When storing to a local, stop killing the tokens of other locals,
unless they might overlap with the stored local. This helps some
procedures that juggle locals when the locals aren't in registers.
Also use FRAME_V tokens for locals in statically enclosing procedures.
Rewrite _lxa_ as _lxl_, to skip the `addi ?,?,8` if we can add 8 to
the next constant. The PowerPC code from _lxl_ is now sometimes
better, sometimes worse than before.
The i386 table provided the idea to use %size to find overlapping
locals.
Prefer the rule with REG FREG, by coercing IND_RC_D or IND_RR_D to
FREG. This rule looks better to ncg. When ncg chose between coercion
to REG IND_RC_D or coercion to REG FREG, it chose REG FREG. It only
chose REG IND_RC_D if the stack had exact REG IND_RC_D.
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.
When a rule `uses REG ... yields %a`, the result %a is always a
temporary, never a regvar. If the EM code uses _stl_ to put the
result in a regvar, then ncg emits _mr_ to move %a to the regvar.
There are two ways to put the result in the regvar without %a:
1. Yield a token, as in `yields {MUL_RR, %2, %1}`, so that _stl_
can move the token to the regvar without using %a.
2. Provide a pattern, like `sli stl`, that just puts the result
in `{LOCAL, $2}` and not %a.
Allow some tokens, like SUM_RIS and XEQ, onto the stack; and add
tokens like MUL_RR, and patterns like `sli stl`.
Delete patterns for `stl lol` and `sdl ldl` to avoid an extra
temporary %a when the local is a regvar. Delete `lal sti lal loi`
because it would emit wrong code.
Rename token CONST to C. Define set CONST = C + CONST_STACK. The
instructions with CONST operands can now accept CONST_STACK tokens;
some cases of {CONST, %1.val} become %1.
Also simplify two of _rlwinm_ into _slwi_ and _srwi_.
EM instructions _rol_ and _ror_ do rotate an integer left or right.
Our compilers and optimizers never emit _rol_ nor _ror_, but I might
want to use them in the future.
Add _rol_ and _ror_ to powerpc. Fix `rol 4` and `ror 4` in both i80
and i86, where the rules for `rol 4` and `ror 4` seem to have never
been tested until now.
This breaks all machines because the declared return type void
disagrees with the implicit return type int (when I compile mach.c
with clang). Unbreak i386, i80, i86, m68020, powerpc, vc4 by adding
the return types to mach.c. We don't build any other machines; they
are broken since commit a46ee91 (May 19, 2013) declared void prolog()
and commit fd91851 (Nov 10, 2016) declared void mes(), with both
declarations in mach/proto/ncg/fillem.c.
Also fix mach/vc4/ncg/mach.c where type full is long, so fprintf()
must use "%ld" not "%d" to print full nlocals.
In util/ncgg, add two more errors for tables using reglap:
- "Two sizes of reg_float can't be same size"
- "Missing reg_float of size %d to contain %s"
In mach/proto/ncg, rename macro isregvar_size() to PICK_REGVAR(), so
the macro doesn't look like a function. This macro sometimes doesn't
evaluate its second argument.
In mach/powerpc/ncg/mach.c, change type of lfs_set to uint32_t, and
change the left shifts from 1U<<regno to (uint32_t)1<<regno, because
1U would be too small for machines with 16-bit int.
Because lwzu or stwu moves the pointer, I can remove an addi
instruction from the loop, so the loop is slightly faster.
I wrote a benchmark in Modula-2 that exercises some of these loops. I
measured its time on my old PowerPC Mac. Its user time decreases from
8.401s to 8.217s with the tighter loops.
The result of single-precision fadds, fsubs, and such can go into a
register variable, like we already do with double precision. This
avoids an extra fmr from a temporary register to the regvar.
Do the conversion by calling .cif8 or .cuf8 in libem, as it was done
before my commit 1de1e8f. I used the inline conversion to experiment
with the register allocator, which was too slow until c5bb3be.
Now that libem has the only copy of the code, move some comments and
code changes there.
Rename GPRE to GPR_EXPR, then define FPR_EXPR and FSREG_EXPR. Use
them for moves to register variables.
Keep "kills regvar($1)", because deleting it and recompiling libc
would cause many failures in my test programs. Add comment to warn,
/* ncg fails to infer that regvar($1) is dead! */
Remove "kills LOCAL %off==$1" because it seems to have no effect.
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.
After c5bb3be, ncg began to allocate regvars from r13 up. I reorder
the regvars so ncg again allocates them from r31 down. I also reorder
the other registers.
This exposed a bug in my rule for ret 8. It was wrong if item %2 was
in r3, because I moved %1 to r3 before %2 to r4. Fix it by adding
back an individual register class for r3 (called REG3 here, GPR3 in
c5bb3be).
Also fix my typo in mach.c that made a syntax error in assembly.
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.
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.
