This relocation is specific to PowerPC. @davidgiven suggested the
name RELOPPC_LIS in
https://github.com/davidgiven/ack/pull/52#issuecomment-279856501
Reindent the list in h/out.h and util/led/ack.out.5 because
RELOLIS_PPC is a long name. I use spaces and no tabs because the tabs
looked bad in the manual page.
If the ncg table uses reglap, then regvar($1, reg_float) would have
two sizes of registers. An error from ncgg would happen if regvar()
was in a token that allows only one size. Now one can pick a size
with regvar_w() for word size or regvar_d() for double-word size.
Add regvar_d and regvar_w as keywords in ncgg. Modify EX_REGVAR to
include the register size. In ncg, add some checks for the register
size. In tables without reglap, regvar() works as before, and ncg
ignores the register size in EX_REGVAR.
This merges several fixes and improvements from upstream. This
includes commit 5f6a773 to turn off qemuppc. I see several failing
tests from qemuppc; this merge will hide the test failures.
The new feature "reglap" allows two sizes of floating-point register
variables (reg_float), if each register overlaps a single register of
the other size. PowerPC ncg uses reglap to define 4-byte instances
of f14 to f31 that overlap the 8-byte instances.
When ncgg sees the definition of fs14("f14")=f14, it removes the
8-byte f14 from its rvnumbers array, and adds the 4-byte fs14 in its
place. Later, when ncg puts a variable in fs14, if it is an 8-byte
variable, then ncg switches to the 8-byte f14. The code has
/* reglap */ comments in util/ncgg or #ifdef REGLAP in mach/proto/ncg
reglap became necessary because my commit a20b87c caused PowerPC ego
to allocate reg_float in both 4-byte and 8-byte sizes.
same base name and generate multiple files based on it, we can't really use
mkstemp() for every temporary file. Instead, use mkstemp() once on a
placeholder, then generate temporary names based on this. (And delete the
placeholder once we've finished.)
The size of a reg_float isn't in the descr file, so ego doesn't know.
PowerPC and SPARC are the only arches with floating-point registers in
their descr files. PowerPC and SPARC registers can hold both 4-byte
and 8-byte floats, so I want ego to do both sizes.
This might break our SPARC code expander because ego doesn't know that
8-byte values take 2 registers in SPARC. (So ego might allocate too
many registers and deallocate too much stack space.) We don't build
the SPARC code expander, and its descr file is already wrong: its list
of register save costs is too short, so ego will read past the end of
the array.
This commit doesn't fix the problem with ego and PowerPC ncg. Right
now, ncg refuses to put 4-byte floats in registers, but ego expects
them to get registers and deallocates their stack space. So ncg emits
programs that use the deallocated space, and the values of 4-byte
floats become corrupt.
Use f14 to f31 as register variables for 8-byte double-precison.
There are no regvars for 4-byte double precision, because all
regvar(reg_float) must have the same size. I expect more programs to
prefer 8-byte double precision.
Teach mach/powerpc/ncg/mach.c to emit stfd and lfd instructions to
save and restore 8-byte regvars. Delay emitting the function prolog
until f_regsave(), so we can use one addi to make stack space for both
local vars and saved registers. Be more careful with types in mach.c;
don't assume that int and long and full are the same.
In ncg table, add f14 to f31 as register variables, and some rules to
use them. Add rules to put the result of fadd, fsub, fmul, fdiv, fneg
in a regvar. Without such rules, the result would go in a scratch
FREG, and we would need fmr to move it to the regvar. Also add a rule
for pat sdl inreg($1)==reg_float with STACK, so we can unstack the
value directly into the regvar, again without a scratch FREG and fmr.
Edit util/ego/descr/powerpc.descr to tell ego about the new float
regvars. This might not be working right; ego usually decides against
using any float regvars, so ack -O1 (not running ego) uses the
regvars, but ack -O4 (running ego) doesn't use the regvars.
Beware that ack -mosxppc runs ego using powerpc.descr but -mlinuxppc
and -mqemuppc run ego without a config file (since 8ef7c31). I am
testing powerpc.descr with a local edit to plat/linuxppc/descr to run
ego with powerpc.descr there, but I did not commit my local edit.
I hastily chose the name RELOLIS for this relocation type. If we want
to rename it, we only need to edit these files:
- h/out.h
- mach/powerpc/as/mach5.c
- util/amisc/ashow.c
- util/led/ack.out.5
- util/led/relocate.c
The new relocation type RELOLIS handles these instructions:
lis RT, ha16[expr] == addis RT, r0, ha16[expr]
lis RT, hi16[expr] == addis RT, r0, hi16[expr]
RELOLIS stores a 32-bit value in the program text. In this value, the
high bit is a ha16 flag, the next 5 bits are the target register RT,
and the low bits are a signed 26-bit offset. The linker replaces this
value with the lis instruction.
The old RELOPPC relocated a ha16/lo16 or hi16/lo16 pair. The new
RELOLIS relocates only a ha16 or hi16, so it is no longer necessary to
have a matching lo16 in the next instruction. The disadvantage is
that RELOLIS has only a signed 26-bit offset, not a 32-bit offset.
Switch the assembler to use RELOLIS for ha16 or hi16 and RELO2 for
lo16. The li32 instruction still uses the old RELOPPC relocation.
This is not the same as my RELOPPC change from my recent mail to
tack-devel (https://sourceforge.net/p/tack/mailman/message/35651528/).
This commit is on a different branch. Here I am throwing away my
RELOPPC change and instead trying RELOLIS.
