1) For 8-bit registers try to use first the ones that are parts of the
   same register (AL then AH). This way we only alias 2 16/32-bit
   registers after allocating 4 8-bit variables.

2) Move EBX as the last register to allocate. This will cause less
   spills to happen since we will have 8-bit registers available up to
   register excaustion (assuming we use the allocation order). It
   would be nice if we could push all of the 8-bit aliased registers
   towards the end but we much prefer to keep callee saved register to
   the end to avoid saving them on entry and exit of the function.

For example this gives a slight reduction of spills with linear scan
on 164.gzip.

Before:

11221 asm-printer           - Number of machine instrs printed
  975 spiller               - Number of loads added
  675 spiller               - Number of stores added
  398 spiller               - Number of register spills

After:

11182 asm-printer           - Number of machine instrs printed
  952 spiller               - Number of loads added
  652 spiller               - Number of stores added
  386 spiller               - Number of register spills

llvm-svn: 11996

their names more decriptive. A name consists of the base name, a
default operand size followed by a character per operand with an
optional special size. For example:

ADD8rr -> add, 8-bit register, 8-bit register

IMUL16rmi -> imul, 16-bit register, 16-bit memory, 16-bit immediate

IMUL16rmi8 -> imul, 16-bit register, 16-bit memory, 8-bit immediate

MOVSX32rm16 -> movsx, 32-bit register, 16-bit memory

llvm-svn: 11995

Replace uses of addZImm with addImm.

llvm-svn: 11992

block loops.

llvm-svn: 11990

llvm-svn: 11987

llvm-svn: 11984

llvm-svn: 11974

to denote this fact.

llvm-svn: 11972

denote this fact.

llvm-svn: 11971

parse. The name is now I (operand size)*. For example:

Im32 -> instruction with 32-bit memory operands.

Im16i8 -> instruction with 16-bit memory operands and 8 bit immediate
          operands.

llvm-svn: 11970

operand but their sizes differ.

llvm-svn: 11969

the size of the immediate and the memory operand on instructions that
use them. This resolves problems with instructions that take both a
memory and an immediate operand but their sizes differ (i.e. ADDmi32b).

llvm-svn: 11967

operands. The X86 backend doesn't handle them properly right now.

llvm-svn: 11944

llvm-svn: 11933

llvm-svn: 11932

an 8-bit immediate. So mark the shifts that take immediates as taking
an 8-bit argument. The rest with the implicit use of CL are marked
appropriately.

A bug still exists:

def SHLDmri32  : I2A8 <"shld", 0xA4, MRMDestMem>, TB;           // [mem32] <<= [mem32],R32 imm8

The immediate in the above instruction is 8-bit but the memory
reference is 32-bit. The printer prints this as an 8-bit reference
which confuses the assembler. Same with SHRDmri32.

llvm-svn: 11931

instructions.

llvm-svn: 11923

them so that they are consistent with AND, XOR, etc...

llvm-svn: 11922

llvm-svn: 11921

instructions.

llvm-svn: 11907

llvm-svn: 11905

llvm-svn: 11903

consistent with the rest and also pepare for the addition of their
memory operand variants.

llvm-svn: 11902

MRegisterInfo::is{Physical,Virtual}Register. Apply appropriate fixes
to relevant files.

llvm-svn: 11882

bugs.  Thanks Brian!

llvm-svn: 11859

where there did not used to be any before

llvm-svn: 11829

scaled indexes.  This allows us to compile GEP's like this:

int* %test([10 x { int, { int } }]* %X, int %Idx) {
        %Idx = cast int %Idx to long
        %X = getelementptr [10 x { int, { int } }]* %X, long 0, long %Idx, ubyte 1, ubyte 0
        ret int* %X
}

Into a single address computation:

test:
        mov %EAX, DWORD PTR [%ESP + 4]
        mov %ECX, DWORD PTR [%ESP + 8]
        lea %EAX, DWORD PTR [%EAX + 8*%ECX + 4]
        ret

Before it generated:
test:
        mov %EAX, DWORD PTR [%ESP + 4]
        mov %ECX, DWORD PTR [%ESP + 8]
        shl %ECX, 3
        add %EAX, %ECX
        lea %EAX, DWORD PTR [%EAX + 4]
        ret

This is useful for things like int/float/double arrays, as the indexing can be folded into
the loads&stores, reducing register pressure and decreasing the pressure on the decode unit.
With these changes, I expect our performance on 256.bzip2 and gzip to improve a lot.  On
bzip2 for example, we go from this:

10665 asm-printer           - Number of machine instrs printed
   40 ra-local              - Number of loads/stores folded into instructions
 1708 ra-local              - Number of loads added
 1532 ra-local              - Number of stores added
 1354 twoaddressinstruction - Number of instructions added
 1354 twoaddressinstruction - Number of two-address instructions
 2794 x86-peephole          - Number of peephole optimization performed

to this:
9873 asm-printer           - Number of machine instrs printed
  41 ra-local              - Number of loads/stores folded into instructions
1710 ra-local              - Number of loads added
1521 ra-local              - Number of stores added
 789 twoaddressinstruction - Number of instructions added
 789 twoaddressinstruction - Number of two-address instructions
2142 x86-peephole          - Number of peephole optimization performed

... and these types of instructions are often in tight loops.