This fixes lxl 1 (so it follows the static chain, not the dynamic
chain) and provides lxl 2 and greater. The Modula-2 compiler uses lxl
for nested procedures, so they can access the variables of the
enclosing procedures.
I added REG_PAIR in cfbc537 to speed up the register allocator,
because ncg was taking about 2 seconds on each sti 8. I defined only
4 such pairs, so allocating REG_PAIR was much faster than allocating
REG REG.
After my last commit c5bb3be, allocation of REG REG is fast, and
REG_PAIR seems unnecessary.
The table for PowerPC had placed each GPR and FPR into an individual
register class (like GPR3, GPR4, FPR1, FPR2), and had used these
classes to coerce stack values into specific registers. But ncg does
not like having many register classes.
In http://tack.sourceforge.net/olddocs/ncg.pdf
Hans van Staveren wrote:
> Every extra property means the register set is more unorthogonal and
> *cg* execution time is influenced by that, because it has to take
> into account a larger set of registers that are not equivalent. So
> try to keep the number of different register classes to a minimum.
Recent changes to the PowerPC table have removed many coercions to
specific registers. Many functions in libem switched from taking
values in registers to taking them from the stack (see dc05cb2).
I now remove all 64 individual register classes of GPR and FPR. In
the few cases where I need a stack value in a specific register, I now
do a move (as the arm and m68020 tables do).
This commit speeds the compilation of some files. For my test file
fconv.c, the compilation time goes from over 20 seconds to under 1
second. My fconv.c has 4 conversions from floats to integers, and the
table has my experimental rules that do the conversions by allocating
4 or 5 registers.
Switch .cms to pass inputs and outputs on the real stack, not in
registers; like we do with .and, .or (81c677d) and .xor (c578c49).
At this point, nearly all functions in libem use the real stack, not
registers, for passing inputs and outputs. This simplifies the ncg
table (which needs fewer lists of specific registers) but slows calls
to libem.
For example, after ba9b021, each call to .aar4 is about 10
instructions slower. I moved 3 inputs and 1 output from registers to
the real stack. A program would take 4 instructions to move registers
to stack, 4 to move stack to registers, and perhaps 2 to adjust the
stack pointer.
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.
Reorder the code in .fef8 and .fif8 so that in the usual case, we fall
through to the blr without taking any branches. The usual case, by my
guess, is .fef8 with normalized numbers or .fif8 with small integers.
I change .fef8 and .fif8 to pass values on the real stack, not in
specific registers. This simplifies the ncg table, and might help me
experiment with changes to the ncg table.
This change might or might not help mcg. Seems that mcg always uses
the stack to pass values to libem, but I have not tested .fef8 or
.fif8 with mcg.
Switch some conversions from libem calls to inline code. The
conversions from integers to floats are now too slow, because each
conversion allocates 4 or 5 registers, and the register allocator is
too slow. I might use these slow conversions to experiment with the
register allocator.
I add the missing conversions between 4-byte single floats and
integers, simply by going through 8-byte double floats. (These
replace the calls to nonexistant functions in libem.)
I remove the placeholder for fef 4, because it doesn't exist in libem,
and our language runtimes only use fef 8.
This replaces a call to memmove() in libc. That was working for me,
but it can fail because EM programs don't always link to libc.
blm and bls only need to copy aligned words. They don't need to copy
bytes, and they don't need to copy between overlapping buffers, as
memmove() does. So the new loop is simpler than memmove().
Remove one addi instruction from some loops. These loops had
increased 2 pointers, they now increase 1 index. I must initialize
the index, so I add "li r6, 0" before each loop.
Change .zer to use subf instead of neg, add.
Change .xor to take the size on the real stack, as .and and .or have
done since 81c677d.
Use extended "mr" instead of basic "or" to move registers. Both "mr"
and "or" encode the same machine instruction. With "mr", I can more
easily search the assembly output for register moves.
Fold several stacking rules into a single rule ANY_BHW-REG to STACK.
Remove the EM patterns for loc mlu $2==2 and loc slu. The first
pattern had the wrong size (should be $2==4, not $2==2). Both
patterns were redundant. They rewrote loc mlu as loc mli and loc slu
as loc sli, but this table doesn't have patterns for loc mli or loc
sli, so it is enough to rewrite mlu as mli and slu as sli.
Add the tokens IND_RL_B, IND_RL_H, IND_RL_H_S, IND_RL_D, along with
the rules to use them. These rules emit shorter code. For example,
loading a byte becomes lis, lbz instead of lis, addi, lbz.
While making this, I wrongly set IND_RL_D to size 4. Then ncg made
infinite recursion in codegen() and stackupto(), until it crashed by
stack overflow. I correctly set IND_RL_D to size 8, preventing the
crash.
Remove coercion from LABEL to REG. The coercion never happens because
I have stopped putting LABEL on the stack. Also remove LABEL from set
ANY_BHW. Retain the move from LABEL to REG because pat gto uses it.
Remove li32 instruction, unused after the switch to the hi16, ha16,
lo16 syntax.
