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[Statepoints 1/4] Statepoint infrastructure for garbage collection: IR Intrinsics

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The statepoint intrinsics are intended to enable precise root tracking through the compiler as to support garbage collectors of all types. The addition of the statepoint intrinsics to LLVM should have no impact on the compilation of any program which does not contain them. There are no side tables created, no extra metadata, and no inhibited optimizations.

A statepoint works by transforming a call site (or safepoint poll site) into an explicit relocation operation. It is the frontend's responsibility (or eventually the safepoint insertion pass we've developed, but that's not part of this patch series) to ensure that any live pointer to a GC object is correctly added to the statepoint and explicitly relocated. The relocated value is just a normal SSA value (as seen by the optimizer), so merges of relocated and unrelocated values are just normal phis. The explicit relocation operation, the fact the statepoint is assumed to clobber all memory, and the optimizers standard semantics ensure that the relocations flow through IR optimizations correctly.

This is the first patch in a small series.  This patch contains only the IR parts; the documentation and backend support will be following separately.  The entire series can be seen as one combined whole in http://reviews.llvm.org/D5683.

Reviewed by: atrick, ributzka





git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@223078 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Philip Reames
2014-12-01 21:18:12 +00:00
parent b043278834
commit 204e21b51a
4 changed files with 151 additions and 0 deletions
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16
include/llvm/IR/Intrinsics.td
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@@ -493,6 +493,22 @@ def int_experimental_patchpoint_i64 : Intrinsic<[llvm_i64_ty],
llvm_vararg_ty],
[Throws]>;
//===------------------------ Garbage Collection Intrinsics ---------------===//
// These are documented in docs/Statepoint.rst
def int_experimental_gc_statepoint : Intrinsic<[llvm_i32_ty],
[llvm_anyptr_ty, llvm_i32_ty,
llvm_i32_ty, llvm_vararg_ty]>;
def int_experimental_gc_result_int : Intrinsic<[llvm_anyint_ty], [llvm_i32_ty]>;
def int_experimental_gc_result_float : Intrinsic<[llvm_anyfloat_ty],
[llvm_i32_ty]>;
def int_experimental_gc_result_ptr : Intrinsic<[llvm_anyptr_ty], [llvm_i32_ty]>;
def int_experimental_gc_relocate : Intrinsic<[llvm_anyptr_ty],
[llvm_i32_ty, llvm_i32_ty, llvm_i32_ty]>;
//===-------------------------- Other Intrinsics --------------------------===//
//
def int_flt_rounds : Intrinsic<[llvm_i32_ty]>,