[LLVMbugs] [Bug 2616] [CellSPU] Code generation failure

[bugzilla-daemon at cs.uiuc.edu]

http://llvm.org/bugs/show_bug.cgi?id=2616


Scott Michel <scooter.phd at gmail.com> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|REOPENED                    |RESOLVED
         Resolution|                            |WORKSFORME




--- Comment #4 from Scott Michel <scooter.phd at gmail.com>  2008-10-31 15:58:10 ---
I just tested this with "llc -march=cellspu -o - zzz.bc" (where zzz.ll has the
example code in the initial bug report, which was then llvm-as-ed to zzz.bc).

Other than the ellipsis that indicates a vararg function, llc accepts it just
fine and generates code w/o an assert.

Heisenbug caused by something else other than the backend?

If you take out the ellipsis, i.e.:

; ModuleID = 't0038.ubc'

define i32 @main() {
entry:
        %retval = alloca i32            ; <i32*> [#uses=2]
        store i32 0, i32* %retval
        %i = alloca i32         ; <i32*> [#uses=0]
        br label %return

return:         ; preds = %entry
        load i32* %retval               ; <i32>:0 [#uses=1]
        ret i32 %0
}

llc produces the following (it isn't the greatest code produced, but it is
assert-free):

        .text


        .align  3
        .global main
        .type   main, @function
main:
        stqd    $lr, 16($sp)
        stqd    $sp, -64($sp)
        ai      $sp, $sp, -64
        lqd     $3, 0($sp)
        cwd     $4, 0($sp)
        il      $5, 0
        shufb   $3, $5, $3, $4
        stqd    $3, 0($sp)
.LBB1_1:        # return
        lqd     $3, 0($sp)
        rotqby  $3, $3, $sp
        lqd     $lr, 80($sp)
        ai      $sp, $sp, 64
        bi      $lr
        .size   main,.-main

        .ident  "(llvm 2.2+) STI CBEA Cell SPU backend"

Note: This is similar to what would be produced by llc with the ellipsis, but
without the spillage of 48 registers to the stack:

        .text


        .align  3
        .global main
        .type   main, @function
main:
        stqd    $lr, 16($sp)
        stqd    $sp, -64($sp)
        ai      $sp, $sp, -64
        stqd    $79, 1312($sp)
        stqd    $78, 1296($sp)
        stqd    $77, 1280($sp)
        stqd    $76, 1264($sp)
        stqd    $75, 1248($sp)
        stqd    $74, 1232($sp)
        stqd    $73, 1216($sp)
        stqd    $72, 1200($sp)
        stqd    $71, 1184($sp)
        stqd    $70, 1168($sp)
        stqd    $69, 1152($sp)
        stqd    $68, 1136($sp)
        stqd    $67, 1120($sp)
        stqd    $66, 1104($sp)
        stqd    $65, 1088($sp)
        stqd    $64, 1072($sp)
        stqd    $63, 1056($sp)
        stqd    $62, 1040($sp)
        stqd    $61, 1024($sp)
        stqd    $60, 1008($sp)
        stqd    $59, 992($sp)
        stqd    $58, 976($sp)
        stqd    $57, 960($sp)
        stqd    $56, 944($sp)
        stqd    $55, 928($sp)
        stqd    $54, 912($sp)
        stqd    $53, 896($sp)
        stqd    $52, 880($sp)
        stqd    $51, 864($sp)
        stqd    $50, 848($sp)
        stqd    $49, 832($sp)
        stqd    $48, 816($sp)
        stqd    $47, 800($sp)
        stqd    $46, 784($sp)
        stqd    $45, 768($sp)
        stqd    $44, 752($sp)
        stqd    $43, 736($sp)
        stqd    $42, 720($sp)
        stqd    $41, 704($sp)
        stqd    $40, 688($sp)
        stqd    $39, 672($sp)
        stqd    $38, 656($sp)
        stqd    $37, 640($sp)
        stqd    $36, 624($sp)
        stqd    $35, 608($sp)
        stqd    $34, 592($sp)
        stqd    $33, 576($sp)
        stqd    $32, 560($sp)
        stqd    $31, 544($sp)
        stqd    $30, 528($sp)
        stqd    $29, 512($sp)
        stqd    $28, 496($sp)
        stqd    $27, 480($sp)
        stqd    $26, 464($sp)
        stqd    $25, 448($sp)
        stqd    $24, 432($sp)
        stqd    $23, 416($sp)
        stqd    $22, 400($sp)
        stqd    $21, 384($sp)
        stqd    $20, 368($sp)
        stqd    $19, 352($sp)
        stqd    $18, 336($sp)
        stqd    $17, 320($sp)
        stqd    $16, 304($sp)
        stqd    $15, 288($sp)
        stqd    $14, 272($sp)
        stqd    $13, 256($sp)
        stqd    $12, 240($sp)
        stqd    $11, 224($sp)
        stqd    $10, 208($sp)
        stqd    $9, 192($sp)
        stqd    $8, 176($sp)
        stqd    $7, 160($sp)
        stqd    $6, 144($sp)
        stqd    $5, 128($sp)
        stqd    $4, 112($sp)
        stqd    $3, 96($sp)
        lqd     $3, 0($sp)
        cwd     $4, 0($sp)
        il      $5, 0
        shufb   $3, $5, $3, $4
        stqd    $3, 0($sp)
.LBB1_1:        # return
        lqd     $3, 0($sp)
        rotqby  $3, $3, $sp
        lqd     $lr, 80($sp)
        ai      $sp, $sp, 64
        bi      $lr
        .size   main,.-main

        .ident  "(llvm 2.2+) STI CBEA Cell SPU backend"


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