[llvm] r243502 - [Statepoints] Let patchable statepoints have a symbolic call target.
Sanjoy Das
sanjoy at playingwithpointers.com
Tue Jul 28 16:50:30 PDT 2015
Author: sanjoy
Date: Tue Jul 28 18:50:30 2015
New Revision: 243502
URL: http://llvm.org/viewvc/llvm-project?rev=243502&view=rev
Log:
[Statepoints] Let patchable statepoints have a symbolic call target.
Summary:
As added initially, statepoints required their call targets to be a
constant pointer null if ``numPatchBytes`` was non-zero. This turns out
to be a problem ergonomically, since there is no way to mark patchable
statepoints as calling a (readable) symbolic value.
This change remove the restriction of requiring ``null`` call targets
for patchable statepoints, and changes PlaceSafepoints to maintain the
symbolic call target through its transformation.
Reviewers: reames, swaroop.sridhar
Subscribers: llvm-commits
Differential Revision: http://reviews.llvm.org/D11550
Removed:
llvm/trunk/test/Verifier/invalid-patchable-statepoint.ll
Modified:
llvm/trunk/docs/Statepoints.rst
llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
llvm/trunk/lib/IR/Verifier.cpp
llvm/trunk/lib/Transforms/Scalar/PlaceSafepoints.cpp
llvm/trunk/test/Transforms/PlaceSafepoints/patchable-statepoints.ll
Modified: llvm/trunk/docs/Statepoints.rst
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/docs/Statepoints.rst?rev=243502&r1=243501&r2=243502&view=diff
==============================================================================
--- llvm/trunk/docs/Statepoints.rst (original)
+++ llvm/trunk/docs/Statepoints.rst Tue Jul 28 18:50:30 2015
@@ -331,14 +331,16 @@ the user will patch over the 'num patch
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
Modified: llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp?rev=243502&r1=243501&r2=243502&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp (original)
+++ llvm/trunk/lib/CodeGen/SelectionDAG/StatepointLowering.cpp Tue Jul 28 18:50:30 2015
@@ -289,7 +289,23 @@ lowerCallFromStatepoint(ImmutableStatepo
ImmutableCallSite CS(ISP.getCallSite());
- SDValue ActualCallee = Builder.getValue(ISP.getCalledValue());
+ SDValue ActualCallee;
+
+ if (ISP.getNumPatchBytes() > 0) {
+ // If we've been asked to emit a nop sequence instead of a call instruction
+ // for this statepoint then don't lower the call target, but use a constant
+ // `null` instead. Not lowering the call target lets statepoint clients get
+ // away without providing a physical address for the symbolic call target at
+ // link time.
+
+ const auto &TLI = Builder.DAG.getTargetLoweringInfo();
+ const auto &DL = Builder.DAG.getDataLayout();
+
+ unsigned AS = ISP.getCalledValue()->getType()->getPointerAddressSpace();
+ ActualCallee = Builder.DAG.getConstant(0, Builder.getCurSDLoc(),
+ TLI.getPointerTy(DL, AS));
+ } else
+ ActualCallee = Builder.getValue(ISP.getCalledValue());
assert(CS.getCallingConv() != CallingConv::AnyReg &&
"anyregcc is not supported on statepoints!");
Modified: llvm/trunk/lib/IR/Verifier.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/IR/Verifier.cpp?rev=243502&r1=243501&r2=243502&view=diff
==============================================================================
--- llvm/trunk/lib/IR/Verifier.cpp (original)
+++ llvm/trunk/lib/IR/Verifier.cpp Tue Jul 28 18:50:30 2015
@@ -1544,12 +1544,6 @@ void Verifier::VerifyStatepoint(Immutabl
"gc.statepoint callee must be of function pointer type", &CI, Target);
FunctionType *TargetFuncType = cast<FunctionType>(PT->getElementType());
- if (NumPatchBytes)
- Assert(isa<ConstantPointerNull>(Target->stripPointerCasts()),
- "gc.statepoint must have null as call target if number of patchable "
- "bytes is non zero",
- &CI);
-
const Value *NumCallArgsV = CS.getArgument(3);
Assert(isa<ConstantInt>(NumCallArgsV),
"gc.statepoint number of arguments to underlying call "
Modified: llvm/trunk/lib/Transforms/Scalar/PlaceSafepoints.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/PlaceSafepoints.cpp?rev=243502&r1=243501&r2=243502&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/PlaceSafepoints.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/PlaceSafepoints.cpp Tue Jul 28 18:50:30 2015
@@ -917,15 +917,10 @@ static Value *ReplaceWithStatepoint(cons
CS.getInstruction()->getContext(), AttributeSet::FunctionIndex,
AttrsToRemove);
- 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(
- ID, NumPatchBytes, StatepointTarget,
+ ID, NumPatchBytes, CS.getCalledValue(),
makeArrayRef(CS.arg_begin(), CS.arg_end()), None, None,
"safepoint_token");
Call->setTailCall(ToReplace->isTailCall());
@@ -951,7 +946,7 @@ static Value *ReplaceWithStatepoint(cons
// original block.
Builder.SetInsertPoint(ToReplace->getParent());
InvokeInst *Invoke = Builder.CreateGCStatepointInvoke(
- ID, NumPatchBytes, StatepointTarget, ToReplace->getNormalDest(),
+ ID, NumPatchBytes, CS.getCalledValue(), ToReplace->getNormalDest(),
ToReplace->getUnwindDest(), makeArrayRef(CS.arg_begin(), CS.arg_end()),
None, None, "safepoint_token");
Modified: llvm/trunk/test/Transforms/PlaceSafepoints/patchable-statepoints.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/PlaceSafepoints/patchable-statepoints.ll?rev=243502&r1=243501&r2=243502&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/PlaceSafepoints/patchable-statepoints.ll (original)
+++ llvm/trunk/test/Transforms/PlaceSafepoints/patchable-statepoints.ll Tue Jul 28 18:50:30 2015
@@ -22,7 +22,7 @@ define void @test_num_patch_bytes() gc "
; 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,
+; CHECK: invoke i32 (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_isVoidf(i64 2882400000, i32 99, void ()* @f,
invoke void @f() "statepoint-num-patch-bytes"="99" to label %normal_return unwind label %exceptional_return
normal_return:
Removed: llvm/trunk/test/Verifier/invalid-patchable-statepoint.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Verifier/invalid-patchable-statepoint.ll?rev=243501&view=auto
==============================================================================
--- llvm/trunk/test/Verifier/invalid-patchable-statepoint.ll (original)
+++ llvm/trunk/test/Verifier/invalid-patchable-statepoint.ll (removed)
@@ -1,14 +0,0 @@
-; RUN: not opt -verify 2>&1 < %s | FileCheck %s
-
-; CHECK: gc.statepoint must have null as call target if number of patchable bytes is non zero
-
-define i1 @invalid_patchable_statepoint() gc "statepoint-example" {
-entry:
- %safepoint_token = tail call i32 (i64, i32, i1 ()*, i32, i32, ...) @llvm.experimental.gc.statepoint.p0f_i1f(i64 0, i32 3, i1 ()* @func, i32 0, i32 0, i32 0, i32 0)
- %call1 = call i1 @llvm.experimental.gc.result.i1(i32 %safepoint_token)
- ret i1 %call1
-}
-
-declare i32 @llvm.experimental.gc.statepoint.p0f_i1f(i64, i32, i1 ()*, i32, i32, ...)
-declare i1 @llvm.experimental.gc.result.i1(i32)
-declare i1 @func()
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