llvm-6502/lib/Target/SystemZ
Rafael Espindola 7d7d99622f Replace PROLOG_LABEL with a new CFI_INSTRUCTION.
The old system was fairly convoluted:
* A temporary label was created.
* A single PROLOG_LABEL was created with it.
* A few MCCFIInstructions were created with the same label.

The semantics were that the cfi instructions were mapped to the PROLOG_LABEL
via the temporary label. The output position was that of the PROLOG_LABEL.
The temporary label itself was used only for doing the mapping.

The new CFI_INSTRUCTION has a 1:1 mapping to MCCFIInstructions and points to
one by holding an index into the CFI instructions of this function.

I did consider removing MMI.getFrameInstructions completelly and having
CFI_INSTRUCTION own a MCCFIInstruction, but MCCFIInstructions have non
trivial constructors and destructors and are somewhat big, so the this setup
is probably better.

The net result is that we don't create temporary labels that are never used.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@203204 91177308-0d34-0410-b5e6-96231b3b80d8
2014-03-07 06:08:31 +00:00
..
AsmParser [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
Disassembler [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
InstPrinter [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
MCTargetDesc [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
TargetInfo Prune redundant dependencies in LLVMBuild.txt. 2013-12-11 00:30:57 +00:00
CMakeLists.txt [CMake] Let add_public_tablegen_target responsible to provide dependency to CommonTableGen. 2013-11-28 17:04:04 +00:00
LLVMBuild.txt Add proper dependencies to LLVMBuild.txt in llvm/lib. 2013-12-10 05:39:34 +00:00
Makefile [SystemZ] Add disassembler support 2013-05-14 10:17:52 +00:00
README.txt Add TargetLowering::prepareVolatileOrAtomicLoad 2013-12-10 10:49:34 +00:00
SystemZ.h [SystemZ] Update namespace formatting to match current guidelines 2014-03-06 10:38:30 +00:00
SystemZ.td Change the default of AsmWriterClassName and isMCAsmWriter. 2013-12-02 04:55:42 +00:00
SystemZAsmPrinter.cpp [SystemZ] Use "auto" for cast results 2014-03-06 11:22:58 +00:00
SystemZAsmPrinter.h [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZCallingConv.cpp
SystemZCallingConv.h [SystemZ] Update namespace formatting to match current guidelines 2014-03-06 10:38:30 +00:00
SystemZCallingConv.td [SystemZ] Rename 32-bit GPR registers 2013-09-30 08:48:38 +00:00
SystemZConstantPoolValue.cpp [SystemZ] Use "auto" for cast results 2014-03-06 11:22:58 +00:00
SystemZConstantPoolValue.h [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZElimCompare.cpp [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZFrameLowering.cpp Replace PROLOG_LABEL with a new CFI_INSTRUCTION. 2014-03-07 06:08:31 +00:00
SystemZFrameLowering.h [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZInstrBuilder.h [SystemZ] Update namespace formatting to match current guidelines 2014-03-06 10:38:30 +00:00
SystemZInstrFormats.td [SystemZ] Add MC support for interlocked-access 1 instructions 2013-12-24 15:14:05 +00:00
SystemZInstrFP.td [SystemZ] Use LOAD AND TEST for comparisons with -0 2013-12-06 09:59:12 +00:00
SystemZInstrInfo.cpp [SystemZ] Update namespace formatting to match current guidelines 2014-03-06 10:38:30 +00:00
SystemZInstrInfo.h [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZInstrInfo.td Fix known typos 2014-01-24 17:20:08 +00:00
SystemZISelDAGToDAG.cpp [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZISelLowering.cpp [SystemZ] Use "auto" for cast results 2014-03-06 11:22:58 +00:00
SystemZISelLowering.h [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZLongBranch.cpp [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZMachineFunctionInfo.cpp [weak vtables] Remove a bunch of weak vtables 2013-11-19 00:57:56 +00:00
SystemZMachineFunctionInfo.h [SystemZ] Update namespace formatting to match current guidelines 2014-03-06 10:38:30 +00:00
SystemZMCInstLower.cpp Move the llvm mangler to lib/IR. 2014-01-07 21:19:40 +00:00
SystemZMCInstLower.h Re-sort all of the includes with ./utils/sort_includes.py so that 2014-01-07 11:48:04 +00:00
SystemZOperands.td [SystemZ] Improve handling of PC-relative addresses 2013-09-27 15:14:04 +00:00
SystemZOperators.td [SystemZ] Use "auto" for cast results 2014-03-06 11:22:58 +00:00
SystemZPatterns.td [SystemZ] Use LOAD AND TEST for comparisons with -0 2013-12-06 09:59:12 +00:00
SystemZProcessors.td [SystemZ] Use interlocked-access 1 instructions for CodeGen 2013-12-24 15:18:04 +00:00
SystemZRegisterInfo.cpp [SystemZ] Use "auto" for cast results 2014-03-06 11:22:58 +00:00
SystemZRegisterInfo.h [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZRegisterInfo.td [SystemZ] Use upper words of GR64s for codegen 2013-10-01 11:26:28 +00:00
SystemZSelectionDAGInfo.cpp [SystemZ] Use "auto" for cast results 2014-03-06 11:22:58 +00:00
SystemZSelectionDAGInfo.h [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZShortenInst.cpp [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZSubtarget.cpp Re-sort all of the includes with ./utils/sort_includes.py so that 2014-01-07 11:48:04 +00:00
SystemZSubtarget.h [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZTargetMachine.cpp [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00
SystemZTargetMachine.h [SystemZ] Remove "virtual" from override methods 2014-03-06 12:03:36 +00:00

