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cbe: add doNotOptimizeAwayC to handle not having __asm support in msvc

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This commit is contained in:
kcbanner 2022-12-13 21:58:03 -05:00
parent b86a8b4a5b
commit 9a77743cc7
1 changed files with 23 additions and 7 deletions
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30
lib/std/mem.zig
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@ -3771,7 +3771,7 @@ pub fn doNotOptimizeAway(val: anytype) void {
.Bool => doNotOptimizeAway(@boolToInt(val)),
.Int => {
const bits = t.Int.bits;
if (bits <= max_gp_register_bits) {
if (bits <= max_gp_register_bits and builtin.zig_backend != .stage2_c) {
const val2 = @as(
std.meta.Int(t.Int.signedness, @max(8, std.math.ceilPowerOfTwoAssert(u16, bits))),
val,
@ -3783,18 +3783,24 @@ pub fn doNotOptimizeAway(val: anytype) void {
} else doNotOptimizeAway(&val);
},
.Float => {
if (t.Float.bits == 32 or t.Float.bits == 64) {
if ((t.Float.bits == 32 or t.Float.bits == 64) and builtin.zig_backend != .stage2_c) {
asm volatile (""
:
: [val] "rm" (val),
);
} else doNotOptimizeAway(&val);
},
.Pointer => asm volatile (""
:
: [val] "m" (val),
: "memory"
),
.Pointer => {
if (builtin.zig_backend == .stage2_c) {
doNotOptimizeAwayC(val);
} else {
asm volatile (""
:
: [val] "m" (val),
: "memory"
);
}
},
.Array => {
if (t.Array.len * @sizeOf(t.Array.child) <= 64) {
for (val) |v| doNotOptimizeAway(v);
@ -3804,6 +3810,16 @@ pub fn doNotOptimizeAway(val: anytype) void {
}
}
/// .stage2_c doesn't support asm blocks yet, so use volatile stores instead
var deopt_target: if (builtin.zig_backend == .stage2_c) u8 else void = undefined;
fn doNotOptimizeAwayC(ptr: anytype) void {
const dest = @ptrCast(*volatile u8, &deopt_target);
for (asBytes(ptr)) |b| {
dest.* = b;
}
dest.* = 0;
}
test "doNotOptimizeAway" {
comptime doNotOptimizeAway("test");