cmd/compile: force folding of MOVDaddr into storezero

Fold MOVDaddr ops into MOVXstorezero ops.
Also fold ADDconst into MOVDaddr so we're sure there isn't
(MOVDstorezero (ADDconst (MOVDaddr ..)))

Without this CL, we get:

v1 = MOVDaddr {s}
v2 = VARDEF {s}
v3 = MOVDstorezero v1 v2

The liveness pass thinks the MOVDaddr is a read of s, so s is
incorrectly thought to be live at the start of the function.

Fixes #17194

Change-Id: I2b4a2f13b12aa5b072941ee1c7b89f3793650cdc
Reviewed-on: https://go-review.googlesource.com/30086
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Lynn Boger <laboger@linux.vnet.ibm.com>
Reviewed-by: Michael Munday <munday@ca.ibm.com>

src/cmd/compile/internal/ssa/gen/PPC64.rules

@@ -523,6 +523,7 @@
 (ADD (MOVDconst [c]) x) && is32Bit(c) -> (ADDconst [c] x)
 (ADD x (MOVDconst [c])) && is32Bit(c) -> (ADDconst [c] x)
 (ADDconst [c] (ADDconst [d] x)) && is32Bit(c+d) -> (ADDconst [c+d] x)
+(ADDconst [c] (MOVDaddr [d] {sym} x)) -> (MOVDaddr [c+d] {sym} x)
 (ADDconst [0] x) -> x
 (ANDconst [-1] x) -> x
 (ANDconst [0] _) -> (MOVDconst [0])
@@ -600,6 +601,16 @@
 (MOVBstorezero [off1] {sym} (ADDconst [off2] x) mem) && is16Bit(off1+off2) ->
     (MOVBstorezero [off1+off2] {sym} x mem)
 
+// Fold symbols into storezero
+(MOVDstorezero [off1] {sym1} (MOVDaddr [off2] {sym2} x) mem) && canMergeSym(sym1,sym2) ->
+    (MOVDstorezero [off1+off2] {mergeSym(sym1,sym2)} x mem)
+(MOVWstorezero [off1] {sym1} (MOVDaddr [off2] {sym2} x) mem) && canMergeSym(sym1,sym2) ->
+    (MOVWstorezero [off1+off2] {mergeSym(sym1,sym2)} x mem)
+(MOVHstorezero [off1] {sym1} (MOVDaddr [off2] {sym2} x) mem) && canMergeSym(sym1,sym2) ->
+    (MOVHstorezero [off1+off2] {mergeSym(sym1,sym2)} x mem)
+(MOVBstorezero [off1] {sym1} (MOVDaddr [off2] {sym2} x) mem) && canMergeSym(sym1,sym2) ->
+    (MOVBstorezero [off1+off2] {mergeSym(sym1,sym2)} x mem)
+
 // Lowering extension
 // Note: we always extend to 64 bits even though some ops don't need that many result bits.
 (SignExt8to16  x) -> (MOVBreg x)

