cmd/compile: don't allow NaNs in floating-point constant ops

Trying this CL again, with a fixed test that allows platforms
to disagree on the exact behavior of converting NaNs.

We store 32-bit floating point constants in a 64-bit field, by
converting that 32-bit float to 64-bit float to store it, and convert
it back to use it.

That works for *almost* all floating-point constants. The exception is
signaling NaNs. The round trip described above means we can't represent
a 32-bit signaling NaN, because conversions strip the signaling bit.

To fix this issue, just forbid NaNs as floating-point constants in SSA
form. This shouldn't affect any real-world code, as people seldom
constant-propagate NaNs (except in test code).

Additionally, NaNs are somewhat underspecified (which of the many NaNs
do you get when dividing 0/0?), so when cross-compiling there's a
danger of using the compiler machine's NaN regime for some math, and
the target machine's NaN regime for other math. Better to use the
target machine's NaN regime always.

Update #36400

Change-Id: Idf203b688a15abceabbd66ba290d4e9f63619ecb
Reviewed-on: https://go-review.googlesource.com/c/go/+/221790
Run-TryBot: Keith Randall <khr@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Josh Bleecher Snyder <josharian@gmail.com>

diff --git a/src/cmd/compile/internal/gc/float_test.go b/src/cmd/compile/internal/gc/float_test.go
index c5c604003ab8dd54e494aeca9123092ee2d2d0e9..6ae363be22920a06f231a767592a0f74ffbc56cb 100644 (file)
--- a/src/cmd/compile/internal/gc/float_test.go
+++ b/src/cmd/compile/internal/gc/float_test.go
@@ -483,6 +483,64 @@ func TestFloat32StoreToLoadConstantFold(t *testing.T) {
        }
 }
 
+// Signaling NaN values as constants.
+const (
+       snan32bits uint32 = 0x7f800001
+       snan64bits uint64 = 0x7ff0000000000001
+)
+
+// Signaling NaNs as variables.
+var snan32bitsVar uint32 = snan32bits
+var snan64bitsVar uint64 = snan64bits
+
+func TestFloatSignalingNaN(t *testing.T) {
+       // Make sure we generate a signaling NaN from a constant properly.
+       // See issue 36400.
+       f32 := math.Float32frombits(snan32bits)
+       g32 := math.Float32frombits(snan32bitsVar)
+       x32 := math.Float32bits(f32)
+       y32 := math.Float32bits(g32)
+       if x32 != y32 {
+               t.Errorf("got %x, want %x (diff=%x)", x32, y32, x32^y32)
+       }
+
+       f64 := math.Float64frombits(snan64bits)
+       g64 := math.Float64frombits(snan64bitsVar)
+       x64 := math.Float64bits(f64)
+       y64 := math.Float64bits(g64)
+       if x64 != y64 {
+               t.Errorf("got %x, want %x (diff=%x)", x64, y64, x64^y64)
+       }
+}
+
+func TestFloatSignalingNaNConversion(t *testing.T) {
+       // Test to make sure when we convert a signaling NaN, we get a NaN.
+       // (Ideally we want a quiet NaN, but some platforms don't agree.)
+       // See issue 36399.
+       s32 := math.Float32frombits(snan32bitsVar)
+       if s32 == s32 {
+               t.Errorf("converting a NaN did not result in a NaN")
+       }
+       s64 := math.Float64frombits(snan64bitsVar)
+       if s64 == s64 {
+               t.Errorf("converting a NaN did not result in a NaN")
+       }
+}
+
+func TestFloatSignalingNaNConversionConst(t *testing.T) {
+       // Test to make sure when we convert a signaling NaN, it converts to a NaN.
+       // (Ideally we want a quiet NaN, but some platforms don't agree.)
+       // See issue 36399 and 36400.
+       s32 := math.Float32frombits(snan32bits)
+       if s32 == s32 {
+               t.Errorf("converting a NaN did not result in a NaN")
+       }
+       s64 := math.Float64frombits(snan64bits)
+       if s64 == s64 {
+               t.Errorf("converting a NaN did not result in a NaN")
+       }
+}
+
 var sinkFloat float64
 
