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|
{-# LANGUAGE CPP, TypeFamilies #-}
-----------------------------------------------------------------------------
--
-- Machine-dependent assembly language
--
-- (c) The University of Glasgow 1993-2004
--
-----------------------------------------------------------------------------
module X86.Instr (Instr(..), Operand(..), PrefetchVariant(..), JumpDest(..),
getJumpDestBlockId, canShortcut, shortcutStatics,
shortcutJump, allocMoreStack,
maxSpillSlots, archWordFormat )
where
#include "HsVersions.h"
#include "nativeGen/NCG.h"
import GhcPrelude
import X86.Cond
import X86.Regs
import Instruction
import Format
import RegClass
import Reg
import TargetReg
import BlockId
import Hoopl.Collections
import Hoopl.Label
import CodeGen.Platform
import Cmm
import FastString
import Outputable
import Platform
import BasicTypes (Alignment)
import CLabel
import DynFlags
import UniqSet
import Unique
import UniqSupply
import Debug (UnwindTable)
import Control.Monad
import Data.Maybe (fromMaybe)
-- Format of an x86/x86_64 memory address, in bytes.
--
archWordFormat :: Bool -> Format
archWordFormat is32Bit
| is32Bit = II32
| otherwise = II64
-- | Instruction instance for x86 instruction set.
instance Instruction Instr where
regUsageOfInstr = x86_regUsageOfInstr
patchRegsOfInstr = x86_patchRegsOfInstr
isJumpishInstr = x86_isJumpishInstr
jumpDestsOfInstr = x86_jumpDestsOfInstr
patchJumpInstr = x86_patchJumpInstr
mkSpillInstr = x86_mkSpillInstr
mkLoadInstr = x86_mkLoadInstr
takeDeltaInstr = x86_takeDeltaInstr
isMetaInstr = x86_isMetaInstr
mkRegRegMoveInstr = x86_mkRegRegMoveInstr
takeRegRegMoveInstr = x86_takeRegRegMoveInstr
mkJumpInstr = x86_mkJumpInstr
mkStackAllocInstr = x86_mkStackAllocInstr
mkStackDeallocInstr = x86_mkStackDeallocInstr
-- -----------------------------------------------------------------------------
-- Intel x86 instructions
{-
Intel, in their infinite wisdom, selected a stack model for floating
point registers on x86. That might have made sense back in 1979 --
nowadays we can see it for the nonsense it really is. A stack model
fits poorly with the existing nativeGen infrastructure, which assumes
flat integer and FP register sets. Prior to this commit, nativeGen
could not generate correct x86 FP code -- to do so would have meant
somehow working the register-stack paradigm into the register
allocator and spiller, which sounds very difficult.
We have decided to cheat, and go for a simple fix which requires no
infrastructure modifications, at the expense of generating ropey but
correct FP code. All notions of the x86 FP stack and its insns have
been removed. Instead, we pretend (to the instruction selector and
register allocator) that x86 has six floating point registers, %fake0
.. %fake5, which can be used in the usual flat manner. We further
claim that x86 has floating point instructions very similar to SPARC
and Alpha, that is, a simple 3-operand register-register arrangement.
Code generation and register allocation proceed on this basis.
When we come to print out the final assembly, our convenient fiction
is converted to dismal reality. Each fake instruction is
independently converted to a series of real x86 instructions.
%fake0 .. %fake5 are mapped to %st(0) .. %st(5). To do reg-reg
arithmetic operations, the two operands are pushed onto the top of the
FP stack, the operation done, and the result copied back into the
relevant register. There are only six %fake registers because 2 are
needed for the translation, and x86 has 8 in total.
The translation is inefficient but is simple and it works. A cleverer
translation would handle a sequence of insns, simulating the FP stack
contents, would not impose a fixed mapping from %fake to %st regs, and
hopefully could avoid most of the redundant reg-reg moves of the
current translation.
We might as well make use of whatever unique FP facilities Intel have
chosen to bless us with (let's not be churlish, after all).
Hence GLDZ and GLD1. Bwahahahahahahaha!
-}
{-
Note [x86 Floating point precision]
Intel's internal floating point registers are by default 80 bit
extended precision. This means that all operations done on values in
registers are done at 80 bits, and unless the intermediate values are
truncated to the appropriate size (32 or 64 bits) by storing in
memory, calculations in registers will give different results from
calculations which pass intermediate values in memory (eg. via
function calls).
One solution is to set the FPU into 64 bit precision mode. Some OSs
do this (eg. FreeBSD) and some don't (eg. Linux). The problem here is
that this will only affect 64-bit precision arithmetic; 32-bit
calculations will still be done at 64-bit precision in registers. So
it doesn't solve the whole problem.
There's also the issue of what the C library is expecting in terms of
precision. It seems to be the case that glibc on Linux expects the
FPU to be set to 80 bit precision, so setting it to 64 bit could have
unexpected effects. Changing the default could have undesirable
effects on other 3rd-party library code too, so the right thing would
be to save/restore the FPU control word across Haskell code if we were
to do this.
gcc's -ffloat-store gives consistent results by always storing the
results of floating-point calculations in memory, which works for both
32 and 64-bit precision. However, it only affects the values of
user-declared floating point variables in C, not intermediate results.
