cmd/compile: fix large load/store offsets on 386

Pointer arithemetic is done mod 2^32 on 386, so we can just
drop the high bits of any large constant offsets.

The bounds check will make sure wraparounds are never observed.

Fixes #21655

Change-Id: I68ae5bbea9f02c73968ea2b21ca017e5ecb89223
Reviewed-on: https://go-review.googlesource.com/82675
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: David Chase <drchase@google.com>

src/cmd/compile/internal/ssa/gen/386.rules

@@ -799,45 +799,45 @@
 (MOVLstoreconstidx1 [c] {sym} ptr (SHLLconst [2] idx) mem) -> (MOVLstoreconstidx4 [c] {sym} ptr idx mem)
 
 // combine ADDL into indexed loads and stores
-(MOVBloadidx1 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVBloadidx1 [c+d] {sym} ptr idx mem)
-(MOVWloadidx1 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVWloadidx1 [c+d] {sym} ptr idx mem)
-(MOVWloadidx2 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVWloadidx2 [c+d] {sym} ptr idx mem)
-(MOVLloadidx1 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVLloadidx1 [c+d] {sym} ptr idx mem)
-(MOVLloadidx4 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVLloadidx4 [c+d] {sym} ptr idx mem)
-(MOVSSloadidx1 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVSSloadidx1 [c+d] {sym} ptr idx mem)
-(MOVSSloadidx4 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVSSloadidx4 [c+d] {sym} ptr idx mem)
-(MOVSDloadidx1 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVSDloadidx1 [c+d] {sym} ptr idx mem)
-(MOVSDloadidx8 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVSDloadidx8 [c+d] {sym} ptr idx mem)
-
-(MOVBstoreidx1 [c] {sym} (ADDLconst [d] ptr) idx val mem) -> (MOVBstoreidx1 [c+d] {sym} ptr idx val mem)
-(MOVWstoreidx1 [c] {sym} (ADDLconst [d] ptr) idx val mem) -> (MOVWstoreidx1 [c+d] {sym} ptr idx val mem)
-(MOVWstoreidx2 [c] {sym} (ADDLconst [d] ptr) idx val mem) -> (MOVWstoreidx2 [c+d] {sym} ptr idx val mem)
-(MOVLstoreidx1 [c] {sym} (ADDLconst [d] ptr) idx val mem) -> (MOVLstoreidx1 [c+d] {sym} ptr idx val mem)
-(MOVLstoreidx4 [c] {sym} (ADDLconst [d] ptr) idx val mem) -> (MOVLstoreidx4 [c+d] {sym} ptr idx val mem)
-(MOVSSstoreidx1 [c] {sym} (ADDLconst [d] ptr) idx val mem) -> (MOVSSstoreidx1 [c+d] {sym} ptr idx val mem)
-(MOVSSstoreidx4 [c] {sym} (ADDLconst [d] ptr) idx val mem) -> (MOVSSstoreidx4 [c+d] {sym} ptr idx val mem)
-(MOVSDstoreidx1 [c] {sym} (ADDLconst [d] ptr) idx val mem) -> (MOVSDstoreidx1 [c+d] {sym} ptr idx val mem)
-(MOVSDstoreidx8 [c] {sym} (ADDLconst [d] ptr) idx val mem) -> (MOVSDstoreidx8 [c+d] {sym} ptr idx val mem)
-
-(MOVBloadidx1 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVBloadidx1 [c+d] {sym} ptr idx mem)
-(MOVWloadidx1 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVWloadidx1 [c+d] {sym} ptr idx mem)
-(MOVWloadidx2 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVWloadidx2 [c+2*d] {sym} ptr idx mem)
-(MOVLloadidx1 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVLloadidx1 [c+d] {sym} ptr idx mem)
-(MOVLloadidx4 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVLloadidx4 [c+4*d] {sym} ptr idx mem)
-(MOVSSloadidx1 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVSSloadidx1 [c+d] {sym} ptr idx mem)