 func BenchmarkMul2(b *testing.B) {

diff --git a/src/cmd/compile/internal/ssa/check.go b/src/cmd/compile/internal/ssa/check.go
index a6746805f7ffff85ee852e50dc0aba0c8c38935a..4c694a03acc1afb2a2e29d5239f32ff3eca78f73 100644 (file)
--- a/src/cmd/compile/internal/ssa/check.go
+++ b/src/cmd/compile/internal/ssa/check.go
@@ -141,15 +141,23 @@ func checkFunc(f *Func) {
                                        f.Fatalf("bad int32 AuxInt value for %v", v)
                                }
                                canHaveAuxInt = true
-                       case auxInt64, auxFloat64, auxARM64BitField:
+                       case auxInt64, auxARM64BitField:
                                canHaveAuxInt = true
                        case auxInt128:
                                // AuxInt must be zero, so leave canHaveAuxInt set to false.
                        case auxFloat32:
                                canHaveAuxInt = true
+                               if math.IsNaN(v.AuxFloat()) {
+                                       f.Fatalf("value %v has an AuxInt that encodes a NaN", v)
+                               }
                                if !isExactFloat32(v.AuxFloat()) {
                                        f.Fatalf("value %v has an AuxInt value that is not an exact float32", v)
                                }
+                       case auxFloat64:
+                               canHaveAuxInt = true
+                               if math.IsNaN(v.AuxFloat()) {
+                                       f.Fatalf("value %v has an AuxInt that encodes a NaN", v)
+                               }
                        case auxString, auxSym, auxTyp, auxArchSpecific:
                                canHaveAux = true
                        case auxSymOff, auxSymValAndOff, auxTypSize:

diff --git a/src/cmd/compile/internal/ssa/gen/PPC64.rules b/src/cmd/compile/internal/ssa/gen/PPC64.rules
index f2b2b9b8988338f6aab1ffdeef7efe239754bc37..c53ec0fde1135ca0d30a2be1f5aea14e61d50166 100644 (file)
--- a/src/cmd/compile/internal/ssa/gen/PPC64.rules
+++ b/src/cmd/compile/internal/ssa/gen/PPC64.rules
@@ -80,7 +80,7 @@
 
 // Constant folding
 (FABS (FMOVDconst [x])) -> (FMOVDconst [auxFrom64F(math.Abs(auxTo64F(x)))])
-(FSQRT (FMOVDconst [x])) -> (FMOVDconst [auxFrom64F(math.Sqrt(auxTo64F(x)))])
+(FSQRT (FMOVDconst [x])) && auxTo64F(x) >= 0 -> (FMOVDconst [auxFrom64F(math.Sqrt(auxTo64F(x)))])
 (FFLOOR (FMOVDconst [x])) -> (FMOVDconst [auxFrom64F(math.Floor(auxTo64F(x)))])
 (FCEIL (FMOVDconst [x])) -> (FMOVDconst [auxFrom64F(math.Ceil(auxTo64F(x)))])
 (FTRUNC (FMOVDconst [x])) -> (FMOVDconst [auxFrom64F(math.Trunc(auxTo64F(x)))])

diff --git a/src/cmd/compile/internal/ssa/gen/Wasm.rules b/src/cmd/compile/internal/ssa/gen/Wasm.rules
index cdcbc28c306a9451932c49bd0777621c68ef05e2..bf2b904baf0381779abaa6daf2d6997b711c434a 100644 (file)
--- a/src/cmd/compile/internal/ssa/gen/Wasm.rules
+++ b/src/cmd/compile/internal/ssa/gen/Wasm.rules
@@ -357,7 +357,7 @@
 (I64Or  (I64Const [x]) (I64Const [y])) -> (I64Const [x | y])
 (I64Xor (I64Const [x]) (I64Const [y])) -> (I64Const [x ^ y])
 (F64Add (F64Const [x]) (F64Const [y])) -> (F64Const [auxFrom64F(auxTo64F(x) + auxTo64F(y))])
-(F64Mul (F64Const [x]) (F64Const [y])) -> (F64Const [auxFrom64F(auxTo64F(x) * auxTo64F(y))])
+(F64Mul (F64Const [x]) (F64Const [y])) && !math.IsNaN(auxTo64F(x) * auxTo64F(y)) -> (F64Const [auxFrom64F(auxTo64F(x) * auxTo64F(y))])
 (I64Eq  (I64Const [x]) (I64Const [y])) && x == y -> (I64Const [1])
 (I64Eq  (I64Const [x]) (I64Const [y])) && x != y -> (I64Const [0])
 (I64Ne  (I64Const [x]) (I64Const [y])) && x == y -> (I64Const [0])
@@ -367,15 +367,16 @@
 (I64ShrU (I64Const [x]) (I64Const [y])) -> (I64Const [int64(uint64(x) >> uint64(y))])
 (I64ShrS (I64Const [x]) (I64Const [y])) -> (I64Const [x >> uint64(y)])
 