GHC in -fvia-C mode uses -ffloat-store (see the -fexcess-precision
flag).
Another problem is how to spill floating point registers in the
register allocator. Should we spill the whole 80 bits, or just 64?
On an OS which is set to 64 bit precision, spilling 64 is fine. On
Linux, spilling 64 bits will round the results of some operations.
This is what gcc does. Spilling at 80 bits requires taking up a full
128 bit slot (so we get alignment). We spill at 80-bits and ignore
the alignment problems.
In the future [edit: now available in GHC 7.0.1, with the -msse2
flag], we'll use the SSE registers for floating point. This requires
a CPU that supports SSE2 (ordinary SSE only supports 32 bit precision
float ops), which means P4 or Xeon and above. Using SSE will solve
all these problems, because the SSE registers use fixed 32 bit or 64
bit precision.
--SDM 1/2003
-}
data Instr
-- comment pseudo-op
= COMMENT FastString
-- location pseudo-op (file, line, col, name)
| LOCATION Int Int Int String
-- some static data spat out during code
-- generation. Will be extracted before
-- pretty-printing.
| LDATA Section (Alignment, CmmStatics)
-- start a new basic block. Useful during
-- codegen, removed later. Preceding
-- instruction should be a jump, as per the
-- invariants for a BasicBlock (see Cmm).
| NEWBLOCK BlockId
-- unwinding information
-- See Note [Unwinding information in the NCG].
| UNWIND CLabel UnwindTable
-- specify current stack offset for benefit of subsequent passes.
-- This carries a BlockId so it can be used in unwinding information.
| DELTA Int
-- Moves.
| MOV Format Operand Operand
| CMOV Cond Format Operand Reg
| MOVZxL Format Operand Operand -- format is the size of operand 1
| MOVSxL Format Operand Operand -- format is the size of operand 1
-- x86_64 note: plain mov into a 32-bit register always zero-extends
-- into the 64-bit reg, in contrast to the 8 and 16-bit movs which
-- don't affect the high bits of the register.
-- Load effective address (also a very useful three-operand add instruction :-)
| LEA Format Operand Operand
-- Int Arithmetic.
| ADD Format Operand Operand
| ADC Format Operand Operand
| SUB Format Operand Operand
| SBB Format Operand Operand
| MUL Format Operand Operand
| MUL2 Format Operand -- %edx:%eax = operand * %rax
| IMUL Format Operand Operand -- signed int mul
| IMUL2 Format Operand -- %edx:%eax = operand * %eax
| DIV Format Operand -- eax := eax:edx/op, edx := eax:edx%op
| IDIV Format Operand -- ditto, but signed
-- Int Arithmetic, where the effects on the condition register
-- are important. Used in specialized sequences such as MO_Add2.
-- Do not rewrite these instructions to "equivalent" ones that
-- have different effect on the condition register! (See #9013.)
| ADD_CC Format Operand Operand
| SUB_CC Format Operand Operand
-- Simple bit-twiddling.
| AND Format Operand Operand
| OR Format Operand Operand
| XOR Format Operand Operand
| NOT Format Operand
| NEGI Format Operand -- NEG instruction (name clash with Cond)
| BSWAP Format Reg
-- Shifts (amount may be immediate or %cl only)
| SHL Format Operand{-amount-} Operand
| SAR Format Operand{-amount-} Operand
| SHR Format Operand{-amount-} Operand
| BT Format Imm Operand
| NOP
-- We need to support the FSTP (x87 store and pop) instruction
-- so that we can correctly read off the return value of an
-- x86 CDECL C function call when its floating point.
-- so we dont include a register argument, and just use st(0)
-- this instruction is used ONLY for return values of C ffi calls
-- in x86_32 abi
| X87Store Format AddrMode -- st(0), dst
-- SSE2 floating point: we use a restricted set of the available SSE2
-- instructions for floating-point.
-- use MOV for moving (either movss or movsd (movlpd better?))
| CVTSS2SD Reg Reg -- F32 to F64
| CVTSD2SS Reg Reg -- F64 to F32
| CVTTSS2SIQ Format Operand Reg -- F32 to I32/I64 (with truncation)
| CVTTSD2SIQ Format Operand Reg -- F64 to I32/I64 (with truncation)
| CVTSI2SS Format Operand Reg -- I32/I64 to F32
| CVTSI2SD Format Operand Reg -- I32/I64 to F64
-- use ADD, SUB, and SQRT for arithmetic. In both cases, operands
-- are Operand Reg.
-- SSE2 floating-point division:
| FDIV Format Operand Operand -- divisor, dividend(dst)
-- use CMP for comparisons. ucomiss and ucomisd instructions
-- compare single/double prec floating point respectively.
| SQRT Format Operand Reg -- src, dst
-- Comparison
| TEST Format Operand Operand
| CMP Format Operand Operand
| SETCC Cond Operand
-- Stack Operations.
| PUSH Format Operand
| POP Format Operand
-- both unused (SDM):
-- | PUSHA
-- | POPA
-- Jumping around.
| JMP Operand [Reg] -- including live Regs at the call
| JXX Cond BlockId -- includes unconditional branches
| JXX_GBL Cond Imm -- non-local version of JXX
-- Table jump
| JMP_TBL Operand -- Address to jump to
[Maybe JumpDest] -- Targets of the jump table
Section -- Data section jump table should be put in
CLabel -- Label of jump table
| CALL (Either Imm Reg) [Reg]
-- Other things.
