SPARC NCG: Give regs o0-o5 back to the allocator

[ghc-hetmet.git] / compiler / nativeGen / RegAlloc / Linear / SPARC / FreeRegs.hs

diff --git a/compiler/nativeGen/RegAlloc/Linear/SPARC/FreeRegs.hs b/compiler/nativeGen/RegAlloc/Linear/SPARC/FreeRegs.hs
index d284a45..e46d87d 100644 (file)
--- a/compiler/nativeGen/RegAlloc/Linear/SPARC/FreeRegs.hs
+++ b/compiler/nativeGen/RegAlloc/Linear/SPARC/FreeRegs.hs
@@ -120,15 +120,53 @@ releaseReg :: RegNo -> FreeRegs -> FreeRegs
 releaseReg r regs@(FreeRegs g f d)
 
        -- used by STG machine, or otherwise unavailable
-       | r >= 0  && r <= 15    = regs
---     | r >= 3  && r <= 15    = regs
-
-       | r >= 17 && r <= 21    = regs
+       --      see includes/MachRegs.h for more info
+
+       -- Global Regs g0-g7
+       --         r0: always zero
+       --      r1-r4: allocable
+       --      r5-r7: reserved for OS
+       | r == 0                = regs
+       | r >= 5 && r <= 7      = regs
+       
+       -- Output Regs o0-o7
+       --   caller saves
+       --   r8 - r13: allocable
+       --        r14: C stack ptr
+       --        r15: C ret addr
+       | r >= 14 && r <= 15    = regs
+       
+       -- Local Regs 
+       --        r16: allocable
+       --  r17 - r21: R1-R5
+       --  r22 - r23: allocable
+       | r >= 17 && r <= 21    = regs          
+
+       -- Input Regs
+       --  r24 - r29: Sp, Base, SpLim, Hp, HpLim, R6
+       --        r30: C frame ptr
+       --        r31: C ret addr
        | r >= 24 && r <= 31    = regs
+       
+       -- Float regs
+       --  r32 & r33: floating point return from C fun
+       --  r34 & r35: D1
+       --  r36 & r37: D2
+       --  r38 & r39: NCG spill tmp
+       --  r40 & r41: NCG spill tmp
        | r >= 32 && r <= 41    = regs
+
+       --  r42 - r53: allocatable as double prec float regs
+
+       --  r54 - r57: F1-F4
+       --  r58 - r59: NCG spill tmps
        | r >= 54 && r <= 59    = regs
 
+       --  r60-r64: allocatable as single prec float regs.
+
+
        -- never release the high part of double regs.
+       --      this prevents them from being allocated as single precison regs.
        | r == 43               = regs
        | r == 45               = regs
        | r == 47               = regs