[llvm] r282150 - [RS4GC] Remat in presence of phi and use live value
Anna Thomas via llvm-commits
llvm-commits at lists.llvm.org
Sat Oct 1 18:36:10 PDT 2016
Hi Philip.
I had actually updated the comment in the Phabricator, after the commit.
https://reviews.llvm.org/rL282150
Forgot to amend the commit before submit:
Summary:
When rematerializing for geps and casts in presence of phis, we need to make
sure that unrelocated values (the current Phi node) should never be used.
The relocation is only done for the base version of the phi, which is generated
by findBasePointers function.
This is a fix when IR verifier for safepoints identifies uses of unrelocated values,
which was generated due to commit rL279975<https://reviews.llvm.org/rL279975>.
Reviewers: Philip
Differential Revision: https://reviews.llvm.org/D24399
Thanks,
Anna
On Sep 27, 2016, at 7:20 PM, Philip Reames <listmail at philipreames.com<mailto:listmail at philipreames.com>> wrote:
Anna,
It looks like the commit message lost the link with the review. Can you reply with a more full commit message and a link to the review thread?
Philip
On 09/22/2016 06:13 AM, Anna Thomas via llvm-commits wrote:
Author: annat
Date: Thu Sep 22 08:13:06 2016
New Revision: 282150
URL: http://llvm.org/viewvc/llvm-project?rev=282150&view=rev
Log:
[RS4GC] Remat in presence of phi and use live value
Summary:
Reviewers:
Subscribers:
Modified:
llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
llvm/trunk/test/Transforms/RewriteStatepointsForGC/rematerialize-derived-pointers.ll
Modified: llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp?rev=282150&r1=282149&r2=282150&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/RewriteStatepointsForGC.cpp Thu Sep 22 08:13:06 2016
@@ -1976,7 +1976,8 @@ static void rematerializeLiveValues(Call
// Utility function which clones all instructions from "ChainToBase"
// and inserts them before "InsertBefore". Returns rematerialized value
// which should be used after statepoint.
- auto rematerializeChain = [&ChainToBase](Instruction *InsertBefore) {
+ auto rematerializeChain = [&ChainToBase](
+ Instruction *InsertBefore, Value *RootOfChain, Value *AlternateLiveBase) {
Instruction *LastClonedValue = nullptr;
Instruction *LastValue = nullptr;
for (Instruction *Instr: ChainToBase) {
@@ -1996,13 +1997,24 @@ static void rematerializeLiveValues(Call
assert(LastValue);
ClonedValue->replaceUsesOfWith(LastValue, LastClonedValue);
#ifndef NDEBUG
- // Assert that cloned instruction does not use any instructions from
- // this chain other than LastClonedValue
for (auto OpValue : ClonedValue->operand_values()) {
+ // Assert that cloned instruction does not use any instructions from
+ // this chain other than LastClonedValue
assert(!is_contained(ChainToBase, OpValue) &&
"incorrect use in rematerialization chain");
+ // Assert that the cloned instruction does not use the RootOfChain
+ // or the AlternateLiveBase.
+ assert(OpValue != RootOfChain && OpValue != AlternateLiveBase);
}
#endif
+ } else {
+ // For the first instruction, replace the use of unrelocated base i.e.
+ // RootOfChain/OrigRootPhi, with the corresponding PHI present in the
+ // live set. They have been proved to be the same PHI nodes. Note
+ // that the *only* use of the RootOfChain in the ChainToBase list is
+ // the first Value in the list.
