Add a rule for sdl ldl $1==$2 to work around a bug.

In our powerpc table, sdl fails to kill the old value of the local.
This is a bug, because a later ldl can load the old value instead of
the newly stored value.  By rewriting "sdl 0" "ldl 0" as "dup 8" "sdl
0", the newly added rule works around the bug, but only when the ldl
is immediately after the sdl.

This rule improves code that uses double-precision floating point.
The output of printf("%f", 6.0) in C changes from all zero digits to
"6000000" but still doesn't print the decimal point.  The result of
atof("-123.456") becomes correct.  In startrek, I can now move the
Enterprise, but I still can't fire phasers without crashing the game.

We already have a rule for stl lol $1==$2.  We had two copies of the
rule, so I am deleting the second copy.

diff --git a/mach/powerpc/ncg/table b/mach/powerpc/ncg/table
index 93b7722..1cb51c2 100644 (file)
--- a/mach/powerpc/ncg/table
+++ b/mach/powerpc/ncg/table
@@ -923,10 +923,14 @@ PATTERNS
        pat dup $1==INT32                  /* Duplicate word on top of stack */
                with GPR
                        yields %1 %1
+               with FSREG
+                       yields %1 %1
                                                                
        pat dup $1==INT64                  /* Duplicate double-word on top of stack */
                with GPR GPR
                        yields %2 %1 %2 %1
+               with FREG
+                       yields %1 %1
                                                                
        pat exg $1==INT32                  /* Exchange top two words on stack */
                with GPR GPR
@@ -936,7 +940,12 @@ PATTERNS
                leaving
                        dup 4
                        stl $1
-                       
+
+       pat sdl ldl $1==$2                 /* Store then load double local */
+               leaving
+                       dup 8
+                       sdl $1
+
        pat lal sti lal loi $1==$3 && $2==$4 /* Store then load local, of a different size */
                leaving
                        dup INT32
@@ -1045,12 +1054,7 @@ PATTERNS
                leaving
                        lol $1
                        sti INT32
-                       
-       pat stl lol $1==$2                 /* Save then load (generated by C compiler) */
-               leaving
-                       dup 4
-                       stl $1
-                       
+
        pat zrl                             /* Zero local */
                leaving
                        loc 0