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llvm-mirror/lib/Target/Sparc
James Y Knight af99ad073e [Sparc] Support user-specified stack object overalignment.
Note: I do not implement a base pointer, so it's still impossible to
have dynamic realignment AND dynamic alloca in the same function.

This also moves the code for determining the frame index reference
into getFrameIndexReference, where it belongs, instead of inline in
eliminateFrameIndex.

[Begin long-winded screed]

Now, stack realignment for Sparc is actually a silly thing to support,
because the Sparc ABI has no need for it -- unlike the situation on
x86, the stack is ALWAYS aligned to the required alignment for the CPU
instructions: 8 bytes on sparcv8, and 16 bytes on sparcv9.

However, LLVM unfortunately implements user-specified overalignment
using stack realignment support, so for now, I'm going to go along
with that tradition. GCC instead treats objects which have alignment
specification greater than the maximum CPU-required alignment for the
target as a separate block of stack memory, with their own virtual
base pointer (which gets aligned). Doing it that way avoids needing to
implement per-target support for stack realignment, except for the
targets which *actually* have an ABI-specified stack alignment which
is too small for the CPU's requirements.

Further unfortunately in LLVM, the default canRealignStack for all
targets effectively returns true, despite that implementing that is
something a target needs to do specifically. So, the previous behavior
on Sparc was to silently ignore the user's specified stack
alignment. Ugh.

Yet MORE unfortunate, if a target actually does return false from
canRealignStack, that also causes the user-specified alignment to be
*silently ignored*, rather than emitting an error.

(I started looking into fixing that last, but it broke a bunch of
tests, because LLVM actually *depends* on having it silently ignored:
some architectures (e.g. non-linux i386) have smaller stack alignment
than spilled-register alignment. But, the fact that a register needs
spilling is not known until within the register allocator. And by that
point, the decision to not reserve the frame pointer has been frozen
in place. And without a frame pointer, stack realignment is not
possible. So, canRealignStack() returns false, and
needsStackRealignment() then returns false, assuming everyone can just
go on their merry way assuming the alignment requirements were
probably just suggestions after-all. Sigh...)

