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[dev.ssa] cmd/compile: implement GO386=387

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Last part of the 386 SSA port.

Modify the x86 backend to simulate SSE registers and
instructions with 387 registers and instructions.
The simulation isn't terribly performant, but it works,
and the old implementation wasn't very performant either.
Leaving to people who care about 387 to optimize if they want.

Turn on SSA backend for 386 by default.

Fixes #16358

Change-Id: I678fb59132620b2c47e993c1c10c4c21135f70c0
Reviewed-on: https://go-review.googlesource.com/25271
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Keith Randall <khr@golang.org>
This commit is contained in:
Keith Randall 2016-07-26 11:51:33 -07:00
parent 77ef597f38
commit c069bc4996
13 changed files with 482 additions and 48 deletions
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14
src/cmd/compile/internal/ssa/regalloc.go
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@ -507,6 +507,9 @@ func (s *regAllocState) init(f *Func) {
s.allocatable &^= 1 << 15 // R15 - reserved for nacl
}
}
if s.f.Config.use387 {
s.allocatable &^= 1 << 15 // X7 disallowed (one 387 register is used as scratch space during SSE->387 generation in ../x86/387.go)
}
s.regs = make([]regState, s.numRegs)
s.values = make([]valState, f.NumValues())
@ -834,6 +837,9 @@ func (s *regAllocState) regalloc(f *Func) {
if phiRegs[i] != noRegister {
continue
}
if s.f.Config.use387 && v.Type.IsFloat() {
continue // 387 can't handle floats in registers between blocks
}
m := s.compatRegs(v.Type) &^ phiUsed &^ s.used
if m != 0 {
r := pickReg(m)
@ -1300,6 +1306,11 @@ func (s *regAllocState) regalloc(f *Func) {
s.freeUseRecords = u
}
// Spill any values that can't live across basic block boundaries.
if s.f.Config.use387 {
s.freeRegs(s.f.Config.fpRegMask)
}
// If we are approaching a merge point and we are the primary
// predecessor of it, find live values that we use soon after
// the merge point and promote them to registers now.
@ -1323,6 +1334,9 @@ func (s *regAllocState) regalloc(f *Func) {
continue
}
v := s.orig[vid]
if s.f.Config.use387 && v.Type.IsFloat() {
continue // 387 can't handle floats in registers between blocks
}
m := s.compatRegs(v.Type) &^ s.used
if m&^desired.avoid != 0 {
m &^= desired.avoid