diff options
Diffstat (limited to 'src/ortho/mcode/ortho_code-x86-insns.adb')
| -rw-r--r-- | src/ortho/mcode/ortho_code-x86-insns.adb | 174 |
1 files changed, 122 insertions, 52 deletions
diff --git a/src/ortho/mcode/ortho_code-x86-insns.adb b/src/ortho/mcode/ortho_code-x86-insns.adb index d57938a..e975455 100644 --- a/src/ortho/mcode/ortho_code-x86-insns.adb +++ b/src/ortho/mcode/ortho_code-x86-insns.adb @@ -15,6 +15,52 @@ -- along with GCC; see the file COPYING. If not, write to the Free -- Software Foundation, 59 Temple Place - Suite 330, Boston, MA -- 02111-1307, USA. + +-- Instruction pass for mcode x86. +-- +-- The purpose of this pass is the transform the AST (the input) into a list +-- of x86 instructions and to allocate registers. +-- +-- The AST given in input is already linearized: ifs, loops, cases have been +-- translated to labels and jumps. So the input is a list of statement to +-- execute, intermixed with declaration blocks. +-- +-- The first purpose of this pass is to translate statements (and expressions) +-- to x86 instructions. This isn't particularly difficult as they are already +-- low-level statements and expression (by design of the language). The +-- algorithm simply try to put as much as possible into an instruction (in +-- order to use the address operand encoding of x86: base, index and scale): +-- AST is split into small trees (sometime as small as a single node) and +-- linearized. Each node represent a fix pattern of one or a few instructions +-- (in some case, like a 64 bit addition, we need more than one x86 +-- instruction). +-- The core functions of this package (Gen_Insn and Gen_Insn_Stmt) do the +-- work: they call Gen_Insn for each operand, then append themself to the +-- result using Link_Stmt. +-- +-- The second purpose of this pass is to perform register allocation. This +-- is done in the same time. +-- There are two sources of constraints for register allocation: +-- - external constraint on the result: for example, the return value of +-- a function must be in a fixed register (defined by the ABI). +-- - instruction constraint on the result: some x86 instructions (like div) +-- specify the result register. This constraint will be forward propagated +-- to next instructions. +-- - instruction constraint on the operand: most x86 instructions set the +-- result in one of the operand register, and some instructions (like shl) +-- have a fixed register for an operand (like the shift count). This +-- constraint has to be backward propagated to previous instructions. +-- Obviously constraints may be incompatible: the result of an instruction +-- may be in a different register than the input of the next instruction. +-- In this case, move instructions are added. +-- It is possible (and quite easily) to run out of registers. In that case +-- some values must be spilt (save) on the stack and will be reloaded later. +-- Registers are allocated statement by statement. So after each statement +-- all registers should be unused (this is a very basic register allocator). +-- +-- Finally, this pass also allocate stack slots for local variables, and +-- compute the size of the frame. + with Interfaces; with Ada.Text_IO; with Ortho_Code.Abi; @@ -24,6 +70,7 @@ with Ortho_Code.Debug; with Ortho_Code.X86.Flags; package body Ortho_Code.X86.Insns is + -- Add STMT to the list of instructions. procedure Link_Stmt (Stmt : O_Enode) is use Ortho_Code.Abi; @@ -35,6 +82,7 @@ package body Ortho_Code.X86.Insns is end if; end Link_Stmt; + -- Return the 'any register' constraint for mode MODE. function Get_Reg_Any (Mode : Mode_Type) return O_Reg is begin case Mode is @@ -104,9 +152,11 @@ package body Ortho_Code.X86.Insns is case Get_Decl_Kind (Decl) is when OD_Local => Decl_Type := Get_Decl_Type (Decl); + -- Align and allocate (on the stack). Stack_Offset := Do_Align (Stack_Offset, Decl_Type); Stack_Offset := Stack_Offset + Get_Type_Size (Decl_Type); Set_Local_Offset (Decl, -Int32 (Stack_Offset)); + -- If the frame gets