[commit: ghc] wip/carter/remove_x87Registers: adding some fall throughs for earlier termination (e3130c7)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/carter/remove_x87Registers
Link       : http://ghc.haskell.org/trac/ghc/changeset/e3130c7c80ad24daf451229197c6d6840d823809/ghc

>---------------------------------------------------------------

commit e3130c7c80ad24daf451229197c6d6840d823809
Author: Carter Tazio Schonwald <carter.schonwald at gmail.com>
Date:   Fri Dec 21 19:57:31 2018 -0500

    adding some fall throughs for earlier termination


>---------------------------------------------------------------

e3130c7c80ad24daf451229197c6d6840d823809
 compiler/nativeGen/RegAlloc/Linear/X86_64/FreeRegs.hs | 5 +++++
 compiler/nativeGen/X86/Regs.hs                        | 3 ++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/compiler/nativeGen/RegAlloc/Linear/X86_64/FreeRegs.hs b/compiler/nativeGen/RegAlloc/Linear/X86_64/FreeRegs.hs
index 3a6e340..07b0e56 100644
--- a/compiler/nativeGen/RegAlloc/Linear/X86_64/FreeRegs.hs
+++ b/compiler/nativeGen/RegAlloc/Linear/X86_64/FreeRegs.hs
@@ -39,10 +39,15 @@ getFreeRegs platform cls (FreeRegs f) = go f 0
           | n .&. 1 /= 0 && classOfRealReg platform (RealRegSingle m) == cls
           = RealRegSingle m : (go (n `shiftR` 1) $! (m+1))
 
+          | m > finalRegister = []
+
           | otherwise
           = go (n `shiftR` 1) $! (m+1)
         -- ToDo: there's no point looking through all the integer registers
         -- in order to find a floating-point one.
+        -- Because they're seperate subintervals. A problem for another day.
+
+        finalRegister = lastxmm platform
 
 allocateReg :: RealReg -> FreeRegs -> FreeRegs
 allocateReg (RealRegSingle r) (FreeRegs f)
diff --git a/compiler/nativeGen/X86/Regs.hs b/compiler/nativeGen/X86/Regs.hs
index ef55d18..14870b4 100644
--- a/compiler/nativeGen/X86/Regs.hs
+++ b/compiler/nativeGen/X86/Regs.hs
@@ -254,6 +254,7 @@ classOfRealReg platform reg
         _   -> panic "X86.Regs.classOfRealReg: RegPairs on this arch"
 
 -- | Get the name of the register with this number.
+-- NOTE: fixme, we dont track which "way" the XMM registers are used
 showReg :: Platform -> RegNo -> String
 showReg platform n
         | n >= firstxmm && n <= lastxmm  platform = "%xmm" ++ show (n-firstxmm)
@@ -358,7 +359,7 @@ xmm11 = regSingle 27
 xmm12 = regSingle 28
 xmm13 = regSingle 29
 xmm14 = regSingle 30
-xmm15 = regSingle 21
+xmm15 = regSingle 31
 
 ripRel :: Displacement -> AddrMode
 ripRel imm      = AddrBaseIndex EABaseRip EAIndexNone imm