define i8 addrspace(1)* @test1(i8 addrspace(1)* %obj)
gc "statepoint-example" {
- %0 = call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @foo, i32 0, i32 0, i32 0, i8 addrspace(1)* %obj)
- %obj.relocated = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(i32 %0, i32 4, i32 4)
+ %0 = call i32 (i64, i32, void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @foo, i32 0, i32 0, i32 0, i32 0, i8 addrspace(1)* %obj)
+ %obj.relocated = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(i32 %0, i32 7, i32 7)
ret i8 addrspace(1)* %obj.relocated
}
opt -rewrite-statepoints-for-gc test/Transforms/RewriteStatepointsForGC/basics.ll -S | llc -debug-only=stackmaps
+Base & Derived Pointers
+^^^^^^^^^^^^^^^^^^^^^^^
+
+A base pointer is one which points to the base of an allocation (object). A
+derived pointer is one which is offset from a base pointer by some amount.
+When relocating objects, a garbage collector needs to be able to relocate each
+derived pointer associated with an allocation to the same offset from the new
+address.
+
+Derived pointers fall in to two categories:
+ * "Interior derived pointers" remain within the bounds of the allocation
+ they're associated with. As a result, the base object can be found at
+ runtime provided the bounds of allocations are known to the runtime system.
+ * "Exterior derived pointers" are outside the bounds of the associated object;
+ they may even fall within *another* allocations address range. As a result,
+ there is no way for a garbage collector to determine which allocation they
+ are associated with at runtime and compiler support is needed.
GC Transitions
^^^^^^^^^^^^^^^^^^
define i8 addrspace(1)* @test1(i8 addrspace(1) *%obj)
gc "hypothetical-gc" {
- %0 = call i32 (void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @foo, i32 0, i32 1, i32* @Flag, i32 0, i8 addrspace(1)* %obj)
- %obj.relocated = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(i32 %0, i32 4, i32 4)
+ %0 = call i32 (i64, i32, void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 0, i32 0, void ()* @foo, i32 0, i32 1, i32* @Flag, i32 0, i8 addrspace(1)* %obj)
+ %obj.relocated = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(i32 %0, i32 7, i32 7)
ret i8 addrspace(1)* %obj.relocated
}
calling sequence specific to their runtime before executing the
generated machine code. There are no guarantees with respect to the
alignment of the nop sequence. Unlike :doc:`StackMaps` statepoints do
-not have a concept of shadow bytes.
+not have a concept of shadow bytes. Note that semantically the
+statepoint still represents a call or invoke to 'target', and the nop
+sequence after patching is expected to represent an operation
+equivalent to a call or invoke to 'target'.
The 'target' operand is the function actually being called. The
target can be specified as either a symbolic LLVM function, or as an
arbitrary Value of appropriate function type. Note that the function
type must match the signature of the callee and the types of the 'call
-parameters' arguments. If 'num patch bytes' is non-zero then 'target'
-has to be the constant pointer null of the appropriate function type.
+parameters' arguments.
The '#call args' operand is the number of arguments to the actual
call. It must exactly match the number of arguments passed in the
local restrictions on the intrinsics mentioned in their respective
documentation. The current implementation in LLVM does not check the
key relocation invariant, but this is ongoing work on developing such
-a verifier. Please ask on llvmdev if you're interested in
+a verifier. Please ask on llvm-dev if you're interested in
experimenting with the current version.
.. _statepoint-utilities:
define i8 addrspace(1)* @test1(i8 addrspace(1)* %obj)
gc "statepoint-example" {
%0 = call i32 (i64, i32, void ()*, i32, i32, ...)* @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 2882400000, i32 0, void ()* @foo, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0, i8 addrspace(1)* %obj)
- %obj.relocated = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(i32 %0, i32 9, i32 9)
+ %obj.relocated = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(i32 %0, i32 12, i32 12)
ret i8 addrspace(1)* %obj.relocated
}
you should probably schedule this pass immediately before it. The exception
would be if you need to preserve abstract frame information (e.g. for
deoptimization or introspection) at safepoints. In that case, ask on the
-llvmdev mailing list for suggestions.
+llvm-dev mailing list for suggestions.
+
+
+Supported Architectures
+=======================
+Support for statepoint generation requires some code for each backend.
+Today, only X86_64 is supported.
Bugs and Enhancements
=====================
<http://llvm.org/bugs/buglist.cgi?cmdtype=runnamed&namedcmd=Statepoint%20Bugs&list_id=64342>`_
for [Statepoint] in the summary field. When filing new bugs, please
use this tag so that interested parties see the newly filed bug. As
-with most LLVM features, design discussions take place on `llvmdev
-<http://lists.cs.uiuc.edu/mailman/listinfo/llvmdev>`_, and patches
+with most LLVM features, design discussions take place on `llvm-dev
+<http://lists.llvm.org/mailman/listinfo/llvm-dev>`_, and patches
should be sent to `llvm-commits
-<http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits>`_ for review.
+<http://lists.llvm.org/mailman/listinfo/llvm-commits>`_ for review.
projects / oota-llvm.git / blobdiff