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cmd/internal/obj/arm64: fix constant pool size calculation error
The current calculation method of constant pool size is: c.pool.size = -c.pool.size & (funcAlign - 1) c.pool.size += uint32(sz) This doesn't make sense. This CL changes it as: if q.As == ADWORD { c.pool.size = roundUp(c.pool.size, 8) } c.pool.size += uint32(sz) which takes into account the padding size generated by aligning DWORD to 8 bytes. It's unnecessary to set the Pc field in addpool and addpool128 because the Pc value will be reset in function span7, so remove the related lines. Change-Id: I5eb8f259be55a6b97fc2c20958b4a602bffa4f88 Reviewed-on: https://go-review.googlesource.com/c/go/+/298609 Reviewed-by: eric fang <eric.fang@arm.com> Reviewed-by: Cherry Zhang <cherryyz@google.com> Trust: eric fang <eric.fang@arm.com> Run-TryBot: eric fang <eric.fang@arm.com> TryBot-Result: Go Bot <gobot@golang.org>
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@ -1200,19 +1200,16 @@ func (c *ctxt7) flushpool(p *obj.Prog, skip int) {
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// addpool128 adds a 128-bit constant to literal pool by two consecutive DWORD
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// instructions, the 128-bit constant is formed by ah.Offset<<64+al.Offset.
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func (c *ctxt7) addpool128(p *obj.Prog, al, ah *obj.Addr) {
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lit := al.Offset
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q := c.newprog()
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q.As = ADWORD
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q.To.Type = obj.TYPE_CONST
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q.To.Offset = lit
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q.Pc = int64(c.pool.size)
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q.To.Offset = al.Offset
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lit = ah.Offset
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t := c.newprog()
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t.As = ADWORD
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t.To.Type = obj.TYPE_CONST
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t.To.Offset = lit
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t.Pc = int64(c.pool.size + 8)
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t.To.Offset = ah.Offset
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q.Link = t
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if c.blitrl == nil {
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@ -1223,6 +1220,7 @@ func (c *ctxt7) addpool128(p *obj.Prog, al, ah *obj.Addr) {
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}
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c.elitrl = t
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c.pool.size = roundUp(c.pool.size, 16)
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c.pool.size += 16
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p.Pool = q
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}
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@ -1267,7 +1265,6 @@ func (c *ctxt7) addpool(p *obj.Prog, a *obj.Addr) {
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q := c.newprog()
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*q = *t
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q.Pc = int64(c.pool.size)
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if c.blitrl == nil {
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c.blitrl = q
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c.pool.start = uint32(p.Pc)
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@ -1275,11 +1272,24 @@ func (c *ctxt7) addpool(p *obj.Prog, a *obj.Addr) {
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c.elitrl.Link = q
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}
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c.elitrl = q
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c.pool.size = -c.pool.size & (funcAlign - 1)
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if q.As == ADWORD {
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// make DWORD 8-byte aligned, this is not required by ISA,
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// just to avoid performance penalties when loading from
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// the constant pool across a cache line.
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c.pool.size = roundUp(c.pool.size, 8)
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}
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c.pool.size += uint32(sz)
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p.Pool = q
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}
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// roundUp rounds up x to "to".
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func roundUp(x, to uint32) uint32 {
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if to == 0 || to&(to-1) != 0 {
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log.Fatalf("rounded up to a value that is not a power of 2: %d\n", to)
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}
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return (x + to - 1) &^ (to - 1)
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}
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func (c *ctxt7) regoff(a *obj.Addr) uint32 {
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c.instoffset = 0
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c.aclass(a)
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