//===---------------------------------------------------------------------===//
// Random notes about and ideas for the SystemZ backend.
//===---------------------------------------------------------------------===//

The initial backend is deliberately restricted to z10.  We should add support
for later architectures at some point.

--

SystemZDAGToDAGISel::SelectInlineAsmMemoryOperand() is passed "m" for all
inline asm memory constraints; it doesn't get to see the original constraint.
This means that it must conservatively treat all inline asm constraints
as the most restricted type, "R".

--

If an inline asm ties an i32 "r" result to an i64 input, the input
will be treated as an i32, leaving the upper bits uninitialised.
For example:

define void @f4(i32 *%dst) {
  %val = call i32 asm "blah $0", "=r,0" (i64 103)
  store i32 %val, i32 *%dst
  ret void
}

from CodeGen/SystemZ/asm-09.ll will use LHI rather than LGHI.
to load 103.  This seems to be a general target-independent problem.

--

The tuning of the choice between LOAD ADDRESS (LA) and addition in
SystemZISelDAGToDAG.cpp is suspect.  It should be tweaked based on
performance measurements.

--

There is no scheduling support.

--

We don't use the BRANCH ON INDEX instructions.

--

We might want to use BRANCH ON CONDITION for conditional indirect calls
and conditional returns.

--

We don't use the TEST DATA CLASS instructions.

--

We could use the generic floating-point forms of LOAD COMPLEMENT,
LOAD NEGATIVE and LOAD POSITIVE in cases where we don't need the
condition codes.  For example, we could use LCDFR instead of LCDBR.

--

We only use MVC, XC and CLC for constant-length block operations.
We could extend them to variable-length operations too,
using EXECUTE RELATIVE LONG.

MVCIN, MVCLE and CLCLE may be worthwhile too.

--

We don't use CUSE or the TRANSLATE family of instructions for string
operations.  The TRANSLATE ones are probably more difficult to exploit.

--

We don't take full advantage of builtins like fabsl because the calling
conventions require f128s to be returned by invisible reference.

--

ADD LOGICAL WITH SIGNED IMMEDIATE could be useful when we need to
produce a carry.  SUBTRACT LOGICAL IMMEDIATE could be useful when we
need to produce a borrow.  (Note that there are no memory forms of
ADD LOGICAL WITH CARRY and SUBTRACT LOGICAL WITH BORROW, so the high
part of 128-bit memory operations would probably need to be done
via a register.)

--

We don't use the halfword forms of LOAD REVERSED and STORE REVERSED
(LRVH and STRVH).

--

We don't use ICM or STCM.

--

DAGCombiner doesn't yet fold truncations of extended loads.  Functions like:

    unsigned long f (unsigned long x, unsigned short *y)
    {
      return (x << 32) | *y;
    }

therefore end up as:

        sllg    %r2, %r2, 32
        llgh    %r0, 0(%r3)
        lr      %r2, %r0
        br      %r14

but truncating the load would give:

        sllg    %r2, %r2, 32
        lh      %r2, 0(%r3)
        br      %r14

--

Functions like:

define i64 @f1(i64 %a) {
  %and = and i64 %a, 1
  ret i64 %and
}

ought to be implemented as:

        lhi     %r0, 1
        ngr     %r2, %r0
        br      %r14

but two-address optimisations reverse the order of the AND and force:

        lhi     %r0, 1
        ngr     %r0, %r2
        lgr     %r2, %r0
        br      %r14

CodeGen/SystemZ/and-04.ll has several examples of this.

--

Out-of-range displacements are usually handled by loading the full
address into a register.  In many cases it would be better to create
an anchor point instead.  E.g. for:

define void @f4a(i128 *%aptr, i64 %base) {
  %addr = add i64 %base, 524288
  %bptr = inttoptr i64 %addr to i128 *
  %a = load volatile i128 *%aptr
  %b = load i128 *%bptr
  %add = add i128 %a, %b
  store i128 %add, i128 *%aptr
  ret void
}

(from CodeGen/SystemZ/int-add-08.ll) we load %base+524288 and %base+524296
into separate registers, rather than using %base+524288 as a base for both.

--

Dynamic stack allocations round the size to 8 bytes and then allocate
that rounded amount.  It would be simpler to subtract the unrounded
size from the copy of the stack pointer and then align the result.
See CodeGen/SystemZ/alloca-01.ll for an example.

--

If needed, we can support 16-byte atomics using LPQ, STPQ and CSDG.

--

We might want to model all access registers and use them to spill
32-bit values.