Remove COMMENT(...) lines from most moves. In my opinion, they took
too much space, both in the table and in the assembly output. The
stacking rules and coercions keep their COMMENT(...) lines.
In test GPR, don't write to RSCRATCH.
Fold several coercions into a single coercion from ANY_BHW uses REG.
Use REG instead of GPR in stack patterns. REG and GPR act the same,
because every GPR on the stack is a REG, but I want to be clear that I
expect a REG, not r0.
In code rules, sort SUM_RC before SORT_RR, so I can add SUM_RL later.
Remove rules to optimize loc loc cii loc loc cii. If $2==$4, the
peephole optimizer can optimize it. If $2!=$4, then the EM program is
missing a conversion from size $2 to size $4.
Remove rules to store a SEX_B with sti 1 or a SEX_H with sti 2. These
rules would never get used, unless the EM program is missing a
conversion from size 4 to size 1 or 2.
Use it to generate code like
lis r12,ha16[__II0]
lis r11,ha16[_f]
lfs f1,lo16[_f](r11)
lfs f2,lo16[__II0](r12)
fadds f13,f2,f1
stfs f13,lo16[_f](r11)
Here ncg has allocated r11 for ha16[_f]. We use r11 in lfs and again
in stfs. Before this change, we needed an extra lis before stfs,
because ncg did not remember that ha16[_f] was in a register.
This example has a gap between ha16[__II0] and lo16[__II0], because
the lo16 is not in the next instruction. This requires my previous
commit 1bf58cf for RELOLIS. There is a gap because ncg emits the lis
as soon as I allocate it. The "lfs f2,lo16[__II0](r12)" happens in a
coercion from IND_RL_W to FSREG. The coercion allocates one FSREG but
may not allocate any other registers. So I must allocate r12 earlier.
I allocate r12 in pat lae, but this causes a gap.
A 4-byte load from a label yields a token IND_RL_W. This token emits
either lis/lwz or lis/lfs, if we want a general-purpose register or a
floating-point register.
Remove the GPRINDIRECT token, and use the IND_RC_* tokens as operands
to instructions. We no longer need to unpack an IND_RC_* token and
repack it as a GPRINDIRECT to use it in an instruction.
Allow storing IND_ALL_B and IND_ALL_H in register variables. Create a
set ANY_BHW for anything that we can store in a regvar.
Push register variables on the stack without using GPRE, by changing
stwu to accept LOCAL. Then ncg will replace the string ">>> BUG IN
LOCAL" with the register name. (I copied ">>> BUG IN LOCAL" from
mach/arm/ncg/table.)
Fix the rule for "pat lil inreg($1)>0" to yield a IND_RC_W token, not
a register. We might need to kill the token with "kills MEMORY".
Rename CONST_ALL to CONST_STACK, because it only includes constants on
the stack, and excludes CONST tokens. Instructions still don't allow
CONST_STACK operands, so we still need to repack each CONST_STACK as a
CONST to use it in an instruction.
Rename LABEL_OFFSET_HI to just LABEL_HI, and same for LABEL_HA and
LABEL_HO.
r0 is a special case and can't be used when adding a register to a
constant. The few remaining users of the scratch register don't do
that. I removed other usages of the scratch register in 7c64dab,
5b5f774, 19f0eb8, f64b7d8.
The rewritten code rules bring 3 new features:
1. The new rules compare a small constant with a register by
reversing the comparison and using `cmpwi` or `cmplwi`. The old
rules put the constant in a register.
2. The new rules emit shorter code to yield the test results,
without referencing the tables in mach/powerpc/ncg/tge.s.
3. The new rules use the extended `beq` and relatives, not the
basic `bc`, in the assembly output.
I delete the old tristate tokens and the old moves, because they
confused me. Some of the old moves weren't really moves. For
example, `move R3, C0` and then `move C0, R0` did not move r3 to r0.
I rename C0 to CR0.
This fixes the coercion from IND_ALL_D to FREG. The coercion had
never happened, because IND_ALL_D had 8 bytes but FREG had 4 bytes.
Instead, ncg always stacked the IND_ALL_D and unstacked a FREG. The
stacking rule uses f0, so the code did load f0 with the indirect
value, push f0 to stack, load f1 to stack, move stack pointer. Now
that FREG has 8 bytes, ncg does the coercion, and the code just loads
f1 with the indirect value.
Always use 'kills ALL' when reaching a label, because our registers
and tokens have the wrong values if the program jumps to this label
from somewhere else.
When falling through a label, if the top element is in r3, then
require that the rest of the stack is in the real STACK, not in
registers or tokens.
I'm doing this to be certain that the missing constraints are not
causing bugs. I did not find any such bug, perhaps because the labels
are usually near other instructions (like conditional branches and
function calls) that stack or kill tokens.
This is for fef 8 and fif 8. I changed .fef8 so it no longer kills
r7, but I don't want to update the list. We already use "kills ALL"
for most other calls to libem.
