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cmd/compile: stop rematerializable ops from clobbering flags

Rematerializable ops can be inserted after the flagalloc phase,
they must therefore not clobber flags. This CL adds a check to
ensure this doesn't happen and fixes the instances where it
does currently.

amd64: ADDQconst and ADDLconst were recently changed to be
rematerializable in CL 54393 (only in tip, not 1.9). That change
has been reverted.

s390x: MOVDaddr could clobber flags when using dynamic linking due
to a ADD with immediate instruction. Change the code generation to
use LA/LAY instead.

Fixes #21080.

Change-Id: Ia85c882afa2a820a309e93775354b3169ec6d034
Reviewed-on: https://go-review.googlesource.com/63030
Run-TryBot: Michael Munday <mike.munday@ibm.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Reviewed-by: Ilya Tocar <ilya.tocar@intel.com>
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mundaym committed Sep 11, 2017
1 parent 3628c2d commit 2cb61aa3f77e05f265ccacebf48c2ebf53de1494
@@ -190,8 +190,8 @@ func init() {
// binary ops
{name: "ADDQ", argLength: 2, reg: gp21sp, asm: "ADDQ", commutative: true, clobberFlags: true}, // arg0 + arg1
{name: "ADDL", argLength: 2, reg: gp21sp, asm: "ADDL", commutative: true, clobberFlags: true}, // arg0 + arg1
{name: "ADDQconst", argLength: 1, reg: gp11sp, asm: "ADDQ", aux: "Int32", typ: "UInt64", clobberFlags: true, rematerializeable: true}, // arg0 + auxint
{name: "ADDLconst", argLength: 1, reg: gp11sp, asm: "ADDL", aux: "Int32", clobberFlags: true, rematerializeable: true}, // arg0 + auxint
{name: "ADDQconst", argLength: 1, reg: gp11sp, asm: "ADDQ", aux: "Int32", typ: "UInt64", clobberFlags: true}, // arg0 + auxint
{name: "ADDLconst", argLength: 1, reg: gp11sp, asm: "ADDL", aux: "Int32", clobberFlags: true}, // arg0 + auxint
{name: "ADDQconstmem", argLength: 2, reg: gpstoreconst, asm: "ADDQ", aux: "SymValAndOff", clobberFlags: true, faultOnNilArg0: true, symEffect: "Write"}, // add ValAndOff(AuxInt).Val() to arg0+ValAndOff(AuxInt).Off()+aux, arg1=mem
{name: "ADDLconstmem", argLength: 2, reg: gpstoreconst, asm: "ADDL", aux: "SymValAndOff", clobberFlags: true, faultOnNilArg0: true, symEffect: "Write"}, // add ValAndOff(AuxInt).Val() to arg0+ValAndOff(AuxInt).Off()+aux, arg1=mem
@@ -368,8 +368,8 @@ func init() {
{name: "LEDBR", argLength: 1, reg: fp11, asm: "LEDBR"}, // convert float64 to float32
{name: "LDEBR", argLength: 1, reg: fp11, asm: "LDEBR"}, // convert float32 to float64
{name: "MOVDaddr", argLength: 1, reg: addr, aux: "SymOff", rematerializeable: true, clobberFlags: true, symEffect: "Read"}, // arg0 + auxint + offset encoded in aux
{name: "MOVDaddridx", argLength: 2, reg: addridx, aux: "SymOff", clobberFlags: true, symEffect: "Read"}, // arg0 + arg1 + auxint + aux
{name: "MOVDaddr", argLength: 1, reg: addr, aux: "SymOff", rematerializeable: true, symEffect: "Read"}, // arg0 + auxint + offset encoded in aux
{name: "MOVDaddridx", argLength: 2, reg: addridx, aux: "SymOff", symEffect: "Read"}, // arg0 + arg1 + auxint + aux
