movw. That is we promote the destination operand to r16. So
        %CH = TRUNC_R16_R8 %BP
is emitted as
        movw %bp, %cx.

This is incorrect. If %cl is live, it would be clobbered.
Ideally we want to do the opposite, that is emitted it as
        movb ??, %ch
But this is not possible since %bp does not have a r8 sub-register.

We are now defining a new register class R16_ which is a subclass of R16
containing only those 16-bit registers that have r8 sub-registers (i.e.
AX - DX). We isel the truncate to two instructions, a MOV16to16_ to copy the
value to the R16_ class, followed by a TRUNC_R16_R8.

Due to bug 770, the register colaescer is not going to coalesce between R16 and
R16_. That will be fixed later so we can eliminate the MOV16to16_. Right now, it
can only be eliminated if we are lucky that source and destination registers are
the same.

llvm-svn: 28164

llvm-svn: 28158

llvm-svn: 28148

llvm-svn: 28139

llvm-svn: 28133

llvm-svn: 28131

llvm-svn: 28127

that gets emitted as movl (for r32 to i16, i8) or a movw (for r16 to i8). And
if the destination gets allocated a subregister of the source operand, then
the instruction will not be emitted at all.

llvm-svn: 28119

llvm-svn: 28105

llvm-svn: 28104

llvm-svn: 28102

llvm-svn: 28099

llvm-svn: 28096

llvm-svn: 28095

llvm-svn: 28094

llvm-svn: 28093

llvm-svn: 28092

llvm-svn: 28091

llvm-svn: 28090

movlps cannot be used (e.g. when load from m64 has multiple uses).

llvm-svn: 28089

in MachineRelocation to create Relocations.

llvm-svn: 28088

llvm-svn: 28083

simplifies the MachineCodeEmitter interface just a little bit and makes
BasicBlocks work like constant pools and jump tables.

llvm-svn: 28082

instruction.

llvm-svn: 28080

Refactor TargetMachine, pushing handling of TargetData into the target-specific subclasses.  This has one caller-visible change: getTargetData() now returns a pointer instead of a reference.

This fixes PR 759.

llvm-svn: 28074

llvm-svn: 28069

1. Change several methods in the MachineCodeEmitter class to be pure virtual.
2. Suck emitConstantPool/initJumpTableInfo into startFunction, removing them
   from the MachineCodeEmitter interface, and reducing the amount of target-
   specific code.
3. Change the JITEmitter so that it allocates constantpools and jump tables
   *right* next to the functions that they belong to, instead of in a separate
   pool of memory.  This makes all memory for a function be contiguous, and
   means the JITEmitter only tracks one block of memory now.

llvm-svn: 28065

llvm-svn: 28063

byte format.  This doesn't work when using the code emitter in a cross target
environment.  Since the code emitter is only really used by the JIT, this
isn't a current problem, but if we ever start emitting .o files, it would be.

llvm-svn: 28060

code emission location into the base class, instead of being in the derived classes.

This change means that low-level methods like emitByte/emitWord now are no longer
virtual (yaay for speed), and we now have a framework to support growable code
segments.  This implements feature request #1 of PR469.

llvm-svn: 28059

llvm-svn: 28056

llvm-svn: 28053

basic block labels, consolidating the code to do so in one place for each
target.

llvm-svn: 28050

llvm-svn: 28047

llvm-svn: 28046

llvm-svn: 28045

llvm-svn: 28044

llvm-svn: 28027

llvm-svn: 28023

llvm-svn: 28021