| CLTD Format -- sign extend %eax into %edx:%eax
| FETCHGOT Reg -- pseudo-insn for ELF position-independent code
-- pretty-prints as
-- call 1f
-- 1: popl %reg
-- addl __GLOBAL_OFFSET_TABLE__+.-1b, %reg
| FETCHPC Reg -- pseudo-insn for Darwin position-independent code
-- pretty-prints as
-- call 1f
-- 1: popl %reg
-- bit counting instructions
| POPCNT Format Operand Reg -- [SSE4.2] count number of bits set to 1
| LZCNT Format Operand Reg -- [BMI2] count number of leading zeros
| TZCNT Format Operand Reg -- [BMI2] count number of trailing zeros
| BSF Format Operand Reg -- bit scan forward
| BSR Format Operand Reg -- bit scan reverse
-- bit manipulation instructions
| PDEP Format Operand Operand Reg -- [BMI2] deposit bits to the specified mask
| PEXT Format Operand Operand Reg -- [BMI2] extract bits from the specified mask
-- prefetch
| PREFETCH PrefetchVariant Format Operand -- prefetch Variant, addr size, address to prefetch
-- variant can be NTA, Lvl0, Lvl1, or Lvl2
| LOCK Instr -- lock prefix
| XADD Format Operand Operand -- src (r), dst (r/m)
| CMPXCHG Format Operand Operand -- src (r), dst (r/m), eax implicit
| MFENCE
data PrefetchVariant = NTA | Lvl0 | Lvl1 | Lvl2
data Operand
= OpReg Reg -- register
| OpImm Imm -- immediate value
| OpAddr AddrMode -- memory reference
-- | Returns which registers are read and written as a (read, written)
-- pair.
x86_regUsageOfInstr :: Platform -> Instr -> RegUsage
x86_regUsageOfInstr platform instr
= case instr of
MOV _ src dst -> usageRW src dst
CMOV _ _ src dst -> mkRU (use_R src [dst]) [dst]
MOVZxL _ src dst -> usageRW src dst
MOVSxL _ src dst -> usageRW src dst
LEA _ src dst -> usageRW src dst
ADD _ src dst -> usageRM src dst
ADC _ src dst -> usageRM src dst
SUB _ src dst -> usageRM src dst
SBB _ src dst -> usageRM src dst
IMUL _ src dst -> usageRM src dst
-- Result of IMULB will be in just in %ax
IMUL2 II8 src -> mkRU (eax:use_R src []) [eax]
-- Result of IMUL for wider values, will be split between %dx/%edx/%rdx and
-- %ax/%eax/%rax.
IMUL2 _ src -> mkRU (eax:use_R src []) [eax,edx]
MUL _ src dst -> usageRM src dst
MUL2 _ src -> mkRU (eax:use_R src []) [eax,edx]
DIV _ op -> mkRU (eax:edx:use_R op []) [eax,edx]
IDIV _ op -> mkRU (eax:edx:use_R op []) [eax,edx]
ADD_CC _ src dst -> usageRM src dst
SUB_CC _ src dst -> usageRM src dst
AND _ src dst -> usageRM src dst
OR _ src dst -> usageRM src dst
XOR _ (OpReg src) (OpReg dst)
| src == dst -> mkRU [] [dst]
XOR _ src dst -> usageRM src dst
NOT _ op -> usageM op
BSWAP _ reg -> mkRU [reg] [reg]
NEGI _ op -> usageM op
SHL _ imm dst -> usageRM imm dst
SAR _ imm dst -> usageRM imm dst
SHR _ imm dst -> usageRM imm dst
BT _ _ src -> mkRUR (use_R src [])
PUSH _ op -> mkRUR (use_R op [])
POP _ op -> mkRU [] (def_W op)
TEST _ src dst -> mkRUR (use_R src $! use_R dst [])
CMP _ src dst -> mkRUR (use_R src $! use_R dst [])
SETCC _ op -> mkRU [] (def_W op)
JXX _ _ -> mkRU [] []
JXX_GBL _ _ -> mkRU [] []
JMP op regs -> mkRUR (use_R op regs)
JMP_TBL op _ _ _ -> mkRUR (use_R op [])
CALL (Left _) params -> mkRU params (callClobberedRegs platform)
CALL (Right reg) params -> mkRU (reg:params) (callClobberedRegs platform)
CLTD _ -> mkRU [eax] [edx]
NOP -> mkRU [] []
X87Store _ dst -> mkRUR ( use_EA dst [])
CVTSS2SD src dst -> mkRU [src] [dst]
CVTSD2SS src dst -> mkRU [src] [dst]
CVTTSS2SIQ _ src dst -> mkRU (use_R src []) [dst]
CVTTSD2SIQ _ src dst -> mkRU (use_R src []) [dst]
CVTSI2SS _ src dst -> mkRU (use_R src []) [dst]
CVTSI2SD _ src dst -> mkRU (use_R src []) [dst]
FDIV _ src dst -> usageRM src dst
SQRT _ src dst -> mkRU (use_R src []) [dst]
FETCHGOT reg -> mkRU [] [reg]
FETCHPC reg -> mkRU [] [reg]
COMMENT _ -> noUsage
LOCATION{} -> noUsage
UNWIND{} -> noUsage
DELTA _ -> noUsage
POPCNT _ src dst -> mkRU (use_R src []) [dst]
LZCNT _ src dst -> mkRU (use_R src []) [dst]
TZCNT _ src dst -> mkRU (use_R src []) [dst]
BSF _ src dst -> mkRU (use_R src []) [dst]
BSR _ src dst -> mkRU (use_R src []) [dst]
PDEP _ src mask dst -> mkRU (use_R src $ use_R mask []) [dst]
PEXT _ src mask dst -> mkRU (use_R src $ use_R mask []) [dst]
-- note: might be a better way to do this
PREFETCH _ _ src -> mkRU (use_R src []) []
LOCK i -> x86_regUsageOfInstr platform i
XADD _ src dst -> usageMM src dst
CMPXCHG _ src dst -> usageRMM src dst (OpReg eax)
MFENCE -> noUsage
_other -> panic "regUsage: unrecognised instr"
where
-- # Definitions
--
-- Written: If the operand is a register, it's written. If it's an
-- address, registers mentioned in the address are read.