-(I64Add (I64Const [x]) y) -> (I64Add y (I64Const [x]))
-(I64Mul (I64Const [x]) y) -> (I64Mul y (I64Const [x]))
-(I64And (I64Const [x]) y) -> (I64And y (I64Const [x]))
-(I64Or  (I64Const [x]) y) -> (I64Or  y (I64Const [x]))
-(I64Xor (I64Const [x]) y) -> (I64Xor y (I64Const [x]))
-(F64Add (F64Const [x]) y) -> (F64Add y (F64Const [x]))
-(F64Mul (F64Const [x]) y) -> (F64Mul y (F64Const [x]))
-(I64Eq  (I64Const [x]) y) -> (I64Eq y  (I64Const [x]))
-(I64Ne  (I64Const [x]) y) -> (I64Ne y  (I64Const [x]))
+// TODO: declare these operations as commutative and get rid of these rules?
+(I64Add (I64Const [x]) y) && y.Op != OpWasmI64Const -> (I64Add y (I64Const [x]))
+(I64Mul (I64Const [x]) y) && y.Op != OpWasmI64Const -> (I64Mul y (I64Const [x]))
+(I64And (I64Const [x]) y) && y.Op != OpWasmI64Const -> (I64And y (I64Const [x]))
+(I64Or  (I64Const [x]) y) && y.Op != OpWasmI64Const -> (I64Or  y (I64Const [x]))
+(I64Xor (I64Const [x]) y) && y.Op != OpWasmI64Const -> (I64Xor y (I64Const [x]))
+(F64Add (F64Const [x]) y) && y.Op != OpWasmF64Const -> (F64Add y (F64Const [x]))
+(F64Mul (F64Const [x]) y) && y.Op != OpWasmF64Const -> (F64Mul y (F64Const [x]))
+(I64Eq  (I64Const [x]) y) && y.Op != OpWasmI64Const -> (I64Eq y  (I64Const [x]))
+(I64Ne  (I64Const [x]) y) && y.Op != OpWasmI64Const -> (I64Ne y  (I64Const [x]))
 
 (I64Eq x (I64Const [0])) -> (I64Eqz x)
 (I64Ne x (I64Const [0])) -> (I64Eqz (I64Eqz x))

diff --git a/src/cmd/compile/internal/ssa/gen/generic.rules b/src/cmd/compile/internal/ssa/gen/generic.rules
index bc16f5a7af11f40e3b0d6d51036fff6597237996..8ec22d86e7a07068f53efda2ee531a10048b965e 100644 (file)
--- a/src/cmd/compile/internal/ssa/gen/generic.rules
+++ b/src/cmd/compile/internal/ssa/gen/generic.rules
@@ -119,8 +119,8 @@
 (Mul16  (Const16 [c])  (Const16 [d]))  -> (Const16 [int64(int16(c*d))])
 (Mul32  (Const32 [c])  (Const32 [d]))  -> (Const32 [int64(int32(c*d))])
 (Mul64  (Const64 [c])  (Const64 [d]))  -> (Const64 [c*d])
-(Mul32F (Const32F [c]) (Const32F [d])) -> (Const32F [auxFrom32F(auxTo32F(c) * auxTo32F(d))])
-(Mul64F (Const64F [c]) (Const64F [d])) -> (Const64F [auxFrom64F(auxTo64F(c) * auxTo64F(d))])
+(Mul32F (Const32F [c]) (Const32F [d])) && !math.IsNaN(float64(auxTo32F(c) * auxTo32F(d))) -> (Const32F [auxFrom32F(auxTo32F(c) * auxTo32F(d))])
+(Mul64F (Const64F [c]) (Const64F [d])) && !math.IsNaN(auxTo64F(c) * auxTo64F(d)) -> (Const64F [auxFrom64F(auxTo64F(c) * auxTo64F(d))])
 
 (And8   (Const8 [c])   (Const8 [d]))   -> (Const8  [int64(int8(c&d))])
 (And16  (Const16 [c])  (Const16 [d]))  -> (Const16 [int64(int16(c&d))])
@@ -145,8 +145,8 @@
 (Div16u (Const16 [c])  (Const16 [d])) && d != 0 -> (Const16 [int64(int16(uint16(c)/uint16(d)))])
 (Div32u (Const32 [c])  (Const32 [d])) && d != 0 -> (Const32 [int64(int32(uint32(c)/uint32(d)))])
 (Div64u (Const64 [c])  (Const64 [d])) && d != 0 -> (Const64 [int64(uint64(c)/uint64(d))])
-(Div32F (Const32F [c]) (Const32F [d])) -> (Const32F [auxFrom32F(auxTo32F(c) / auxTo32F(d))])
-(Div64F (Const64F [c]) (Const64F [d])) -> (Const64F [auxFrom64F(auxTo64F(c) / auxTo64F(d))])
+(Div32F (Const32F [c]) (Const32F [d])) && !math.IsNaN(float64(auxTo32F(c) / auxTo32F(d))) -> (Const32F [auxFrom32F(auxTo32F(c) / auxTo32F(d))])
+(Div64F (Const64F [c]) (Const64F [d])) && !math.IsNaN(auxTo64F(c) / auxTo64F(d)) -> (Const64F [auxFrom64F(auxTo64F(c) / auxTo64F(d))])
 (Select0 (Div128u (Const64 [0]) lo y)) -> (Div64u lo y)
 (Select1 (Div128u (Const64 [0]) lo y)) -> (Mod64u lo y)
 