+ if (RootOfChain != AlternateLiveBase)
+ ClonedValue->replaceUsesOfWith(RootOfChain, AlternateLiveBase);
}
LastClonedValue = ClonedValue;
@@ -2017,7 +2029,8 @@ static void rematerializeLiveValues(Call
if (CS.isCall()) {
Instruction *InsertBefore = CS.getInstruction()->getNextNode();
assert(InsertBefore);
- Instruction *RematerializedValue = rematerializeChain(InsertBefore);
+ Instruction *RematerializedValue = rematerializeChain(
+ InsertBefore, RootOfChain, Info.PointerToBase[LiveValue]);
Info.RematerializedValues[RematerializedValue] = LiveValue;
} else {
InvokeInst *Invoke = cast<InvokeInst>(CS.getInstruction());
@@ -2027,10 +2040,10 @@ static void rematerializeLiveValues(Call
Instruction *UnwindInsertBefore =
&*Invoke->getUnwindDest()->getFirstInsertionPt();
- Instruction *NormalRematerializedValue =
- rematerializeChain(NormalInsertBefore);
- Instruction *UnwindRematerializedValue =
- rematerializeChain(UnwindInsertBefore);
+ Instruction *NormalRematerializedValue = rematerializeChain(
+ NormalInsertBefore, RootOfChain, Info.PointerToBase[LiveValue]);
+ Instruction *UnwindRematerializedValue = rematerializeChain(
+ UnwindInsertBefore, RootOfChain, Info.PointerToBase[LiveValue]);
Info.RematerializedValues[NormalRematerializedValue] = LiveValue;
Info.RematerializedValues[UnwindRematerializedValue] = LiveValue;
Modified: llvm/trunk/test/Transforms/RewriteStatepointsForGC/rematerialize-derived-pointers.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/Transforms/RewriteStatepointsForGC/rematerialize-derived-pointers.ll?rev=282150&r1=282149&r2=282150&view=diff
==============================================================================
--- llvm/trunk/test/Transforms/RewriteStatepointsForGC/rematerialize-derived-pointers.ll (original)
+++ llvm/trunk/test/Transforms/RewriteStatepointsForGC/rematerialize-derived-pointers.ll Thu Sep 22 08:13:06 2016
@@ -285,7 +285,7 @@ merge:
; CHECK: %statepoint_token = call token (i64, i32, void ()*, i32, i32, ...) @llvm.experimental.gc.statepoint
; CHECK: %basephi.base.relocated = call coldcc i8 addrspace(1)* @llvm.experimental.gc.relocate.p1i8(token %statepoint_token, i32 7, i32 7) ; (%basephi.base, %basephi.base)
; CHECK: %basephi.base.relocated.casted = bitcast i8 addrspace(1)* %basephi.base.relocated to i32 addrspace(1)*
- ; CHECK: %ptr.gep.remat = getelementptr i32, i32 addrspace(1)* %basephi, i32 15
+ ; CHECK: %ptr.gep.remat = getelementptr i32, i32 addrspace(1)* %basephi.base.relocated.casted, i32 15
; CHECK: call void @use_obj32(i32 addrspace(1)* %ptr.gep.remat)
@@ -296,3 +296,35 @@ merge:
call void @use_obj32(i32 addrspace(1)* %ptr.gep)
ret void
}
+
+
+define void @test_intersecting_chains_with_phi(i1 %cond) gc "statepoint-example" {
+; CHECK-LABEL: test_intersecting_chains_with_phi
+entry:
+ %base1 = call i32 addrspace(1)* @new_instance()
+ %base2 = call i32 addrspace(1)* @new_instance()
+ br i1 %cond, label %here, label %there
+
+here:
+ br label %merge
+
+there:
+ br label %merge
+
+merge:
+ %basephi = phi i32 addrspace(1)* [ %base1, %here ], [ %base2, %there ]
+ %ptr.gep = getelementptr i32, i32 addrspace(1)* %basephi, i32 15
+ %ptr.cast = bitcast i32 addrspace(1)* %ptr.gep to i64 addrspace(1)*
+ %ptr.cast2 = bitcast i32 addrspace(1)* %ptr.gep to i16 addrspace(1)*
+ call void @do_safepoint() [ "deopt"() ]
+ ; CHECK: statepoint
+ ; CHECK: %ptr.gep.remat1 = getelementptr i32, i32 addrspace(1)* %basephi.base.relocated.casted, i32 15
+ ; CHECK: %ptr.cast.remat = bitcast i32 addrspace(1)* %ptr.gep.remat1 to i64 addrspace(1)*
+ ; CHECK: %ptr.gep.remat = getelementptr i32, i32 addrspace(1)* %basephi.base.relocated.casted, i32 15
+ ; CHECK: %ptr.cast2.remat = bitcast i32 addrspace(1)* %ptr.gep.remat to i16 addrspace(1)*
+ ; CHECK: call void @use_obj64(i64 addrspace(1)* %ptr.cast.remat)
+ ; CHECK: call void @use_obj16(i16 addrspace(1)* %ptr.cast2.remat)
+ call void @use_obj64(i64 addrspace(1)* %ptr.cast)
+ call void @use_obj16(i16 addrspace(1)* %ptr.cast2)
+ ret void
+}
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