cmd/compile: fix zero extend after float->int conversion

Don't do direct loads from argument slots if the sizes don't match.
This prevents us from loading from a float32 using a uint64 load
during expressions like uint64(math.float32Bits(f)) where f is a float32 arg.

Fixes #25322

Change-Id: I3887d76f78c844ba546243e7721d811c3d4a9700
Reviewed-on: https://go-review.googlesource.com/112637
Run-TryBot: Keith Randall <khr@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/cmd/compile/internal/ssa/gen/AMD64.rules

@@ -2396,10 +2396,10 @@
 
 // Load args directly into the register class where it will be used.
 // We do this by just modifying the type of the Arg.
-(MOVQf2i <t> (Arg [off] {sym})) -> @b.Func.Entry (Arg <t> [off] {sym})
-(MOVLf2i <t> (Arg [off] {sym})) -> @b.Func.Entry (Arg <t> [off] {sym})
-(MOVQi2f <t> (Arg [off] {sym})) -> @b.Func.Entry (Arg <t> [off] {sym})
-(MOVLi2f <t> (Arg [off] {sym})) -> @b.Func.Entry (Arg <t> [off] {sym})
+(MOVQf2i <t> (Arg <u> [off] {sym})) && t.Size() == u.Size() -> @b.Func.Entry (Arg <t> [off] {sym})
+(MOVLf2i <t> (Arg <u> [off] {sym})) && t.Size() == u.Size() -> @b.Func.Entry (Arg <t> [off] {sym})
+(MOVQi2f <t> (Arg <u> [off] {sym})) && t.Size() == u.Size() -> @b.Func.Entry (Arg <t> [off] {sym})
+(MOVLi2f <t> (Arg <u> [off] {sym})) && t.Size() == u.Size() -> @b.Func.Entry (Arg <t> [off] {sym})
 
 // LEAQ is rematerializeable, so this helps to avoid register spill.
 // See issue 22947 for details

src/cmd/compile/internal/ssa/gen/AMD64Ops.go

@@ -482,7 +482,7 @@ func init() {
 		{name: "MOVQi2f", argLength: 1, reg: gpfp, typ: "Float64"}, // move 64 bits from int to float reg
 		{name: "MOVQf2i", argLength: 1, reg: fpgp, typ: "UInt64"},  // move 64 bits from float to int reg
 		{name: "MOVLi2f", argLength: 1, reg: gpfp, typ: "Float32"}, // move 32 bits from int to float reg
-		{name: "MOVLf2i", argLength: 1, reg: fpgp, typ: "UInt32"},  // move 32 bits from float to int reg
+		{name: "MOVLf2i", argLength: 1, reg: fpgp, typ: "UInt32"},  // move 32 bits from float to int reg, zero extend
 
 		{name: "PXOR", argLength: 2, reg: fp21, asm: "PXOR", commutative: true, resultInArg0: true}, // exclusive or, applied to X regs for float negation.
 

