* utils-sim.scm (-gen-decode-bits): New argument `entire-val'.

	All callers updated.  Work around -ve shifts by referencing the
	entire value.

diff --git a/cgen/ChangeLog b/cgen/ChangeLog
index d1d9de0..9d3fd4c 100644 (file)
--- a/cgen/ChangeLog
+++ b/cgen/ChangeLog
@@ -1,5 +1,9 @@
 2009-07-09  Doug Evans  <dje@sebabeach.org>
 
+       * utils-sim.scm (-gen-decode-bits): New argument `entire-val'.
+       All callers updated.  Work around -ve shifts by referencing the
+       entire value.
+
        * utils.scm (message): Handle pairs.
 
 2009-07-08  DJ Delorie  <dj@redhat.com>

diff --git a/cgen/utils-sim.scm b/cgen/utils-sim.scm
index 4422cf6..e14f889 100644 (file)
--- a/cgen/utils-sim.scm
+++ b/cgen/utils-sim.scm
@@ -521,11 +521,14 @@
 ; LSB0? is non-#f if bit number 0 is the least significant bit.
 ; FIXME: START may not be handled right in words beyond first.
 ;
+; ENTIRE-VAL is passed as a hack for cgen 1.1 which would previously generate
+; negative shifts.  FIXME: Revisit for 1.2.
+;
 ; e.g. (-gen-decode-bits '(0 1 2 3 8 9 10 11) 0 16 "insn" #f)
 ; --> "(((insn >> 8) & 0xf0) | ((insn >> 4) & 0xf))"
 ; FIXME: The generated code has some inefficiencies in edge cases.  Later.
 
-(define (-gen-decode-bits bitnums start size val lsb0?)
+(define (-gen-decode-bits bitnums start size val entire-val lsb0?)
 
   ; Compute a list of lists of three numbers:
   ; (first bitnum in group, position in result (0=LSB), bits in result)
@@ -563,16 +566,23 @@
                            (bits (caddr group))
                            ; Difference between where value is and where
                            ; it needs to be.
-                           ; FIXME: Need to handle left (-ve) shift.
                            (shift (- (if lsb0?
                                          (- first bits -1)
                                          (- (+ start size) (+ first bits)))
                                      pos)))
-                    (string-append
-                     " | ((" val " >> " (number->string shift)
-                     ") & ("
-                     (number->string (- (integer-expt 2 bits) 1))
-                     " << " (number->string pos) "))")))
+                      ; FIXME: There should never be a -ve shift here,
+                      ; but it can occur on the m32r.  Compensate here
+                      ; with hack and fix in 1.2.
+                      (if (< shift 0)
+                          (begin
+                            (set! val entire-val)
+                            (set! shift (+ shift size))))
+                      ; END-FIXME
+                      (string-append
+                       " | ((" val " >> " (number->string shift)
+                       ") & ("
+                       (number->string (- (integer-expt 2 bits) 1))
+                       " << " (number->string pos) "))")))
                   groups))
      ")"))
 )
@@ -945,7 +955,8 @@
 ; else {}
 ; may well be less stressful on the compiler to optimize than small switch() stmts.
 
-(define (-gen-decoder-switch switch-num startbit decode-bitsize table-guts indent lsb0? invalid-insn fn?)
+(define (-gen-decoder-switch switch-num startbit decode-bitsize table-guts
+                            indent lsb0? invalid-insn fn?)
   ; For entries that are a single insn, we're done, otherwise recurse.
 
   (string-list
@@ -965,7 +976,8 @@
        (string-append indent "  unsigned int val = "))
    (-gen-decode-bits (dtable-guts-bitnums table-guts)
                     (dtable-guts-startbit table-guts)
-                    (dtable-guts-bitsize table-guts) "insn" lsb0?)
+                    (dtable-guts-bitsize table-guts)
+                    "insn" "entire_insn" lsb0?)
    ";\n"
    indent "  switch (val)\n"
    indent "  {\n"