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cmd/internal/obj/arm64: optimize constant pool for 32-bit constants

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Current assembler encodes "ADD $0xaaaaaaaa, Rx" to "MOVD off(PC), Rtmp"
 + "ADD Rtmp, Rx", and a 64-bit item is stored in the constant pool.

This patch optimizes it to "MOVWU off(PC), Rtmp" + "ADD Rtmp, Rx",
and a 32-bit item is stored.

The total size of the executable binary go and the library files in
pkg/linux_arm64 decreased about 3KB by this patch.

Change-Id: Ieb1592f78ef9ed52f5d3ad232d6cdf87d0923de1
Reviewed-on: https://go-review.googlesource.com/107516
Reviewed-by: Wei Xiao <Wei.Xiao@arm.com>
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:
Ben Shi 2018-04-17 07:52:19 +00:00 committed by Cherry Zhang
parent 4e6fe71380
commit be88d117bd
1 changed files with 20 additions and 15 deletions
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35
src/cmd/internal/obj/arm64/asm7.go
View file

@ -971,16 +971,12 @@ func (c *ctxt7) addpool(p *obj.Prog, a *obj.Addr) {
t.As = AWORD
sz := 4
if p.As == AMOVD && a.Type == obj.TYPE_CONST {
// simplify MOVD to MOVW/MOVWU to reduce constant pool size
if lit == int64(int32(lit)) { // -0x80000000 ~ 0x7fffffff
p.As = AMOVW
} else if uint64(lit) == uint64(uint32(lit)) { // 0 ~ 0xffffffff
p.As = AMOVWU
} else { // 64-bit
if a.Type == obj.TYPE_CONST {
if lit != int64(int32(lit)) && uint64(lit) != uint64(uint32(lit)) {
// out of range -0x80000000 ~ 0xffffffff, must store 64-bit
t.As = ADWORD
sz = 8
}
} // else store 32-bit
} else if p.As == AMOVD && a.Type != obj.TYPE_MEM || cls == C_ADDR || cls == C_VCON || lit != int64(int32(lit)) || uint64(lit) != uint64(uint32(lit)) {
// conservative: don't know if we want signed or unsigned extension.
// in case of ambiguity, store 64-bit
@ -5929,26 +5925,35 @@ func (c *ctxt7) omovlit(as obj.As, p *obj.Prog, a *obj.Addr, dr int) uint32 {
o1 |= ((v & 0xFFF) << 10) | (REGZERO & 31 << 5) | int32(dr&31)
} else {
fp := 0
w := 0 /* default: 32 bit, unsigned */
fp, w := 0, 0
switch as {
case AFMOVS:
fp = 1
w = 0 /* 32-bit SIMD/FP */
case AFMOVD:
fp = 1
w = 1 /* 64 bit simd&fp */
w = 1 /* 64-bit SIMD/FP */
case AMOVD:
if p.Pcond.As == ADWORD {
w = 1 /* 64 bit */
w = 1 /* 64-bit */
} else if p.Pcond.To.Offset < 0 {
w = 2 /* sign extend */
w = 2 /* 32-bit, sign-extended to 64-bit */
} else if p.Pcond.To.Offset >= 0 {
w = 0 /* 32-bit, zero-extended to 64-bit */
} else {
c.ctxt.Diag("invalid operand %v in %v", a, p)
}
case AMOVBU, AMOVHU, AMOVWU:
w = 0 /* 32-bit, zero-extended to 64-bit */
case AMOVB, AMOVH, AMOVW:
w = 2 /* 32 bit, sign-extended to 64 */
break
w = 2 /* 32-bit, sign-extended to 64-bit */
default:
c.ctxt.Diag("invalid operation %v in %v", as, p)
}
v := int32(c.brdist(p, 0, 19, 2))