--
-- Modified: If the operand is a register, it's both read and
-- written. If it's an address, registers mentioned in the address
-- are read.
-- 2 operand form; first operand Read; second Written
usageRW :: Operand -> Operand -> RegUsage
usageRW op (OpReg reg) = mkRU (use_R op []) [reg]
usageRW op (OpAddr ea) = mkRUR (use_R op $! use_EA ea [])
usageRW _ _ = panic "X86.RegInfo.usageRW: no match"
-- 2 operand form; first operand Read; second Modified
usageRM :: Operand -> Operand -> RegUsage
usageRM op (OpReg reg) = mkRU (use_R op [reg]) [reg]
usageRM op (OpAddr ea) = mkRUR (use_R op $! use_EA ea [])
usageRM _ _ = panic "X86.RegInfo.usageRM: no match"
-- 2 operand form; first operand Modified; second Modified
usageMM :: Operand -> Operand -> RegUsage
usageMM (OpReg src) (OpReg dst) = mkRU [src, dst] [src, dst]
usageMM (OpReg src) (OpAddr ea) = mkRU (use_EA ea [src]) [src]
usageMM _ _ = panic "X86.RegInfo.usageMM: no match"
-- 3 operand form; first operand Read; second Modified; third Modified
usageRMM :: Operand -> Operand -> Operand -> RegUsage
usageRMM (OpReg src) (OpReg dst) (OpReg reg) = mkRU [src, dst, reg] [dst, reg]
usageRMM (OpReg src) (OpAddr ea) (OpReg reg) = mkRU (use_EA ea [src, reg]) [reg]
usageRMM _ _ _ = panic "X86.RegInfo.usageRMM: no match"
-- 1 operand form; operand Modified
usageM :: Operand -> RegUsage
usageM (OpReg reg) = mkRU [reg] [reg]
usageM (OpAddr ea) = mkRUR (use_EA ea [])
usageM _ = panic "X86.RegInfo.usageM: no match"
-- Registers defd when an operand is written.
def_W (OpReg reg) = [reg]
def_W (OpAddr _ ) = []
def_W _ = panic "X86.RegInfo.def_W: no match"
-- Registers used when an operand is read.
use_R (OpReg reg) tl = reg : tl
use_R (OpImm _) tl = tl
use_R (OpAddr ea) tl = use_EA ea tl
-- Registers used to compute an effective address.
use_EA (ImmAddr _ _) tl = tl
use_EA (AddrBaseIndex base index _) tl =
use_base base $! use_index index tl
where use_base (EABaseReg r) tl = r : tl
use_base _ tl = tl
use_index EAIndexNone tl = tl
use_index (EAIndex i _) tl = i : tl
mkRUR src = src' `seq` RU src' []
where src' = filter (interesting platform) src
mkRU src dst = src' `seq` dst' `seq` RU src' dst'
where src' = filter (interesting platform) src
dst' = filter (interesting platform) dst
-- | Is this register interesting for the register allocator?
interesting :: Platform -> Reg -> Bool
interesting _ (RegVirtual _) = True
interesting platform (RegReal (RealRegSingle i)) = freeReg platform i
interesting _ (RegReal (RealRegPair{})) = panic "X86.interesting: no reg pairs on this arch"
-- | Applies the supplied function to all registers in instructions.
