llvm-6502/lib/Target/PowerPC/PPCCallingConv.td
Ulrich Weigand d4542a8cdc [PowerPC] ELFv2 aggregate passing support
This patch adds infrastructure support for passing array types
directly.  These can be used by the front-end to pass aggregate
types (coerced to an appropriate array type).  The details of the
array type being used inform the back-end about ABI-relevant
properties.  Specifically, the array element type encodes:
- whether the parameter should be passed in FPRs, VRs, or just
  GPRs/stack slots  (for float / vector / integer element types,
  respectively)
- what the alignment requirements of the parameter are when passed in
  GPRs/stack slots  (8 for float / 16 for vector / the element type
  size for integer element types) -- this corresponds to the
  "byval align" field

Using the infrastructure provided by this patch, a companion patch
to clang will enable two features:
- In the ELFv2 ABI, pass (and return) "homogeneous" floating-point
  or vector aggregates in FPRs and VRs (this is similar to the ARM
  homogeneous aggregate ABI)
- As an optimization for both ELFv1 and ELFv2 ABIs, pass aggregates
  that fit fully in registers without using the "byval" mechanism

The patch uses the functionArgumentNeedsConsecutiveRegisters callback
to encode that special treatment is required for all directly-passed
array types.  The isInConsecutiveRegs / isInConsecutiveRegsLast bits set
as a results are then used to implement the required size and alignment
rules in CalculateStackSlotSize / CalculateStackSlotAlignment etc.

As a related change, the ABI routines have to be modified to support
passing floating-point types in GPRs.  This is necessary because with
homogeneous aggregates of 4-byte float type we can now run out of FPRs
*before* we run out of the 64-byte argument save area that is shadowed
by GPRs.  Any extra floating-point arguments that no longer fit in FPRs
must now be passed in GPRs until we run out of those too.

Note that there was already code to pass floating-point arguments in
GPRs used with vararg parameters, which was done by writing the argument
out to the argument save area first and then reloading into GPRs.  The
patch re-implements this, however, in favor of code packing float arguments
directly via extension/truncation, BITCAST, and BUILD_PAIR operations.

This is required to support the ELFv2 ABI, since we cannot unconditionally
write to the argument save area (which the caller might not have allocated).
The change does, however, affect ELFv1 varags routines too; but even here
the overall effect should be advantageous: Instead of loading the argument
into the FPR, then storing the argument to the stack slot, and finally
reloading the argument from the stack slot into a GPR, the new code now
just loads the argument into the FPR, and subsequently loads the argument
into the GPR (via BITCAST).  That BITCAST might imply a save/reload from
a stack temporary (in which case we're no worse than before); but it
might be implemented more efficiently in some cases.

The final part of the patch enables up to 8 FPRs and VRs for argument
return in PPCCallingConv.td; this is required to support returning
ELFv2 homogeneous aggregates.  (Note that this doesn't affect other ABIs
since LLVM wil only look for which register to use if the parameter is
marked as "direct" return anyway.)

Reviewed by Hal Finkel.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@213493 91177308-0d34-0410-b5e6-96231b3b80d8
2014-07-21 00:13:26 +00:00

