Rename the 'cretonne' crate to 'cretonne-codegen'.

This fixes the next part of #287.

lib/codegen/meta/isa/x86/registers.py

@@ -0,0 +1,68 @@
+"""
+x86 register banks.
+
+While the floating-point registers are straight-forward, the general purpose
+register bank has a few quirks on x86. We have these encodings of the 8-bit
+registers:
+
+         I32 I64  |  16b 32b  64b
+    000  AL  AL   |  AX  EAX  RAX
+    001  CL  CL   |  CX  ECX  RCX
+    010  DL  DL   |  DX  EDX  RDX
+    011  BL  BL   |  BX  EBX  RBX
+    100  AH  SPL  |  SP  ESP  RSP
+    101  CH  BPL  |  BP  EBP  RBP
+    110  DH  SIL  |  SI  ESI  RSI
+    111  BH  DIL  |  DI  EDI  RDI
+
+Here, the I64 column refers to the registers you get with a REX prefix. Without
+the REX prefix, you get the I32 registers.
+
+The 8-bit registers are not that useful since WebAssembly only has i32 and i64
+data types, and the H-registers even less so. Rather than trying to model the
+H-registers accurately, we'll avoid using them in both I32 and I64 modes.
+"""
+from __future__ import absolute_import
+from cdsl.registers import RegBank, RegClass, Stack
+from .defs import ISA
+
+
+IntRegs = RegBank(
+        'IntRegs', ISA,
+        'General purpose registers',
+        units=16, prefix='r',
+        names='rax rcx rdx rbx rsp rbp rsi rdi'.split())
+
+FloatRegs = RegBank(
+        'FloatRegs', ISA,
+        'SSE floating point registers',
+        units=16, prefix='xmm')
+
+FlagRegs = RegBank(
+        'FlagRegs', ISA,
+        'Flag registers',
+        units=1,
+        pressure_tracking=False,
+        names=['rflags'])
+
+GPR = RegClass(IntRegs)
+# Certain types of deref encodings cannot be used with all registers.
+#   R13/RBP cannot be used with zero-offset load or store instructions.
+#   R12 cannot be used with a non-SIB-byte encoding of all derefs.
+GPR_DEREF_SAFE = GPR.without(GPR.rsp, GPR.r12)
+GPR_ZERO_DEREF_SAFE = GPR_DEREF_SAFE.without(GPR.rbp, GPR.r13)
+GPR8 = GPR[0:8]
+GPR8_DEREF_SAFE = GPR8.without(GPR.rsp)
+GPR8_ZERO_DEREF_SAFE = GPR8_DEREF_SAFE.without(GPR.rbp)
+ABCD = GPR[0:4]
+FPR = RegClass(FloatRegs)
+FPR8 = FPR[0:8]
+FLAG = RegClass(FlagRegs)
+
+# Constraints for stack operands.
+
+# Stack operand with a 32-bit signed displacement from either RBP or RSP.
+StackGPR32 = Stack(GPR)
+StackFPR32 = Stack(FPR)
+
+RegClass.extract_names(globals())