lager, set the maximum size. if Stack_Offset > Stack_Max then Stack_Max := Stack_Offset; end if; @@ -127,6 +177,7 @@ package body Ortho_Code.X86.Insns is end loop; end Expand_Decls; + -- Condition code for unsigned comparaison. function Ekind_Unsigned_To_Cc (Kind : OE_Kind_Cmp) return O_Reg is begin case Kind is @@ -145,6 +196,7 @@ package body Ortho_Code.X86.Insns is end case; end Ekind_Unsigned_To_Cc; + -- Condition code for signed comparaison. function Ekind_Signed_To_Cc (Kind : OE_Kind_Cmp) return O_Reg is begin case Kind is @@ -211,7 +263,7 @@ package body Ortho_Code.X86.Insns is end case; end Reverse_Cc; - -- Get the register in which a result of MODE is returned. + -- Get the register in which a function result for MODE is returned. function Get_Return_Register (Mode : Mode_Type) return O_Reg is begin case Mode is @@ -289,7 +341,6 @@ package body Ortho_Code.X86.Insns is return Insn_Num; end Get_Insn_Num; - type Reg_Info_Type is record -- Statement number which use this register. -- This is a distance. @@ -301,7 +352,7 @@ package body Ortho_Code.X86.Insns is Stmt : O_Enode; -- If set, this register has been used. - -- All callee-saved registers marked must be saved. + -- All callee-saved registers marked 'used' must be saved in the prolog. Used : Boolean; end record; @@ -390,34 +441,26 @@ package body Ortho_Code.X86.Insns is -- Mark a register as unused. procedure Free_R32 (Reg : O_Reg) is begin - if Regs (Reg).Num = O_Free then - raise Program_Error; - end if; + pragma Assert (Regs (Reg).Num /= O_Free); Regs (Reg).Num := O_Free; end Free_R32; procedure Free_Fp is begin - if Fp_Regs (Fp_Top).Stmt = O_Enode_Null then - raise Program_Error; - end if; - Fp_Regs (Fp_Top).Stmt := O_Enode_Null; + pragma Assert (Fp_Regs (Fp_Top).Num /= O_Free); + Fp_Regs (Fp_Top).Num := O_Free; Fp_Top := Fp_Top + 1; end Free_Fp; procedure Free_Cc is begin - if Reg_Cc.Num = O_Free then - raise Program_Error; - end if; + pragma Assert (Reg_Cc.Num /= O_Free); Reg_Cc.Num := O_Free; end Free_Cc; procedure Free_Xmm (Reg : O_Reg) is begin - if Xmm_Regs (Reg).Num = O_Free then - raise Program_Error; - end if; + pragma Assert (Xmm_Regs (Reg).Num /= O_Free); Xmm_Regs (Reg).Num := O_Free; end Free_Xmm; @@ -491,7 +534,7 @@ package body Ortho_Code.X86.Insns is end case; end Spill_R32; - procedure Alloc_R32 (Reg : O_Reg; Stmt : O_Enode; Num : O_Inum) is + procedure Alloc_R32 (Reg : Regs_R32; Stmt : O_Enode; Num : O_Inum) is begin if Regs (Reg).Num /= O_Free then Spill_R32 (Reg); @@ -879,6 +922,22 @@ package body Ortho_Code.X86.Insns is Link_Stmt (N); end Insert_Arg; + -- Mark all registers that aren't preserved by a call as clobbered, so that + -- they are saved. + procedure Clobber_Caller_Saved_Registers is + begin + Clobber_R32 (R_Ax); + Clobber_R32 (R_Dx); + Clobber_R32 (R_Cx); + -- FIXME: fp regs. + + if Abi.Flag_Sse2 then + for R in Regs_Xmm loop + Clobber_Xmm (R); + end loop; + end if; + end Clobber_Caller_Saved_Registers; + function Insert_Intrinsic (Stmt : O_Enode; Reg : O_Reg; Num : O_Inum) return O_Enode is @@ -929,9 +988,7 @@ package body Ortho_Code.X86.Insns is end case; -- Save caller-saved registers. - Clobber_R32 (R_Ax); - Clobber_R32 (R_Dx); - Clobber_R32 (R_Cx); + Clobber_Caller_Saved_Registers; N := New_Enode (OE_Intrinsic, Mode, O_Tnode_Null, O_Enode (Op), O_Enode_Null); @@ -976,6 +1033,27 @@ package body Ortho_Code.X86.Insns is return Stmt; end Gen_Conv_From_Fp_Insn; + procedure Gen_Stack_Adjust (Off : Int32) + is + use Ortho_Code.Abi; + Stmt : O_Enode; + begin + if Get_Expr_Kind (Last_Link) = OE_Stack_Adjust then + -- The last instruction was already a stack_adjust. Change the + -- value. + Set_Stack_Adjust (Last_Link, + Get_Stack_Adjust (Last_Link) + Off); + if Debug.Flag_Debug_Insn then + Ada.Text_IO.Put (" patched:"); + Disp_Stmt (Last_Link); + end if; + else + Stmt := New_Enode (OE_Stack_Adjust, Mode_Nil, O_Tnode_Null, + O_Enode (Off), O_Enode_Null); + Link_Stmt (Stmt); + end if; + end Gen_Stack_Adjust; + function Gen_Call (Stmt : O_Enode; Reg : O_Reg; Pnum : O_Inum) return O_Enode is @@ -992,8 +1070,7 @@ package body Ortho_Code.X86.Insns is Pad := (Push_Size + Push_Offset) and Uns32 (Flags.Stack_Boundary - 1); if Pad /= 0 then Pad := Uns32 (Flags.Stack_Boundary) - Pad; - Link_Stmt (New_Enode (OE_Stack_Adjust, Mode_Nil, O_Tnode_Null, - O_Enode (Pad), O_Enode_Null)); + Gen_Stack_Adjust (Int32 (Pad)); end if; -- The stack has been adjusted by Pad bytes. Push_Offset := Push_Offset + Pad; @@ -1005,16 +1082,7 @@ package body Ortho_Code.X86.Insns is end if; -- Clobber registers. - Clobber_R32 (R_Ax); - Clobber_R32 (R_Dx); - Clobber_R32 (R_Cx); - -- FIXME: fp regs. - - if Abi.Flag_Sse2 then - for R in Regs_Xmm loop - Clobber_Xmm (R); - end loop; - end if; + Clobber_Caller_Saved_Registers; -- Add the call. Reg_Res := Get_Return_Register (Get_Expr_Mode (Stmt)); @@ -1023,11 +1091,7 @@ package body Ortho_Code.X86.Insns is Res_Stmt := Stmt; if Push_Size + Pad /= 0 then - Res_Stmt := - New_Enode (OE_Stack_Adjust, Get_Expr_Mode (Stmt), O_Tnode_Null, - O_Enode (-Int32 (Push_Size + Pad)), O_Enode_Null); - Set_Expr_Reg (Res_Stmt, Reg_Res); - Link_Stmt (Res_Stmt); + Gen_Stack_Adjust (-Int32 (Push_Size + Pad)); end if; -- The stack has been restored (just after the call). @@ -1589,10 +1653,10 @@ package body Ortho_Code.X86.Insns is | Regs_R64 | Regs_Fp | Regs_Xmm => - Right := Gen_Insn (Right, R_Irm, Num); Left := Gen_Insn (Left, Reg, Num); - Right := Reload (Right, R_Irm, Num); + Right := Gen_Insn (Right, R_Irm, Num); Left := Reload (Left, Reg, Num); + Right := Reload (Right, R_Irm, Num); Reg_Res := Get_Expr_Reg (Left); when others => Error_Gen_Insn (Stmt, Reg); @@ -1667,10 +1731,10 @@ package body Ortho_Code.X86.Insns is else Reg_Res := R_St0; end if; - Right := Gen_Insn (Right, R_Irm, Num); Left := Gen_Insn (Left, Reg_Res, Num); - Right := Reload (Right, R_Irm, Num); + Right := Gen_Insn (Right, R_Irm, Num); Left := Reload (Left, Reg_Res, Num); + Right := Reload (Right, R_Irm, Num); Reg_Res := Get_Expr_Reg (Left); Set_Expr_Right (Stmt, Right); Set_Expr_Left (Stmt, Left); @@ -1874,19 +1938,20 @@ package body Ortho_Code.X86.Insns is | R_Ir | R_Sib | R_Any32 - | Regs_R32 | R_Any64 | R_Any8 + | R_Any_Xmm => + Reg_Res := Get_Reg_Any (Stmt); + when Regs_R32 | Regs_R64 | Regs_Fp - | R_Any_Xmm | Regs_Xmm => - Free_Insn_Regs (Left); - Set_Expr_Reg - (Stmt, Alloc_Reg (Get_Reg_Any (Stmt), Stmt, Pnum)); + Reg_Res := Reg; when others => Error_Gen_Insn (Stmt, Reg); end case; + Free_Insn_Regs (Left); + Set_Expr_Reg (Stmt, Alloc_Reg (Reg_Res, Stmt, Pnum)); Link_Stmt (Stmt); return Stmt; end; @@ -1969,12 +2034,12 @@ package body Ortho_Code.X86.Insns is case Kind is when OE_Asgn => - Left := Gen_Insn (Get_Expr_Operand (Stmt), R_Ir, Num); - Right := Gen_Insn (Get_Assign_Target (Stmt), R_Sib, Num); - Left := Reload (Left, R_Ir, Num); - --Right := Reload (Right, R_Sib, Num); - Set_Expr_Operand (Stmt, Left); - Set_Assign_Target (Stmt, Right); + Right := Gen_Insn (Get_Expr_Operand (Stmt), R_Ir, Num); + Left := Gen_Insn (Get_Assign_Target (Stmt), R_Sib, Num); + Right := Reload (Right, R_Ir, Num); + --Left := Reload (Left, R_Sib, Num); + Set_Expr_Operand (Stmt, Right); + Set_Assign_Target (Stmt, Left); Link_Stmt (Stmt); Free_Insn_Regs (Left); Free_Insn_Regs (Right); @@ -1995,11 +2060,15 @@ package body Ortho_Code.X86.Insns is begin Cur_Block := Stmt; Block_Decl := Get_Block_Decls (Cur_Block); + -- Save current frame size (to be restored at end of block). Set_Block_Max_Stack (Block_Decl, Stack_Offset); + -- Allocate slots for local declarations. Expand_Decls (Block_Decl); end; Link_Stmt (Stmt); when OE_End => + -- Restore current frame size (so deallocate the slots for the + -- local declarations). Swap_Stack_Offset (Get_Block_Decls (Cur_Block)); Cur_Block := Get_Block_Parent (Cur_Block); Link_Stmt (Stmt); @@ -2042,6 +2111,7 @@ package body Ortho_Code.X86.Insns is case Kind is when OE_Beg | OE_End => + -- Stack offset has been explicitely changed for local variables. null; when others => Stack_Offset := Prev_Stack_Offset; |