[Bug rtl-optimization/33927] replace_read in dse.c could handle cases where GET_MODE_CLASS (read_mode) != GET_MODE_CLASS (store_mode) (and the size is the same)

["eres at il dot ibm dot com" <gcc-bugzilla at gcc dot gnu dot org>]

------- Comment #6 from eres at il dot ibm dot com  2008-03-23 07:20 -------
(In reply to comment #5)
> (In reply to comment #4)
> > I've applied a patch that should fix this.  No-one's confirmed
> > whether it does though, so I'm marking the PR as waiting.
> And I just confirmed, it does fix it, on powerpc64-darwin:

It also fixes the problem on spu-gcc, but on powerpc64-linux 
it seems that the problem still exists:

-----------------------------------
On spu-gcc:

 test2:
-       hbr     .L5,$lr
+       fa      $4,$4,$4
        stqd    $sp,-128($sp)
+       fa      $3,$3,$3
        ai      $sp,$sp,-128
-       stqd    $3,64($sp)
-       stqd    $4,80($sp)
-       lqd     $4,80($sp)
-       lqd     $5,64($sp)
-       fa      $3,$4,$4
-       fa      $2,$5,$5
-       stqd    $3,48($sp)
-       stqd    $2,32($sp)
-       lqd     $4,48($sp)
-       lqd     $3,32($sp)
        ai      $sp,$sp,128
-.L5:
        bi      $lr

-----------------------------------

On powerpc64-linux :

        .file   "struct1.c"
        .section        ".text"
        .align 2
        .p2align 4,,15
        .globl test1
        .type   test1, @function
test1:
        stwu 1,-32(1)
        mfvrsave 0
        stw 0,28(1)
        oris 0,0,0xc000
        mtvrsave 0
        lvx 0,0,4
        lvx 1,0,5
        vaddfp 0,0,1
        lwz 12,28(1)
        stvx 0,0,3
        mtvrsave 12
        addi 1,1,32
        blr
        .size   test1,.-test1
        .align 2
        .p2align 4,,15
        .globl test2
        .type   test2, @function
test2:
        stwu 1,-32(1)
        mfvrsave 0
        stw 0,28(1)
        oris 0,0,0xc000
        mtvrsave 0
        li 0,16
        lvx 1,0,4
        lvx 0,4,0
        vaddfp 1,1,1
        vaddfp 0,0,0
        lwz 12,28(1)
        stvx 1,0,4
        stvx 0,4,0
        stvx 0,3,0
        stvx 1,0,3
        mtvrsave 12
        addi 1,1,32
        blr
        .size   test2,.-test2
        .ident  "GCC: (GNU) 4.4.0 20080323 (experimental)"
        .section        .note.GNU-stack,"",@progbits


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=33927