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[RS4GC] Re-purpose `normalizeForInvokeSafepoint`; NFC. 

`normalizeForInvokeSafepoint` in RewriteStatepointsForGC.cpp, as it is
written today, deals with `gc.relocate` and `gc.result` uses of a
statepoint equally well.  This change documents this fact and adds a
test case.

There is no functional change here -- only documentation of existing
functionality.

llvm-svn: 250784
This commit is contained in:
Sanjoy Das 2015-10-20 01:06:24 +00:00
parent ff3dba736a
commit 7ad67640e9
2 changed files with 41 additions and 9 deletions
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18
llvm/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
View File

@ -1239,12 +1239,12 @@ static void recomputeLiveInValues(
}
}
// When inserting gc.relocate calls, we need to ensure there are no uses
// of the original value between the gc.statepoint and the gc.relocate call.
// One case which can arise is a phi node starting one of the successor blocks.
// We also need to be able to insert the gc.relocates only on the path which
// goes through the statepoint. We might need to split an edge to make this
// possible.
// When inserting gc.relocate and gc.result calls, we need to ensure there are
// no uses of the original value / return value between the gc.statepoint and
// the gc.relocate / gc.result call. One case which can arise is a phi node
// starting one of the successor blocks. We also need to be able to insert the
// gc.relocates only on the path which goes through the statepoint. We might
// need to split an edge to make this possible.
static BasicBlock *
normalizeForInvokeSafepoint(BasicBlock *BB, BasicBlock *InvokeParent,
DominatorTree &DT) {
@ -1252,14 +1252,14 @@ normalizeForInvokeSafepoint(BasicBlock *BB, BasicBlock *InvokeParent,
if (!BB->getUniquePredecessor())
Ret = SplitBlockPredecessors(BB, InvokeParent, "", &DT);
// Now that 'ret' has unique predecessor we can safely remove all phi nodes
// Now that 'Ret' has unique predecessor we can safely remove all phi nodes
// from it
FoldSingleEntryPHINodes(Ret);
assert(!isa<PHINode>(Ret->begin()) &&
"All PHI nodes should have been removed!");
// At this point, we can safely insert a gc.relocate as the first instruction
// in Ret if needed.
// At this point, we can safely insert a gc.relocate or gc.result as the first
// instruction in Ret if needed.
return Ret;
}

32
llvm/test/Transforms/RewriteStatepointsForGC/deopt-bundles/rewrite-invoke.ll Normal file
View File

@ -0,0 +1,32 @@
; RUN: opt -rewrite-statepoints-for-gc -rs4gc-use-deopt-bundles -verify -S < %s | FileCheck %s
declare i8 addrspace(1)* @gc_call()
declare i32* @fake_personality_function()
define i8 addrspace(1)* @test(i1 %c) gc "statepoint-example" personality i32* ()* @fake_personality_function {
; CHECK-LABEL: @test(
entry:
br i1 %c, label %gc_invoke, label %normal_dest
gc_invoke:
; CHECK: [[TOKEN:%[^ ]+]] = invoke i32 {{[^@]+}}@llvm.experimental.gc.statepoint{{[^@]+}}@gc_call
%obj = invoke i8 addrspace(1)* @gc_call() [ "deopt"(i32 0, i32 -1, i32 0, i32 0, i32 0) ]
to label %normal_dest unwind label %unwind_dest
unwind_dest:
; CHECK: unwind_dest:
%lpad = landingpad { i8*, i32 }
cleanup
resume { i8*, i32 } undef
; CHECK: [[NORMAL_DEST_SPLIT:[^:]+:]]
; CHECK-NEXT: [[RET_VAL:%[^ ]+]] = call i8 addrspace(1)* @llvm.experimental.gc.result.p1i8(i32 [[TOKEN]])
; CHECK-NEXT: br label %normal_dest
normal_dest:
; CHECK: normal_dest:
; CHECK-NEXT: %merge = phi i8 addrspace(1)* [ null, %entry ], [ %obj.2, %normal_dest1 ]
%merge = phi i8 addrspace(1)* [ null, %entry ], [ %obj, %gc_invoke ]
ret i8 addrspace(1)* %merge
}