[X86] Deduplicate static calling convention helpers for code size, NFC

Summary:
Right now we include ${TGT}GenCallingConv.inc once per each instruction
selection method implemented by ${TGT}:
- ${TGT}ISelLowering.cpp
- ${TGT}CallLowering.cpp
- ${TGT}FastISel.cpp

Instead, add a mechanism to tablegen for marking a particular convention
as "External", which causes tablegen to emit into the ::llvm namespace,
instead of as a static helper. This allows us to provide a header to
forward declare it, so we can simply call the function from all the
places it is referenced. Typically the calling convention analyzer is
called indirectly, so it doesn't benefit from inlining.

This saves a bit of final binary size, but mostly just saves object file
size:

before  after   diff   artifact
12852K  12492K  -360K  X86ISelLowering.cpp.obj
4640K   4280K   -360K  X86FastISel.cpp.obj
1704K   2092K   +388K  X86CallingConv.cpp.obj
52448K  52336K  -112K  llc.exe

I didn't collect before numbers for X86CallLowering.cpp.obj, which is
for GlobalISel, but we should save 360K there as well.

This patch applies the strategy to the X86 backend, but there is no
reason it couldn't be applied to the other backends that implement
multiple ISel strategies, like AArch64.

Reviewers: craig.topper, hfinkel, efriedma

Subscribers: javed.absar, kristof.beyls, hiraditya, llvm-commits

Differential Revision: https://reviews.llvm.org/D56883

llvm-svn: 351616

1 files changed, 5 insertions, 38 deletions

diff --git a/llvm/lib/Target/X86/X86CallingConv.h b/llvm/lib/Target/X86/X86CallingConv.h
index eb1b7736f33..235bde5c198 100644
--- a/llvm/lib/Target/X86/X86CallingConv.h
+++ b/llvm/lib/Target/X86/X86CallingConv.h
@@ -21,45 +21,12 @@
 
 namespace llvm {
 
-/// When regcall calling convention compiled to 32 bit arch, special treatment
-/// is required for 64 bit masks.
-/// The value should be assigned to two GPRs.
-/// \return true if registers were allocated and false otherwise.
-bool CC_X86_32_RegCall_Assign2Regs(unsigned &ValNo, MVT &ValVT, MVT &LocVT,
-                                   CCValAssign::LocInfo &LocInfo,
-                                   ISD::ArgFlagsTy &ArgFlags, CCState &State);
+bool RetCC_X86(unsigned ValNo, MVT ValVT, MVT LocVT,
+               CCValAssign::LocInfo LocInfo, ISD::ArgFlagsTy ArgFlags,
+               CCState &State);
 
-/// Vectorcall calling convention has special handling for vector types or
-/// HVA for 64 bit arch.
-/// For HVAs shadow registers might be allocated on the first pass
-/// and actual XMM registers are allocated on the second pass.
-/// For vector types, actual XMM registers are allocated on the first pass.
-/// \return true if registers were allocated and false otherwise.
-bool CC_X86_64_VectorCall(unsigned &ValNo, MVT &ValVT, MVT &LocVT,
-                          CCValAssign::LocInfo &LocInfo,
-                          ISD::ArgFlagsTy &ArgFlags, CCState &State);
-
-/// Vectorcall calling convention has special handling for vector types or
-/// HVA for 32 bit arch.
-/// For HVAs actual XMM registers are allocated on the second pass.
-/// For vector types, actual XMM registers are allocated on the first pass.
-/// \return true if registers were allocated and false otherwise.
-bool CC_X86_32_VectorCall(unsigned &ValNo, MVT &ValVT, MVT &LocVT,
-                          CCValAssign::LocInfo &LocInfo,
-                          ISD::ArgFlagsTy &ArgFlags, CCState &State);
-
-inline bool CC_X86_AnyReg_Error(unsigned &, MVT &, MVT &,
-                                CCValAssign::LocInfo &, ISD::ArgFlagsTy &,
-                                CCState &) {
-  llvm_unreachable("The AnyReg calling convention is only supported by the " \
-                   "stackmap and patchpoint intrinsics.");
-  // gracefully fallback to X86 C calling convention on Release builds.
-  return false;
-}
-
-bool CC_X86_32_MCUInReg(unsigned &ValNo, MVT &ValVT, MVT &LocVT,
-                        CCValAssign::LocInfo &LocInfo,
-                        ISD::ArgFlagsTy &ArgFlags, CCState &State);
+bool CC_X86(unsigned ValNo, MVT ValVT, MVT LocVT, CCValAssign::LocInfo LocInfo,
+            ISD::ArgFlagsTy ArgFlags, CCState &State);
 
 } // End llvm namespace