Missing GTF_ASG and GTF_ALL_EFFECT on GenTree nodes.

[sandreenko]

Sometimes we are missing GTF_ASG flag for calls when create a setup argument node in fgArgInfo::EvalArgsToTemps(). It creates an unwanted effect that call to gtUpdateSideEffects(tree, stmt) could change flags when the trees are unchanged:

before calling gtUpdateSideEffects(000055, stmt):

N019 ( 51, 40) [000068] --CXG-------              *  JTRUE     void
N018 ( 49, 38) [000067] J-CXG--N----              \--*  LT        int    $148
N016 ( 47, 36) [000065] --CXG------- HERE            +--*  CALLV stub int    System.Collections.IComparer.Compare $383
N010 ( 18, 11) [000131] -ACXG---R-L- arg2 SETUP      |  +--*  ASG       ref    $346
N009 (  1,  1) [000130] D------N----                 |  |  +--*  LCL_VAR   ref    V12 tmp5         d:2 $346
N008 ( 18, 11) [000059] --CXG-------                 |  |  \--*  CALL r2r_ind ref    System.Array.GetValue $346
N006 (  3,  2) [000049] *--XG------- this in rcx     |  |     +--*  IND       ref    <l:$286, c:$285>
N005 (  1,  1) [000048] ------------                 |  |     |  \--*  LCL_VAR   byref  V00 this         u:1 Zero Fseq[keys] $80
N007 (  1,  1) [000055] ------------ arg1 in rdx     |  |     \--*  LCL_VAR   int    V05 loc2         u:5 (last use) $147
N012 (  1,  1) [000132] ------------ arg2 in rdx     |  +--*  LCL_VAR   ref    V12 tmp5         u:2 (last use) $346
N013 (  1,  1) [000064] ------------ arg3 in r8      |  +--*  LCL_VAR   ref    V04 loc1         u:2 $205
N014 (  1,  1) [000062] ------------ this in rcx     |  +--*  LCL_VAR   ref    V09 tmp2         u:2 (last use) <l:$241, c:$341>
N015 (  3, 10) [000127] ------------ arg1 in r11     |  \--*  CNS_INT(h) long   0xd1ffab1e ftn REG r11 $480
N017 (  1,  1) [000066] ------------                 \--*  CNS_INT   int    0 $40

after:

N019 ( 51, 40) [000068] -ACXG-------              *  JTRUE     void
N018 ( 49, 38) [000067] JACXG--N----              \--*  LT        int    $148
N016 ( 47, 36) [000065] -ACXG------- HERE                        +--*  CALLV stub int    System.Collections.IComparer.Compare $383
N010 ( 18, 11) [000131] -ACXG---R-L- arg2 SETUP      |  +--*  ASG       ref    $346
N009 (  1,  1) [000130] D------N----                 |  |  +--*  LCL_VAR   ref    V12 tmp5         d:2 $346
N008 ( 18, 11) [000059] --CXG-------                 |  |  \--*  CALL r2r_ind ref    System.Array.GetValue $346
N006 (  3,  2) [000049] *--XG------- this in rcx     |  |     +--*  IND       ref    <l:$286, c:$285>
N005 (  1,  1) [000048] ------------                 |  |     |  \--*  LCL_VAR   byref  V00 this         u:1 Zero Fseq[keys] $80
N007 (  1,  1) [000055] ------------ arg1 in rdx     |  |     \--*  LCL_VAR   int    V05 loc2         u:5 (last use) $147
N012 (  1,  1) [000132] ------------ arg2 in rdx     |  +--*  LCL_VAR   ref    V12 tmp5         u:2 (last use) $346
N013 (  1,  1) [000064] ------------ arg3 in r8      |  +--*  LCL_VAR   ref    V04 loc1         u:2 $205
N014 (  1,  1) [000062] ------------ this in rcx     |  +--*  LCL_VAR   ref    V09 tmp2         u:2 (last use) <l:$241, c:$341>
N015 (  3, 10) [000127] ------------ arg1 in r11     |  \--*  CNS_INT(h) long   0xd1ffab1e ftn REG r11 $480
N017 (  1,  1) [000066] ------------                 \--*  CNS_INT   int    0 $40

see that flags on [000065] have changed, but they should not.

The same happens with GTF_ALL_EFFECT on addr modes.

The fix for it is simple and published in dotnet/coreclr#27732, however, the fix create 0.1% size regression because of another issue. So I will postpone it until another issue is fixed.

Along the way fix that we don't print fgMorphTree block, stmt(after) if only the flags were changed.

category:correctness
theme:ir
skill-level:intermediate
cost:medium

[AndyAyersMS]

Moving this to future.