@@ -623,8 +623,8 @@
        -> x
 
 // Pass constants through math.Float{32,64}bits and math.Float{32,64}frombits
-(Load <t1> p1 (Store {t2} p2 (Const64  [x]) _)) && isSamePtr(p1,p2) && sizeof(t2) == 8 && is64BitFloat(t1) -> (Const64F [x])
-(Load <t1> p1 (Store {t2} p2 (Const32  [x]) _)) && isSamePtr(p1,p2) && sizeof(t2) == 4 && is32BitFloat(t1) -> (Const32F [auxFrom32F(math.Float32frombits(uint32(x)))])
+        (Load <t1> p1 (Store {t2} p2 (Const64  [x]) _)) && isSamePtr(p1,p2) && sizeof(t2) == 8 && is64BitFloat(t1) && !math.IsNaN(math.Float64frombits(uint64(x))) -> (Const64F [x])
+        (Load <t1> p1 (Store {t2} p2 (Const32  [x]) _)) && isSamePtr(p1,p2) && sizeof(t2) == 4 && is32BitFloat(t1) && !math.IsNaN(float64(math.Float32frombits(uint32(x)))) -> (Const32F [auxFrom32F(math.Float32frombits(uint32(x)))])
 (Load <t1> p1 (Store {t2} p2 (Const64F [x]) _)) && isSamePtr(p1,p2) && sizeof(t2) == 8 && is64BitInt(t1)   -> (Const64  [x])
 (Load <t1> p1 (Store {t2} p2 (Const32F [x]) _)) && isSamePtr(p1,p2) && sizeof(t2) == 4 && is32BitInt(t1)   -> (Const32  [int64(int32(math.Float32bits(auxTo32F(x))))])
 
@@ -1893,7 +1893,7 @@
 (Div32F x (Const32F <t> [c])) && reciprocalExact32(auxTo32F(c)) -> (Mul32F x (Const32F <t> [auxFrom32F(1/auxTo32F(c))]))
 (Div64F x (Const64F <t> [c])) && reciprocalExact64(auxTo64F(c)) -> (Mul64F x (Const64F <t> [auxFrom64F(1/auxTo64F(c))]))
 
-(Sqrt (Const64F [c])) -> (Const64F [auxFrom64F(math.Sqrt(auxTo64F(c)))])
+(Sqrt (Const64F [c])) && !math.IsNaN(math.Sqrt(auxTo64F(c))) -> (Const64F [auxFrom64F(math.Sqrt(auxTo64F(c)))])
 
 // recognize runtime.newobject and don't Zero/Nilcheck it
 (Zero (Load (OffPtr [c] (SP)) mem) mem)

diff --git a/src/cmd/compile/internal/ssa/gen/genericOps.go b/src/cmd/compile/internal/ssa/gen/genericOps.go
index 54c6968c5b16cc40ad2eecc882e82314b697f23b..b7e91a1f20e3149da7d929abcf0cecb564dbe78b 100644 (file)
--- a/src/cmd/compile/internal/ssa/gen/genericOps.go
+++ b/src/cmd/compile/internal/ssa/gen/genericOps.go
@@ -323,7 +323,12 @@ var genericOps = []opData{
        {name: "Const32", aux: "Int32"},      // auxint is sign-extended 32 bits
        // Note: ConstX are sign-extended even when the type of the value is unsigned.
        // For instance, uint8(0xaa) is stored as auxint=0xffffffffffffffaa.
-       {name: "Const64", aux: "Int64"},    // value is auxint
+       {name: "Const64", aux: "Int64"}, // value is auxint
+       // Note: for both Const32F and Const64F, we disallow encoding NaNs.
+       // Signaling NaNs are tricky because if you do anything with them, they become quiet.
+       // Particularly, converting a 32 bit sNaN to 64 bit and back converts it to a qNaN.
+       // See issue 36399 and 36400.
+       // Encodings of +inf, -inf, and -0 are fine.
        {name: "Const32F", aux: "Float32"}, // value is math.Float64frombits(uint64(auxint)) and is exactly representable as float 32
        {name: "Const64F", aux: "Float64"}, // value is math.Float64frombits(uint64(auxint))
        {name: "ConstInterface"},           // nil interface

diff --git a/src/cmd/compile/internal/ssa/rewrite.go b/src/cmd/compile/internal/ssa/rewrite.go
index fcbb76cf3493b844cf0e5632ab001705a064974d..238e2430963ee3e25dfb65395bc21e9f5744ef2f 100644 (file)
--- a/src/cmd/compile/internal/ssa/rewrite.go
+++ b/src/cmd/compile/internal/ssa/rewrite.go
@@ -487,11 +487,17 @@ func DivisionNeedsFixUp(v *Value) bool {
 
 // auxFrom64F encodes a float64 value so it can be stored in an AuxInt.
 func auxFrom64F(f float64) int64 {
+       if f != f {
+               panic("can't encode a NaN in AuxInt field")
+       }
        return int64(math.Float64bits(f))
 }
 
