[Sbcl-commits] master: hppa: Prevent XEP-ALLOCATE-FRAME from trashing NARGS

[Alastair B. <lis...@us...>]

The branch "master" has been updated in SBCL:
       via  0cb0cd9687074e4da4900d3e03a7a0a122625b43 (commit)
      from  e500bac63d0a392b226fc2b6f76f2c5c5f780d34 (commit)

- Log -----------------------------------------------------------------
commit 0cb0cd9687074e4da4900d3e03a7a0a122625b43
Author: Alastair Bridgewater <ala...@gm...>
Date:   Sun Nov 29 17:07:58 2015 -0500

    hppa: Prevent XEP-ALLOCATE-FRAME from trashing NARGS
    
      * I don't know why this hadn't been found before, given that it
    seems to be possible on any platform where NARGS is a
    NON-DESCRIPTOR-REG and the COMPUTE-CODE-FROM-whatever instruction
    in XEP-ALLOCATE-FRAME needs a temporary register, but whatever.
    
      * And, actually, I have little else to say beyond the commentary
    in the patch itself.
---
 src/compiler/hppa/call.lisp |    7 ++++++-
 1 files changed, 6 insertions(+), 1 deletions(-)

diff --git a/src/compiler/hppa/call.lisp b/src/compiler/hppa/call.lisp
index 7fdb9d8..87b60a3 100644
--- a/src/compiler/hppa/call.lisp
+++ b/src/compiler/hppa/call.lisp
@@ -104,7 +104,12 @@
 
 (define-vop (xep-allocate-frame)
   (:info start-lab)
-  (:temporary (:scs (non-descriptor-reg)) temp)
+  ;; KLUDGE: Specify an explicit offset for TEMP because NARGS is a
+  ;; non-descriptor-reg, but is also live, yet the register allocator
+  ;; does not know that it is, and if TEMP collides NARGS and
+  ;; COMPUTE-CODE-FROM-LIP needs TEMP then we run into trouble very
+  ;; quickly.
+  (:temporary (:sc non-descriptor-reg :offset nl5-offset) temp)
   (:generator 1
     ;; Make sure the function is aligned, and drop a label pointing to this
     ;; function header.

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