[AArch64] Implement GHC calling convention
Original patch by Luke Iannini. Minor improvements and test added by
Erik de Castro Lopo.
Differential Revision: http://reviews.llvm.org/D6877
From: Erik de Castro Lopo <erikd@mega-nerd.com>
llvm-svn: 226473
diff --git a/llvm/lib/Target/AArch64/AArch64CallingConvention.td b/llvm/lib/Target/AArch64/AArch64CallingConvention.td
index 1a80402..a391e76 100644
--- a/llvm/lib/Target/AArch64/AArch64CallingConvention.td
+++ b/llvm/lib/Target/AArch64/AArch64CallingConvention.td
@@ -204,6 +204,44 @@
[Q0, Q1, Q2, Q3, Q4, Q5, Q6, Q7]>>
]>;
+//===----------------------------------------------------------------------===//
+// ARM64 Calling Convention for GHC
+//===----------------------------------------------------------------------===//
+
+// This calling convention is specific to the Glasgow Haskell Compiler.
+// The only documentation is the GHC source code, specifically the C header
+// file:
+//
+// https://github.com/ghc/ghc/blob/master/includes/stg/MachRegs.h
+//
+// which defines the registers for the Spineless Tagless G-Machine (STG) that
+// GHC uses to implement lazy evaluation. The generic STG machine has a set of
+// registers which are mapped to appropriate set of architecture specific
+// registers for each CPU architecture.
+//
+// The STG Machine is documented here:
+//
+// https://ghc.haskell.org/trac/ghc/wiki/Commentary/Compiler/GeneratedCode
+//
+// The AArch64 register mapping is under the heading "The ARMv8/AArch64 ABI
+// register mapping".
+
+def CC_AArch64_GHC : CallingConv<[
+ // Handle all vector types as either f64 or v2f64.
+ CCIfType<[v1i64, v2i32, v4i16, v8i8, v2f32], CCBitConvertToType<f64>>,
+ CCIfType<[v2i64, v4i32, v8i16, v16i8, v4f32, f128], CCBitConvertToType<v2f64>>,
+
+ CCIfType<[v2f64], CCAssignToReg<[Q4, Q5]>>,
+ CCIfType<[f32], CCAssignToReg<[S8, S9, S10, S11]>>,
+ CCIfType<[f64], CCAssignToReg<[D12, D13, D14, D15]>>,
+
+ // Promote i8/i16/i32 arguments to i64.
+ CCIfType<[i8, i16, i32], CCPromoteToType<i64>>,
+
+ // Pass in STG registers: Base, Sp, Hp, R1, R2, R3, R4, R5, R6, SpLim
+ CCIfType<[i64], CCAssignToReg<[X19, X20, X21, X22, X23, X24, X25, X26, X27, X28]>>
+]>;
+
// FIXME: LR is only callee-saved in the sense that *we* preserve it and are
// presumably a callee to someone. External functions may not do so, but this
// is currently safe since BL has LR as an implicit-def and what happens after a
@@ -249,3 +287,4 @@
(sequence "S%u", 0, 31), (sequence "D%u", 0, 31),
(sequence "Q%u", 0, 31))>;
+def CSR_AArch64_NoRegs : CalleeSavedRegs<(add)>;
diff --git a/llvm/lib/Target/AArch64/AArch64FastISel.cpp b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
index 419fbc8..ca4e97b 100644
--- a/llvm/lib/Target/AArch64/AArch64FastISel.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FastISel.cpp
@@ -302,6 +302,8 @@
CCAssignFn *AArch64FastISel::CCAssignFnForCall(CallingConv::ID CC) const {
if (CC == CallingConv::WebKit_JS)
return CC_AArch64_WebKit_JS;
+ if (CC == CallingConv::GHC)
+ return CC_AArch64_GHC;
return Subtarget->isTargetDarwin() ? CC_AArch64_DarwinPCS : CC_AArch64_AAPCS;
}
diff --git a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
index 66aa216..d8e9156 100644
--- a/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64FrameLowering.cpp
@@ -215,6 +215,11 @@
bool HasFP = hasFP(MF);
DebugLoc DL = MBB.findDebugLoc(MBBI);
+ // All calls are tail calls in GHC calling conv, and functions have no
+ // prologue/epilogue.
+ if (MF.getFunction()->getCallingConv() == CallingConv::GHC)
+ return;
+
int NumBytes = (int)MFI->getStackSize();
if (!AFI->hasStackFrame()) {
assert(!HasFP && "unexpected function without stack frame but with FP");
@@ -451,6 +456,11 @@
int NumBytes = MFI->getStackSize();
const AArch64FunctionInfo *AFI = MF.getInfo<AArch64FunctionInfo>();
+ // All calls are tail calls in GHC calling conv, and functions have no
+ // prologue/epilogue.
+ if (MF.getFunction()->getCallingConv() == CallingConv::GHC)
+ return;
+
// Initial and residual are named for consitency with the prologue. Note that
// in the epilogue, the residual adjustment is executed first.
uint64_t ArgumentPopSize = 0;
diff --git a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
index 0d44f99..19f51ce 100644
--- a/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -1990,6 +1990,8 @@
llvm_unreachable("Unsupported calling convention.");
case CallingConv::WebKit_JS:
return CC_AArch64_WebKit_JS;
+ case CallingConv::GHC:
+ return CC_AArch64_GHC;
case CallingConv::C:
case CallingConv::Fast:
if (!Subtarget->isTargetDarwin())
diff --git a/llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp b/llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp
index d734d43..6a49af8 100644
--- a/llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp
+++ b/llvm/lib/Target/AArch64/AArch64RegisterInfo.cpp
@@ -40,6 +40,10 @@
const MCPhysReg *
AArch64RegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
assert(MF && "Invalid MachineFunction pointer.");
+ if (MF->getFunction()->getCallingConv() == CallingConv::GHC)
+ // GHC set of callee saved regs is empty as all those regs are
+ // used for passing STG regs around
+ return CSR_AArch64_NoRegs_SaveList;
if (MF->getFunction()->getCallingConv() == CallingConv::AnyReg)
return CSR_AArch64_AllRegs_SaveList;
else
@@ -48,6 +52,9 @@
const uint32_t *
AArch64RegisterInfo::getCallPreservedMask(CallingConv::ID CC) const {
+ if (CC == CallingConv::GHC)
+ // This is academic becase all GHC calls are (supposed to be) tail calls
+ return CSR_AArch64_NoRegs_RegMask;
if (CC == CallingConv::AnyReg)
return CSR_AArch64_AllRegs_RegMask;
else
@@ -63,7 +70,7 @@
}
const uint32_t *
-AArch64RegisterInfo::getThisReturnPreservedMask(CallingConv::ID) const {
+AArch64RegisterInfo::getThisReturnPreservedMask(CallingConv::ID CC) const {
// This should return a register mask that is the same as that returned by
// getCallPreservedMask but that additionally preserves the register used for
// the first i64 argument (which must also be the register used to return a
@@ -71,6 +78,7 @@
//
// In case that the calling convention does not use the same register for
// both, the function should return NULL (does not currently apply)
+ assert(CC != CallingConv::GHC && "should not be GHC calling convention.");
return CSR_AArch64_AAPCS_ThisReturn_RegMask;
}