 // auxFrom32F encodes a float32 value so it can be stored in an AuxInt.
 func auxFrom32F(f float32) int64 {
+       if f != f {
+               panic("can't encode a NaN in AuxInt field")
+       }
        return int64(math.Float64bits(extend32Fto64F(f)))
 }
 

diff --git a/src/cmd/compile/internal/ssa/rewritePPC64.go b/src/cmd/compile/internal/ssa/rewritePPC64.go
index fe15e71a3efd69e2fbb560bb1c1cf12fef3c6c3c..0094ba1b7468bfca252f68d5df65559efac6cc64 100644 (file)
--- a/src/cmd/compile/internal/ssa/rewritePPC64.go
+++ b/src/cmd/compile/internal/ssa/rewritePPC64.go
@@ -5191,12 +5191,16 @@ func rewriteValuePPC64_OpPPC64FNEG(v *Value) bool {
 func rewriteValuePPC64_OpPPC64FSQRT(v *Value) bool {
        v_0 := v.Args[0]
        // match: (FSQRT (FMOVDconst [x]))
+       // cond: auxTo64F(x) >= 0
        // result: (FMOVDconst [auxFrom64F(math.Sqrt(auxTo64F(x)))])
        for {
                if v_0.Op != OpPPC64FMOVDconst {
                        break
                }
                x := v_0.AuxInt
+               if !(auxTo64F(x) >= 0) {
+                       break
+               }
                v.reset(OpPPC64FMOVDconst)
                v.AuxInt = auxFrom64F(math.Sqrt(auxTo64F(x)))
                return true

diff --git a/src/cmd/compile/internal/ssa/rewriteWasm.go b/src/cmd/compile/internal/ssa/rewriteWasm.go
index 2c7add49969ced2410efefb86bc0d32598aad3c1..be1b51e7aa794ba3b344e20ae2b3f5236b61b402 100644 (file)
--- a/src/cmd/compile/internal/ssa/rewriteWasm.go
+++ b/src/cmd/compile/internal/ssa/rewriteWasm.go
@@ -3,6 +3,7 @@
 
 package ssa
 
+import "math"
 import "cmd/internal/objabi"
 import "cmd/compile/internal/types"
 
