llvm-svn: 31364

Two-address instructions no longer have to be A := A op C. Now any pair of dest / src operands can be tied together.

llvm-svn: 31363

http://lists.cs.uiuc.edu/pipermail/llvm-commits/Week-of-Mon-20061009/038518.html

llvm-svn: 30906

It's turning:
        movl -24(%ebp), %esp
        subl $16, %esp
        movl -24(%ebp), %ecx
into
        movl -24(%ebp), %esp
        subl $16, %esp
        movl %esp, (%esp)

llvm-svn: 30902

the stack slot.  This fixes PR943.

llvm-svn: 30898

actually *removes* one of the operands, instead of just assigning both operands
the same register.  This make reasoning about instructions unnecessarily complex,
because you need to know if you are before or after register allocation to match
up operand #'s with the target description file.

Changing this also gets rid of a bunch of hacky code in various places.

This patch also includes changes to fold loads into cmp/test instructions in
the X86 backend, along with a significant simplification to the X86 spill
folding code.

llvm-svn: 30108

llvm-svn: 29911

instructions which define each value#) to simplify and improve the coallescer.
In particular, this patch:

1. Implements iterative coallescing.
2. Reverts an unsafe hack from handlePhysRegDef, superceeding it with a
   better solution.
3. Implements PR865, "coallescing" away the second copy in code like:

   A = B
   ...
   B = A

This also includes changes to symbolically print registers in intervals
when possible.

llvm-svn: 29862

    MOV R0, R1
    MOV R1, R0

the second machine instruction is removed. Added a regression test.

llvm-svn: 29792

llvm-svn: 29250

llvm-svn: 29220

llvm-svn: 28973

llvm-svn: 28102

instructions in the virtregfolded map that were deleted.  Because they
were deleted, newly allocated instructions could end up at the same address,
magically finding themselves in the map.  The solution is to remove entries
from the map when we delete the instructions.

llvm-svn: 28041

instruction folded with spill code, make sure the remove the load from
the virt reg folded map.

llvm-svn: 28040

llvm-svn: 28039

Remove temp. option -spiller-check-liveout, it didn't cause any failure nor performance regressions.

llvm-svn: 28029

But this is incorrect if the spilled value live range extends beyond the
current BB.
It is currently controlled by a temporary option -spiller-check-liveout.

llvm-svn: 28024

the same.  In this case, don't emit a noop copy.

llvm-svn: 28008

and is already available, instead of falling back to emitting a load, fall
back to emitting a reg-reg copy.  This generates significantly better code
for some SSE testcases, as SSE has lots of two-address instructions and
none of them are read/modify/write.  As one example, this change does:

        pshufd %XMM5, XMMWORD PTR [%ESP + 84], 255
        xorps %XMM2, %XMM5
        cmpltps %XMM1, %XMM0
-       movaps XMMWORD PTR [%ESP + 52], %XMM0
-       movapd %XMM6, XMMWORD PTR [%ESP + 52]
+       movaps %XMM6, %XMM0
        cmpltps %XMM6, XMMWORD PTR [%ESP + 68]
        movapd XMMWORD PTR [%ESP + 52], %XMM6
        movaps %XMM6, %XMM0
        cmpltps %XMM6, XMMWORD PTR [%ESP + 36]
        cmpltps %XMM3, %XMM0
-       movaps XMMWORD PTR [%ESP + 20], %XMM0
-       movapd %XMM7, XMMWORD PTR [%ESP + 20]
+       movaps %XMM7, %XMM0
        cmpltps %XMM7, XMMWORD PTR [%ESP + 4]
        movapd XMMWORD PTR [%ESP + 20], %XMM7
        cmpltps %XMM4, %XMM0

... which is far better than a store followed by a load!

llvm-svn: 28001

exposed with a fastcc problem (breaking pcompress2 on x86 with -enable-x86-fastcc).

When reloading a reused reg, make sure to invalidate the reloaded reg, and
check to see if there are any other pending uses of the same register.

llvm-svn: 26369

Add a minor compile time win, no codegen change.

llvm-svn: 26368

This gets rid of two gotos, which is always nice, and also adds some comments.

No functionality change, this is just a refactor.

llvm-svn: 26367

llvm-svn: 25957

llvm-svn: 25949

store EAX -> [ss#0]
[ss#0] += 1
...
use(EAX)

In this case, it is not valid to rewrite this as:


store EAX -> [ss#0]
EAX += 1
store EAX -> [ss#0]  ;;; this would also delete the store above
...
use(EAX)

... because EAX is not a dead at that point.  Keep track of which registers
we are allowed to clobber, and which ones we aren't, and don't clobber the
ones we're not supposed to.  :)

This should resolve the issues on X86 last night.

llvm-svn: 25948

and PhysRegsAvailable maps out into a new AvailableSpills struct.  No
functionality change.

This paves the way for a bugfix, coming up next.

llvm-svn: 25947

a std::multimap iterator value.  For some reason, GCC doesn't have a problem with this.

llvm-svn: 25927

llvm-svn: 25926

llvm-svn: 25924

1. a target doesn't know how to fold load/stores into copies, or
2. the spiller rewrites the input to a copy to the same register as the dest
   instead of to the reloaded reg.

