN: opt -place-safepoints -S < %s | FileCheck %s
+
+declare void @f()
+declare i32 @personality_function()
+
+define void @test_id() gc "statepoint-example" {
+; CHECK-LABEL: @test_id(
+entry:
+; CHECK-LABEL: entry:
+; CHECK: invoke i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 100, i32 0, void ()* @f
+  invoke void @f()  "statepoint-id"="100" to label %normal_return unwind label %exceptional_return
+
+normal_return:
+  ret void
+
+exceptional_return:
+  %landing_pad4 = landingpad {i8*, i32} personality i32 ()* @personality_function cleanup
+  ret void
+}
+
+define void @test_num_patch_bytes() gc "statepoint-example" {
+; CHECK-LABEL: @test_num_patch_bytes(
+entry:
+; CHECK-LABEL: entry:
+; CHECK: invoke i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 2882400000, i32 99, void ()* null,
+  invoke void @f()  "statepoint-num-patch-bytes"="99" to label %normal_return unwind label %exceptional_return
+
+normal_return:
+  ret void
+
+exceptional_return:
+  %landing_pad4 = landingpad {i8*, i32} personality i32 ()* @personality_function cleanup
+  ret void
+}
+
+declare void @do_safepoint()
+define void @gc.safepoint_poll() {
+entry:
+  call void @do_safepoint()
+  ret void
+}

EMAIL PREFERENCES
  http://reviews.llvm.org/settings/panel/emailpreferences/
-------------- next part --------------
A non-text attachment was scrubbed...
Name: D9735.25663.patch
Type: text/x-patch
Size: 3707 bytes
Desc: not available
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20150513/1ad18018/attachment.bin>