200 lines
8.9 KiB
TableGen

//===- PPCCallingConv.td - Calling Conventions for PowerPC -*- tablegen -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This describes the calling conventions for the PowerPC 32- and 64-bit
// architectures.
//
//===----------------------------------------------------------------------===//
/// CCIfSubtarget - Match if the current subtarget has a feature F.
class CCIfSubtarget<string F, CCAction A>
: CCIf<!strconcat("State.getTarget().getSubtarget<PPCSubtarget>().", F), A>;
class CCIfNotSubtarget<string F, CCAction A>
: CCIf<!strconcat("!State.getTarget().getSubtarget<PPCSubtarget>().", F), A>;
//===----------------------------------------------------------------------===//
// Return Value Calling Convention
//===----------------------------------------------------------------------===//
// Return-value convention for PowerPC
def RetCC_PPC : CallingConv<[
// On PPC64, integer return values are always promoted to i64
CCIfType<[i32, i1], CCIfSubtarget<"isPPC64()", CCPromoteToType<i64>>>,
CCIfType<[i1], CCIfNotSubtarget<"isPPC64()", CCPromoteToType<i32>>>,
CCIfType<[i32], CCAssignToReg<[R3, R4, R5, R6, R7, R8, R9, R10]>>,
CCIfType<[i64], CCAssignToReg<[X3, X4, X5, X6]>>,
CCIfType<[i128], CCAssignToReg<[X3, X4, X5, X6]>>,
// Floating point types returned as "direct" go into F1 .. F8; note that
// only the ELFv2 ABI fully utilizes all these registers.
CCIfType<[f32], CCAssignToReg<[F1, F2, F3, F4, F5, F6, F7, F8]>>,
CCIfType<[f64], CCAssignToReg<[F1, F2, F3, F4, F5, F6, F7, F8]>>,
// Vector types returned as "direct" go into V2 .. V9; note that only the
// ELFv2 ABI fully utilizes all these registers.
CCIfType<[v16i8, v8i16, v4i32, v4f32],
CCAssignToReg<[V2, V3, V4, V5, V6, V7, V8, V9]>>,
CCIfType<[v2f64, v2i64],
CCAssignToReg<[VSH2, VSH3, VSH4, VSH5, VSH6, VSH7, VSH8, VSH9]>>
]>;
// Note that we don't currently have calling conventions for 64-bit
// PowerPC, but handle all the complexities of the ABI in the lowering
// logic. FIXME: See if the logic can be simplified with use of CCs.
// This may require some extensions to current table generation.
// Simple calling convention for 64-bit ELF PowerPC fast isel.
// Only handle ints and floats. All ints are promoted to i64.
// Vector types and quadword ints are not handled.
def CC_PPC64_ELF_FIS : CallingConv<[
CCIfType<[i1], CCPromoteToType<i64>>,
CCIfType<[i8], CCPromoteToType<i64>>,
CCIfType<[i16], CCPromoteToType<i64>>,
CCIfType<[i32], CCPromoteToType<i64>>,
CCIfType<[i64], CCAssignToReg<[X3, X4, X5, X6, X7, X8, X9, X10]>>,
CCIfType<[f32, f64], CCAssignToReg<[F1, F2, F3, F4, F5, F6, F7, F8]>>
]>;
// Simple return-value convention for 64-bit ELF PowerPC fast isel.
// All small ints are promoted to i64. Vector types, quadword ints,
// and multiple register returns are "supported" to avoid compile
// errors, but none are handled by the fast selector.
def RetCC_PPC64_ELF_FIS : CallingConv<[
CCIfType<[i1], CCPromoteToType<i64>>,
CCIfType<[i8], CCPromoteToType<i64>>,
CCIfType<[i16], CCPromoteToType<i64>>,
CCIfType<[i32], CCPromoteToType<i64>>,
CCIfType<[i64], CCAssignToReg<[X3, X4]>>,
CCIfType<[i128], CCAssignToReg<[X3, X4, X5, X6]>>,
CCIfType<[f32], CCAssignToReg<[F1, F2, F3, F4, F5, F6, F7, F8]>>,
CCIfType<[f64], CCAssignToReg<[F1, F2, F3, F4, F5, F6, F7, F8]>>,
CCIfType<[v16i8, v8i16, v4i32, v4f32],
CCAssignToReg<[V2, V3, V4, V5, V6, V7, V8, V9]>>,
CCIfType<[v2f64, v2i64],
CCAssignToReg<[VSH2, VSH3, VSH4, VSH5, VSH6, VSH7, VSH8, VSH9]>>
]>;
//===----------------------------------------------------------------------===//
// PowerPC System V Release 4 32-bit ABI
//===----------------------------------------------------------------------===//
def CC_PPC32_SVR4_Common : CallingConv<[
CCIfType<[i1], CCPromoteToType<i32>>,
// The ABI requires i64 to be passed in two adjacent registers with the first
// register having an odd register number.
