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cmd/compile: ensure equal functions don't do unaligned loads

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On architectures which don't support unaligned loads, make sure we
don't generate code that requires them.

Generated hash functions also matter in this respect, but they all look ok.

Update #37716
Fixes #46283

Change-Id: I6197fdfe04da4428092c99bd871d93738789e16b
Reviewed-on: https://go-review.googlesource.com/c/go/+/322151
Trust: Keith Randall <khr@golang.org>
Trust: Josh Bleecher Snyder <josharian@gmail.com>
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
Reviewed-by: eric fang <eric.fang@arm.com>
TryBot-Result: Go Bot <gobot@golang.org>
This commit is contained in:
Keith Randall 2021-05-23 12:38:59 -07:00
parent b83610699a
commit 873401df5b
3 changed files with 135 additions and 0 deletions
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20
src/cmd/compile/internal/reflectdata/alg.go
View file

@ -6,6 +6,7 @@ package reflectdata
import (
"fmt"
"math/bits"
"sort"
"cmd/compile/internal/base"
@ -47,6 +48,11 @@ func eqCanPanic(t *types.Type) bool {
func AlgType(t *types.Type) types.AlgKind {
a, _ := types.AlgType(t)
if a == types.AMEM {
if t.Alignment() < int64(base.Ctxt.Arch.Alignment) && t.Alignment() < t.Width {
// For example, we can't treat [2]int16 as an int32 if int32s require
// 4-byte alignment. See issue 46283.
return a
}
switch t.Width {
case 0:
return types.AMEM0
@ -769,6 +775,20 @@ func memrun(t *types.Type, start int) (size int64, next int) {
if f := t.Field(next); f.Sym.IsBlank() || !isRegularMemory(f.Type) {
break
}
// For issue 46283, don't combine fields if the resulting load would
// require a larger alignment than the component fields.
if base.Ctxt.Arch.Alignment > 1 {
align := t.Alignment()
if off := t.Field(start).Offset; off&(align-1) != 0 {
// Offset is less aligned than the containing type.
// Use offset to determine alignment.
align = 1 << uint(bits.TrailingZeros64(uint64(off)))
}
size := t.Field(next).End() - t.Field(start).Offset
if size > align {
break
}
}
}
return t.Field(next-1).End() - t.Field(start).Offset, next
}