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5c7f7462e4
This changes the shape of the statepoint intrinsic from:
@llvm.experimental.gc.statepoint(anyptr target, i32 # call args, i32 unused, ...call args, i32 # deopt args, ...deopt args, ...gc args)
to:
@llvm.experimental.gc.statepoint(anyptr target, i32 # call args, i32 flags, ...call args, i32 # transition args, ...transition args, i32 # deopt args, ...deopt args, ...gc args)
This extension offers the backend the opportunity to insert (somewhat) arbitrary code to manage the transition from GC-aware code to code that is not GC-aware and back.
In order to support the injection of transition code, this extension wraps the STATEPOINT ISD node generated by the usual lowering lowering with two additional nodes: GC_TRANSITION_START and GC_TRANSITION_END. The transition arguments that were passed passed to the intrinsic (if any) are lowered and provided as operands to these nodes and may be used by the backend during code generation.
Eventually, the lowering of the GC_TRANSITION_{START,END} nodes should be informed by the GC strategy in use for the function containing the intrinsic call; for now, these nodes are instead replaced with no-ops.
Differential Revision: http://reviews.llvm.org/D9501
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@236888 91177308-0d34-0410-b5e6-96231b3b80d8
101 lines
4.6 KiB
LLVM
101 lines
4.6 KiB
LLVM
; RUN: opt %s -rewrite-statepoints-for-gc -S 2>&1 | FileCheck %s
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declare i64 addrspace(1)* @generate_obj()
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declare void @use_obj(i64 addrspace(1)*)
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; The rewriting needs to make %obj loop variant by inserting a phi
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; of the original value and it's relocation.
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define void @def_use_safepoint() gc "statepoint-example" {
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; CHECK-LABEL: def_use_safepoint
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entry:
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%obj = call i64 addrspace(1)* @generate_obj()
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br label %loop
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loop:
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; CHECK: phi i64 addrspace(1)*
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; CHECK-DAG: [ %obj.relocated, %loop ]
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; CHECK-DAG: [ %obj, %entry ]
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call void @use_obj(i64 addrspace(1)* %obj)
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%safepoint_token = call i32 (void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @do_safepoint, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
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br label %loop
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}
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declare void @do_safepoint()
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declare void @parse_point(i64 addrspace(1)*)
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define i64 addrspace(1)* @test1(i32 %caller, i8 addrspace(1)* %a, i8 addrspace(1)* %b, i32 %unknown) gc "statepoint-example" {
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; CHECK-LABEL: test1
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entry:
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br i1 undef, label %left, label %right
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left:
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%a.cast = bitcast i8 addrspace(1)* %a to i64 addrspace(1)*
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; CHECK: left:
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; CHECK-NEXT: %a.cast = bitcast i8 addrspace(1)* %a to i64 addrspace(1)*
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; CHECK-NEXT: [[CAST_L:%.*]] = bitcast i8 addrspace(1)* %a to i64 addrspace(1)*
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; Our safepoint placement pass calls removeUnreachableBlocks, which does a bunch
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; of simplifications to branch instructions. This bug is visible only when
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; there are multiple branches into the same block from the same predecessor, and
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; the following ceremony is to make that artefact survive a call to
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; removeUnreachableBlocks. As an example, "br i1 undef, label %merge, label %merge"
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; will get simplified to "br label %merge" by removeUnreachableBlocks.
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switch i32 %unknown, label %right [ i32 0, label %merge
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i32 1, label %merge
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i32 5, label %merge
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i32 3, label %right ]
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right:
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%b.cast = bitcast i8 addrspace(1)* %b to i64 addrspace(1)*
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br label %merge
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; CHECK: right:
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; CHECK-NEXT: %b.cast = bitcast i8 addrspace(1)* %b to i64 addrspace(1)*
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; CHECK-NEXT: [[CAST_R:%.*]] = bitcast i8 addrspace(1)* %b to i64 addrspace(1)*
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merge:
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; CHECK: merge:
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; CHECK-NEXT: %base_phi = phi i64 addrspace(1)* [ [[CAST_L]], %left ], [ [[CAST_L]], %left ], [ [[CAST_L]], %left ], [ [[CAST_R]], %right ], !is_base_value !0
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%value = phi i64 addrspace(1)* [ %a.cast, %left], [ %a.cast, %left], [ %a.cast, %left], [ %b.cast, %right]
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%safepoint_token = call i32 (void (i64 addrspace(1)*)*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidp1i64f(void (i64 addrspace(1)*)* @parse_point, i32 1, i32 0, i64 addrspace(1)* %value, i32 0, i32 5, i32 0, i32 0, i32 0, i32 0, i32 0)
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ret i64 addrspace(1)* %value
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}
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;; The purpose of this test is to ensure that when two live values share a
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;; base defining value with inherent conflicts, we end up with a *single*
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;; base phi/select per such node. This is testing an optimization, not a
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;; fundemental correctness criteria
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define void @test2(i1 %cnd, i64 addrspace(1)* %base_obj, i64 addrspace(1)* %base_arg2) gc "statepoint-example" {
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; CHECK-LABEL: @test2
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entry:
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%obj = getelementptr i64, i64 addrspace(1)* %base_obj, i32 1
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br label %loop
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loop: ; preds = %loop, %entry
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; CHECK-LABEL: loop
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; CHECK: %base_phi = phi i64 addrspace(1)*
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; CHECK-DAG: [ %base_obj, %entry ]
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; Given the two selects are equivelent, so are their base phis - ideally,
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; we'd have commoned these, but that's a missed optimization, not correctness.
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; CHECK-DAG: [ [[DISCARD:%base_select.*.relocated]], %loop ]
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; CHECK-NOT: base_phi2
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; CHECK: next = select
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; CHECK: base_select
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; CHECK: extra2 = select
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; CHECK: base_select
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; CHECK: statepoint
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;; Both 'next' and 'extra2' are live across the backedge safepoint...
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%current = phi i64 addrspace(1)* [ %obj, %entry ], [ %next, %loop ]
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%extra = phi i64 addrspace(1)* [ %obj, %entry ], [ %extra2, %loop ]
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%nexta = getelementptr i64, i64 addrspace(1)* %current, i32 1
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%next = select i1 %cnd, i64 addrspace(1)* %nexta, i64 addrspace(1)* %base_arg2
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%extra2 = select i1 %cnd, i64 addrspace(1)* %nexta, i64 addrspace(1)* %base_arg2
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%safepoint_token = call i32 (void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()* @foo, i32 0, i32 0, i32 0, i32 5, i32 0, i32 -1, i32 0, i32 0, i32 0)
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br label %loop
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}
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declare void @foo()
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declare i32 @llvm.experimental.gc.statepoint.p0f_isVoidf(void ()*, i32, i32, ...)
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declare i32 @llvm.experimental.gc.statepoint.p0f_isVoidp1i64f(void (i64 addrspace(1)*)*, i32, i32, ...)
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