// auxint+aux == add auxint and the offset of the symbol in aux (if any) to the effective address
{name: "MOVBZload", argLength: 2, reg: gpload, asm: "MOVBZ", aux: "SymOff", typ: "UInt8", clobberFlags: true, faultOnNilArg0: true, symEffect: "Read"}, // load byte from arg0+auxint+aux. arg1=mem. Zero extend.
@@ -169,6 +169,9 @@ func genOp() {
if v.reg.clobbers != 0 {
log.Fatalf("%s is rematerializeable and clobbers registers", v.name)
}
if v.clobberFlags {
log.Fatalf("%s is rematerializeable and clobbers flags", v.name)
}
fmt.Fprintln(w, "rematerializeable: true,")
}
if v.commutative {
@@ -4863,12 +4863,11 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "ADDQconst",
auxType: auxInt32,
argLen: 1,
rematerializeable: true,
clobberFlags: true,
asm: x86.AADDQ,
name: "ADDQconst",
auxType: auxInt32,
argLen: 1,
clobberFlags: true,
asm: x86.AADDQ,
reg: regInfo{
inputs: []inputInfo{
{0, 65535}, // AX CX DX BX SP BP SI DI R8 R9 R10 R11 R12 R13 R14 R15
@@ -4879,12 +4878,11 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "ADDLconst",
auxType: auxInt32,
argLen: 1,
rematerializeable: true,
clobberFlags: true,
asm: x86.AADDL,
name: "ADDLconst",
auxType: auxInt32,
argLen: 1,
clobberFlags: true,
asm: x86.AADDL,
reg: regInfo{
inputs: []inputInfo{
{0, 65535}, // AX CX DX BX SP BP SI DI R8 R9 R10 R11 R12 R13 R14 R15
@@ -20304,7 +20302,6 @@ var opcodeTable = [...]opInfo{
auxType: auxSymOff,
argLen: 1,
rematerializeable: true,
clobberFlags: true,
symEffect: SymRead,
reg: regInfo{
inputs: []inputInfo{
@@ -20316,11 +20313,10 @@ var opcodeTable = [...]opInfo{
},
},
{
name: "MOVDaddridx",
auxType: auxSymOff,
argLen: 2,
clobberFlags: true,
symEffect: SymRead,
name: "MOVDaddridx",
auxType: auxSymOff,
argLen: 2,
symEffect: SymRead,
reg: regInfo{
inputs: []inputInfo{
{0, 4295000064}, // SP SB
@@ -122,21 +122,31 @@ func (c *ctxtz) rewriteToUseGot(p *obj.Prog) {
// We only care about global data: NAME_EXTERN means a global
// symbol in the Go sense, and p.Sym.Local is true for a few
// internally defined symbols.
// Rewrites must not clobber flags and therefore cannot use the
// ADD instruction.
if p.From.Type == obj.TYPE_ADDR && p.From.Name == obj.NAME_EXTERN && !p.From.Sym.Local() {
// MOVD $sym, Rx becomes MOVD sym@GOT, Rx
// MOVD $sym+<off>, Rx becomes MOVD sym@GOT, Rx; ADD <off>, Rx
// MOVD $sym+<off>, Rx becomes MOVD sym@GOT, Rx; MOVD $<off>(Rx or REGTMP2), Rx
if p.To.Type != obj.TYPE_REG || p.As != AMOVD {
c.ctxt.Diag("do not know how to handle LEA-type insn to non-register in %v with -dynlink", p)
}
p.From.Type = obj.TYPE_MEM
p.From.Name = obj.NAME_GOTREF
q := p
if p.From.Offset != 0 {
q = obj.Appendp(p, c.newprog)
q.As = AADD
q.From.Type = obj.TYPE_CONST
target := p.To.Reg
if target == REG_R0 {
// Cannot use R0 as input to address calculation.
// REGTMP might be used by the assembler.
p.To.Reg = REGTMP2
}
q = obj.Appendp(q, c.newprog)
q.As = AMOVD
q.From.Type = obj.TYPE_ADDR
q.From.Offset = p.From.Offset
q.To = p.To
q.From.Reg = p.To.Reg
q.To.Type = obj.TYPE_REG
q.To.Reg = target
p.From.Offset = 0
}
}

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