Linear scan is also helped, but not as much.  It goes from:

8787 asm-printer           - Number of machine instrs printed
2389 liveintervals         - Number of identity moves eliminated after coalescing
2288 liveintervals         - Number of interval joins performed
3522 liveintervals         - Number of intervals after coalescing
5810 liveintervals         - Number of original intervals
 700 spiller               - Number of loads added
 487 spiller               - Number of stores added
 303 spiller               - Number of register spills
1354 twoaddressinstruction - Number of instructions added
1354 twoaddressinstruction - Number of two-address instructions
 363 x86-peephole          - Number of peephole optimization performed

to:

7982 asm-printer           - Number of machine instrs printed
1759 liveintervals         - Number of identity moves eliminated after coalescing
1658 liveintervals         - Number of interval joins performed
3282 liveintervals         - Number of intervals after coalescing
4940 liveintervals         - Number of original intervals
 635 spiller               - Number of loads added
 452 spiller               - Number of stores added
 288 spiller               - Number of register spills
 789 twoaddressinstruction - Number of instructions added
 789 twoaddressinstruction - Number of two-address instructions
 258 x86-peephole          - Number of peephole optimization performed

Though I'm not complaining about the drop in the number of intervals.  :)

llvm-svn: 11820

  to do analysis.

*** FOLD getelementptr instructions into loads and stores when possible,
    making use of some of the crazy X86 addressing modes.

For example, the following C++ program fragment:

struct complex {
    double re, im;
    complex(double r, double i) : re(r), im(i) {}
};
inline complex operator+(const complex& a, const complex& b) {
    return complex(a.re+b.re, a.im+b.im);
}
complex addone(const complex& arg) {
    return arg + complex(1,0);
}

Used to be compiled to:
_Z6addoneRK7complex:
        mov %EAX, DWORD PTR [%ESP + 4]
        mov %ECX, DWORD PTR [%ESP + 8]
***     mov %EDX, %ECX
        fld QWORD PTR [%EDX]
        fld1
        faddp %ST(1)
***     add %ECX, 8
        fld QWORD PTR [%ECX]
        fldz
        faddp %ST(1)
***     mov %ECX, %EAX
        fxch %ST(1)
        fstp QWORD PTR [%ECX]
***     add %EAX, 8
        fstp QWORD PTR [%EAX]
        ret

Now it is compiled to:
_Z6addoneRK7complex:
        mov %EAX, DWORD PTR [%ESP + 4]
        mov %ECX, DWORD PTR [%ESP + 8]
        fld QWORD PTR [%ECX]
        fld1
        faddp %ST(1)
        fld QWORD PTR [%ECX + 8]
        fldz
        faddp %ST(1)
        fxch %ST(1)
        fstp QWORD PTR [%EAX]
        fstp QWORD PTR [%EAX + 8]
        ret

Other programs should see similar improvements, across the board.  Note that
in addition to reducing instruction count, this also reduces register pressure
a lot, always a good thing on X86.  :)

llvm-svn: 11819

llvm-svn: 11818

into a single LEA instruction.  This should improve the code generated for
things like X->A.B.C[12].D.

The bigger benefit is still coming though.  Note that this uses an LEA instruction
instead of an add, giving the register allocator more freedom.  We should probably
never generate ADDri32's.

llvm-svn: 11817

an intermediate register.

llvm-svn: 11816

block into MachineBasicBlock::getFirstTerminator().

This also fixes a bug in the implementation of the above in both
RegAllocLocal and InstrSched, where instructions where added after the
terminator if the basic block's only instruction was a terminator (it
shouldn't matter for RegAllocLocal since this case never occurs in
practice).

llvm-svn: 11748

block we are in might be empty

llvm-svn: 11744

eventually get an assignment due to elimination of PHIs.

llvm-svn: 11743

llvm-svn: 11729

llvm-svn: 11728

Implement cast Type::ULongTy -> double

llvm-svn: 11726

llvm-svn: 11722

use FP instructions.  This reduces the number of instructions inserted in
176.gcc (for example) from 58074 to 101 (it doesn't use much FP, which
is typical).  This reduction speeds up the entire code generator.  In the
case of 176.gcc, llc went from taking 31.38s to 24.78s.  The passes that
sped up the most are the register allocator and the 2 live variable analysis
passes, which sped up 2.3, 1.3, and 1.5s respectively.  The asmprinter
pass also sped up because it doesn't print the instructions in comments :)

Note that this patch is likely to expose latent bugs in machine code passes,
because now basicblock can be empty, where they were never empty before.  I
cleaned out regalloclocal, but who knows about linscan :)

llvm-svn: 11717

switch statements in the constructors and simplifies the
implementation of the getUseType() member function. You will have to
specify defs using MachineOperand::Def instead of MOTy::Def though
(similarly for Use and UseAndDef).

llvm-svn: 11715