CCIfType<[i32], CCIfSplit<CCCustom<"CC_PPC32_SVR4_Custom_AlignArgRegs">>>,
// The first 8 integer arguments are passed in integer registers.
CCIfType<[i32], CCAssignToReg<[R3, R4, R5, R6, R7, R8, R9, R10]>>,
// Make sure the i64 words from a long double are either both passed in
// registers or both passed on the stack.
CCIfType<[f64], CCIfSplit<CCCustom<"CC_PPC32_SVR4_Custom_AlignFPArgRegs">>>,
// FP values are passed in F1 - F8.
CCIfType<[f32, f64], CCAssignToReg<[F1, F2, F3, F4, F5, F6, F7, F8]>>,
// Split arguments have an alignment of 8 bytes on the stack.
CCIfType<[i32], CCIfSplit<CCAssignToStack<4, 8>>>,
CCIfType<[i32], CCAssignToStack<4, 4>>,
// Floats are stored in double precision format, thus they have the same
// alignment and size as doubles.
CCIfType<[f32,f64], CCAssignToStack<8, 8>>,
// Vectors get 16-byte stack slots that are 16-byte aligned.
CCIfType<[v16i8, v8i16, v4i32, v4f32, v2f64, v2i64], CCAssignToStack<16, 16>>
]>;
// This calling convention puts vector arguments always on the stack. It is used
// to assign vector arguments which belong to the variable portion of the
// parameter list of a variable argument function.
def CC_PPC32_SVR4_VarArg : CallingConv<[
CCDelegateTo<CC_PPC32_SVR4_Common>
]>;
// In contrast to CC_PPC32_SVR4_VarArg, this calling convention first tries to
// put vector arguments in vector registers before putting them on the stack.
def CC_PPC32_SVR4 : CallingConv<[
// The first 12 Vector arguments are passed in AltiVec registers.
CCIfType<[v16i8, v8i16, v4i32, v4f32],
CCAssignToReg<[V2, V3, V4, V5, V6, V7, V8, V9, V10, V11, V12, V13]>>,
CCIfType<[v2f64, v2i64],
CCAssignToReg<[VSH2, VSH3, VSH4, VSH5, VSH6, VSH7, VSH8, VSH9,
VSH10, VSH11, VSH12, VSH13]>>,
CCDelegateTo<CC_PPC32_SVR4_Common>
]>;
// Helper "calling convention" to handle aggregate by value arguments.
// Aggregate by value arguments are always placed in the local variable space
// of the caller. This calling convention is only used to assign those stack
// offsets in the callers stack frame.
//
// Still, the address of the aggregate copy in the callers stack frame is passed
// in a GPR (or in the parameter list area if all GPRs are allocated) from the
// caller to the callee. The location for the address argument is assigned by
// the CC_PPC32_SVR4 calling convention.
//
// The only purpose of CC_PPC32_SVR4_Custom_Dummy is to skip arguments which are
// not passed by value.
def CC_PPC32_SVR4_ByVal : CallingConv<[
CCIfByVal<CCPassByVal<4, 4>>,
CCCustom<"CC_PPC32_SVR4_Custom_Dummy">
]>;
def CSR_Altivec : CalleeSavedRegs<(add V20, V21, V22, V23, V24, V25, V26, V27,
V28, V29, V30, V31)>;
def CSR_Darwin32 : CalleeSavedRegs<(add R13, R14, R15, R16, R17, R18, R19, R20,
R21, R22, R23, R24, R25, R26, R27, R28,
R29, R30, R31, F14, F15, F16, F17, F18,
F19, F20, F21, F22, F23, F24, F25, F26,
F27, F28, F29, F30, F31, CR2, CR3, CR4
)>;
def CSR_Darwin32_Altivec : CalleeSavedRegs<(add CSR_Darwin32, CSR_Altivec)>;
def CSR_SVR432 : CalleeSavedRegs<(add R14, R15, R16, R17, R18, R19, R20,
R21, R22, R23, R24, R25, R26, R27, R28,
R29, R30, R31, F14, F15, F16, F17, F18,
F19, F20, F21, F22, F23, F24, F25, F26,
F27, F28, F29, F30, F31, CR2, CR3, CR4
)>;
def CSR_SVR432_Altivec : CalleeSavedRegs<(add CSR_SVR432, CSR_Altivec)>;
def CSR_Darwin64 : CalleeSavedRegs<(add X13, X14, X15, X16, X17, X18, X19, X20,
X21, X22, X23, X24, X25, X26, X27, X28,
X29, X30, X31, F14, F15, F16, F17, F18,
F19, F20, F21, F22, F23, F24, F25, F26,
F27, F28, F29, F30, F31, CR2, CR3, CR4
)>;
def CSR_Darwin64_Altivec : CalleeSavedRegs<(add CSR_Darwin64, CSR_Altivec)>;
def CSR_SVR464 : CalleeSavedRegs<(add X14, X15, X16, X17, X18, X19, X20,
X21, X22, X23, X24, X25, X26, X27, X28,
X29, X30, X31, F14, F15, F16, F17, F18,
F19, F20, F21, F22, F23, F24, F25, F26,
F27, F28, F29, F30, F31, CR2, CR3, CR4
)>;
def CSR_SVR464_Altivec : CalleeSavedRegs<(add CSR_SVR464, CSR_Altivec)>;
def CSR_NoRegs : CalleeSavedRegs<(add)>;