-- Typically used to change virtual registers to real registers.
x86_patchRegsOfInstr :: Instr -> (Reg -> Reg) -> Instr
x86_patchRegsOfInstr instr env
= case instr of
MOV fmt src dst -> patch2 (MOV fmt) src dst
CMOV cc fmt src dst -> CMOV cc fmt (patchOp src) (env dst)
MOVZxL fmt src dst -> patch2 (MOVZxL fmt) src dst
MOVSxL fmt src dst -> patch2 (MOVSxL fmt) src dst
LEA fmt src dst -> patch2 (LEA fmt) src dst
ADD fmt src dst -> patch2 (ADD fmt) src dst
ADC fmt src dst -> patch2 (ADC fmt) src dst
SUB fmt src dst -> patch2 (SUB fmt) src dst
SBB fmt src dst -> patch2 (SBB fmt) src dst
IMUL fmt src dst -> patch2 (IMUL fmt) src dst
IMUL2 fmt src -> patch1 (IMUL2 fmt) src
MUL fmt src dst -> patch2 (MUL fmt) src dst
MUL2 fmt src -> patch1 (MUL2 fmt) src
IDIV fmt op -> patch1 (IDIV fmt) op
DIV fmt op -> patch1 (DIV fmt) op
ADD_CC fmt src dst -> patch2 (ADD_CC fmt) src dst
SUB_CC fmt src dst -> patch2 (SUB_CC fmt) src dst
AND fmt src dst -> patch2 (AND fmt) src dst
OR fmt src dst -> patch2 (OR fmt) src dst
XOR fmt src dst -> patch2 (XOR fmt) src dst
NOT fmt op -> patch1 (NOT fmt) op
BSWAP fmt reg -> BSWAP fmt (env reg)
NEGI fmt op -> patch1 (NEGI fmt) op
SHL fmt imm dst -> patch1 (SHL fmt imm) dst
SAR fmt imm dst -> patch1 (SAR fmt imm) dst
SHR fmt imm dst -> patch1 (SHR fmt imm) dst
BT fmt imm src -> patch1 (BT fmt imm) src
TEST fmt src dst -> patch2 (TEST fmt) src dst
CMP fmt src dst -> patch2 (CMP fmt) src dst
PUSH fmt op -> patch1 (PUSH fmt) op
POP fmt op -> patch1 (POP fmt) op
SETCC cond op -> patch1 (SETCC cond) op
JMP op regs -> JMP (patchOp op) regs
JMP_TBL op ids s lbl -> JMP_TBL (patchOp op) ids s lbl
-- literally only support storing the top x87 stack value st(0)
X87Store fmt dst -> X87Store fmt (lookupAddr dst)
CVTSS2SD src dst -> CVTSS2SD (env src) (env dst)
CVTSD2SS src dst -> CVTSD2SS (env src) (env dst)
CVTTSS2SIQ fmt src dst -> CVTTSS2SIQ fmt (patchOp src) (env dst)
CVTTSD2SIQ fmt src dst -> CVTTSD2SIQ fmt (patchOp src) (env dst)
CVTSI2SS fmt src dst -> CVTSI2SS fmt (patchOp src) (env dst)
CVTSI2SD fmt src dst -> CVTSI2SD fmt (patchOp src) (env dst)
FDIV fmt src dst -> FDIV fmt (patchOp src) (patchOp dst)
SQRT fmt src dst -> SQRT fmt (patchOp src) (env dst)
CALL (Left _) _ -> instr
CALL (Right reg) p -> CALL (Right (env reg)) p
FETCHGOT reg -> FETCHGOT (env reg)
FETCHPC reg -> FETCHPC (env reg)
NOP -> instr
COMMENT _ -> instr
LOCATION {} -> instr
UNWIND {} -> instr
DELTA _ -> instr
JXX _ _ -> instr
JXX_GBL _ _ -> instr
CLTD _ -> instr
POPCNT fmt src dst -> POPCNT fmt (patchOp src) (env dst)
LZCNT fmt src dst -> LZCNT fmt (patchOp src) (env dst)
TZCNT fmt src dst -> TZCNT fmt (patchOp src) (env dst)
PDEP fmt src mask dst -> PDEP fmt (patchOp src) (patchOp mask) (env dst)
PEXT fmt src mask dst -> PEXT fmt (patchOp src) (patchOp mask) (env dst)
BSF fmt src dst -> BSF fmt (patchOp src) (env dst)
BSR fmt src dst -> BSR fmt (patchOp src) (env dst)
PREFETCH lvl format src -> PREFETCH lvl format (patchOp src)
LOCK i -> LOCK (x86_patchRegsOfInstr i env)
XADD fmt src dst -> patch2 (XADD fmt) src dst
CMPXCHG fmt src dst -> patch2 (CMPXCHG fmt) src dst
MFENCE -> instr
_other -> panic "patchRegs: unrecognised instr"
where
patch1 :: (Operand -> a) -> Operand -> a
patch1 insn op = insn $! patchOp op
patch2 :: (Operand -> Operand -> a) -> Operand -> Operand -> a
patch2 insn src dst = (insn $! patchOp src) $! patchOp dst
patchOp (OpReg reg) = OpReg $! env reg
patchOp (OpImm imm) = OpImm imm
patchOp (OpAddr ea) = OpAddr $! lookupAddr ea
lookupAddr (ImmAddr imm off) = ImmAddr imm off
lookupAddr (AddrBaseIndex base index disp)
= ((AddrBaseIndex $! lookupBase base) $! lookupIndex index) disp
where
lookupBase EABaseNone = EABaseNone
lookupBase EABaseRip = EABaseRip
lookupBase (EABaseReg r) = EABaseReg $! env r
lookupIndex EAIndexNone = EAIndexNone
lookupIndex (EAIndex r i) = (EAIndex $! env r) i
--------------------------------------------------------------------------------
x86_isJumpishInstr
:: Instr -> Bool
x86_isJumpishInstr instr
= case instr of
JMP{} -> True
JXX{} -> True
JXX_GBL{} -> True
JMP_TBL{} -> True
CALL{} -> True
_ -> False
x86_jumpDestsOfInstr
:: Instr
-> [BlockId]
x86_jumpDestsOfInstr insn
= case insn of
JXX _ id -> [id]
JMP_TBL _ ids _ _ -> [id | Just (DestBlockId id) <- ids]
_ -> []
x86_patchJumpInstr
:: Instr -> (BlockId -> BlockId) -> Instr
x86_patchJumpInstr insn patchF
= case insn of
JXX cc id -> JXX cc (patchF id)
JMP_TBL op ids section lbl
-> JMP_TBL op (map (fmap (patchJumpDest patchF)) ids) section lbl
_ -> insn
where
patchJumpDest f (DestBlockId id) = DestBlockId (f id)
patchJumpDest _ dest = dest
-- -----------------------------------------------------------------------------
-- | Make a spill instruction.
