diff options
Diffstat (limited to 'x86/Op.v')
| -rw-r--r-- | x86/Op.v | 26 |
1 files changed, 21 insertions, 5 deletions
@@ -201,9 +201,25 @@ Global Opaque eq_condition eq_addressing eq_operation. mode is valid, i.e. that the offsets are in range. The check always succeeds in 32-bit mode because offsets are always 32-bit integers and are normalized as 32-bit signed integers - during code generation (see [Asmgen.normalize_addrmode_32]). *) + during code generation (see [Asmgen.normalize_addrmode_32]). -Definition offset_in_range (n: Z) : bool := zle Int.min_signed n && zle n Int.max_signed. + Moreover, in 64-bit mode, we use RIP-relative addressing for + access to globals. (This is the "small code model" from the + x86_64 ELF ABI.) Thus, for addressing global variables, + the offset from the variable plus the RIP-relative offset + must fit in 32 bits. The "small code model" guarantees that + this will fit if the offset is between [-2^24] and [2^24-1], + under the assumption that no global variable is bigger than + [2^24] bytes. *) + +Definition offset_in_range (n: Z) : bool := + zle Int.min_signed n && zle n Int.max_signed. + +Definition ptroffset_min := -16777216. (**r [-2^24] *) +Definition ptroffset_max := 16777215. (**r [2^24 - 1] *) + +Definition ptroffset_in_range (n: ptrofs) : bool := + let n := Ptrofs.signed n in zle ptroffset_min n && zle n ptroffset_max. Definition addressing_valid (a: addressing) : bool := if Archi.ptr64 then @@ -212,9 +228,9 @@ Definition addressing_valid (a: addressing) : bool := | Aindexed2 n => offset_in_range n | Ascaled sc ofs => offset_in_range ofs | Aindexed2scaled sc ofs => offset_in_range ofs - | Aglobal s ofs => true - | Abased s ofs => true - | Abasedscaled sc s ofs => true + | Aglobal s ofs => ptroffset_in_range ofs + | Abased s ofs => ptroffset_in_range ofs + | Abasedscaled sc s ofs => ptroffset_in_range ofs | Ainstack ofs => offset_in_range (Ptrofs.signed ofs) end else true. |