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jump optimizer works

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This commit is contained in:
Araq 2013-10-29 16:47:40 +01:00
commit be45263623
4 changed files with 20 additions and 15 deletions
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27
compiler/vmgen.nim
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@ -1243,12 +1243,11 @@ proc optimizeJumps(c: PCtx; start: int) =
case opc
of opcTJmp, opcFJmp:
var reg = c.code[i].regA
var d = i + c.code[i].regBx
var iters = maxIterations
while iters > 0:
var d = i + c.code[i].jmpDiff
for iters in countdown(maxIterations, 0):
case c.code[d].opcode
of opcJmp:
d = d + c.code[d].regBx
d = d + c.code[d].jmpDiff
of opcTJmp, opcFJmp:
if c.code[d].regA != reg: break
# tjmp x, 23
@ -1256,22 +1255,26 @@ proc optimizeJumps(c: PCtx; start: int) =
# tjmp x, 12
# -- we know 'x' is true, and so can jump to 12+13:
if c.code[d].opcode == opc:
d = d + c.code[d].regBx
d = d + c.code[d].jmpDiff
else:
# tjmp x, 23
# fjmp x, 22
# We know 'x' is true so skip to the next instruction:
d = d + 1
else: break
dec iters
c.finalJumpTarget(i, d - i)
if d != i + c.code[i].jmpDiff:
c.finalJumpTarget(i, d - i)
of opcJmp:
var d = i + c.code[i].regBx
var d = i + c.code[i].jmpDiff
var iters = maxIterations
while c.code[d].opcode == opcJmp and iters > 0:
d = d + c.code[d].regBx
d = d + c.code[d].jmpDiff
dec iters
c.finalJumpTarget(i, d - i)
if c.code[d].opcode == opcRet:
# optimize 'jmp to ret' to 'ret' here
c.code[i] = c.code[d]
elif d != i + c.code[i].jmpDiff:
c.finalJumpTarget(i, d - i)
else: discard
proc genProc(c: PCtx; s: PSym): int =
@ -1300,9 +1303,11 @@ proc genProc(c: PCtx; s: PSym): int =
# generate final 'return' statement:
c.gABC(body, opcRet)
c.patch(procStart)
c.gABC(body, opcEof, eofInstr.regA)
c.optimizeJumps(result)
s.position = c.prc.maxSlots
#if s.name.s == "temp":
# c.echoCode
c.prc = oldPrc
else:
c.prc.maxSlots = s.position