[Issue 859] New: Improve compiler inlining

[d-bugmail at puremagic.com]

http://d.puremagic.com/issues/show_bug.cgi?id=859

           Summary: Improve compiler inlining
           Product: D
           Version: 1.00
          Platform: PC
        OS/Version: Windows
            Status: NEW
          Severity: enhancement
          Priority: P2
         Component: DMD
        AssignedTo: bugzilla at digitalmars.com
        ReportedBy: digitalmars-com at baysmith.com


Compiler inlining of functions gives much worse performance than manually
inlined functions (at least in some cases). In the attached example, the
performance is 6 times slower.

C:\>dmd -O -inline -release -g testinline.d
C:\>testinline.exe
compiler inlined time: 374058
manually inlined time: 61362

C:\>obj2asm testinline.obj -ctestinline.asm

See line 486 for the compiler inlined code
See line 544 for the manually inlined code

The compiler inlined code extra instructions like the following:
        lea     ESI,-080h[EBP]
        lea     EDI,-048h[EBP]
        movsd
        movsd
        movsd
        lea     ESI,-074h[EBP]
        lea     EDI,-03Ch[EBP]
        movsd
        movsd
        movsd

These instructions are absent in the manually inlined code, and may be the
cause of the poor performance.


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