diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/cmd/internal/obj/loong64/asm.go | 55 |
1 files changed, 47 insertions, 8 deletions
diff --git a/src/cmd/internal/obj/loong64/asm.go b/src/cmd/internal/obj/loong64/asm.go index 75b9302f24..fe2c91becf 100644 --- a/src/cmd/internal/obj/loong64/asm.go +++ b/src/cmd/internal/obj/loong64/asm.go @@ -28,6 +28,7 @@ type ctxt0 struct { const ( FuncAlign = 4 + loopAlign = 16 ) type Optab struct { @@ -45,6 +46,10 @@ type Optab struct { const ( NOTUSETMP = 1 << iota // p expands to multiple instructions, but does NOT use REGTMP + + // branchLoopHead marks loop entry. + // Used to insert padding for under-aligned loops. + branchLoopHead ) var optab = []Optab{ @@ -421,24 +426,58 @@ func span0(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) { c.cursym.Size = pc - /* - * if any procedure is large enough to - * generate a large SBRA branch, then - * generate extra passes putting branches - * around jmps to fix. this is rare. - */ - bflag := 1 + // mark loop entry instructions for padding + // loop entrances are defined as targets of backward branches + for p = c.cursym.Func().Text.Link; p != nil; p = p.Link { + if q := p.To.Target(); q != nil && q.Pc < p.Pc { + q.Mark |= branchLoopHead + } + } + // Run these passes until convergence. + bflag := 1 var otxt int64 var q *obj.Prog for bflag != 0 { bflag = 0 pc = 0 - for p = c.cursym.Func().Text.Link; p != nil; p = p.Link { + prev := c.cursym.Func().Text + for p = prev.Link; p != nil; prev, p = p, p.Link { p.Pc = pc o = c.oplook(p) + // Prepend a PCALIGN $loopAlign to each of the loop heads + // that need padding, if not already done so (because this + // pass may execute more than once). + // + // This needs to come before any pass that look at pc, + // because pc will be adjusted if padding happens. + if p.Mark&branchLoopHead != 0 && pc&(loopAlign-1) != 0 && + !(prev.As == obj.APCALIGN && prev.From.Offset >= loopAlign) { + q = c.newprog() + prev.Link = q + q.Link = p + q.Pc = pc + q.As = obj.APCALIGN + q.From.Type = obj.TYPE_CONST + q.From.Offset = loopAlign + // Don't associate the synthesized PCALIGN with + // the original source position, for deterministic + // mapping between source and corresponding asm. + // q.Pos = p.Pos + + // Manually make the PCALIGN come into effect, + // since this loop iteration is for p. + pc += int64(pcAlignPadLength(ctxt, pc, loopAlign)) + p.Pc = pc + } + // very large conditional branches + // + // if any procedure is large enough to + // generate a large SBRA branch, then + // generate extra passes putting branches + // around jmps to fix. this is rare. if o.type_ == 6 && p.To.Target() != nil { otxt = p.To.Target().Pc - pc if otxt < -(1<<17)+10 || otxt >= (1<<17)-10 { |