x86_mkSpillInstr
:: DynFlags
-> Reg -- register to spill
-> Int -- current stack delta
-> Int -- spill slot to use
-> Instr
x86_mkSpillInstr dflags reg delta slot
= let off = spillSlotToOffset platform slot - delta
in
case targetClassOfReg platform reg of
RcInteger -> MOV (archWordFormat is32Bit)
(OpReg reg) (OpAddr (spRel dflags off))
RcDouble -> MOV FF64 (OpReg reg) (OpAddr (spRel dflags off))
_ -> panic "X86.mkSpillInstr: no match"
where platform = targetPlatform dflags
is32Bit = target32Bit platform
-- | Make a spill reload instruction.
x86_mkLoadInstr
:: DynFlags
-> Reg -- register to load
-> Int -- current stack delta
-> Int -- spill slot to use
-> Instr
x86_mkLoadInstr dflags reg delta slot
= let off = spillSlotToOffset platform slot - delta
in
case targetClassOfReg platform reg of
RcInteger -> MOV (archWordFormat is32Bit)
(OpAddr (spRel dflags off)) (OpReg reg)
RcDouble -> MOV FF64 (OpAddr (spRel dflags off)) (OpReg reg)
_ -> panic "X86.x86_mkLoadInstr"
where platform = targetPlatform dflags
is32Bit = target32Bit platform
spillSlotSize :: Platform -> Int
spillSlotSize dflags = if is32Bit then 12 else 8
where is32Bit = target32Bit dflags
maxSpillSlots :: DynFlags -> Int
maxSpillSlots dflags
= ((rESERVED_C_STACK_BYTES dflags - 64) `div` spillSlotSize (targetPlatform dflags)) - 1
-- = 0 -- useful for testing allocMoreStack
-- number of bytes that the stack pointer should be aligned to
stackAlign :: Int
stackAlign = 16
-- convert a spill slot number to a *byte* offset, with no sign:
-- decide on a per arch basis whether you are spilling above or below
-- the C stack pointer.
spillSlotToOffset :: Platform -> Int -> Int
spillSlotToOffset platform slot
= 64 + spillSlotSize platform * slot
--------------------------------------------------------------------------------
-- | See if this instruction is telling us the current C stack delta
x86_takeDeltaInstr
:: Instr
-> Maybe Int
x86_takeDeltaInstr instr
= case instr of
DELTA i -> Just i
_ -> Nothing
x86_isMetaInstr
:: Instr
-> Bool
x86_isMetaInstr instr
= case instr of
COMMENT{} -> True
LOCATION{} -> True
LDATA{} -> True
NEWBLOCK{} -> True
UNWIND{} -> True
DELTA{} -> True
_ -> False
--- TODO: why is there
-- | Make a reg-reg move instruction.
-- On SPARC v8 there are no instructions to move directly between
-- floating point and integer regs. If we need to do that then we
-- have to go via memory.
--
x86_mkRegRegMoveInstr
:: Platform
-> Reg
-> Reg
-> Instr
x86_mkRegRegMoveInstr platform src dst
= case targetClassOfReg platform src of
RcInteger -> case platformArch platform of
ArchX86 -> MOV II32 (OpReg src) (OpReg dst)
ArchX86_64 -> MOV II64 (OpReg src) (OpReg dst)
_ -> panic "x86_mkRegRegMoveInstr: Bad arch"
RcDouble -> MOV FF64 (OpReg src) (OpReg dst)
-- this code is the lie we tell ourselves because both float and double
-- use the same register class.on x86_64 and x86 32bit with SSE2,
-- more plainly, both use the XMM registers
_ -> panic "X86.RegInfo.mkRegRegMoveInstr: no match"
-- | Check whether an instruction represents a reg-reg move.
-- The register allocator attempts to eliminate reg->reg moves whenever it can,
-- by assigning the src and dest temporaries to the same real register.
--
x86_takeRegRegMoveInstr
:: Instr
-> Maybe (Reg,Reg)
x86_takeRegRegMoveInstr (MOV _ (OpReg r1) (OpReg r2))
= Just (r1,r2)
x86_takeRegRegMoveInstr _ = Nothing
-- | Make an unconditional branch instruction.
x86_mkJumpInstr
:: BlockId
-> [Instr]
x86_mkJumpInstr id
= [JXX ALWAYS id]
-- Note [Windows stack layout]
-- | On most OSes the kernel will place a guard page after the current stack
-- page. If you allocate larger than a page worth you may jump over this
-- guard page. Not only is this a security issue, but on certain OSes such
-- as Windows a new page won't be allocated if you don't hit the guard. This
-- will cause a segfault or access fault.