@@ -3467,6 +3468,7 @@ func rewriteValueWasm_OpWasmF64Add(v *Value) bool {
                return true
        }
        // match: (F64Add (F64Const [x]) y)
+       // cond: y.Op != OpWasmF64Const
        // result: (F64Add y (F64Const [x]))
        for {
                if v_0.Op != OpWasmF64Const {
@@ -3474,6 +3476,9 @@ func rewriteValueWasm_OpWasmF64Add(v *Value) bool {
                }
                x := v_0.AuxInt
                y := v_1
+               if !(y.Op != OpWasmF64Const) {
+                       break
+               }
                v.reset(OpWasmF64Add)
                v0 := b.NewValue0(v.Pos, OpWasmF64Const, typ.Float64)
                v0.AuxInt = x
@@ -3488,6 +3493,7 @@ func rewriteValueWasm_OpWasmF64Mul(v *Value) bool {
        b := v.Block
        typ := &b.Func.Config.Types
        // match: (F64Mul (F64Const [x]) (F64Const [y]))
+       // cond: !math.IsNaN(auxTo64F(x) * auxTo64F(y))
        // result: (F64Const [auxFrom64F(auxTo64F(x) * auxTo64F(y))])
        for {
                if v_0.Op != OpWasmF64Const {
@@ -3498,11 +3504,15 @@ func rewriteValueWasm_OpWasmF64Mul(v *Value) bool {
                        break
                }
                y := v_1.AuxInt
+               if !(!math.IsNaN(auxTo64F(x) * auxTo64F(y))) {
+                       break
+               }
                v.reset(OpWasmF64Const)
                v.AuxInt = auxFrom64F(auxTo64F(x) * auxTo64F(y))
                return true
        }
        // match: (F64Mul (F64Const [x]) y)
+       // cond: y.Op != OpWasmF64Const
        // result: (F64Mul y (F64Const [x]))
        for {
                if v_0.Op != OpWasmF64Const {
@@ -3510,6 +3520,9 @@ func rewriteValueWasm_OpWasmF64Mul(v *Value) bool {
                }
                x := v_0.AuxInt
                y := v_1
+               if !(y.Op != OpWasmF64Const) {
+                       break
+               }
                v.reset(OpWasmF64Mul)
                v0 := b.NewValue0(v.Pos, OpWasmF64Const, typ.Float64)
                v0.AuxInt = x
@@ -3539,6 +3552,7 @@ func rewriteValueWasm_OpWasmI64Add(v *Value) bool {
                return true
        }
        // match: (I64Add (I64Const [x]) y)
+       // cond: y.Op != OpWasmI64Const
        // result: (I64Add y (I64Const [x]))
        for {
                if v_0.Op != OpWasmI64Const {
@@ -3546,6 +3560,9 @@ func rewriteValueWasm_OpWasmI64Add(v *Value) bool {
                }
                x := v_0.AuxInt
                y := v_1
+               if !(y.Op != OpWasmI64Const) {
+                       break
+               }
                v.reset(OpWasmI64Add)
                v0 := b.NewValue0(v.Pos, OpWasmI64Const, typ.Int64)
                v0.AuxInt = x
@@ -3622,6 +3639,7 @@ func rewriteValueWasm_OpWasmI64And(v *Value) bool {
                return true
        }
        // match: (I64And (I64Const [x]) y)
+       // cond: y.Op != OpWasmI64Const
        // result: (I64And y (I64Const [x]))
        for {
                if v_0.Op != OpWasmI64Const {
@@ -3629,6 +3647,9 @@ func rewriteValueWasm_OpWasmI64And(v *Value) bool {
                }
                x := v_0.AuxInt
                y := v_1
+               if !(y.Op != OpWasmI64Const) {
+                       break
+               }
                v.reset(OpWasmI64And)
                v0 := b.NewValue0(v.Pos, OpWasmI64Const, typ.Int64)
                v0.AuxInt = x
@@ -3681,6 +3702,7 @@ func rewriteValueWasm_OpWasmI64Eq(v *Value) bool {
                return true
        }
        // match: (I64Eq (I64Const [x]) y)
+       // cond: y.Op != OpWasmI64Const
        // result: (I64Eq y (I64Const [x]))
        for {
                if v_0.Op != OpWasmI64Const {
@@ -3688,6 +3710,9 @@ func rewriteValueWasm_OpWasmI64Eq(v *Value) bool {
                }
                x := v_0.AuxInt
                y := v_1
+               if !(y.Op != OpWasmI64Const) {
+                       break
+               }
                v.reset(OpWasmI64Eq)
                v0 := b.NewValue0(v.Pos, OpWasmI64Const, typ.Int64)
                v0.AuxInt = x
@@ -3993,6 +4018,7 @@ func rewriteValueWasm_OpWasmI64Mul(v *Value) bool {
                return true
        }
        // match: (I64Mul (I64Const [x]) y)
+       // cond: y.Op != OpWasmI64Const
        // result: (I64Mul y (I64Const [x]))
        for {
                if v_0.Op != OpWasmI64Const {
@@ -4000,6 +4026,9 @@ func rewriteValueWasm_OpWasmI64Mul(v *Value) bool {
                }
                x := v_0.AuxInt
                y := v_1
+               if !(y.Op != OpWasmI64Const) {
+                       break
+               }
                v.reset(OpWasmI64Mul)
                v0 := b.NewValue0(v.Pos, OpWasmI64Const, typ.Int64)
                v0.AuxInt = x
@@ -4052,6 +4081,7 @@ func rewriteValueWasm_OpWasmI64Ne(v *Value) bool {
                return true
        }
        // match: (I64Ne (I64Const [x]) y)
+       // cond: y.Op != OpWasmI64Const
        // result: (I64Ne y (I64Const [x]))
        for {
                if v_0.Op != OpWasmI64Const {
@@ -4059,6 +4089,9 @@ func rewriteValueWasm_OpWasmI64Ne(v *Value) bool {
                }
                x := v_0.AuxInt
                y := v_1
+               if !(y.Op != OpWasmI64Const) {
+                       break
+               }
                v.reset(OpWasmI64Ne)
                v0 := b.NewValue0(v.Pos, OpWasmI64Const, typ.Int64)
                v0.AuxInt = x
@@ -4101,6 +4134,7 @@ func rewriteValueWasm_OpWasmI64Or(v *Value) bool {
                return true
        }
        // match: (I64Or (I64Const [x]) y)
+       // cond: y.Op != OpWasmI64Const
        // result: (I64Or y (I64Const [x]))
        for {
                if v_0.Op != OpWasmI64Const {
@@ -4108,6 +4142,9 @@ func rewriteValueWasm_OpWasmI64Or(v *Value) bool {
                }
                x := v_0.AuxInt
                y := v_1
+               if !(y.Op != OpWasmI64Const) {
+                       break
+               }
                v.reset(OpWasmI64Or)
                v0 := b.NewValue0(v.Pos, OpWasmI64Const, typ.Int64)
                v0.AuxInt = x
@@ -4301,6 +4338,7 @@ func rewriteValueWasm_OpWasmI64Xor(v *Value) bool {
                return true
        }
        // match: (I64Xor (I64Const [x]) y)
+       // cond: y.Op != OpWasmI64Const
        // result: (I64Xor y (I64Const [x]))
        for {
                if v_0.Op != OpWasmI64Const {
@@ -4308,6 +4346,9 @@ func rewriteValueWasm_OpWasmI64Xor(v *Value) bool {
                }
                x := v_0.AuxInt
                y := v_1
+               if !(y.Op != OpWasmI64Const) {
+                       break
+               }
                v.reset(OpWasmI64Xor)
                v0 := b.NewValue0(v.Pos, OpWasmI64Const, typ.Int64)
                v0.AuxInt = x

diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go
index 9e743838ab961f803ce6a6120a7acf8ee4358bad..13873b2ac86b9d781da5190b396bcaf4e913f143 100644 (file)
--- a/src/cmd/compile/internal/ssa/rewritegeneric.go
+++ b/src/cmd/compile/internal/ssa/rewritegeneric.go
@@ -4734,6 +4734,7 @@ func rewriteValuegeneric_OpDiv32F(v *Value) bool {
        v_0 := v.Args[0]
        b := v.Block
        // match: (Div32F (Const32F [c]) (Const32F [d]))
+       // cond: !math.IsNaN(float64(auxTo32F(c) / auxTo32F(d)))
        // result: (Const32F [auxFrom32F(auxTo32F(c) / auxTo32F(d))])
        for {
                if v_0.Op != OpConst32F {
@@ -4744,6 +4745,9 @@ func rewriteValuegeneric_OpDiv32F(v *Value) bool {
                        break
                }
                d := v_1.AuxInt
+               if !(!math.IsNaN(float64(auxTo32F(c) / auxTo32F(d)))) {
+                       break
+               }
                v.reset(OpConst32F)
                v.AuxInt = auxFrom32F(auxTo32F(c) / auxTo32F(d))
                return true
@@ -5171,6 +5175,7 @@ func rewriteValuegeneric_OpDiv64F(v *Value) bool {
        v_0 := v.Args[0]
        b := v.Block
        // match: (Div64F (Const64F [c]) (Const64F [d]))
+       // cond: !math.IsNaN(auxTo64F(c) / auxTo64F(d))
        // result: (Const64F [auxFrom64F(auxTo64F(c) / auxTo64F(d))])
        for {
                if v_0.Op != OpConst64F {
@@ -5181,6 +5186,9 @@ func rewriteValuegeneric_OpDiv64F(v *Value) bool {
                        break
                }
                d := v_1.AuxInt
+               if !(!math.IsNaN(auxTo64F(c) / auxTo64F(d))) {
+                       break
+               }
                v.reset(OpConst64F)
                v.AuxInt = auxFrom64F(auxTo64F(c) / auxTo64F(d))
                return true
@@ -10240,7 +10248,7 @@ func rewriteValuegeneric_OpLoad(v *Value) bool {
                return true
        }
        // match: (Load <t1> p1 (Store {t2} p2 (Const64 [x]) _))
-       // cond: isSamePtr(p1,p2) && sizeof(t2) == 8 && is64BitFloat(t1)
+       // cond: isSamePtr(p1,p2) && sizeof(t2) == 8 && is64BitFloat(t1) && !math.IsNaN(math.Float64frombits(uint64(x)))
        // result: (Const64F [x])
        for {
                t1 := v.Type
@@ -10256,7 +10264,7 @@ func rewriteValuegeneric_OpLoad(v *Value) bool {
                        break
                }
                x := v_1_1.AuxInt
-               if !(isSamePtr(p1, p2) && sizeof(t2) == 8 && is64BitFloat(t1)) {
+               if !(isSamePtr(p1, p2) && sizeof(t2) == 8 && is64BitFloat(t1) && !math.IsNaN(math.Float64frombits(uint64(x)))) {
                        break
                }
                v.reset(OpConst64F)
@@ -10264,7 +10272,7 @@ func rewriteValuegeneric_OpLoad(v *Value) bool {
                return true
        }
        // match: (Load <t1> p1 (Store {t2} p2 (Const32 [x]) _))
-       // cond: isSamePtr(p1,p2) && sizeof(t2) == 4 && is32BitFloat(t1)
+       // cond: isSamePtr(p1,p2) && sizeof(t2) == 4 && is32BitFloat(t1) && !math.IsNaN(float64(math.Float32frombits(uint32(x))))
        // result: (Const32F [auxFrom32F(math.Float32frombits(uint32(x)))])
        for {
                t1 := v.Type
@@ -10280,7 +10288,7 @@ func rewriteValuegeneric_OpLoad(v *Value) bool {
                        break
                }
                x := v_1_1.AuxInt
-               if !(isSamePtr(p1, p2) && sizeof(t2) == 4 && is32BitFloat(t1)) {
+               if !(isSamePtr(p1, p2) && sizeof(t2) == 4 && is32BitFloat(t1) && !math.IsNaN(float64(math.Float32frombits(uint32(x))))) {
                        break
                }
                v.reset(OpConst32F)
@@ -13970,6 +13978,7 @@ func rewriteValuegeneric_OpMul32F(v *Value) bool {
        v_1 := v.Args[1]
        v_0 := v.Args[0]
        // match: (Mul32F (Const32F [c]) (Const32F [d]))
+       // cond: !math.IsNaN(float64(auxTo32F(c) * auxTo32F(d)))
        // result: (Const32F [auxFrom32F(auxTo32F(c) * auxTo32F(d))])
        for {
                for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
@@ -13981,6 +13990,9 @@ func rewriteValuegeneric_OpMul32F(v *Value) bool {
                                continue
                        }
                        d := v_1.AuxInt
+                       if !(!math.IsNaN(float64(auxTo32F(c) * auxTo32F(d)))) {
+                               continue
+                       }
                        v.reset(OpConst32F)
                        v.AuxInt = auxFrom32F(auxTo32F(c) * auxTo32F(d))
                        return true
@@ -14210,6 +14222,7 @@ func rewriteValuegeneric_OpMul64F(v *Value) bool {
        v_1 := v.Args[1]
        v_0 := v.Args[0]
        // match: (Mul64F (Const64F [c]) (Const64F [d]))
+       // cond: !math.IsNaN(auxTo64F(c) * auxTo64F(d))
        // result: (Const64F [auxFrom64F(auxTo64F(c) * auxTo64F(d))])
        for {
                for _i0 := 0; _i0 <= 1; _i0, v_0, v_1 = _i0+1, v_1, v_0 {
@@ -14221,6 +14234,9 @@ func rewriteValuegeneric_OpMul64F(v *Value) bool {
                                continue
                        }
                        d := v_1.AuxInt
+                       if !(!math.IsNaN(auxTo64F(c) * auxTo64F(d))) {
+                               continue
+                       }
                        v.reset(OpConst64F)
                        v.AuxInt = auxFrom64F(auxTo64F(c) * auxTo64F(d))
                        return true
@@ -20966,12 +20982,16 @@ func rewriteValuegeneric_OpSlicemask(v *Value) bool {
 func rewriteValuegeneric_OpSqrt(v *Value) bool {
        v_0 := v.Args[0]
        // match: (Sqrt (Const64F [c]))
+       // cond: !math.IsNaN(math.Sqrt(auxTo64F(c)))
        // result: (Const64F [auxFrom64F(math.Sqrt(auxTo64F(c)))])
        for {
                if v_0.Op != OpConst64F {
                        break
                }
                c := v_0.AuxInt
+               if !(!math.IsNaN(math.Sqrt(auxTo64F(c)))) {
+                       break
+               }
                v.reset(OpConst64F)
                v.AuxInt = auxFrom64F(math.Sqrt(auxTo64F(c)))
                return true

