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cmd/compile: fix load combining from a non-zero pointer offset
When the pointer offset is non-zero in the small loads, we need to add the offset when converting to the larger load. Fixes #14694 Change-Id: I5ba8bcb3b9ce26c7fae0c4951500b9ef0fed54cd Reviewed-on: https://go-review.googlesource.com/20333 Reviewed-by: Keith Randall <khr@golang.org>
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@ -14,6 +14,40 @@ const (
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y = 0x0fffFFFF
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)
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//go:noinline
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func parseLE64(b []byte) uint64 {
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// skip the first two bytes, and parse the remaining 8 as a uint64
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return uint64(b[2]) | uint64(b[3])<<8 | uint64(b[4])<<16 | uint64(b[5])<<24 |
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uint64(b[6])<<32 | uint64(b[7])<<40 | uint64(b[8])<<48 | uint64(b[9])<<56
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}
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//go:noinline
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func parseLE32(b []byte) uint32 {
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return uint32(b[2]) | uint32(b[3])<<8 | uint32(b[4])<<16 | uint32(b[5])<<24
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}
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//go:noinline
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func parseLE16(b []byte) uint16 {
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return uint16(b[2]) | uint16(b[3])<<8
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}
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// testLoadCombine tests for issue #14694 where load combining didn't respect the pointer offset.
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func testLoadCombine() {
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testData := []byte{0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09}
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if want, got := uint64(0x0908070605040302), parseLE64(testData); want != got {
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println("testLargeConst add failed, wanted", want, "got", got)
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failed = true
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}
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if want, got := uint32(0x05040302), parseLE32(testData); want != got {
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println("testLargeConst add failed, wanted", want, "got", got)
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failed = true
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}
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if want, got := uint16(0x0302), parseLE16(testData); want != got {
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println("testLargeConst add failed, wanted", want, "got", got)
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failed = true
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}
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}
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//go:noinline
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func invalidAdd_ssa(x uint32) uint32 {
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return x + y + y + y + y + y + y + y + y + y + y + y + y + y + y + y + y + y
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@ -431,6 +465,7 @@ func main() {
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testArithConstShift()
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testArithRshConst()
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testLargeConst()
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testLoadCombine()
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if failed {
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panic("failed")
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@ -1167,13 +1167,13 @@
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// There are many ways these combinations could occur. This is
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// designed to match the way encoding/binary.LittleEndian does it.
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(ORW (MOVBQZXload [i] {s} p mem)
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(SHLWconst [8] (MOVBQZXload [i+1] {s} p mem))) -> (MOVWload p mem)
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(SHLWconst [8] (MOVBQZXload [i+1] {s} p mem))) -> (MOVWload (ADDQconst [i] p) mem)
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(ORL (ORL (ORL
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(MOVBQZXload [i] {s} p mem)
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(SHLLconst [8] (MOVBQZXload [i+1] {s} p mem)))
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(SHLLconst [16] (MOVBQZXload [i+2] {s} p mem)))
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(SHLLconst [24] (MOVBQZXload [i+3] {s} p mem))) -> (MOVLload p mem)
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(SHLLconst [24] (MOVBQZXload [i+3] {s} p mem))) -> (MOVLload (ADDQconst [i] p) mem)
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(ORQ (ORQ (ORQ (ORQ (ORQ (ORQ (ORQ
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(MOVBQZXload [i] {s} p mem)
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@ -1183,4 +1183,4 @@
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(SHLQconst [32] (MOVBQZXload [i+4] {s} p mem)))
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(SHLQconst [40] (MOVBQZXload [i+5] {s} p mem)))
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(SHLQconst [48] (MOVBQZXload [i+6] {s} p mem)))
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(SHLQconst [56] (MOVBQZXload [i+7] {s} p mem))) -> (MOVQload p mem)
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(SHLQconst [56] (MOVBQZXload [i+7] {s} p mem))) -> (MOVQload (ADDQconst [i] p) mem)
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@ -9465,7 +9465,7 @@ func rewriteValueAMD64_OpAMD64ORL(v *Value, config *Config) bool {
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}
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// match: (ORL (ORL (ORL (MOVBQZXload [i] {s} p mem) (SHLLconst [8] (MOVBQZXload [i+1] {s} p mem))) (SHLLconst [16] (MOVBQZXload [i+2] {s} p mem))) (SHLLconst [24] (MOVBQZXload [i+3] {s} p mem)))
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// cond:
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// result: (MOVLload p mem)
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// result: (MOVLload (ADDQconst [i] p) mem)
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for {
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if v.Args[0].Op != OpAMD64ORL {
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break
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@ -9544,7 +9544,10 @@ func rewriteValueAMD64_OpAMD64ORL(v *Value, config *Config) bool {
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break
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}
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v.reset(OpAMD64MOVLload)
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v.AddArg(p)
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v0 := b.NewValue0(v.Line, OpAMD64ADDQconst, config.fe.TypeUInt64())
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v0.AuxInt = i
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v0.AddArg(p)
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v.AddArg(v0)
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v.AddArg(mem)
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return true
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}
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@ -9646,7 +9649,7 @@ func rewriteValueAMD64_OpAMD64ORQ(v *Value, config *Config) bool {
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}
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// match: (ORQ (ORQ (ORQ (ORQ (ORQ (ORQ (ORQ (MOVBQZXload [i] {s} p mem) (SHLQconst [8] (MOVBQZXload [i+1] {s} p mem))) (SHLQconst [16] (MOVBQZXload [i+2] {s} p mem))) (SHLQconst [24] (MOVBQZXload [i+3] {s} p mem))) (SHLQconst [32] (MOVBQZXload [i+4] {s} p mem))) (SHLQconst [40] (MOVBQZXload [i+5] {s} p mem))) (SHLQconst [48] (MOVBQZXload [i+6] {s} p mem))) (SHLQconst [56] (MOVBQZXload [i+7] {s} p mem)))
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// cond:
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// result: (MOVQload p mem)
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// result: (MOVQload (ADDQconst [i] p) mem)
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for {
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if v.Args[0].Op != OpAMD64ORQ {
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break
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@ -9821,7 +9824,10 @@ func rewriteValueAMD64_OpAMD64ORQ(v *Value, config *Config) bool {
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break
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}
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v.reset(OpAMD64MOVQload)
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v.AddArg(p)
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v0 := b.NewValue0(v.Line, OpAMD64ADDQconst, config.fe.TypeUInt64())
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v0.AuxInt = i
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v0.AddArg(p)
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v.AddArg(v0)
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v.AddArg(mem)
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return true
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}
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@ -9915,7 +9921,7 @@ func rewriteValueAMD64_OpAMD64ORW(v *Value, config *Config) bool {
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}
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// match: (ORW (MOVBQZXload [i] {s} p mem) (SHLWconst [8] (MOVBQZXload [i+1] {s} p mem)))
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// cond:
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// result: (MOVWload p mem)
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// result: (MOVWload (ADDQconst [i] p) mem)
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for {
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if v.Args[0].Op != OpAMD64MOVBQZXload {
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break
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@ -9946,7 +9952,10 @@ func rewriteValueAMD64_OpAMD64ORW(v *Value, config *Config) bool {
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break
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}
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v.reset(OpAMD64MOVWload)
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v.AddArg(p)
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v0 := b.NewValue0(v.Line, OpAMD64ADDQconst, config.fe.TypeUInt64())
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v0.AuxInt = i
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v0.AddArg(p)
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v.AddArg(v0)
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v.AddArg(mem)
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return true
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}
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