This feature has never been used since its introduction, more than 3
years ago, in David Given's commit c93cb69 of May 8, 2013. The commit
was for "PowerPC and M68K work". I am not undoing the entire commit.
I am only removing the stackadjust and stackoffset() feature.
This commit removes the feature from my branch kernigh-linuxppc. This
removal includes the mach/proto/ncg parts. The default branch already
removed most of the feature, but kept the mach/proto/ncg parts. That
removal happened in commit 81778b6 of May 13, 2013 (which was a merge;
git diff af0dede81778b6). The branch dtrg-experimental-powerpc
merged the default branch but without the removal. That merge was
commit 4703db0f of Sep 15, 2016 (git diff 8c94b134703db0). My branch
kernigh-linuxppc is off branch dtrg-experimental-powerpc, so I can no
longer get the removal by merging default.
David Given described the stackadjust feature in
https://sourceforge.net/p/tack/mailman/message/30814691/
The instruction stackadjust would add a value to the offset, and the
function stackoffset() would return this offset. One would use this
to track sp - fp, then omit the frame pointer by not keeping fp in a
register.
We only need GPRE in a few places where we write {GPRE, regvar(...)}
because ncgg can't parse plain regvar(...). In all other places, a
plain GPR works.
Also remove gpr_gpr_gpr and a few other unused and fake instructions
from the list of instructions.
Rename the scratch gpr (currently r11) from SCRATCH to RSCRATCH so I
can search for RSCRATCH without finding FSCRATCH. I also want to
avoid confusion with the SCRATCH keyword of the old code generator (cg
which came before ncg).
Change the stacking rules to prevent stacking of RSCRATCH or FSCRATCH
or any other GPR or FPR that isn't an allocatable REG or FREG. Then
ncgg rejects any rule that tries to stack a GPR or FPR, so change such
rules to stack a REG or FREG.
I copied the definitions from linux386 and linux68k.
This change also moves _errno and the other common symbols in boot.s
from .text to .bss. Common symbols belong in .bss, but the assembler
seems dumb enough to put them in any section.
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.
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.
This fixes code that tried to "addi SP, SP, 4" to drop a value that
was in a register, not on the real stack.
Add a rule to optimize "asp 4" (which becomes "loc 4" "ass") when
the value being dropped is already in a GPR.
When ncg fell back on this rule, it did emit the string "invalid" in
the assembly code and caused a syntax error in the assembler.
Adjust the stacking rules so we can stack LOCAL, CONST, and LABEL
without falling back on the "invalid" rule, and so we can stack them
when we have no free register except the scratch register.
Don't define __POWERPC. I don't know any other compiler that defines
__POWERPC and don't want to invent a new macro. Apple's gcc 4.0.1
from Xcode 2.5 defines __ppc__, _ARCH_PPC, __POWERPC__. Debian's gcc
4.9.2-10 defines _ARCH_PPC, __PPC__, __powerpc__, __PPC, __powerpc,
PPC, powerpc.
Move the base vm address from 0x80000000 down to 0x10000000, as this
is where Debian loads /bin/true. This is still higher than the base
addresses for linux386 and linux68k.
Sync led's arguments with linux386.
If it understands TIOCGETD, then it is a tty, else it isn't one. This
seems to help Basic's input statement so I can see the prompt before
I enter my input.
GNU as has "la %r4,8(%r3)" as an alias for "addi %r4,%r3,8", meaning
to load the address of the thing at 8(%r3). Our 'la', now 'li32',
makes an addis/ori pair to load an immediate 32-bit value. For
example, "li32 r4,23456789" loads a big number.
Upon enabling the check, mach/powerpc/ncg/table fails to build as ncgg
gives many errors of "Previous rule impossible on empty stack". David
Given reported this problem in 2013:
https://sourceforge.net/p/tack/mailman/message/30814694/
Commit c93cb69 commented out the error in util/ncgg/cgg.y to disable
the Hall check. This commit enables it again. In ncgg, the Hall
check is checking that a rule is possible with an empty fake stack.
It would be possible if ncg can coerce the values from the real stack
to the fake stack. The powerpc table defined coercions from STACK to
{FS, %a} and {FD, %a}, but the Hall check didn't understand the
coercions and rejected each rule "with FS" or "with FD".
This commit removes the FS and FD tokens and adds a new group of FSREG
registers for single-precision floats, while keeping FREG registers
for double precision. The registers overlap, with each FSREG
containing one FREG, because it is the same register in PowerPC
hardware. FS tokens become FSREG registers and FD tokens become FREG
registers. The Hall check understands the coercions from STACK to
FSREG and FREG. The idea to define separate but overlapping registers
comes from the PDP-11 table (mach/pdp/ncg/table).
This commit also removes F0 from the FREG group. This is my attempt
to keep F0 off the fake stack, because one of the stacking rules uses
F0 as a scratch register (FSCRATCH).
Unless it is packed, a Pascal char is a C int. Using C types, hilo.p
passed an int *buf to uread(), which expected a char *buf. Then
uread() wrote the char on the end of the int. This worked on
little-endian platforms. This failed on big-endian platforms, as
writing the value to the big end of an int multiplied it by 16777216.
The fix is to use a packed array [0..0] of char in Pascal. I also
change 'string' to a packed array, though this is not a necessary part
of the fix.
Inspired by the sparc code (mach/sparc/libem/lar.s). My powerpc code
might still have bugs, but it's enough for examples/hilo.mod to work.
May need to 'make clean' or touch a build.lua file, so ackbuilder can
notice the new lar4.s and sar4.s files and build them.
calculated incorrectly because of overflow errors.
Replace it with an extended RELOPPC relocation which understands addis/ori
pairs; add an la pseudoop to the assembler which generates these and the
appropriate relocation. Make good.
--HG--
branch : dtrg-experimental-powerpc-branch
cf/cf_loop.c and share/put.c tried to read the next pointer in an
element of a linked list after freeing the element. ud/ud_copy.c
tried to read beyond the end of the _defs_ array: it only has
_nrexpldefs_ elements, not _nrdefs_ elements.
These bugs caused core dumps on OpenBSD. Its malloc() put _defs_ near
the end of a page, so reading beyond the end crossed into an unmapped
page. Its free() wrote junk bytes and changed the next pointer to
0xdfdfdfdfdfdfdfdf.
and generate invalid calls to the optimisers.
Previously ego would generate a temporary file template that looked like
/tmp/ego.A.BB.XXXXXX, call mktemp() on it to randomise the XXXXXX, and then
replace A and BB with data.
However, it used strrchr to find the A and B. Which would fine, except when
mktemp produced an A or a B in the randomised part...
This code was written on 4 March 1991. I was 16.
This needed lots of refactoring to ego --- not all platforms have ego descr
files, and ego will just crash if you invoke it without one. I think originally
it was never intended that these platforms would be used at -O2 or above.
Plats now only specify the ego descr file if they have one.