src/cmd/compile/internal/ssa/rewriteAMD64.go

@@ -13143,8 +13143,8 @@ func rewriteValueAMD64_OpAMD64MOVLatomicload_0(v *Value) bool {
 func rewriteValueAMD64_OpAMD64MOVLf2i_0(v *Value) bool {
 	b := v.Block
 	_ = b
-	// match: (MOVLf2i <t> (Arg [off] {sym}))
-	// cond:
+	// match: (MOVLf2i <t> (Arg <u> [off] {sym}))
+	// cond: t.Size() == u.Size()
 	// result: @b.Func.Entry (Arg <t> [off] {sym})
 	for {
 		t := v.Type
@@ -13152,8 +13152,12 @@ func rewriteValueAMD64_OpAMD64MOVLf2i_0(v *Value) bool {
 		if v_0.Op != OpArg {
 			break
 		}
+		u := v_0.Type
 		off := v_0.AuxInt
 		sym := v_0.Aux
+		if !(t.Size() == u.Size()) {
+			break
+		}
 		b = b.Func.Entry
 		v0 := b.NewValue0(v.Pos, OpArg, t)
 		v.reset(OpCopy)
@@ -13167,8 +13171,8 @@ func rewriteValueAMD64_OpAMD64MOVLf2i_0(v *Value) bool {
 func rewriteValueAMD64_OpAMD64MOVLi2f_0(v *Value) bool {
 	b := v.Block
 	_ = b
-	// match: (MOVLi2f <t> (Arg [off] {sym}))
-	// cond:
+	// match: (MOVLi2f <t> (Arg <u> [off] {sym}))
+	// cond: t.Size() == u.Size()
 	// result: @b.Func.Entry (Arg <t> [off] {sym})
 	for {
 		t := v.Type
@@ -13176,8 +13180,12 @@ func rewriteValueAMD64_OpAMD64MOVLi2f_0(v *Value) bool {
 		if v_0.Op != OpArg {
 			break
 		}
+		u := v_0.Type
 		off := v_0.AuxInt
 		sym := v_0.Aux
+		if !(t.Size() == u.Size()) {
+			break
+		}
 		b = b.Func.Entry
 		v0 := b.NewValue0(v.Pos, OpArg, t)
 		v.reset(OpCopy)
@@ -15520,8 +15528,8 @@ func rewriteValueAMD64_OpAMD64MOVQatomicload_0(v *Value) bool {
 func rewriteValueAMD64_OpAMD64MOVQf2i_0(v *Value) bool {
 	b := v.Block
 	_ = b
-	// match: (MOVQf2i <t> (Arg [off] {sym}))
-	// cond:
+	// match: (MOVQf2i <t> (Arg <u> [off] {sym}))
+	// cond: t.Size() == u.Size()
 	// result: @b.Func.Entry (Arg <t> [off] {sym})
 	for {
 		t := v.Type
@@ -15529,8 +15537,12 @@ func rewriteValueAMD64_OpAMD64MOVQf2i_0(v *Value) bool {
 		if v_0.Op != OpArg {
 			break
 		}
+		u := v_0.Type
 		off := v_0.AuxInt
 		sym := v_0.Aux
+		if !(t.Size() == u.Size()) {
+			break
+		}
 		b = b.Func.Entry
 		v0 := b.NewValue0(v.Pos, OpArg, t)
 		v.reset(OpCopy)
@@ -15544,8 +15556,8 @@ func rewriteValueAMD64_OpAMD64MOVQf2i_0(v *Value) bool {
 func rewriteValueAMD64_OpAMD64MOVQi2f_0(v *Value) bool {
 	b := v.Block
 	_ = b
-	// match: (MOVQi2f <t> (Arg [off] {sym}))
-	// cond:
+	// match: (MOVQi2f <t> (Arg <u> [off] {sym}))
+	// cond: t.Size() == u.Size()
 	// result: @b.Func.Entry (Arg <t> [off] {sym})
 	for {
 		t := v.Type
@@ -15553,8 +15565,12 @@ func rewriteValueAMD64_OpAMD64MOVQi2f_0(v *Value) bool {
 		if v_0.Op != OpArg {
 			break
 		}
+		u := v_0.Type
 		off := v_0.AuxInt
 		sym := v_0.Aux
+		if !(t.Size() == u.Size()) {
+			break
+		}
 		b = b.Func.Entry
 		v0 := b.NewValue0(v.Pos, OpArg, t)
 		v.reset(OpCopy)

test/fixedbugs/issue25322.go

+// cmpout
+
+// 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.
+
+// Missing zero extension when converting a float32
+// to a uint64.
+
+package main
+
+import (
+	"fmt"
+	"math"
+)
+
+func Foo(v float32) {
+	fmt.Printf("%x\n", uint64(math.Float32bits(v)))
+}
+
+func main() {
+	Foo(2.0)
+}

test/fixedbugs/issue25322.out

+40000000