--
-- This function defines if the current allocation amount requires a probe.
-- On Windows (for now) we emit a call to _chkstk for this. For other OSes
-- this is not yet implemented.
-- See https://docs.microsoft.com/en-us/windows/desktop/DevNotes/-win32-chkstk
-- The Windows stack looks like this:
--
-- +-------------------+
-- | SP |
-- +-------------------+
-- | |
-- | GUARD PAGE |
-- | |
-- +-------------------+
-- | |
-- | |
-- | UNMAPPED |
-- | |
-- | |
-- +-------------------+
--
-- In essense each allocation larger than a page size needs to be chunked and
-- a probe emitted after each page allocation. You have to hit the guard
-- page so the kernel can map in the next page, otherwise you'll segfault.
--
needs_probe_call :: Platform -> Int -> Bool
needs_probe_call platform amount
= case platformOS platform of
OSMinGW32 -> case platformArch platform of
ArchX86 -> amount > (4 * 1024)
ArchX86_64 -> amount > (8 * 1024)
_ -> False
_ -> False
x86_mkStackAllocInstr
:: Platform
-> Int
-> [Instr]
x86_mkStackAllocInstr platform amount
= case platformOS platform of
OSMinGW32 ->
-- These will clobber AX but this should be ok because
--
-- 1. It is the first thing we do when entering the closure and AX is
-- a caller saved registers on Windows both on x86_64 and x86.
--
-- 2. The closures are only entered via a call or longjmp in which case
-- there are no expectations for volatile registers.
--
-- 3. When the target is a local branch point it is re-targeted
-- after the dealloc, preserving #2. See note [extra spill slots].
--
-- We emit a call because the stack probes are quite involved and
-- would bloat code size a lot. GHC doesn't really have an -Os.
-- __chkstk is guaranteed to leave all nonvolatile registers and AX
-- untouched. It's part of the standard prologue code for any Windows
-- function dropping the stack more than a page.
-- See Note [Windows stack layout]
case platformArch platform of
ArchX86 | needs_probe_call platform amount ->
[ MOV II32 (OpImm (ImmInt amount)) (OpReg eax)
, CALL (Left $ strImmLit "___chkstk_ms") [eax]
, SUB II32 (OpReg eax) (OpReg esp)
]
| otherwise ->
[ SUB II32 (OpImm (ImmInt amount)) (OpReg esp)
, TEST II32 (OpReg esp) (OpReg esp)
]
ArchX86_64 | needs_probe_call platform amount ->
[ MOV II64 (OpImm (ImmInt amount)) (OpReg rax)
, CALL (Left $ strImmLit "___chkstk_ms") [rax]
, SUB II64 (OpReg rax) (OpReg rsp)
]
| otherwise ->
[ SUB II64 (OpImm (ImmInt amount)) (OpReg rsp)
, TEST II64 (OpReg rsp) (OpReg rsp)
]
_ -> panic "x86_mkStackAllocInstr"
_ ->
case platformArch platform of
ArchX86 -> [ SUB II32 (OpImm (ImmInt amount)) (OpReg esp) ]
ArchX86_64 -> [ SUB II64 (OpImm (ImmInt amount)) (OpReg rsp) ]
_ -> panic "x86_mkStackAllocInstr"
x86_mkStackDeallocInstr
:: Platform
-> Int
-> [Instr]
x86_mkStackDeallocInstr platform amount
= case platformArch platform of
ArchX86 -> [ADD II32 (OpImm (ImmInt amount)) (OpReg esp)]
ArchX86_64 -> [ADD II64 (OpImm (ImmInt amount)) (OpReg rsp)]
_ -> panic "x86_mkStackDeallocInstr"
--
-- Note [extra spill slots]
--
-- If the register allocator used more spill slots than we have
-- pre-allocated (rESERVED_C_STACK_BYTES), then we must allocate more
-- C stack space on entry and exit from this proc. Therefore we
-- insert a "sub $N, %rsp" at every entry point, and an "add $N, %rsp"
-- before every non-local jump.
--
-- This became necessary when the new codegen started bundling entire
-- functions together into one proc, because the register allocator
-- assigns a different stack slot to each virtual reg within a proc.
-- To avoid using so many slots we could also:
--
-- - split up the proc into connected components before code generator
--
-- - rename the virtual regs, so that we re-use vreg names and hence
-- stack slots for non-overlapping vregs.
--
-- Note that when a block is both a non-local entry point (with an
-- info table) and a local branch target, we have to split it into
-- two, like so:
--
-- <info table>
-- L:
-- <code>
--
-- becomes
--
-- <info table>
-- L:
-- subl $rsp, N
-- jmp Lnew
-- Lnew:
-- <code>
--
-- and all branches pointing to L are retargetted to point to Lnew.
-- Otherwise, we would repeat the $rsp adjustment for each branch to
-- L.
--
-- Returns a list of (L,Lnew) pairs.
