math: fix ./v -prod -cstrict -cc gcc-11 vlib/math/math_bench_test.v (use unions to implement f64_bits/1 and f64_from_bits/1 for compilers != tcc)

spytheman · spytheman · commit e66e9960d35e · 2025-03-08T12:28:25.000+02:00
diff --git a/vlib/math/math_bench_test.v b/vlib/math/math_bench_test.v
@@ -3,7 +3,7 @@ module main
 import math
 import benchmark
 
-const max_iter = 1000
+const max_iter = 100_000
 
 fn test_benchmark_acos() {
 	mut x := 0.0
diff --git a/vlib/math/unsafe.v b/vlib/math/unsafe.v
@@ -3,13 +3,24 @@
 // that can be found in the LICENSE file.
 module math
 
+union U32_F32 {
+	u u32
+	f f32
+}
+
 // f32_bits returns the IEEE 754 binary representation of f,
 // with the sign bit of f and the result in the same bit position.
 // f32_bits(f32_from_bits(x)) == x.
 @[inline]
 pub fn f32_bits(f f32) u32 {
-	p := *unsafe { &u32(&f) }
-	return p
+	$if tinyc {
+		return *unsafe { &u32(&f) } // this is faster for tcc, but causes `error: dereferencing type-punned pointer will break strict-aliasing rules` on gcc, with -cstrict
+	}
+	return unsafe {
+		U32_F32{
+			f: f
+		}.u
+	}
 }
 
 // f32_from_bits returns the floating-point number corresponding
@@ -18,17 +29,34 @@ pub fn f32_bits(f f32) u32 {
 // f32_from_bits(f32_bits(x)) == x.
 @[inline]
 pub fn f32_from_bits(b u32) f32 {
-	p := *unsafe { &f32(&b) }
-	return p
+	$if tinyc {
+		return *unsafe { &f32(&b) }
+	}
+	return unsafe {
+		U32_F32{
+			u: b
+		}.f
+	}
+}
+
+union U64_F64 {
+	u u64
+	f f64
 }
 
 // f64_bits returns the IEEE 754 binary representation of f,
 // with the sign bit of f and the result in the same bit position,
 // and f64_bits(f64_from_bits(x)) == x.
 @[inline]
 pub fn f64_bits(f f64) u64 {
-	p := *unsafe { &u64(&f) }
-	return p
+	$if tinyc {
+		return *unsafe { &u64(&f) }
+	}
+	return unsafe {
+		U64_F64{
+			f: f
+		}.u
+	}
 }
 
 // f64_from_bits returns the floating-point number corresponding
@@ -37,8 +65,14 @@ pub fn f64_bits(f f64) u64 {
 // f64_from_bits(f64_bits(x)) == x.
 @[inline]
 pub fn f64_from_bits(b u64) f64 {
-	p := *unsafe { &f64(&b) }
-	return p
+	$if tinyc {
+		return *unsafe { &f64(&b) }
+	}
+	return unsafe {
+		U64_F64{
+			u: b
+		}.f
+	}
 }
 
 // with_set_low_word sets low word of `f` to `lo`
