qbit/go
1
0
Fork 0
mirror of https://github.com/golang/go synced 2024-09-29 14:24:32 -06:00
Code Releases Activity

cmd/internal/obj/riscv: split immediates larger than 12-bits

Browse Source 
Handle immediates larger than 12-bits by rewriting as an LUI instruction with
the high bits, followed by the original instruction with the low bits.

Based on the riscv-go port.

Updates #27532

Change-Id: I8ed6d6e6db06fb8a27f3ab75f467ec2b7ff1f075
Reviewed-on: https://go-review.googlesource.com/c/go/+/204626
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Joel Sing 2019-11-04 03:25:53 +11:00
parent 1046a9cb1b
commit 8cf5293caa
1 changed files with 110 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

110
src/cmd/internal/obj/riscv/obj.go
View File

@ -486,6 +486,116 @@ func preprocess(ctxt *obj.Link, cursym *obj.LSym, newprog obj.ProgAlloc) {
}
}
// Split immediates larger than 12-bits.
for p := cursym.Func.Text; p != nil; p = p.Link {
switch p.As {
// <opi> $imm, REG, TO
case AADDI, AANDI, AORI, AXORI:
// LUI $high, TMP
// ADDI $low, TMP, TMP
// <op> TMP, REG, TO
q := *p
low, high, err := Split32BitImmediate(p.From.Offset)
if err != nil {
ctxt.Diag("%v: constant %d too large", p, p.From.Offset, err)
}
if high == 0 {
break // no need to split
}
p.As = ALUI
p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: high}
p.Reg = 0
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
p.Spadj = 0 // needed if TO is SP
p = obj.Appendp(p, newprog)
p.As = AADDIW
p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: low}
p.Reg = REG_TMP
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
p = obj.Appendp(p, newprog)
switch q.As {
case AADDI:
p.As = AADD
case AANDI:
p.As = AAND
case AORI:
p.As = AOR
case AXORI:
p.As = AXOR
default:
ctxt.Diag("progedit: unsupported inst %v for splitting", q)
}
p.Spadj = q.Spadj
p.To = q.To
p.Reg = q.Reg
p.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
// <load> $imm, REG, TO (load $imm+(REG), TO)
// <store> $imm, REG, TO (store $imm+(TO), REG)
case ALD, ALB, ALH, ALW, ALBU, ALHU, ALWU,
ASD, ASB, ASH, ASW:
// LUI $high, TMP
// ADDI $low, TMP, TMP
q := *p
low, high, err := Split32BitImmediate(p.From.Offset)
if err != nil {
ctxt.Diag("%v: constant %d too large", p, p.From.Offset)
}
if high == 0 {
break // no need to split
}
switch q.As {
case ALD, ALB, ALH, ALW, ALBU, ALHU, ALWU:
// LUI $high, TMP
// ADD TMP, REG, TMP
// <load> $low, TMP, TO
p.As = ALUI
p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: high}
p.Reg = 0
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
p.Spadj = 0 // needed if TO is SP
p = obj.Appendp(p, newprog)
p.As = AADD
p.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
p.Reg = q.Reg
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
p = obj.Appendp(p, newprog)
p.As = q.As
p.To = q.To
p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: low}
p.Reg = REG_TMP
case ASD, ASB, ASH, ASW:
// LUI $high, TMP
// ADD TMP, TO, TMP
// <store> $low, REG, TMP
p.As = ALUI
p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: high}
p.Reg = 0
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
p.Spadj = 0 // needed if TO is SP
p = obj.Appendp(p, newprog)
p.As = AADD
p.From = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
p.Reg = q.To.Reg
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
p = obj.Appendp(p, newprog)
p.As = q.As
p.Reg = q.Reg
p.To = obj.Addr{Type: obj.TYPE_REG, Reg: REG_TMP}
p.From = obj.Addr{Type: obj.TYPE_CONST, Offset: low}
}
}
}
setPCs(cursym.Func.Text, 0)
// Resolve branch and jump targets.