diff --git a/test/codegen/math.go b/test/codegen/math.go
index 80e5d60d963a080bc7706d2035412d27482a6387..1ebfda04052fc8b83703e3756f79121eabee42eb 100644 (file)
--- a/test/codegen/math.go
+++ b/test/codegen/math.go
@@ -151,13 +151,13 @@ func toFloat32(u32 uint32) float32 {
 func constantCheck64() bool {
        // amd64:"MOVB\t[$]0",-"FCMP",-"MOVB\t[$]1"
        // s390x:"MOV(B|BZ|D)\t[$]0,",-"FCMPU",-"MOV(B|BZ|D)\t[$]1,"
-       return 0.5 == float64(uint32(1)) || 1.5 > float64(uint64(1<<63)) || math.NaN() == math.NaN()
+       return 0.5 == float64(uint32(1)) || 1.5 > float64(uint64(1<<63))
 }
 
 func constantCheck32() bool {
        // amd64:"MOVB\t[$]1",-"FCMP",-"MOVB\t[$]0"
        // s390x:"MOV(B|BZ|D)\t[$]1,",-"FCMPU",-"MOV(B|BZ|D)\t[$]0,"
-       return float32(0.5) <= float32(int64(1)) && float32(1.5) >= float32(int32(-1<<31)) && float32(math.NaN()) != float32(math.NaN())
+       return float32(0.5) <= float32(int64(1)) && float32(1.5) >= float32(int32(-1<<31))
 }
 
 // Test that integer constants are converted to floating point constants
@@ -186,3 +186,32 @@ func constantConvertInt32(x uint32) uint32 {
        }
        return x
 }
+
+func nanGenerate64() float64 {
+       // Test to make sure we don't generate a NaN while constant propagating.
+       // See issue 36400.
+       zero := 0.0
+       // amd64:-"DIVSD"
+       inf := 1 / zero // +inf. We can constant propagate this one.
+       negone := -1.0
+
+       // amd64:"DIVSD"
+       z0 := zero / zero
+       // amd64:"MULSD"
+       z1 := zero * inf
+       // amd64:"SQRTSD"
+       z2 := math.Sqrt(negone)
+       return z0 + z1 + z2
+}
+
+func nanGenerate32() float32 {
+       zero := float32(0.0)
+       // amd64:-"DIVSS"
+       inf := 1 / zero // +inf. We can constant propagate this one.
+
+       // amd64:"DIVSS"
+       z0 := zero / zero
+       // amd64:"MULSS"
+       z1 := zero * inf
+       return z0 + z1
+}