This commit slightly improves the formatting of the manuals. My
OpenBSD machine uses mandoc(1) to format manuals. I check the manuals
with `mandoc -T lint` and fix most of the warnings. I also make
other changes where mandoc didn't warn me.
roff(7) says, "Each sentence should terminate at the end of an input
line," but we often forgot this rule. I insert some newlines after
sentences that had ended mid-line.
roff(7) also says that blank lines "are only permitted within literal
contexts." I delete blank lines. This removes some extra blank lines
from mandoc's output. If I do want a blank line in the output, I call
".sp 1" to make it in man(7). If I want a blank line in the source,
but not the output, I put a plain dot "." so roff ignores it.
Hyphens used for command-line options, like \-a, should be escaped by
a backslash. I insert a few missing backslashes.
mandoc warns if the date in .TH doesn't look like a date. Our manuals
had a missing date or the RCS keyword "$Revision$". Git doesn't
expand RCS keywords. I put in today's date, 2017-01-18.
Some manuals used tab characters in filled mode. That doesn't work.
I use .nf to turn off filled mode, or I use .IP in man(7) to make the
indentation without a tab character.
ack(1) defined a macro .SB but never used it, so I delete the
definition. I also remove a call to the missing macro .RF.
mandoc warns about empty paragraphs. I deleted them. mandoc also
warned about these macro pairs in anm(1):
.SM
.B text
The .SM did nothing because the .B text is on a different line. I
changed each pair to .SB for small bold text.
I make a few other small changes.
---snip---
The ELF spec at http://www.sco.com/developers/gabi/ says, "In each
symbol table, all symbols with STB_LOCAL binding precede the weak and
global symbols," and that sh_info is the index of the first non-local
symbol.
I was mixing local and global symbols and setting sh_info to zero. I
also forgot to set the type of the .shstrtab section.
---snip---
assembler directives, ha16() and has16(), for the upper half; has16() applies
the sign adjustment. .powerpcfixup is now gone, as we generate the relocation
in ha*() instead. Add special logic to the linker for undoing and redoing the
sign adjustment when reading/writing fixups. Tests still pass.
Convert each ack.out symbol to ELF, preserving its name and value, and
some but not all other symbol info. The ELF symbol table comes with
ELF section headers. If the input file has no symbols (ack -Rled-s),
then the output file has no ELF section headers.
Append the symbol table and section headers to the ELF file. Linux
ignores this appended info when it execs the file. The info might
pollute the last page of the ELF segment, but Linux clears this
pollution. Tools like nm and gdb can read the ELF symbol table.
I include code to translate debugger symbols to an ELF .stab section.
I did not test this code, because I did not find a platform that can
put S_STB symbols in the ack.out file.
Put end of sentence at end of line. This is roff(7) syntax so the
formatter can make spacing between sentences.
Use the macro .PP to break paragraphs. Use bold for the command name
in SYNOPSIS, to match other ack manuals.
No change to linuxppc and qemuppc. They continue to run ego without
any descr file.
I copied m68020.descr to powerpc.descr and changed some numbers. My
numbers are guesses; I know little about PowerPC cycle counts, and
almost nothing about ego. This powerpc.descr causes most of the
example programs to shrink in size (without descr -> with descr):
65429 -> 57237 hilo_b.osxppc -8192
36516 -> 32420 hilo_c.osxppc -4096
55782 -> 51686 hilo_mod.osxppc -4096
20096 -> 20096 hilo_p.osxppc 0
8813 -> 8813 mandelbrot_c.osxppc 0
93355 -> 89259 paranoia_c.osxppc -4096
92751 -> 84559 startrek_c.osxppc -8192
(Each file has 2 Mach segments, then a symbol table. Each segment
takes a multiple of 4096 bytes. When the code shrinks, we lose a
multiple of 4096 bytes.)
I used "ack -mosxppc -O6 -c.so" to examine the assembly code for
hilo.mod and mandelbrot.c, both without and with descr. This reveals
optimizations made only with descr, from 2 ego phases: SP (stack
pollution) and RA (register allocation). In hilo.mod, SP deletes some
instructions that remove items from the stack. These items get
removed when the function returns. In both hilo.mod and mandelbrot.c,
RA moves some values into local variables, so ncg can make them into
register variables. This shrinks code size, probably because register
variables get preserved across function calls. More values stay in
registers, and ncg emits shorter code.
I believe that the ego descr file uses (time,space) tuples but the ncg
table uses (space,time) tuples. This is confusing. Perhaps I am
wrong, and some or all tuples are backwards. My time values are the
cycle counts in latency from the MPC7450 Reference Manual (but not
including complications like "store serialization").
In powerpc.descr, I give the cost for saving and restoring registers
as if I was using chains of stw and lwz instructions. Actually ncg
uses single stmw and lmw instructions with at least 2 instructions.
The (time,space) for stmw and lmw would be much less than the
(time,space) for chains of stw and lwz. But this ignores the pipeline
of the MPC7450. The chains of stw and lwz may run faster than stmw
and lmw in the pipeline, because the throughput may be better than the
latency. By using the wrong values for (time,space), I'm trying to
tell ego that stmw and lmw are not better than chains of stw and lwz.
This brings in David Given's PowerPC changes, including the addition
of the modern code generator (mcg) for PowerPC.
Resolve minor conflicts in top build.lua and util/led/main.c
This uses uint32_t for the base, file offset, and alignment of each
section, to be consistent with the usage of uint32_t in h/out.h
Also declare setbit() as static.
