Fold c2 in (x << c1) | c2 where (c2 < c1)
e.g.
int test(int x) {
return (x << 3) + 7;
}
This can be codegen'd as:
leal 7(,%eax,8), %eax
llvm-svn: 28550
If it reads the chain result of the call, then the use, callseq_start,
and call would form a cycle!
- Don't forget handle node replacement!
- There could also be a TokenFactor between the load and the callseq_start.
llvm-svn: 28420
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
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
* Cleaned up and tweaked LEA cost analysis code. Removed some hacks.
* Handle ADD $X, c to MOV32ri $X+c. These patterns cannot be autogen'd and
they need to be matched before LEA.
llvm-svn: 26376
and ExternalSymbol.
- Use C++ code (rather than tblgen'd selection code) to match the above
mentioned leaf nodes. Do not mutate and nodes and do not record the
selection in CodeGenMap. These nodes should be safe to duplicate. This is
a performance win.
llvm-svn: 26335
X86 addressing mode. Currently we do not allow any node whose target node
produces a chain as well as any node that is at the root of the addressing
mode expression tree.
llvm-svn: 26117
* Allow a register node as SelectAddr() base.
* ExternalSymbol -> TargetExternalSymbol as direct function callee.
* Use X86::ESP register rather than CopyFromReg(X86::ESP) as stack ptr for
call parmater passing.
llvm-svn: 25207
Chris Lattner