cmd/compile: fix OffPtr with negative offset on wasm

The wasm archtecture was missing a rule to handle OffPtr with a
negative offset. This commit makes it so OffPtr always gets lowered
to I64AddConst.

Fixes #25741

Change-Id: I1d48e2954e3ff31deb8cba9a9bf0cab7c4bab71a
Reviewed-on: https://go-review.googlesource.com/116595
Reviewed-by: Cherry Zhang <cherryyz@google.com>
Run-TryBot: Cherry Zhang <cherryyz@google.com>

diff --git a/src/cmd/compile/internal/ssa/gen/Wasm.rules b/src/cmd/compile/internal/ssa/gen/Wasm.rules
index 01f3f5a670a1011e9f9acccfdf8c595049ffc93f..18c208cccb6c17729688b1468c1d15ec4ac2a23d 100644 (file)
--- a/src/cmd/compile/internal/ssa/gen/Wasm.rules
+++ b/src/cmd/compile/internal/ssa/gen/Wasm.rules
@@ -46,8 +46,7 @@
 (Not x) -> (I64Eqz x)
 
 // Lowering pointer arithmetic
-(OffPtr [0] ptr) -> ptr
-(OffPtr [off] ptr) && off > 0 -> (I64AddConst [off] ptr)
+(OffPtr [off] ptr) -> (I64AddConst [off] ptr)
 
 // Lowering extension
 // It is unnecessary to extend loads
@@ -388,6 +387,7 @@
 (I64Ne x (I64Const [0])) -> (I64Eqz (I64Eqz x))
 
 (I64Add x (I64Const [y])) -> (I64AddConst [y] x)
+(I64AddConst [0] x) -> x
 (I64Eqz (I64Eqz (I64Eqz x))) -> (I64Eqz x)
 
 ((I64Load|I64Load32U|I64Load32S|I64Load16U|I64Load16S|I64Load8U|I64Load8S) [off] (I64AddConst [off2] ptr) mem)

diff --git a/src/cmd/compile/internal/ssa/rewriteWasm.go b/src/cmd/compile/internal/ssa/rewriteWasm.go
index 38822a746687fa4a04acc177f3a9025b2dc1765c..f3648ebca1d5f6007f7fb036a10e24aab6cf4026 100644 (file)
--- a/src/cmd/compile/internal/ssa/rewriteWasm.go
+++ b/src/cmd/compile/internal/ssa/rewriteWasm.go
@@ -463,6 +463,8 @@ func rewriteValueWasm(v *Value) bool {
                return rewriteValueWasm_OpWasmF64Mul_0(v)
        case OpWasmI64Add:
                return rewriteValueWasm_OpWasmI64Add_0(v)
+       case OpWasmI64AddConst:
+               return rewriteValueWasm_OpWasmI64AddConst_0(v)
        case OpWasmI64And:
                return rewriteValueWasm_OpWasmI64And_0(v)
        case OpWasmI64Eq:
@@ -3688,34 +3690,17 @@ func rewriteValueWasm_OpNot_0(v *Value) bool {
        }
 }
 func rewriteValueWasm_OpOffPtr_0(v *Value) bool {
-       // match: (OffPtr [0] ptr)
-       // cond:
-       // result: ptr
-       for {
-               if v.AuxInt != 0 {
-                       break
-               }
-               ptr := v.Args[0]
-               v.reset(OpCopy)
-               v.Type = ptr.Type
-               v.AddArg(ptr)
-               return true
-       }
        // match: (OffPtr [off] ptr)
-       // cond: off > 0
+       // cond:
        // result: (I64AddConst [off] ptr)
        for {
                off := v.AuxInt
                ptr := v.Args[0]
-               if !(off > 0) {
-                       break
-               }
                v.reset(OpWasmI64AddConst)
                v.AuxInt = off
                v.AddArg(ptr)
                return true
        }
-       return false
 }
 func rewriteValueWasm_OpOr16_0(v *Value) bool {
        // match: (Or16 x y)
@@ -5211,6 +5196,22 @@ func rewriteValueWasm_OpWasmI64Add_0(v *Value) bool {
        }
        return false
 }
+func rewriteValueWasm_OpWasmI64AddConst_0(v *Value) bool {
+       // match: (I64AddConst [0] x)
+       // cond:
+       // result: x
+       for {
+               if v.AuxInt != 0 {
+                       break
+               }
+               x := v.Args[0]
+               v.reset(OpCopy)
+               v.Type = x.Type
+               v.AddArg(x)
+               return true
+       }
+       return false
+}
 func rewriteValueWasm_OpWasmI64And_0(v *Value) bool {
        b := v.Block
        _ = b

diff --git a/test/fixedbugs/issue25741.go b/test/fixedbugs/issue25741.go
new file mode 100644 (file)
index 0000000..c76e975
--- /dev/null
+++ b/test/fixedbugs/issue25741.go
@@ -0,0 +1,14 @@
+// compile
+
+// Copyright 2018 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+var s []int
+
+func main() {
+       i := -1
+       s[i] = 0
+}