When I wrote fef 8, I forgot to test denormalized numbers. Oops. Now
fix two of my mistakes:
- When checking for zero, `extrwi r6, r3, 22, 12` needs to be
`extrwi r6, r3, 20, 12`. There are only 20 bits to extract.
- After the multiplication by 2**64, I forgot to put the fraction in
[0.5, 1) or (-1, 0.5] by setting IEEE exponent = 1022.
Teach fif 8 about signed zero and NaN.
In ncg/table, change cmf so NaN is not equal to any value, and comment
why ordered comparisons don't work with NaN. Also add cost for
fctwiz, remove extra `uses REG`.
Edit comment in cfu8.s because the conditional branch might be before
or after fctwiz.
With my PowerBook G4, a program that converts values from 1.0 to
4000000.0 runs in about 0.32s with the old .cfu8 and 0.29s with this
shrunken .cfu8
Leave a comment about other ways to implement .cfu8
The new test rck_e.e segfaults on PowerPC unless I make some changes.
The inline code for _rck_ was wrong because it didn't allow the trap
handler to return. _sig_ forgot to push the old trap handler.
Move plat/linuxppc/libsys/trap.s to mach/powerpc/libem/trp.s and
rewrite it with simplified/extended mnemonics. Remove .trap alias for
.trp procedure. Add a missing `mtspr lr, r0` so we can return from
the trap handler. Call write() and _exit() so trp.s works with both
linuxppc and osxppc. Before, Mac OS X was wrongly using the trap.s
for Linux.
In powerpc/libem, simplify .aar4; teach .csa and .csb to raise the
trap if the default target is zero.
C programs don't need these changes. You may relink your C programs
with the changed .csa and .csb, but C code doesn't raise the trap.
Modula-2 code can raise traps, so you may want to relink your Modula-2
programs with the changed libem, but you might keep your old .o files
from Modula-2. You may need to recompile your Pascal programs (delete
old .o files from Pascal) because the Pascal compiler might use _rck_.
Allow asp 4, exg 4 to shuffle tokens without coercing them into
registers; but comment why dup 4, dup 8 coerce tokens into registers.
Allow dup, dus, exg with larger sizes; and add tests dup_e.e and
exg_e.e to check that dup 20, dus, exg 20 work as well in powerpc as
in i80 and i86.
Then powerpc failed to compile loc 2 loc 4 cuu in dup_e.e. Revise the
integer conversions, so powerpc can compile and pass the test.
This removes a wrong-way dependency of libsys on libem. The C
functions in libsys called .ret, but libsys is after libem in the
linker arguments, so the linker didn't find .ret unless something else
had called .ret. Almost everything called .ret, but I got a linker
error when I wrote an assembly program using the EM runtime, because
my assembly program didn't call .ret.
Add a dummy comment to build.lua, so git checkout touches that file,
the build system reconfigures itself, and the *.s glob sees that ret.s
has gone.
Our libem had two implementations of loading a block from a stack, one
for lar 4 and one for los 4. Now lar 4 and los 4 share the code in
.los4. Likewise, sar 4 and sts 4 share the code in .sts4.
Rename .los to .los4 and .sts to .sts4, because they implement los 4
and sts 4. Remove the special case for loading or storing 4 bytes,
because we can do it with 1 iteration of the loop. Remove the lines
to "align size" where the size must already be a multiple of 4.
Fix the upper bound check in .aar4.
Change .aar4, .lar4, .los4, .sar4, .sts4 to pass all operands on the
real stack, except that .los4 and .sts4 take the size in register r3.
Have .aar4 set r3 to the size of the array element. So lar 4 is just
.aar4 then .los4, and sar 4 is just .aar4 then .sts4.
ncg no longer calls .lar4 and .sar4 in libem, because it inlines the
code; but I keep .lar4 and .sar4 in libem, because mcg references
them. They might or might not work in mcg.
This provides and, ior, xor, com, zer, set, cms when defined($1) and
ior, set when !defined($1). I don't provide the other operations
!defined($1) because our Modula-2 compiler hasn't used them.
I wrote a Modula-2 example in
https://gist.github.com/kernigh/add79662bb3c63ffb7c46d01dc8ae788
Put a dummy comment in mach/powerpc/libem/build.lua so git checkout
will touch that file. Without the touch, the build system doesn't see
the new *.s files.
In EM, fef splits a float into exponent and fraction. The old C code,
given an infinite float, got stuck in an infinite loop. The new
assembly code doesn't loop; it extracts the IEEE exponent.