-(MOVSSloadidx4 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVSSloadidx4 [c+4*d] {sym} ptr idx mem)
-(MOVSDloadidx1 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVSDloadidx1 [c+d] {sym} ptr idx mem)
-(MOVSDloadidx8 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVSDloadidx8 [c+8*d] {sym} ptr idx mem)
-
-(MOVBstoreidx1 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVBstoreidx1 [c+d] {sym} ptr idx val mem)
-(MOVWstoreidx1 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVWstoreidx1 [c+d] {sym} ptr idx val mem)
-(MOVWstoreidx2 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVWstoreidx2 [c+2*d] {sym} ptr idx val mem)
-(MOVLstoreidx1 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVLstoreidx1 [c+d] {sym} ptr idx val mem)
-(MOVLstoreidx4 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVLstoreidx4 [c+4*d] {sym} ptr idx val mem)
-(MOVSSstoreidx1 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVSSstoreidx1 [c+d] {sym} ptr idx val mem)
-(MOVSSstoreidx4 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVSSstoreidx4 [c+4*d] {sym} ptr idx val mem)
-(MOVSDstoreidx1 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVSDstoreidx1 [c+d] {sym} ptr idx val mem)
-(MOVSDstoreidx8 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVSDstoreidx8 [c+8*d] {sym} ptr idx val mem)
+(MOVBloadidx1 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVBloadidx1 [int64(int32(c+d))] {sym} ptr idx mem)
+(MOVWloadidx1 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVWloadidx1 [int64(int32(c+d))] {sym} ptr idx mem)
+(MOVWloadidx2 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVWloadidx2 [int64(int32(c+d))] {sym} ptr idx mem)
+(MOVLloadidx1 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVLloadidx1 [int64(int32(c+d))] {sym} ptr idx mem)
+(MOVLloadidx4 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVLloadidx4 [int64(int32(c+d))] {sym} ptr idx mem)
+(MOVSSloadidx1 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVSSloadidx1 [int64(int32(c+d))] {sym} ptr idx mem)
+(MOVSSloadidx4 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVSSloadidx4 [int64(int32(c+d))] {sym} ptr idx mem)
+(MOVSDloadidx1 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVSDloadidx1 [int64(int32(c+d))] {sym} ptr idx mem)
+(MOVSDloadidx8 [c] {sym} (ADDLconst [d] ptr) idx mem) -> (MOVSDloadidx8 [int64(int32(c+d))] {sym} ptr idx mem)
+
+(MOVBstoreidx1 [c] {sym} (ADDLconst [d] ptr) idx val mem)  -> (MOVBstoreidx1 [int64(int32(c+d))] {sym} ptr idx val mem)
+(MOVWstoreidx1 [c] {sym} (ADDLconst [d] ptr) idx val mem)  -> (MOVWstoreidx1 [int64(int32(c+d))] {sym} ptr idx val mem)
+(MOVWstoreidx2 [c] {sym} (ADDLconst [d] ptr) idx val mem)  -> (MOVWstoreidx2 [int64(int32(c+d))] {sym} ptr idx val mem)
+(MOVLstoreidx1 [c] {sym} (ADDLconst [d] ptr) idx val mem)  -> (MOVLstoreidx1 [int64(int32(c+d))] {sym} ptr idx val mem)
+(MOVLstoreidx4 [c] {sym} (ADDLconst [d] ptr) idx val mem)  -> (MOVLstoreidx4 [int64(int32(c+d))] {sym} ptr idx val mem)
+(MOVSSstoreidx1 [c] {sym} (ADDLconst [d] ptr) idx val mem)  -> (MOVSSstoreidx1 [int64(int32(c+d))] {sym} ptr idx val mem)
+(MOVSSstoreidx4 [c] {sym} (ADDLconst [d] ptr) idx val mem)  -> (MOVSSstoreidx4 [int64(int32(c+d))] {sym} ptr idx val mem)
