X86: Implement the vectorcall calling convention

This is a Microsoft calling convention that supports both x86 and x86_64
subtargets. It passes vector and floating point arguments in XMM0-XMM5,
and passes them indirectly once they are consumed.

Homogenous vector aggregates of up to four elements can be passed in
sequential vector registers, but this part is not implemented in LLVM
and will be handled in Clang.

On 32-bit x86, it is similar to fastcall in that it uses ecx:edx as
integer register parameters and is callee cleanup. On x86_64, it
delegates to the normal win64 calling convention.

Reviewers: majnemer

Differential Revision: http://reviews.llvm.org/D5943

llvm-svn: 220745

2 files changed, 77 insertions, 0 deletions

diff --git a/llvm/lib/Target/X86/X86CallingConv.h b/llvm/lib/Target/X86/X86CallingConv.h
index 15a455ae29b..0eb2494f1d6 100644
--- a/llvm/lib/Target/X86/X86CallingConv.h
+++ b/llvm/lib/Target/X86/X86CallingConv.h
@@ -20,6 +20,19 @@
 
 namespace llvm {
 
+inline bool CC_X86_32_VectorCallIndirect(unsigned &ValNo, MVT &ValVT,
+                                         MVT &LocVT,
+                                         CCValAssign::LocInfo &LocInfo,
+                                         ISD::ArgFlagsTy &ArgFlags,
+                                         CCState &State) {
+  // Similar to CCPassIndirect, with the addition of inreg.
+  LocVT = MVT::i32;
+  LocInfo = CCValAssign::Indirect;
+  ArgFlags.setInReg();
+  return false; // Continue the search, but now for i32.
+}
+
+
 inline bool CC_X86_AnyReg_Error(unsigned &, MVT &, MVT &,
                                 CCValAssign::LocInfo &, ISD::ArgFlagsTy &,
                                 CCState &) {
diff --git a/llvm/lib/Target/X86/X86CallingConv.td b/llvm/lib/Target/X86/X86CallingConv.td
index dec73eac606..75a2ec00468 100644
--- a/llvm/lib/Target/X86/X86CallingConv.td
+++ b/llvm/lib/Target/X86/X86CallingConv.td
@@ -124,6 +124,24 @@ def RetCC_X86_32_HiPE : CallingConv<[
   CCIfType<[i32], CCAssignToReg<[ESI, EBP, EAX, EDX]>>
 ]>;
 
+// X86-32 HiPE return-value convention.
+def RetCC_X86_32_VectorCall : CallingConv<[
+  // Vector types are returned in XMM0,XMM1,XMMM2 and XMM3.
+  CCIfType<[f32, f64, v16i8, v8i16, v4i32, v2i64, v4f32, v2f64],
+            CCAssignToReg<[XMM0,XMM1,XMM2,XMM3]>>,
+
+  // 256-bit FP vectors
+  CCIfType<[v32i8, v16i16, v8i32, v4i64, v8f32, v4f64],
+            CCAssignToReg<[YMM0,YMM1,YMM2,YMM3]>>,
+
+  // 512-bit FP vectors
+  CCIfType<[v64i8, v32i16, v16i32, v8i64, v16f32, v8f64],
+            CCAssignToReg<[ZMM0,ZMM1,ZMM2,ZMM3]>>,
+
+  // Return integers in the standard way.
+  CCDelegateTo<RetCC_X86Common>
+]>;
+
 // X86-64 C return-value convention.
 def RetCC_X86_64_C : CallingConv<[
   // The X86-64 calling convention always returns FP values in XMM0.
@@ -179,6 +197,7 @@ def RetCC_X86_32 : CallingConv<[
   CCIfCC<"CallingConv::Fast", CCDelegateTo<RetCC_X86_32_Fast>>,
   // If HiPE, use RetCC_X86_32_HiPE.
   CCIfCC<"CallingConv::HiPE", CCDelegateTo<RetCC_X86_32_HiPE>>,
+  CCIfCC<"CallingConv::X86_VectorCall", CCDelegateTo<RetCC_X86_32_VectorCall>>,
 
   // Otherwise, use RetCC_X86_32_C.
   CCDelegateTo<RetCC_X86_32_C>
@@ -330,6 +349,25 @@ def CC_X86_Win64_C : CallingConv<[
   CCIfType<[f80], CCAssignToStack<0, 0>>
 ]>;
 
