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llvm-mirror/lib/Target/SystemZ/SystemZCallingConv.td
Ulrich Weigand 6643dc8666 [SystemZ] Support large LLVM IR struct return values
Recent mesa/llvmpipe crashes on SystemZ due to a failed assertion when
attempting to compile a routine with a return type of
  { <4 x float>, <4 x float>, <4 x float>, <4 x float> }
on a system without vector instruction support.

This is because after legalizing the vector type, we get a return value
consisting of 16 floats, which cannot all be returned in registers.

Usually, what should happen in this case is that the target's CanLowerReturn
routine rejects the return type, in which case SelectionDAG falls back to
implementing a structure return in memory via implicit reference.

However, the SystemZ target never actually implemented any CanLowerReturn
routine, and thus would accept any struct return type.

This patch fixes the crash by implementing CanLowerReturn.  As a side effect,
this also handles fp128 return values, fixing a todo that was noted in
SystemZCallingConv.td.

llvm-svn: 244889
2015-08-13 13:37:06 +00:00

108 lines
4.9 KiB
TableGen

//=- SystemZCallingConv.td - Calling conventions for SystemZ -*- 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 SystemZ ABI.
//===----------------------------------------------------------------------===//
class CCIfExtend<CCAction A>
: CCIf<"ArgFlags.isSExt() || ArgFlags.isZExt()", A>;
class CCIfSubtarget<string F, CCAction A>
: CCIf<!strconcat("static_cast<const SystemZSubtarget&>"
"(State.getMachineFunction().getSubtarget()).", F),
A>;
// Match if this specific argument is a fixed (i.e. named) argument.
class CCIfFixed<CCAction A>
: CCIf<"static_cast<SystemZCCState *>(&State)->IsFixed(ValNo)", A>;
// Match if this specific argument was widened from a short vector type.
class CCIfShortVector<CCAction A>
: CCIf<"static_cast<SystemZCCState *>(&State)->IsShortVector(ValNo)", A>;
//===----------------------------------------------------------------------===//
// z/Linux return value calling convention
//===----------------------------------------------------------------------===//
def RetCC_SystemZ : CallingConv<[
// Promote i32 to i64 if it has an explicit extension type.
CCIfType<[i32], CCIfExtend<CCPromoteToType<i64>>>,
// ABI-compliant code returns 64-bit integers in R2. Make the other
// call-clobbered argument registers available for code that doesn't
// care about the ABI. (R6 is an argument register too, but is
// call-saved and therefore not suitable for return values.)
CCIfType<[i32], CCAssignToReg<[R2L, R3L, R4L, R5L]>>,
CCIfType<[i64], CCAssignToReg<[R2D, R3D, R4D, R5D]>>,
// ABI-complaint code returns float and double in F0. Make the
// other floating-point argument registers available for code that
// doesn't care about the ABI. All floating-point argument registers
// are call-clobbered, so we can use all of them here.
CCIfType<[f32], CCAssignToReg<[F0S, F2S, F4S, F6S]>>,
CCIfType<[f64], CCAssignToReg<[F0D, F2D, F4D, F6D]>>,
// Similarly for vectors, with V24 being the ABI-compliant choice.
// Sub-128 vectors are returned in the same way, but they're widened
// to one of these types during type legalization.
CCIfSubtarget<"hasVector()",
CCIfType<[v16i8, v8i16, v4i32, v2i64, v4f32, v2f64],
CCAssignToReg<[V24, V26, V28, V30, V25, V27, V29, V31]>>>
]>;
//===----------------------------------------------------------------------===//
// z/Linux argument calling conventions
//===----------------------------------------------------------------------===//
def CC_SystemZ : CallingConv<[
// Promote i32 to i64 if it has an explicit extension type.
// The convention is that true integer arguments that are smaller
// than 64 bits should be marked as extended, but structures that
// are smaller than 64 bits shouldn't.
CCIfType<[i32], CCIfExtend<CCPromoteToType<i64>>>,
// Force long double values to the stack and pass i64 pointers to them.
CCIfType<[f128], CCPassIndirect<i64>>,
// The first 5 integer arguments are passed in R2-R6. Note that R6
// is call-saved.
CCIfType<[i32], CCAssignToReg<[R2L, R3L, R4L, R5L, R6L]>>,
CCIfType<[i64], CCAssignToReg<[R2D, R3D, R4D, R5D, R6D]>>,
// The first 4 float and double arguments are passed in even registers F0-F6.
CCIfType<[f32], CCAssignToReg<[F0S, F2S, F4S, F6S]>>,
CCIfType<[f64], CCAssignToReg<[F0D, F2D, F4D, F6D]>>,
// The first 8 named vector arguments are passed in V24-V31. Sub-128 vectors
// are passed in the same way, but they're widened to one of these types
// during type legalization.
CCIfSubtarget<"hasVector()",
CCIfType<[v16i8, v8i16, v4i32, v2i64, v4f32, v2f64],
CCIfFixed<CCAssignToReg<[V24, V26, V28, V30,
V25, V27, V29, V31]>>>>,
// However, sub-128 vectors which need to go on the stack occupy just a
// single 8-byte-aligned 8-byte stack slot. Pass as i64.
CCIfSubtarget<"hasVector()",
CCIfType<[v16i8, v8i16, v4i32, v2i64, v4f32, v2f64],
CCIfShortVector<CCBitConvertToType<i64>>>>,
// Other vector arguments are passed in 8-byte-aligned 16-byte stack slots.
CCIfSubtarget<"hasVector()",
CCIfType<[v16i8, v8i16, v4i32, v2i64, v4f32, v2f64],
CCAssignToStack<16, 8>>>,
// Other arguments are passed in 8-byte-aligned 8-byte stack slots.
CCIfType<[i32, i64, f32, f64], CCAssignToStack<8, 8>>
]>;
//===----------------------------------------------------------------------===//
// z/Linux callee-saved registers
//===----------------------------------------------------------------------===//
def CSR_SystemZ : CalleeSavedRegs<(add (sequence "R%dD", 6, 15),
(sequence "F%dD", 8, 15))>;