src/cmd/compile/internal/ssa/rewritePPC64.go

@@ -4101,6 +4101,24 @@ func rewriteValuePPC64_OpPPC64ADDconst(v *Value, config *Config) bool {
 		v.AddArg(x)
 		return true
 	}
+	// match: (ADDconst [c] (MOVDaddr [d] {sym} x))
+	// cond:
+	// result: (MOVDaddr [c+d] {sym} x)
+	for {
+		c := v.AuxInt
+		v_0 := v.Args[0]
+		if v_0.Op != OpPPC64MOVDaddr {
+			break
+		}
+		d := v_0.AuxInt
+		sym := v_0.Aux
+		x := v_0.Args[0]
+		v.reset(OpPPC64MOVDaddr)
+		v.AuxInt = c + d
+		v.Aux = sym
+		v.AddArg(x)
+		return true
+	}
 	// match: (ADDconst [0] x)
 	// cond:
 	// result: x
@@ -5263,6 +5281,30 @@ func rewriteValuePPC64_OpPPC64MOVBstorezero(v *Value, config *Config) bool {
 		v.AddArg(mem)
 		return true
 	}
+	// match: (MOVBstorezero [off1] {sym1} (MOVDaddr [off2] {sym2} x) mem)
+	// cond: canMergeSym(sym1,sym2)
+	// result: (MOVBstorezero [off1+off2] {mergeSym(sym1,sym2)} x mem)
+	for {
+		off1 := v.AuxInt
+		sym1 := v.Aux
+		v_0 := v.Args[0]
+		if v_0.Op != OpPPC64MOVDaddr {
+			break
+		}
+		off2 := v_0.AuxInt
+		sym2 := v_0.Aux
+		x := v_0.Args[0]
+		mem := v.Args[1]
+		if !(canMergeSym(sym1, sym2)) {
+			break
+		}
+		v.reset(OpPPC64MOVBstorezero)
+		v.AuxInt = off1 + off2
+		v.Aux = mergeSym(sym1, sym2)
+		v.AddArg(x)
+		v.AddArg(mem)
+		return true
+	}
 	return false
 }
 func rewriteValuePPC64_OpPPC64MOVDload(v *Value, config *Config) bool {
@@ -5422,6 +5464,30 @@ func rewriteValuePPC64_OpPPC64MOVDstorezero(v *Value, config *Config) bool {
 		v.AddArg(mem)
 		return true
 	}
+	// match: (MOVDstorezero [off1] {sym1} (MOVDaddr [off2] {sym2} x) mem)
+	// cond: canMergeSym(sym1,sym2)
+	// result: (MOVDstorezero [off1+off2] {mergeSym(sym1,sym2)} x mem)
+	for {
+		off1 := v.AuxInt
+		sym1 := v.Aux
+		v_0 := v.Args[0]
+		if v_0.Op != OpPPC64MOVDaddr {
+			break
+		}
+		off2 := v_0.AuxInt
+		sym2 := v_0.Aux
+		x := v_0.Args[0]
+		mem := v.Args[1]
+		if !(canMergeSym(sym1, sym2)) {
+			break
+		}
+		v.reset(OpPPC64MOVDstorezero)
+		v.AuxInt = off1 + off2
+		v.Aux = mergeSym(sym1, sym2)
+		v.AddArg(x)
+		v.AddArg(mem)
+		return true
+	}
 	return false
 }
 func rewriteValuePPC64_OpPPC64MOVHZload(v *Value, config *Config) bool {
@@ -5737,6 +5803,30 @@ func rewriteValuePPC64_OpPPC64MOVHstorezero(v *Value, config *Config) bool {
 		v.AddArg(mem)
 		return true
 	}
+	// match: (MOVHstorezero [off1] {sym1} (MOVDaddr [off2] {sym2} x) mem)
+	// cond: canMergeSym(sym1,sym2)
+	// result: (MOVHstorezero [off1+off2] {mergeSym(sym1,sym2)} x mem)
+	for {
+		off1 := v.AuxInt
+		sym1 := v.Aux
+		v_0 := v.Args[0]
+		if v_0.Op != OpPPC64MOVDaddr {
+			break
+		}
+		off2 := v_0.AuxInt
+		sym2 := v_0.Aux
+		x := v_0.Args[0]
+		mem := v.Args[1]
+		if !(canMergeSym(sym1, sym2)) {
+			break
+		}
+		v.reset(OpPPC64MOVHstorezero)
+		v.AuxInt = off1 + off2
+		v.Aux = mergeSym(sym1, sym2)
+		v.AddArg(x)
+		v.AddArg(mem)
+		return true
+	}
 	return false
 }
 func rewriteValuePPC64_OpPPC64MOVWZload(v *Value, config *Config) bool {
@@ -5948,6 +6038,30 @@ func rewriteValuePPC64_OpPPC64MOVWstorezero(v *Value, config *Config) bool {
 		v.AddArg(mem)
 		return true
 	}
+	// match: (MOVWstorezero [off1] {sym1} (MOVDaddr [off2] {sym2} x) mem)
+	// cond: canMergeSym(sym1,sym2)
+	// result: (MOVWstorezero [off1+off2] {mergeSym(sym1,sym2)} x mem)
+	for {
+		off1 := v.AuxInt
+		sym1 := v.Aux
+		v_0 := v.Args[0]
+		if v_0.Op != OpPPC64MOVDaddr {
+			break
+		}
+		off2 := v_0.AuxInt
+		sym2 := v_0.Aux
+		x := v_0.Args[0]
+		mem := v.Args[1]
+		if !(canMergeSym(sym1, sym2)) {
+			break
+		}
+		v.reset(OpPPC64MOVWstorezero)
+		v.AuxInt = off1 + off2
+		v.Aux = mergeSym(sym1, sym2)
+		v.AddArg(x)
+		v.AddArg(mem)
+		return true
+	}
 	return false
 }
 func rewriteValuePPC64_OpPPC64NotEqual(v *Value, config *Config) bool {

test/fixedbugs/issue17194.go

+// compile
+
+// Copyright 2016 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 foo
+
+func f(x []interface{}) (err error) {
+	for _, d := range x {
+		_, ok := d.(*int)
+		if ok {
+			return
+		}
+	}
+	return
+}