This will be moved/improved in the near future, but allows elimination of
some ancient x86 hacks.  This eliminates 92 copies from SMG2000 on X86 and
163 copies from 252.eon.

llvm-svn: 25922

of this, and use it to our advantage (bwahahah).  This allows us to eliminate another
60 instructions from smg2000 on PPC (probably significantly more on X86).  A common
old-new diff looks like this:

        stw r2, 3304(r1)
-       lwz r2, 3192(r1)
        stw r2, 3300(r1)
-       lwz r2, 3192(r1)
        stw r2, 3296(r1)
-       lwz r2, 3192(r1)
        stw r2, 3200(r1)
-       lwz r2, 3192(r1)
        stw r2, 3196(r1)
-       lwz r2, 3192(r1)
+       or r2, r2, r2
        stw r2, 3188(r1)

and

-       lwz r31, 604(r1)
-       lwz r13, 604(r1)
-       lwz r14, 604(r1)
-       lwz r15, 604(r1)
-       lwz r16, 604(r1)
-       lwz r30, 604(r1)
+       or r31, r30, r30
+       or r13, r30, r30
+       or r14, r30, r30
+       or r15, r30, r30
+       or r16, r30, r30
+       or r30, r30, r30

Removal of the R = R copies is coming next...

llvm-svn: 25919

this code:

  store [stack slot #0],  R10
    = add R14, [stack slot #0]

The spiller didn't know that the store made the value of [stackslot#0] available
in R10 *IF* the store came from a copy instruction with the store folded into it.

This patch teaches VirtRegMap to look at these stores and recognize the values
they make available.  In one case Evan provided, this code:

        divsd %XMM0, %XMM1
        movsd %XMM1, QWORD PTR [%ESP + 40]
1)      movsd QWORD PTR [%ESP + 48], %XMM1
2)      movsd %XMM1, QWORD PTR [%ESP + 48]
        addsd %XMM1, %XMM0
3)      movsd QWORD PTR [%ESP + 48], %XMM1
        movsd QWORD PTR [%ESP + 4], %XMM0

turns into:

        divsd %XMM0, %XMM1
        movsd %XMM1, QWORD PTR [%ESP + 40]
        addsd %XMM1, %XMM0
3)      movsd QWORD PTR [%ESP + 48], %XMM1
        movsd QWORD PTR [%ESP + 4], %XMM0

In this case, instruction #2 was removed because of the value made
available by #1, and inst #1 was later deleted because it is now
never used before the stack slot is redefined by #3.

This occurs here and there in a lot of code with high spilling, on PPC
most of the removed loads/stores are LSU-reject-causing loads, which is
nice.

On X86, things are much better (because it spills more), where we nuke
about 1% of the instructions from SMG2000 and several hundred from eon.

More improvements to come...

llvm-svn: 25917

Move isLoadFrom/StoreToStackSlot from MRegisterInfo to TargetInstrInfo,a far more logical place.  Other methods should also be moved if anyoneis interested. :)

llvm-svn: 25913

llvm-svn: 25515

don't help anyone)

llvm-svn: 25081

previous copy elisions and we discover we need to reload a register, make
sure to use the regclass of the original register for the reload, not the
class of the current register.  This avoid using 16-bit loads to reload 32-bit
values.

llvm-svn: 23645

  store r12 -> [ss#2]
  R3 = load [ss#1]
  use R3
  R3 = load [ss#2]
  R4 = load [ss#1]

and turn it into this code:

  store R12 -> [ss#2]
  R3 = load [ss#1]
  use R3
  R3 = R12
  R4 = R3    <- oops!

The problem was that promoting R3 = load[ss#2] to a copy missed the fact that
the instruction invalidated R3 at that point.

llvm-svn: 23638

code.  PrologEpilogInserter hasn't been updated yet though, so targets cannot
use this info.

llvm-svn: 23536

when possible, avoiding the load (and avoiding the copy if the value is already
in the right register).

This patch came about when I noticed code like the following being generated:

  store R17 -> [SS1]
  ...blah...
  R4 = load [SS1]

This was causing an LSU reject on the G5.  This problem was due to the register
allocator folding spill code into a reg-reg copy (producing the load), which
prevented the spiller from being able to rewrite the load into a copy, despite
the fact that the value was already available in a register.  In the case
above, we now rip out the R4 load and replace it with a R4 = R17 copy.

This speeds up several programs on X86 (which spills a lot :) ), e.g.
smg2k from 22.39->20.60s, povray from 12.93->12.66s, 168.wupwise from
68.54->53.83s (!), 197.parser from 7.33->6.62s (!), etc.  This may have a larger
impact in some cases on the G5 (by avoiding LSU rejects), though it probably
won't trigger as often (less spilling in general).

Targets that implement folding of loads/stores into copies should implement
the isLoadFromStackSlot hook to get this.

llvm-svn: 23388