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[dev.ssa] cmd/compile: fix fp constant loads for 386+PIC

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In position-independent 386 code, loading floating-point constants from
the constant pool requires two steps: materializing the address of
the constant pool entry (requires calling a thunk) and then loading
from that address.

Before this CL, the materializing happened implicitly in CX, which
clobbered that register.

Change-Id: Id094e0fb2d3be211089f299e8f7c89c315de0a87
Reviewed-on: https://go-review.googlesource.com/26811
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: David Crawshaw <crawshaw@golang.org>
Reviewed-by: David Chase <drchase@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
This commit is contained in:
Keith Randall 2016-08-11 09:49:48 -07:00
parent ed1ad8f56c
commit 8f955d3664
6 changed files with 196 additions and 26 deletions
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23
src/cmd/compile/internal/x86/ssa.go
View file

@ -456,6 +456,27 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
p.From.Val = math.Float64frombits(uint64(v.AuxInt))
p.To.Type = obj.TYPE_REG
p.To.Reg = x
case ssa.Op386MOVSSconst1, ssa.Op386MOVSDconst1:
var literal string
if v.Op == ssa.Op386MOVSDconst1 {
literal = fmt.Sprintf("$f64.%016x", uint64(v.AuxInt))
} else {
literal = fmt.Sprintf("$f32.%08x", math.Float32bits(float32(math.Float64frombits(uint64(v.AuxInt)))))
}
p := gc.Prog(x86.ALEAL)
p.From.Type = obj.TYPE_MEM
p.From.Name = obj.NAME_EXTERN
p.From.Sym = obj.Linklookup(gc.Ctxt, literal, 0)
p.From.Sym.Local = true
p.To.Type = obj.TYPE_REG
p.To.Reg = gc.SSARegNum(v)
case ssa.Op386MOVSSconst2, ssa.Op386MOVSDconst2:
p := gc.Prog(v.Op.Asm())
p.From.Type = obj.TYPE_MEM
p.From.Reg = gc.SSARegNum(v.Args[0])
p.To.Type = obj.TYPE_REG
p.To.Reg = gc.SSARegNum(v)
case ssa.Op386MOVSSload, ssa.Op386MOVSDload, ssa.Op386MOVLload, ssa.Op386MOVWload, ssa.Op386MOVBload, ssa.Op386MOVBLSXload, ssa.Op386MOVWLSXload:
p := gc.Prog(v.Op.Asm())
p.From.Type = obj.TYPE_MEM
@ -872,6 +893,8 @@ func ssaGenValue(s *gc.SSAGenState, v *ssa.Value) {
if gc.Debug_checknil != 0 && v.Line > 1 { // v.Line==1 in generated wrappers
gc.Warnl(v.Line, "generated nil check")
}
case ssa.Op386FCHS:
v.Fatalf("FCHS in non-387 mode")
default:
v.Unimplementedf("genValue not implemented: %s", v.LongString())
}