+(MOVSDstoreidx1 [c] {sym} (ADDLconst [d] ptr) idx val mem)  -> (MOVSDstoreidx1 [int64(int32(c+d))] {sym} ptr idx val mem)
+(MOVSDstoreidx8 [c] {sym} (ADDLconst [d] ptr) idx val mem)  -> (MOVSDstoreidx8 [int64(int32(c+d))] {sym} ptr idx val mem)
+
+(MOVBloadidx1 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVBloadidx1  [int64(int32(c+d))]   {sym} ptr idx mem)
+(MOVWloadidx1 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVWloadidx1  [int64(int32(c+d))]   {sym} ptr idx mem)
+(MOVWloadidx2 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVWloadidx2  [int64(int32(c+2*d))] {sym} ptr idx mem)
+(MOVLloadidx1 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVLloadidx1  [int64(int32(c+d))]   {sym} ptr idx mem)
+(MOVLloadidx4 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVLloadidx4  [int64(int32(c+4*d))] {sym} ptr idx mem)
+(MOVSSloadidx1 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVSSloadidx1 [int64(int32(c+d))]   {sym} ptr idx mem)
+(MOVSSloadidx4 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVSSloadidx4 [int64(int32(c+4*d))] {sym} ptr idx mem)
+(MOVSDloadidx1 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVSDloadidx1 [int64(int32(c+d))]   {sym} ptr idx mem)
+(MOVSDloadidx8 [c] {sym} ptr (ADDLconst [d] idx) mem) -> (MOVSDloadidx8 [int64(int32(c+8*d))] {sym} ptr idx mem)
+
+(MOVBstoreidx1 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVBstoreidx1  [int64(int32(c+d))]   {sym} ptr idx val mem)
+(MOVWstoreidx1 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVWstoreidx1  [int64(int32(c+d))]   {sym} ptr idx val mem)
+(MOVWstoreidx2 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVWstoreidx2  [int64(int32(c+2*d))] {sym} ptr idx val mem)
+(MOVLstoreidx1 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVLstoreidx1  [int64(int32(c+d))]   {sym} ptr idx val mem)
+(MOVLstoreidx4 [c] {sym} ptr (ADDLconst [d] idx) val mem)  -> (MOVLstoreidx4  [int64(int32(c+4*d))] {sym} ptr idx val mem)
+(MOVSSstoreidx1 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVSSstoreidx1 [int64(int32(c+d))]   {sym} ptr idx val mem)
+(MOVSSstoreidx4 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVSSstoreidx4 [int64(int32(c+4*d))] {sym} ptr idx val mem)
+(MOVSDstoreidx1 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVSDstoreidx1 [int64(int32(c+d))]   {sym} ptr idx val mem)
+(MOVSDstoreidx8 [c] {sym} ptr (ADDLconst [d] idx) val mem) -> (MOVSDstoreidx8 [int64(int32(c+8*d))] {sym} ptr idx val mem)
 
 (MOVBstoreconstidx1 [x] {sym} (ADDLconst [c] ptr) idx mem) ->
 	(MOVBstoreconstidx1 [ValAndOff(x).add(c)] {sym} ptr idx mem)

test/fixedbugs/issue21655.go

@@ -38,3 +38,25 @@ func f6(a []float32, i int64) float32 {
 // like 0x80000000 and silently using them as
 // signed 32 bit offsets.)
 // f4 was ok, but testing it can't hurt.
+
+func f7(ss []*string, i int) string {
+	const offset = 3 << 29 // 3<<29 * 4 = 3<<31 = 1<<31 mod 1<<32.
+	if i > offset {
+		return *ss[i-offset]
+	}
+	return ""
+}
+func f8(ss []*string, i int) string {
+	const offset = 3<<29 + 10
+	if i > offset {
+		return *ss[i-offset]
+	}
+	return ""
+}
+func f9(ss []*string, i int) string {
+	const offset = 3<<29 - 10
+	if i > offset {
+		return *ss[i-offset]
+	}
+	return ""
+}