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Support loop cloning of byte array accesses #48894

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merged 2 commits into from
Mar 2, 2021
Merged

Support loop cloning of byte array accesses #48894

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Support loop cloning of byte array accesses
BruceForstall Feb 18, 2021
25fe5c0
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BruceForstall Mar 1, 2021
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67 changes: 43 additions & 24 deletions src/coreclr/jit/optimizer.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -8453,24 +8453,38 @@ bool Compiler::optIdentifyLoopOptInfo(unsigned loopNum, LoopCloneContext* contex
//
// TODO-CQ: CLONE: After morph make sure this method extracts values before morph.
//
// STMT void(IL 0x007...0x00C)
// [000023] -A-XG+------ * ASG int
// [000022] D----+-N---- +--* LCL_VAR int V06 tmp1
// [000048] ---XG+------ \--* COMMA int
// [000041] ---X-+------ +--* ARR_BOUNDS_CHECK_Rng void
// [000020] -----+------ | +--* LCL_VAR int V04 loc0
// [000040] ---X-+------ | \--* ARR_LENGTH int
// [000019] -----+------ | \--* LCL_VAR ref V00 arg0
// [000021] a--XG+------ \--* IND int
// [000047] -----+------ \--* ADD byref
// [000038] -----+------ +--* LCL_VAR ref V00 arg0
// [000046] -----+------ \--* ADD long
// [000044] -----+------ +--* LSH long
// [000042] -----+------ | +--* CAST long < -int
// [000039] i----+------ | | \--* LCL_VAR int V04 loc0
// [000043] -----+-N---- | \--* CNS_INT long 2
// [000045] -----+------ \--* CNS_INT long 16 Fseq[#FirstElem]

// Example tree to pattern match:
//
// * COMMA int
// +--* ARR_BOUNDS_CHECK_Rng void
// | +--* LCL_VAR int V02 loc1
// | \--* ARR_LENGTH int
// | \--* LCL_VAR ref V00 arg0
// \--* IND int
// \--* ADD byref
// +--* LCL_VAR ref V00 arg0
// \--* ADD long
// +--* LSH long
// | +--* CAST long <- int
// | | \--* LCL_VAR int V02 loc1
// | \--* CNS_INT long 2
// \--* CNS_INT long 16 Fseq[#FirstElem]
//
// Note that byte arrays don't require the LSH to scale the index, so look like this:
//
// * COMMA ubyte
// +--* ARR_BOUNDS_CHECK_Rng void
// | +--* LCL_VAR int V03 loc2
// | \--* ARR_LENGTH int
// | \--* LCL_VAR ref V00 arg0
// \--* IND ubyte
// \--* ADD byref
// +--* LCL_VAR ref V00 arg0
// \--* ADD long
// +--* CAST long <- int
// | \--* LCL_VAR int V03 loc2
// \--* CNS_INT long 16 Fseq[#FirstElem]
//
bool Compiler::optExtractArrIndex(GenTree* tree, ArrIndex* result, unsigned lhsNum)
{
if (tree->gtOper != GT_COMMA)
Expand Down Expand Up @@ -8544,15 +8558,20 @@ bool Compiler::optExtractArrIndex(GenTree* tree, ArrIndex* result, unsigned lhsN
{
return false;
}
if (si->gtOper != GT_LSH)
GenTree* index;
if (si->gtOper == GT_LSH)
{
return false;
GenTree* scale = si->gtGetOp2();
index = si->gtGetOp1();
if (scale->gtOper != GT_CNS_INT)
{
return false;
}
}
GenTree* scale = si->gtGetOp2();
GenTree* index = si->gtGetOp1();
if (scale->gtOper != GT_CNS_INT)
else
{
return false;
// No scale (e.g., byte array).
index = si;
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Do we need to add some assert to make sure the array is what we expect?

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Sorry, I missed this before merge. There's certainly some question about what additional things could/should be checked in this pattern matching. Types, for example. For this case, the index is checked (lower down) to be a lclvar that is the same as the array bounds check base, so we're good.

}
#ifdef TARGET_64BIT
if (index->gtOper != GT_CAST)
Expand Down