cmd/compile, runtime: always enable Wasm signext and satconv features

These features have been standardized since at least Wasm 2.0.
Always enable them.

The corresponding GOWASM settings are now no-op.

Change-Id: I0e59f21696a69a4e289127988aad629a720b002b
Reviewed-on: https://go-review.googlesource.com/c/go/+/707855
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>

2 files changed, 24 insertions, 79 deletions

diff --git a/src/runtime/conv_wasm_test.go b/src/runtime/conv_wasm_test.go
index 5054fca04d..3979a7b618 100644
--- a/src/runtime/conv_wasm_test.go
+++ b/src/runtime/conv_wasm_test.go
@@ -11,6 +11,8 @@ import (
 var res int64
 var ures uint64
 
+// TODO: This test probably should be in a different place.
+
 func TestFloatTruncation(t *testing.T) {
 	testdata := []struct {
 		input      float64
@@ -21,36 +23,37 @@ func TestFloatTruncation(t *testing.T) {
 		// max +- 1
 		{
 			input:      0x7fffffffffffffff,
-			convInt64:  -0x8000000000000000,
+			convInt64:  0x7fffffffffffffff,
 			convUInt64: 0x8000000000000000,
 		},
 		// For out-of-bounds conversion, the result is implementation-dependent.
-		// This test verifies the implementation of wasm architecture.
+		// This test verifies the implementation of wasm architecture, which is,
+		// saturating to the min/max value.
 		{
 			input:      0x8000000000000000,
-			convInt64:  -0x8000000000000000,
+			convInt64:  0x7fffffffffffffff,
 			convUInt64: 0x8000000000000000,
 		},
 		{
 			input:      0x7ffffffffffffffe,
-			convInt64:  -0x8000000000000000,
+			convInt64:  0x7fffffffffffffff,
 			convUInt64: 0x8000000000000000,
 		},
 		// neg max +- 1
 		{
 			input:      -0x8000000000000000,
 			convInt64:  -0x8000000000000000,
-			convUInt64: 0x8000000000000000,
+			convUInt64: 0,
 		},
 		{
 			input:      -0x8000000000000001,
 			convInt64:  -0x8000000000000000,
-			convUInt64: 0x8000000000000000,
+			convUInt64: 0,
 		},
 		{
 			input:      -0x7fffffffffffffff,
 			convInt64:  -0x8000000000000000,
-			convUInt64: 0x8000000000000000,
+			convUInt64: 0,
 		},
 		// trunc point +- 1
 		{
@@ -60,7 +63,7 @@ func TestFloatTruncation(t *testing.T) {
 		},
 		{
 			input:      0x7ffffffffffffe00,
-			convInt64:  -0x8000000000000000,
+			convInt64:  0x7fffffffffffffff,
 			convUInt64: 0x8000000000000000,
 		},
 		{
@@ -72,48 +75,48 @@ func TestFloatTruncation(t *testing.T) {
 		{
 			input:      -0x7ffffffffffffdff,
 			convInt64:  -0x7ffffffffffffc00,
-			convUInt64: 0x8000000000000000,
+			convUInt64: 0,
 		},
 		{
 			input:      -0x7ffffffffffffe00,
 			convInt64:  -0x8000000000000000,
-			convUInt64: 0x8000000000000000,
+			convUInt64: 0,
 		},
 		{
 			input:      -0x7ffffffffffffdfe,
 			convInt64:  -0x7ffffffffffffc00,
-			convUInt64: 0x8000000000000000,
+			convUInt64: 0,
 		},
 		// umax +- 1
 		{
 			input:      0xffffffffffffffff,
-			convInt64:  -0x8000000000000000,
-			convUInt64: 0x8000000000000000,
+			convInt64:  0x7fffffffffffffff,
+			convUInt64: 0xffffffffffffffff,
 		},
 		{
 			input:      0x10000000000000000,
-			convInt64:  -0x8000000000000000,
-			convUInt64: 0x8000000000000000,
+			convInt64:  0x7fffffffffffffff,
+			convUInt64: 0xffffffffffffffff,
 		},
 		{
 			input:      0xfffffffffffffffe,
-			convInt64:  -0x8000000000000000,
-			convUInt64: 0x8000000000000000,
+			convInt64:  0x7fffffffffffffff,
+			convUInt64: 0xffffffffffffffff,
 		},
 		// umax trunc +- 1
 		{
 			input:      0xfffffffffffffbff,
-			convInt64:  -0x8000000000000000,
+			convInt64:  0x7fffffffffffffff,
 			convUInt64: 0xfffffffffffff800,
 		},
 		{
 			input:      0xfffffffffffffc00,
-			convInt64:  -0x8000000000000000,
-			convUInt64: 0x8000000000000000,
+			convInt64:  0x7fffffffffffffff,
+			convUInt64: 0xffffffffffffffff,
 		},
 		{
 			input:      0xfffffffffffffbfe,
-			convInt64:  -0x8000000000000000,
+			convInt64:  0x7fffffffffffffff,
 			convUInt64: 0xfffffffffffff800,
 		},
 	}
diff --git a/src/runtime/sys_wasm.s b/src/runtime/sys_wasm.s
index b7965ec3fa..95c162eb85 100644
--- a/src/runtime/sys_wasm.s
+++ b/src/runtime/sys_wasm.s
@@ -22,64 +22,6 @@ TEXT runtime·wasmDiv(SB), NOSPLIT, $0-0
 	I64DivS
 	Return
 
-TEXT runtime·wasmTruncS(SB), NOSPLIT, $0-0
-	Get R0
-	Get R0
-	F64Ne // NaN
-	If
-		I64Const $0x8000000000000000
-		Return
-	End
-
-	Get R0
-	F64Const $0x7ffffffffffffc00p0 // Maximum truncated representation of 0x7fffffffffffffff
-	F64Gt
-	If
-		I64Const $0x8000000000000000
-		Return
-	End
-
-	Get R0
-	F64Const $-0x7ffffffffffffc00p0 // Minimum truncated representation of -0x8000000000000000
-	F64Lt
-	If
-		I64Const $0x8000000000000000
-		Return
-	End
-
-	Get R0
-	I64TruncF64S
-	Return
-
-TEXT runtime·wasmTruncU(SB), NOSPLIT, $0-0
-	Get R0
-	Get R0
-	F64Ne // NaN
-	If
-		I64Const $0x8000000000000000
-		Return
-	End
-
-	Get R0
-	F64Const $0xfffffffffffff800p0 // Maximum truncated representation of 0xffffffffffffffff
-	F64Gt
-	If
-		I64Const $0x8000000000000000
-		Return
-	End
-
-	Get R0
-	F64Const $0.
-	F64Lt
-	If
-		I64Const $0x8000000000000000
-		Return
-	End
-
-	Get R0
-	I64TruncF64U
-	Return
-
 TEXT runtime·exitThread(SB), NOSPLIT, $0-0
 	UNDEF