--
allocMoreStack
:: Platform
-> Int
-> NatCmmDecl statics X86.Instr.Instr
-> UniqSM (NatCmmDecl statics X86.Instr.Instr, [(BlockId,BlockId)])
allocMoreStack _ _ top@(CmmData _ _) = return (top,[])
allocMoreStack platform slots proc@(CmmProc info lbl live (ListGraph code)) = do
let entries = entryBlocks proc
uniqs <- replicateM (length entries) getUniqueM
let
delta = ((x + stackAlign - 1) `quot` stackAlign) * stackAlign -- round up
where x = slots * spillSlotSize platform -- sp delta
alloc = mkStackAllocInstr platform delta
dealloc = mkStackDeallocInstr platform delta
retargetList = (zip entries (map mkBlockId uniqs))
new_blockmap :: LabelMap BlockId
new_blockmap = mapFromList retargetList
insert_stack_insns (BasicBlock id insns)
| Just new_blockid <- mapLookup id new_blockmap
= [ BasicBlock id $ alloc ++ [JXX ALWAYS new_blockid]
, BasicBlock new_blockid block' ]
| otherwise
= [ BasicBlock id block' ]
where
block' = foldr insert_dealloc [] insns
insert_dealloc insn r = case insn of
JMP _ _ -> dealloc ++ (insn : r)
JXX_GBL _ _ -> panic "insert_dealloc: cannot handle JXX_GBL"
_other -> x86_patchJumpInstr insn retarget : r
where retarget b = fromMaybe b (mapLookup b new_blockmap)
new_code = concatMap insert_stack_insns code
-- in
return (CmmProc info lbl live (ListGraph new_code), retargetList)
data JumpDest = DestBlockId BlockId | DestImm Imm
-- Debug Instance
instance Outputable JumpDest where
ppr (DestBlockId bid) = text "jd<blk>:" <> ppr bid
ppr (DestImm _imm) = text "jd<imm>:noShow"
getJumpDestBlockId :: JumpDest -> Maybe BlockId
getJumpDestBlockId (DestBlockId bid) = Just bid
getJumpDestBlockId _ = Nothing
canShortcut :: Instr -> Maybe JumpDest
canShortcut (JXX ALWAYS id) = Just (DestBlockId id)
canShortcut (JMP (OpImm imm) _) = Just (DestImm imm)
canShortcut _ = Nothing
-- This helper shortcuts a sequence of branches.
-- The blockset helps avoid following cycles.
shortcutJump :: (BlockId -> Maybe JumpDest) -> Instr -> Instr
shortcutJump fn insn = shortcutJump' fn (setEmpty :: LabelSet) insn
where
shortcutJump' :: (BlockId -> Maybe JumpDest) -> LabelSet -> Instr -> Instr
shortcutJump' fn seen insn@(JXX cc id) =
if setMember id seen then insn
else case fn id of
Nothing -> insn
Just (DestBlockId id') -> shortcutJump' fn seen' (JXX cc id')
Just (DestImm imm) -> shortcutJump' fn seen' (JXX_GBL cc imm)
where seen' = setInsert id seen
shortcutJump' fn _ (JMP_TBL addr blocks section tblId) =
let updateBlock (Just (DestBlockId bid)) =
case fn bid of
Nothing -> Just (DestBlockId bid )
Just dest -> Just dest
updateBlock dest = dest
blocks' = map updateBlock blocks
in JMP_TBL addr blocks' section tblId
shortcutJump' _ _ other = other
-- Here because it knows about JumpDest
shortcutStatics :: (BlockId -> Maybe JumpDest) -> (Alignment, CmmStatics) -> (Alignment, CmmStatics)
shortcutStatics fn (align, Statics lbl statics)
= (align, Statics lbl $ map (shortcutStatic fn) statics)
-- we need to get the jump tables, so apply the mapping to the entries
-- of a CmmData too.
shortcutLabel :: (BlockId -> Maybe JumpDest) -> CLabel -> CLabel
shortcutLabel fn lab
| Just blkId <- maybeLocalBlockLabel lab = shortBlockId fn emptyUniqSet blkId
| otherwise = lab
shortcutStatic :: (BlockId -> Maybe JumpDest) -> CmmStatic -> CmmStatic
shortcutStatic fn (CmmStaticLit (CmmLabel lab))
= CmmStaticLit (CmmLabel (shortcutLabel fn lab))
shortcutStatic fn (CmmStaticLit (CmmLabelDiffOff lbl1 lbl2 off w))
= CmmStaticLit (CmmLabelDiffOff (shortcutLabel fn lbl1) lbl2 off w)
-- slightly dodgy, we're ignoring the second label, but this
-- works with the way we use CmmLabelDiffOff for jump tables now.
shortcutStatic _ other_static
= other_static
shortBlockId
:: (BlockId -> Maybe JumpDest)
-> UniqSet Unique
-> BlockId
-> CLabel
shortBlockId fn seen blockid =
case (elementOfUniqSet uq seen, fn blockid) of
(True, _) -> blockLbl blockid
(_, Nothing) -> blockLbl blockid
(_, Just (DestBlockId blockid')) -> shortBlockId fn (addOneToUniqSet seen uq) blockid'
(_, Just (DestImm (ImmCLbl lbl))) -> lbl
(_, _other) -> panic "shortBlockId"
where uq = getUnique blockid
|