X-Git-Url: http://demsky.eecs.uci.edu/git/?a=blobdiff_plain;f=lib%2FTarget%2FX86%2FX86CallingConv.td;h=e9fcbd5a4895f787a01b4316407574651841ac3d;hb=482fa0f2bcfca5274b14c808526c8ae4fe97007d;hp=370bae7a50cf02a7bfac1348e8daea72448b82c5;hpb=82f84159e0ec945657054ddcf465aca3253339ab;p=oota-llvm.git

diff --git a/lib/Target/X86/X86CallingConv.td b/lib/Target/X86/X86CallingConv.td
index 370bae7a50c..e9fcbd5a489 100644
--- a/lib/Target/X86/X86CallingConv.td
+++ b/lib/Target/X86/X86CallingConv.td
@@ -22,13 +22,14 @@ class CCIfSubtarget<string F, CCAction A>
 
 // Return-value conventions common to all X86 CC's.
 def RetCC_X86Common : CallingConv<[
-  // Scalar values are returned in AX first, then DX, except for i8 where
-  // the convention is to return values in AL and AH. However, using AL and
-  // is AH problematic -- a return of {i16,i8} would end up using AX and AH,
-  // and one value would clobber the other. C front-ends are currently expected
-  // to pack two i8 values into an i16 in the rare situations where this
-  // is necessary.
-  CCIfType<[i8] , CCAssignToReg<[AL]>>,
+  // Scalar values are returned in AX first, then DX.  For i8, the ABI
+  // requires the values to be in AL and AH, however this code uses AL and DL
+  // instead. This is because using AH for the second register conflicts with
+  // the way LLVM does multiple return values -- a return of {i16,i8} would end
+  // up in AX and AH, which overlap. Front-ends wishing to conform to the ABI
+  // for functions that return two i8 values are currently expected to pack the
+  // values into an i16 (which uses AX, and thus AL:AH).
+  CCIfType<[i8] , CCAssignToReg<[AL, DL]>>,
   CCIfType<[i16], CCAssignToReg<[AX, DX]>>,
   CCIfType<[i32], CCAssignToReg<[EAX, EDX]>>,
   CCIfType<[i64], CCAssignToReg<[RAX, RDX]>>,
@@ -214,50 +215,6 @@ def CC_X86_Win64_C : CallingConv<[
   CCIfType<[v8i8, v4i16, v2i32, v1i64], CCAssignToStack<8, 16>>
 ]>;
 
-// Tail call convention (fast): One register is reserved for target address,
-// namely R9
-def CC_X86_64_TailCall : CallingConv<[
-  // Handles byval parameters.
-  CCIfByVal<CCPassByVal<8, 8>>,
-
-  // Promote i8/i16 arguments to i32.
-  CCIfType<[i8, i16], CCPromoteToType<i32>>,
-
-  // The 'nest' parameter, if any, is passed in R10.
-  CCIfNest<CCAssignToReg<[R10]>>,
-
-  // The first 6 integer arguments are passed in integer registers.
-  CCIfType<[i32], CCAssignToReg<[EDI, ESI, EDX, ECX, R8D]>>,
-  CCIfType<[i64], CCAssignToReg<[RDI, RSI, RDX, RCX, R8]>>,
-  
-  // The first 8 FP/Vector arguments are passed in XMM registers.
-  CCIfType<[f32, f64, v16i8, v8i16, v4i32, v2i64, v4f32, v2f64],
-            CCIfSubtarget<"hasSSE1()",
-            CCAssignToReg<[XMM0, XMM1, XMM2, XMM3, XMM4, XMM5, XMM6, XMM7]>>>,
-
-  // The first 8 MMX (except for v1i64) vector arguments are passed in XMM
-  // registers on Darwin.
-  CCIfType<[v8i8, v4i16, v2i32, v2f32],
-            CCIfSubtarget<"isTargetDarwin()",
-            CCAssignToReg<[XMM0, XMM1, XMM2, XMM3, XMM4, XMM5, XMM6, XMM7]>>>,
- 
-  // The first 8 v1i64 vector arguments are passed in GPRs on Darwin.
-  CCIfType<[v1i64],
-            CCIfSubtarget<"isTargetDarwin()",
-            CCAssignToReg<[RDI, RSI, RDX, RCX, R8]>>>,
- 
-  // Integer/FP values get stored in stack slots that are 8 bytes in size and
-  // 8-byte aligned if there are no more registers to hold them.
-  CCIfType<[i32, i64, f32, f64], CCAssignToStack<8, 8>>,
-  
-  // Vectors get 16-byte stack slots that are 16-byte aligned.
-  CCIfType<[v16i8, v8i16, v4i32, v2i64, v4f32, v2f64], CCAssignToStack<16, 16>>,
-
-  // __m64 vectors get 8-byte stack slots that are 8-byte aligned.
-  CCIfType<[v8i8, v4i16, v2i32, v1i64], CCAssignToStack<8, 8>>
-]>;
-
-
 //===----------------------------------------------------------------------===//
 // X86 C Calling Convention
 //===----------------------------------------------------------------------===//