+def CC_X86_Win64_VectorCall : CallingConv<[
+  // The first 6 floating point and vector types of 128 bits or less use
+  // XMM0-XMM5.
+  CCIfType<[f32, f64, v16i8, v8i16, v4i32, v2i64, v4f32, v2f64],
+           CCAssignToReg<[XMM0, XMM1, XMM2, XMM3, XMM4, XMM5]>>,
+
+  // 256-bit vectors use YMM registers.
+  CCIfType<[v32i8, v16i16, v8i32, v4i64, v8f32, v4f64],
+           CCAssignToReg<[YMM0, YMM1, YMM2, YMM3, YMM4, YMM5]>>,
+
+  // 512-bit vectors use ZMM registers.
+  CCIfType<[v64i8, v32i16, v16i32, v8i64, v16f32, v8f64],
+           CCAssignToReg<[ZMM0, ZMM1, ZMM2, ZMM3, ZMM4, ZMM5]>>,
+
+  // Delegate to fastcall to handle integer types.
+  CCDelegateTo<CC_X86_Win64_C>
+]>;
+
+
 def CC_X86_64_GHC : CallingConv<[
   // Promote i8/i16/i32 arguments to i64.
   CCIfType<[i8, i16, i32], CCPromoteToType<i64>>,
@@ -463,6 +501,30 @@ def CC_X86_32_FastCall : CallingConv<[
   CCDelegateTo<CC_X86_32_Common>
 ]>;
 
+def CC_X86_32_VectorCall : CallingConv<[
+  // The first 6 floating point and vector types of 128 bits or less use
+  // XMM0-XMM5.
+  CCIfType<[f32, f64, v16i8, v8i16, v4i32, v2i64, v4f32, v2f64],
+           CCAssignToReg<[XMM0, XMM1, XMM2, XMM3, XMM4, XMM5]>>,
+
+  // 256-bit vectors use YMM registers.
+  CCIfType<[v32i8, v16i16, v8i32, v4i64, v8f32, v4f64],
+           CCAssignToReg<[YMM0, YMM1, YMM2, YMM3, YMM4, YMM5]>>,
+
+  // 512-bit vectors use ZMM registers.
+  CCIfType<[v64i8, v32i16, v16i32, v8i64, v16f32, v8f64],
+           CCAssignToReg<[ZMM0, ZMM1, ZMM2, ZMM3, ZMM4, ZMM5]>>,
+
+  // Otherwise, pass it indirectly.
+  CCIfType<[v16i8, v8i16, v4i32, v2i64, v4f32, v2f64,
+            v32i8, v16i16, v8i32, v4i64, v8f32, v4f64,
+            v64i8, v32i16, v16i32, v8i64, v16f32, v8f64],
+           CCCustom<"CC_X86_32_VectorCallIndirect">>,
+
+  // Delegate to fastcall to handle integer types.
+  CCDelegateTo<CC_X86_32_FastCall>
+]>;
+
 def CC_X86_32_ThisCall_Common : CallingConv<[
   // The first integer argument is passed in ECX
   CCIfType<[i32], CCAssignToReg<[ECX]>>,
@@ -576,6 +638,7 @@ def CC_Intel_OCL_BI : CallingConv<[
 // This is the root argument convention for the X86-32 backend.
 def CC_X86_32 : CallingConv<[
   CCIfCC<"CallingConv::X86_FastCall", CCDelegateTo<CC_X86_32_FastCall>>,
+  CCIfCC<"CallingConv::X86_VectorCall", CCDelegateTo<CC_X86_32_VectorCall>>,
   CCIfCC<"CallingConv::X86_ThisCall", CCDelegateTo<CC_X86_32_ThisCall>>,
   CCIfCC<"CallingConv::Fast", CCDelegateTo<CC_X86_32_FastCC>>,
   CCIfCC<"CallingConv::GHC", CCDelegateTo<CC_X86_32_GHC>>,
@@ -593,6 +656,7 @@ def CC_X86_64 : CallingConv<[
   CCIfCC<"CallingConv::AnyReg", CCDelegateTo<CC_X86_64_AnyReg>>,
   CCIfCC<"CallingConv::X86_64_Win64", CCDelegateTo<CC_X86_Win64_C>>,
   CCIfCC<"CallingConv::X86_64_SysV", CCDelegateTo<CC_X86_64_C>>,
+  CCIfCC<"CallingConv::X86_VectorCall", CCDelegateTo<CC_X86_Win64_VectorCall>>,
 
   // Mingw64 and native Win64 use Win64 CC
   CCIfSubtarget<"isTargetWin64()", CCDelegateTo<CC_X86_Win64_C>>,