Differential Revision: http://reviews.llvm.org/D12208

llvm-svn: 245668
2015-08-21 04:17:56 +00:00
..
AsmParser SparcAsmParser.cpp: Appease msc x86. 2015-08-21 01:12:19 +00:00
Disassembler [Sparc] Implement i64 load/store support for 32-bit sparc. 2015-08-10 19:11:39 +00:00
InstPrinter MC: Add target hook to control symbol quoting 2015-06-09 00:31:39 +00:00
MCTargetDesc MC: Remove MCSubtargetInfo() default constructor 2015-07-10 22:43:42 +00:00
TargetInfo [Sparc] Really add sparcel architecture support. 2015-04-29 20:30:57 +00:00
CMakeLists.txt Remove getDataLayout() from TargetSelectionDAGInfo (had no users) 2015-07-09 02:10:08 +00:00
DelaySlotFiller.cpp Reuse a bunch of cached subtargets and remove getSubtarget calls 2015-01-30 23:46:43 +00:00
LLVMBuild.txt
Makefile Reinstate "Nuke the old JIT." 2014-09-02 22:28:02 +00:00
README.txt JIT support has been added awhile ago. 2014-08-30 14:52:34 +00:00
Sparc.h Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
Sparc.td [SparcInstPrinter] Use the subtarget that is passed to the print function 2015-03-28 04:03:51 +00:00
SparcAsmPrinter.cpp Move most user of TargetMachine::getDataLayout to the Module one 2015-07-16 06:11:10 +00:00
SparcCallingConv.td [Sparc] Implement i64 load/store support for 32-bit sparc. 2015-08-10 19:11:39 +00:00
SparcFrameLowering.cpp [Sparc] Support user-specified stack object overalignment. 2015-08-21 04:17:56 +00:00
SparcFrameLowering.h [Sparc] Support user-specified stack object overalignment. 2015-08-21 04:17:56 +00:00
SparcInstr64Bit.td Sparc: Add the "alternate address space" load/store instructions. 2015-05-18 16:35:04 +00:00
SparcInstrAliases.td Add lduw and lwua aliases for SPARCv9. 2015-08-10 23:47:22 +00:00
SparcInstrFormats.td Sparc: support the "set" synthetic instruction. 2015-05-18 16:43:33 +00:00
SparcInstrInfo.cpp PseudoSourceValue: Replace global manager with a manager in a machine function. 2015-08-11 23:09:45 +00:00
SparcInstrInfo.h Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
SparcInstrInfo.td [Sparc]: asm-only support for the ldstub instruction. 2015-08-19 19:30:57 +00:00
SparcInstrVIS.td Fix a whole bunch of binary literals which were the wrong size. All were being silently zero extended to the correct width. 2014-08-07 05:46:54 +00:00
SparcISelDAGToDAG.cpp [Sparc] Implement i64 load/store support for 32-bit sparc. 2015-08-10 19:11:39 +00:00
SparcISelLowering.cpp [SPARC] Fix BooleanContents, so that select of a trunc doesn't 2015-08-19 14:47:04 +00:00
SparcISelLowering.h [Sparc] Implement i64 load/store support for 32-bit sparc. 2015-08-10 19:11:39 +00:00
SparcMachineFunctionInfo.cpp
SparcMachineFunctionInfo.h Revert r240137 (Fixed/added namespace ending comments using clang-tidy. NFC) 2015-06-23 09:49:53 +00:00
SparcMCInstLower.cpp MC: Clean up MCExpr naming. NFC. 2015-05-30 01:25:56 +00:00
SparcRegisterInfo.cpp [Sparc] Support user-specified stack object overalignment. 2015-08-21 04:17:56 +00:00
SparcRegisterInfo.h [Sparc] Support user-specified stack object overalignment. 2015-08-21 04:17:56 +00:00
SparcRegisterInfo.td [SPARC] Enable writing to floating-point-state register. 2015-08-19 18:34:48 +00:00
SparcSubtarget.cpp Remove getDataLayout() from TargetSelectionDAGInfo (had no users) 2015-07-09 02:10:08 +00:00
SparcSubtarget.h Remove getDataLayout() from TargetSelectionDAGInfo (had no users) 2015-07-09 02:10:08 +00:00
SparcTargetMachine.cpp Replace string GNU Triples with llvm::Triple in TargetMachine. NFC. 2015-06-11 19:41:26 +00:00
SparcTargetMachine.h Replace string GNU Triples with llvm::Triple in TargetMachine. NFC. 2015-06-11 19:41:26 +00:00
SparcTargetObjectFile.cpp MC: Clean up MCExpr naming. NFC. 2015-05-30 01:25:56 +00:00
SparcTargetObjectFile.h Canonicalize header guards into a common format. 2014-08-13 16:26:38 +00:00
SparcTargetStreamer.h Canonicalize header guards into a common format. 2014-08-13 16:26:38 +00:00

To-do
-----

* Keep the address of the constant pool in a register instead of forming its
  address all of the time.
* We can fold small constant offsets into the %hi/%lo references to constant
  pool addresses as well.
* When in V9 mode, register allocate %icc[0-3].
* Add support for isel'ing UMUL_LOHI instead of marking it as Expand.
* Emit the 'Branch on Integer Register with Prediction' instructions.  It's
  not clear how to write a pattern for this though:

float %t1(int %a, int* %p) {
        %C = seteq int %a, 0
        br bool %C, label %T, label %F
T:
        store int 123, int* %p
        br label %F
F:
        ret float undef
}

codegens to this:

t1:
        save -96, %o6, %o6
1)      subcc %i0, 0, %l0
1)      bne .LBBt1_2    ! F
        nop
.LBBt1_1:       ! T
        or %g0, 123, %l0
        st %l0, [%i1]
.LBBt1_2:       ! F
        restore %g0, %g0, %g0
        retl
        nop

1) should be replaced with a brz in V9 mode.

* Same as above, but emit conditional move on register zero (p192) in V9
  mode.  Testcase:

int %t1(int %a, int %b) {
        %C = seteq int %a, 0
        %D = select bool %C, int %a, int %b
        ret int %D
}

* Emit MULX/[SU]DIVX instructions in V9 mode instead of fiddling
  with the Y register, if they are faster.

* Codegen bswap(load)/store(bswap) -> load/store ASI

* Implement frame pointer elimination, e.g. eliminate save/restore for
  leaf fns.
* Fill delay slots

* Use %g0 directly to materialize 0. No instruction is required.