Closed
Description
If we CSE an address computation for a GC store, then gcIsWriteBarrierCandidate may no longer be able to tell that the address being stored to is a heap address, and so will switch to using a checked write barrier.
Seems like we could find a way not to lose track of this, info for example marking the store as GTF_IND_TGT_HEAP (or GTF_IND_TGT_NOT_HEAP) if we do a CSE.
For example:
;; compiling System.Int32:CompareTo(int):int:this (MethodHash=c9004add)
CSE #05 def at [000177] replaced in BB06 with def of V12
BB06 requires throw helper block for SCK_RNGCHK_FAIL
optValnumCSE morphed tree:
N023 ( 23, 27) [000086] DA-XGO----- * STORE_LCL_VAR int V11 tmp10 d:1 <l:$199, c:$19d>
N022 ( 19, 24) [000085] -A-XGO----- \--* SUB int <l:$295, c:$294>
N020 ( 17, 22) [000081] VA-XGO----- +--* IND int <l:$292, c:$291>
N019 ( 15, 20) [000165] -A-XGO-N--- | \--* ADD byref <l:$20e, c:$20f>
N017 ( 14, 19) [000232] -A-X-O----- | +--* COMMA byref <l:$20d, c:$20c>
N015 ( 13, 18) CSE #05 (def)[000230] DA-X-O----- | | +--* STORE_LCL_VAR byref V12 cse0 d:1 $VN.Void
N014 ( 13, 18) [000177] ---X-O----- | | | \--* COMMA byref <l:$20d, c:$20c>
N004 ( 8, 11) [000169] ---X-O----- | | | +--* BOUNDS_CHECK_Rng void <l:$199, c:$198>
N001 ( 1, 1) [000078] ----------- | | | | +--* LCL_VAR int V09 tmp8 u:1 <l:$28b, c:$28c>
N003 ( 3, 3) CSE #02 (def)[000168] ---X------- | | | | \--* ARR_LENGTH int <l:$28f, c:$290>
N002 ( 1, 1) [000077] ----------- | | | | \--* LCL_VAR ref V07 tmp6 u:1 <l:$189, c:$108>
N013 ( 5, 7) [000176] -----O----- | | | \--* ARR_ADDR byref System.Collections.Concurrent.ConcurrentQueueSegment`1+Slot[] $81
N012 ( 5, 7) [000175] -------N--- | | | \--* ADD byref <l:$20a, c:$20b>
N005 ( 1, 1) [000166] ----------- | | | +--* LCL_VAR ref V07 tmp6 u:1 <l:$189, c:$108>
N011 ( 5, 6) [000174] -------N--- | | | \--* ADD long <l:$3c4, c:$3c5>
N009 ( 4, 5) CSE #04 (def)[000172] ----------- | | | +--* LSH long <l:$3c2, c:$3c3>
N007 ( 2, 3) CSE #03 (def)[000170] ---------U- | | | | +--* CAST long <- uint <l:$3c0, c:$3c1>
N006 ( 1, 1) [000167] ----------- | | | | | \--* LCL_VAR int V09 tmp8 u:1 <l:$28b, c:$28c>
N008 ( 1, 1) [000171] -------N--- | | | | \--* CNS_INT long 4 $1c6
N010 ( 1, 1) [000173] ----------- | | | \--* CNS_INT long 16 $1c0
N016 ( 1, 1) [000231] ----------- | | \--* LCL_VAR byref V12 cse0 u:1 <l:$20d, c:$20c>
N018 ( 1, 1) [000164] ----------- | \--* CNS_INT long 8 $1c3
N021 ( 1, 1) [000084] ----------- \--* LCL_VAR int V08 tmp7 u:1 $241
-----
Generating: N191 ( 1, 1) [000233] ----------- t233 = LCL_VAR byref V12 cse0 u:1 r14 REG r14 $81
Generating: N193 ( 1, 1) [000009] ----------- t9 = LCL_VAR ref V00 this u:1 rbx (last use) REG rbx $100
/--* t233 byref
+--* t9 ref
Generating: N195 ( 5, 4) [000114] nA--GO----- * STOREIND ref REG NA <l:$199, c:$198>
V00 in reg rbx is becoming dead [000009]
Live regs: 000000000000C048 {rbx rsi r14 r15} - {rbx} => 000000000000C040 {rsi r14 r15}
Debug: Closing V00 debug range.
Live vars after [000009]: {V00 V02 V12 V13} -{V00} => {V02 V12 V13}
GC regs: 0048 {rbx rsi} => 0040 {rsi}
Mapped BB08 to G_M63573_IG08
IN0029: mov rcx, r14
IN002a: mov rdx, rbx
NoGC Call: savedSet=F0E8 {rbx rbp rsi rdi r12 r13 r14 r15}
Call: GCvars=0000000000000000 {}, gcrefRegs=0040 {rsi}, byrefRegs=4000 {r14}
IN002b: call CORINFO_HELP_CHECKED_ASSIGN_REF
We may also want to propagate this info during assertion prop or similar so if there is a manual CSE we still are able to see through it.